Towards a radiologic definition of idiopathic megacolon

Clinical features and outcomes of adult idiopathic megarectum

OBJECTIVE

Idiopathic megarectum is characterized by abnormal, pronounced rectal dilatation in the absence of identifiable organic pathology. Idiopathic megarectum is uncommon and under-recognized. This study aims to describe the clinical features and management of idiopathic megarectum.

METHODS

A retrospective review was undertaken on patients diagnosed with idiopathic megarectum with or without idiopathic megacolon over a 14-year period until 2021. Patients were identified from the hospital's International Classification of Diseases codes, and pre-existing clinic patient databases. Patient demographics, disease characteristics, healthcare utilization and treatment history data were collected.

RESULTS

Eight patients with idiopathic megarectum were identified; half of the patients were female, with the median age of symptom onset being 14 years (interquartile range [IQR] 9-24). The median rectal diameter measured was 11.5 cm (IQR 9.4-12.1). The most common presenting symptom was constipation, bloating and faecal incontinence. All patients required prior sustained periods of regular phosphate enemas and 88% were using ongoing oral aperients. Concomitant anxiety and or depression were found in 63% of patients and 25% were diagnosed with an intellectual disability. Healthcare utilization was high with a median of three emergency department presentations or ward admissions related to idiopathic megarectum per patient over the follow-up period; 38% of patients required surgical intervention during the period of follow-up.

CONCLUSION

Idiopathic megarectum is uncommon and associated with significant physical and psychiatric morbidity and high healthcare utilization.

Evaluating the effectiveness of probiotics in relieving constipation in Parkinson's disease: A systematic review and meta-analysis

Objectives

The aim of this study was to evaluate the effects of probiotics on the treatment of constipation in patients with Parkinson's disease (PD) by analyzing data from published randomized clinical trials (RCTs). PD is a neurodegenerative disease characterized by clinical symptoms such as rigidity, bradykinesia, and resting tremor. Constipation is a common complaint reported by PD patients. Probiotics are often used to treat functional constipation. The potential mechanisms behind PD-related constipation include dysfunction of the enteric nervous system due to alpha-synuclein aggregation, dyssynergic contractions of the puborectalis muscle, and alterations of the gut microbiome.

Method

To conduct this study, we searched Scopus, PubMed, and Google Scholar for published articles on PD, probiotics, and constipation. We selected RCTs from 944 studies, and ultimately included 3 RCTs in our meta-analysis. The frequency of bowel movements per week was the only index that could be summarized among the records. We extracted and analyzed the results as means and standard deviations.

Result

We calculated a standardized mean difference (SMD) of 0.92 (95% CI, 0.65 to 1.19; I-squared = 57.0%; p < 0.001) to determine the treatment effect in terms of frequency of bowel movements per week in the RCTs.

Conclusion

Our results show that probiotic intake has beneficial effects on constipation in PD patients. Further research, including multicenter studies, is needed to assess the long-term efficacy and safety of probiotic supplements in neurodegenerative diseases.

Treatment of megarectum in anorectal malformation with emphasis on preventive aspects: 17 years experience

PURPOSE

Megarectum in anorectal malformation (ARM) causes severe morbidity. To compare conservative management (CM) of megarectum with excision (EX), to propose a new classification and to analyse management strategies.

METHODS

Between 2000-2016, we reviewed all ARM to identify megarectum, defined by radiological recto-pelvic ratio > 0.61. A new classification was proposed: primary megarectum (PM) pre-anorectoplasty, and secondary megarectum (SM) post-anorectoplasty, with sub-types. Complications and Krickenbeck bowel function were compared between CM and EX.

RESULTS

Of 124 ARM, 22 (18%) developed megarectum; of these, 7 underwent EX. There was no difference in functional outcomes when comparing CM vs EX-voluntary bowel movement (both 86%), soiling (40% vs. 57%) and constipation (both 86%). However, EX was associated with major complications (43%) and the requirement for invasive bowel management, compared to CM (85% vs. 27%, P = 0.02). 6/7 EX needed antegrade continence enema (ACE), one of these has a permanent ileostomy. With strategic changes, incidence of megarectum reduced from 20/77 (26%) to 2/47 (4%) after 2013 (P = 0.002).

CONCLUSION

EX did not confer benefit in the functional outcome but carried a high risk of complications, often needing ACE or stoma. By adhering to strategies discussed, we reduced the incidence of megarectum and have avoided EX since 2013.

The Birth, Death, and Renaissance (?) of Dissection: A Critique of Anatomy Teaching With-or Without-the Human Body

A riveting debate regarding the fate of dissection, the classical method of anatomy, is sweeping through medical academia, as imaging tools gain a greater foothold in anatomy teaching programs. This Perspective does not aim to grapple with the question of "how should anatomy be taught" but rather to explain why the transformation of anatomical education is taking place by situating these developments in the broader philosophical context of modern medicine, offered by Michel Foucault's The Birth of the Clinic: An Archaeology of Medical Perception. Emphasizing the body's crucial role in the epistemological change in medical practice in the early 19th century, Foucault coined the term "medical gaze" to denote the doctor's observation of the patient's body in search of signs of disease. Within this new systematic perception of disease, which brought about the anatomo-clinical method, the clinical gaze thus embraced the study of the body via dissection. The author contends that the introduction of medical imaging into the diagnostic process has resulted in a shift in the focus of the clinical gaze from the body to its medical image and that this process is mirrored in anatomy by its discarding of the cadaver. Given the fundamental differences between the phenomenology of the body and its medical image, the author suggests that when using medical images in medical schools and teaching hospitals, one teaches, at the very least, a new kind of anatomy. Foucault's analysis of the painting The Treachery of Images by Réne Magritte lends some support to the ideas presented here.

An unusual cause of idiopathic megacolon in a juvenile: A case report

RATIONALE

Idiopathic megacolon (IMC) is a rare condition in young children. The association of indigestible food and IMC has never been mentioned in literature.

PATIENT CONCERNS

An 11-year-old boy reported with a 1-year duration of intermittent constipation and abdominal distension after having eaten a large amount of fried sticky rice in 1 consumption.

DIAGNOSES

Chronic low colonic obstruction, IMC and malnutrition.

INTERVENTIONS

This patient was managed conservatively for 1 week at first. Then he underwent loop ileostomy since conservative therapy was poorly tolerated. Enteral decompression, gut biopsy, peritoneal lavage, and drainage were performed in the same procedure.

OUTCOMES

Rapid weight gain was observed 4 months after operation.

LESSONS

IMC is difficult to diagnose due to the lack of specific clinical manifestations and pathological features. The protocols for management of IMC remains controversial. To achieve a good long-term outcome, early intervention is recommended.

Abdominal compartment syndrome secondary to megarectum and megasigmoid

A 31-year-old male patient with chronic constipation of unknown aetiology presented emergently with worsening nausea, vomiting and abdominal distension of one week duration. On examination, his abdomen was distended with minimal tenderness. A plain film of the abdomen demonstrated severe faecal loading. The patient was haemodynamically unstable on admission and appeared sick. An urgent CT abdomen and pelvis was conducted showing extensive rectal dilatation and associated proximal colonic stercoral perforation. The patient proceeded straight to theatre for laparotomy as his general condition was deteriorating rapidly. On transfer to the operating table, the patient suffered cardiopulmonary arrest. Resuscitation was immediately commenced. Abdominal compartment syndrome was suspected. Cardiac output was re-established following a midline laparotomy which acted relieve the abdominal pressure. The rectosigmoid faecal content was decompressed via an enterotomy. The perforated segment of transverse colon was resected and an end colostomy fashioned. A year later, the continuity of the bowel was re-established.

Symptoms and diagnostic criteria of acquired Megacolon - a systematic literature review

BACKGROUND

Acquired Megacolon (AMC) is a condition involving persistent dilatation and lengthening of the colon in the absence of organic disease. Diagnosis depends on subjective radiological, endoscopic or surgical findings in the context of a suggestive clinical presentation. This review sets out to investigate diagnostic criteria of AMC.

METHODS

The literature was searched using the databases - PubMed, Medline via OvidSP, ClinicalKey, Informit and the Cochrane Library. Primary studies, published in English, with more than three patients were critically appraised based on study design, methodology and sample size. Exclusion criteria were studies with the following features: post-operative; megarectum-predominant; paediatric; organic megacolon; non-human; and failure to exclude organic causes.

RESULTS

A review of 23 articles found constipation, abdominal pain, distension and gas distress were predominant symptoms. All ages and both sexes were affected, however, symptoms varied with age. Changes in anorectal manometry, histology and colonic transit are consistently reported. Studies involved varying patient numbers, demographics and data acquisition methods.

CONCLUSIONS

Outcome data investigating the diagnosis of AMC must be interpreted in light of the limitations of the low-level evidence studies published to date. Proposed diagnostic criteria include: (1) the exclusion of organic disease; (2) a radiological sigmoid diameter of ~ 10 cm; (3) and constipation, distension, abdominal pain and/or gas distress. A proportion of patients with AMC may be currently misdiagnosed as having functional gastrointestinal disorders. Our conclusions are inevitably tentative, but will hopefully stimulate further research on this enigmatic condition.

Segmental colonic dilation is associated with premature termination of high-amplitude propagating contractions in children with intractable functional constipation

BACKGROUND

Colonic dilation is common in children with intractable functional constipation (FC). Our aim was to describe the association between segmental colonic dilation and colonic dysmotility in children with FC.

METHODS

We performed a retrospective study on 30 children with intractable FC (according to the Rome III criteria) who had undergone colonic manometry and contrast enema within a 12-month time period. Colonic diameter was measured at 5 cm intervals from the anal verge up to the splenic flexure. Moreover, the distance between the lateral margins of the pedicles of vertebra L2 was measured to provide a ratio (colonic diameter or length/distance between the lateral margins; "standardized colon size" [SCS]). All manometry recordings were visually inspected for the presence of high-amplitude propagating contractions (HAPCs); a parameter for colonic motility integrity. The intracolonic location of the manometry catheter sensors was assessed using an abdominal X-ray.

KEY RESULTS

Colonic segments with HAPCs had a significantly smaller median diameter than colonic segments without HAPCs (4.08 cm vs 5.48 cm, P<.001; SCS 1.14 vs 1.66, P=.001). Children with prematurely terminating HAPCs had significantly larger SCS ratios for colonic diameter than children with fully propagating HAPCs (P=.008). SCS ratios for the length of the rectosigmoid and the descending colon and the SCS ratio for sigmoid colon diameter were significantly larger in children with FC compared to a previously described normative population (P<.0001, P<.0001 and P=.0007 respectively).

CONCLUSIONS & INFERENCES

Segmental colonic dilation was associated with prematurely terminating HAPCs and may be a useful indicator of colonic dysmotility.

Evaluating the safety and the effects on colonic compliance of neostigmine during motility testing in patients with chronic constipation

BACKGROUND

Neostigmine, an acetyl cholinesterase inhibitor, stimulates colonic motor activity and may induce vagally mediated cardiovascular effects. Our aim was to evaluate effects of i.v. neostigmine on colonic compliance and its safety in patients with chronic constipation.

METHODS

We retrospectively reviewed medical records of a selected group of 144 outpatients with chronic constipation who were refractory to treatment. These patients had undergone intracolonic motility and compliance measurements with an infinitely compliant balloon linked to a barostat. Data abstracted included barostat balloon mean volumes with increases in pressure (4 mmHg steps from 0 to 44 mmHg) before and after i.v. neostigmine. Vital signs and oxygen saturation before and after neostigmine were recorded.

KEY RESULTS

Of the 144 patients, 133 were female, mean age was 41.0 ± 15.4 years (SD), and duration of constipation was 12.9 ± 13.8 years. Among patients who had undergone colonic transit measurement by scintigraphy, the overall colonic transit at 24 h (geometric center, GC24 [n = 115]) was 1.5 ± 0.7 (normal >1.3), and at 48 h (GC48 [n = 75]) it was 2.3 ± 0.9 (normal >1.9). Neostigmine decreased colonic compliance at lower distension pressures (e.g., 12 and 20 mmHg [both p < 0.001]), but not at 40 mmHg. There were expected minor changes in vital signs in response to neostigmine in 144 patients; however, one patient developed unresponsiveness, significant bradycardia, hypotension, and muscular rigidity that responded to 400 mcg i.v. atropine.

CONCLUSIONS & INFERENCES

Neostigmine significantly decreases colonic compliance in patients with refractory chronic constipation. Symptomatic bradycardia in response to neostigmine should be promptly reversed with atropine.

Clinical Features and Colonic Motor Disturbances in Chronic Megacolon in Adults

BACKGROUND

Chronic megacolon is a rare disease of the colonic motor function characterized by a permanent increase in colonic diameter.

METHODS

We reviewed electronic medical records of all patients diagnosed with chronic megacolon from 1999 to 2014 at Mayo Clinic. Our aim was to summarize clinical and motility features, including colonic compliance and tone measured by colonic barostat-controlled 10-cm-long infinitely compliant balloon. Colonic compliance curves were compared to healthy control (40) and disease (47) control groups.

RESULTS

Among 24 identified patients, the mean maximal colonic diameter on abdominal radiograph was 12.7 ± 0.8 cm. The cause of megacolon was idiopathic in 16 of 24 and secondary in 8 of 24. A relatively high prevalence (10/24) of comorbid pelvic floor dyssynergia was identified. At the time of this report, 16 patients had undergone colectomy. In general, megacolon presented high fasting colonic volume at relatively low pressures (16-20 mmHg), suggesting high colonic compliance; similarly, volumes at operating pressures that ensured apposition of the balloon to the colonic wall suggested low colonic tone. Median balloon volume at 44 mmHg distension was 584 mL (IQR 556.5-600) in patients with megacolon compared to 251 mL (212-281) in healthy, 240 mL (207-286) in functional constipation, and 241 mL (210.8-277.5) in diarrhea-predominant irritable bowel syndrome controls. Colon's tonic response to feeding was generally intact, and there was frequently maintained phasic contractile response to feeding.

CONCLUSIONS

Chronic megacolon is a severe colonic dysmotility, manifesting radiologically with increased colonic diameter; it can be proven by measuring colonic compliance and typically requires colectomy because of failed medical therapy.

Postoperative megarectum in an adult patient with imperforate anus and rectourethral fistula

This report presents a surgical case of postoperative megarectum in an adult patient with imperforate anus/anorectal malformations. A 71-year-old Japanese male presented with a mass in the lower abdomen which was 15 × 12 × 8 cm in diameter, edema in the right lower extremity, and frequent urination. He had undergone sigmoid loop colostomy for an imperforate anus as a newborn infant. At 28 years of age, the sigmoid loop colostomy was changed to sigmoid divided colostomy in the left lower abdomen. Computed tomography revealed a large cystic mass in the lower abdomen. Retrograde urethrography indicated a rectourethral fistula and megarectum with stones. A small laparotomy incision was created in the right lower abdomen, and the wall of the megarectum was identified. Approximately 2,300 mL of gray muddy fluid was identified and drained. A mucous fistula of the upper rectum was created in the right lower abdomen. This is an extremely rare case of postoperative megarectum in an adult patient with an imperforate anus and rectourethral fistula.

Megarectosigmoid in children with anorectal malformations: long term outcome after surgical or conservative treatment

PURPOSE

Megarectosigmoid (MRS) is commonly seen in children with anorectal malformations (ARM) and contributes to the high incidence of constipation. Surgical resection has been advocated by some, whereas others propose intense bowel management as the treatment of choice. The aim of this study was to evaluate outcome of both bowel function and configuration after surgical or conservative treatment of MRS in ARM patients.

MATERIALS AND METHODS

The study included 79 patients with ARM, excluding perineal fistula, (48 boys, 31 girls) from 1986 to 2007. MRS was diagnosed at colostomy formation or contrast enema performed in the neonatal period. Early in the period, the majority of the patients were treated surgically, whereas in the late 1990 s, a conservative approach with intensified bowel treatment was implemented. Contrast enema and bowel function investigations were performed repeatedly during follow-up.

RESULTS

MRS, according to radiological criteria, was diagnosed in 26/79 (33%) of the ARM children. Bowel functional outcome was similar regardless of surgical or conservative treatment and comparable to function in ARM children with non-MRS. The radiological signs of rectal dilatation and elongation disappeared after surgical intervention, but normalisation of the rectosigmoidal configuration was also seen with age in the conservative group.

CONCLUSIONS

Bowel functional outcome in ARM children with MRS was similar after either surgical or conservative treatment during follow-up. The radiological signs of rectal dilatation and elongation disappeared also in the conservatively treated patients over time.

Treatment of megacolon and megarectum

Patients presenting with megacolon and megarectum require extensive specialized testing to distinguish underlying Hirschsprung's disease from other secondary causes. Diagnostic testing and long-term treatment are best initiated after disimpaction has been achieved, by large-volume tap water enemas and/or oral colonic lavage with polyethylene glycol. With intensive treatment (including biofeedback if pelvic floor dysfunction is present), at lease one half of patients can avoid surgery. Maintenance therapy relies on daily use of osmotic laxatives. Stimulant laxatives are used intermittently as rescue treatments if there has not been a satisfactory bowel movement in 3 days. Patients with idiopathic megacolon or megarectum may require surgery if they have refractory symptoms. Depending on age, pelvic floor, and anal sphincter function, patients who have isolated megacolon can be treated with either subtotal colectomy with ileorectostomy or diverting loop ileostomy. Patients with isolated megarectum can be treated with either proctectomy and coloanal anastomosis or vertical reduction rectoplasty. Patients who have combined megacolon and megarectum can be offered diverting loop ileostomy or, if pelvic floor function is normal and they wish to avoid stoma, total proctocolectomy with ileal pouch-anal anastomosis.

Magnetic resonance imaging of rectal volume in patients with irritable bowel syndrome

BACKGROUND

Extreme stool forms (1 and 2, or 6 and 7 of the Bristol stool scale) are frequent in patients with irritable bowel syndrome and are associated with colonic transit, but it is not known whether these alterations influence rectal reservoir function.

AIMS

To investigate rectal reservoir function by assessing magnetic resonance imaging reconstructions of rectal volume in healthy subjects and patients with irritable bowel syndrome, and to establish whether it varies depending on the bowel habits of the patients.

METHODS

Twelve healthy subjects and 20 patients with irritable bowel syndrome (with constipation, diarrhoea, mixed or undefined bowel habit according to the Rome III criteria) underwent pelvic magnetic resonance imaging in the absence of rectal sensations. T2 sagittal images were used to calculate rectal volume by multiplying inter-slice thickness by rectal area, and summing the inter-slice volumes.

RESULTS

Stool form was significantly different in the irritable bowel syndrome patients with diarrhoea or constipation, and bowel movements were more frequent in the irritable bowel syndrome patients than in the healthy subjects. Rectal volume was significantly smaller in the irritable bowel syndrome patients (27 ± 13 mL vs. 44 ± 21 mL; P=0.04), with no significant differences between the bowel habit sub-types.

CONCLUSION

The reduced rectal volume in irritable bowel syndrome patients suggests that rectal tone is increased and that, at least in the absence of rectal sensations, the rectum is not over-distended by stools.

Do gastrointestinal transit times and colonic dimensions change with time since spinal cord injury?

STUDY DESIGN

Long-term follow-up study.

OBJECTIVES

To determine whether gastrointestinal transit times (GITTs) and colonic dimensions change during the first or subsequent decades after spinal cord injury (SCI).

SETTING

Aarhus University Hospital, Denmark.

METHODS

GITT and colonic dimensions were evaluated by means of radio-opaque markers. Group A (n=12) was investigated 1 year after SCI and again 13 (range 11-14) years later. Group B (n=10) was studied 19 (range 9-36) years after injury and again 12 (range 11-12) years later. All had been treated with conservative bowel management.

RESULTS

In group A, the median GITT 1 year after injury was 4.3 (range 1.1-6.5) days and 13 years later, it was 3.2 (range 1.3-6.5) days, P=0.96. In group B, the median GITT 19 year after injury was 3.4 (range 0.6-5.9) days and 12 years later, it was 3.2 (range 1.9-5.5) days, P=0.77. None of the two groups experienced a significant change in the diameter of the caecum/ascending colon, transverse colon, descending colon or the sigmoid during long-term follow-up. Megacolon was present in four patients at baseline and in five at follow-up.

CONCLUSION

GITTs and colonic dimensions did not change, neither during the first decade nor long after SCI.

Diagnosis and follow-up in constipated children: should we use ultrasound?

PURPOSE

We investigated the efficacy of ultrasound in determining megarectum and fecal load and the response to treatment in constipation and tried to specify objective criteria in this study.

METHODS

A total of 66 cases were queried and divided into 2 groups as constipated (n = 35; mean age, 6.8 ± 2.9 years) and control (n = 31; mean age, 8.4 ± 3.8 years) according to Rome III criteria. After the clinical evaluation, pelvic ultrasonography (US) was performed by 2 separate radiologists. The bladder capacity and the transverse rectal diameter were measured with a full bladder. Then the rectal diameter and rectal anterior wall thickness were measured, and the presence of fecal load in the rectum and sigmoid colon was recorded with an empty bladder. The examination and ultrasound were repeated after treatment for a month in these patients.

RESULTS

Comparison of the US measurements of the 2 radiologists performing the US tests did not show any interobserver difference (r = 0.981; P < .001). We therefore believe our results are objective and reproducible. We found a positive correlation between the rectal diameters and the age, height, weight, and bladder capacity. The posturination mean rectal diameter was thicker in the constipated group (3.02 ± 1.04 cm) than in the control group (1.98 ± 0.64 cm) (P < .001). The cutoff point of rectal diameter for a diagnosis of constipation was determined as 2.44 cm (71% sensitive; 76% specific; area under curve, 0.825; P < .001). The rectal anterior wall thickness and fecal load were higher in the constipated patients (P < .001). There was a significant decrease in the constipation score and fecal load after treatment for a month (P < .001), but the rectal diameter had not reached normal limits yet despite the decrease (2.71 ± 0.77 cm) (P > .05).

CONCLUSION

The use of US helps in making a correct diagnosis and in the follow-up with objective criteria and also convinces the patient and the family that the treatment needs to be continued.

Rectal hyposensitivity: pathophysiological mechanisms

Rectal hyposensitivity (RH) relates to a diminished perception of rectal distension. It may occur due to afferent nerve dysfunction and/or secondary to abnormal structural or biomechanical properties of the rectum. The aim of this study was to determine the contribution of these underlying pathophysiological mechanisms by systematically evaluating rectal diameter, compliance and afferent nerve sensitivity in patients with RH, using methodology employed in clinical practice. The study population comprised 45 (33 women; median age 48, range 25-72 years) constipated patients (Rome II criteria) with RH and 20 with normal rectal sensitivity on balloon distension and 20 healthy volunteers. Rectal diameter was measured at minimum distending pressure during isobaric distension under fluoroscopic screening. Rectal compliance was assessed during phasic isobaric distension by measuring the slope of the pressure-volume curve. Electrical stimulation of the rectal mucosa was employed to determine afferent nerve function. Values were compared to normal ranges established in healthy volunteers. The upper limits of normal for rectal diameter, compliance and electrosensitivity were 6.3 cm, 17.9 mL mmHg(-1) and 21.3 mA respectively. Among patients with RH, rectal diameter, but not compliance, was increased above the normal range (megarectum) in seven patients (16%), two of whom had elevated electrosensitivity thresholds. Rectal diameter and compliance were elevated in 23 patients (51%), nine of whom had elevated electrosensitivity thresholds. The remaining 15 patients (33%) with RH had normal rectal compliance and diameter, all of whom had elevated electrosensitivity thresholds. Two-third of the patients with RH on simple balloon distension have elevated rectal compliance and/or diameter, suggesting that impaired perception of rectal distension is due to inadequate stimulation of the rectal afferent pathway. However, a proportion of such patients also appear to have impaired nerve function. In the remaining one-third of the patients, rectal diameter and compliance are normal, while electrosensitivity thresholds are elevated, suggestive of true impaired afferent nerve function. Identification of these subgroups of patients with RH may have implications regarding their management.

Idiopathic proximal hemimegacolon: radiologic findings and analyses of clinical and physiological characteristics

BACKGROUND

Idiopathic megacolon with bowel dilatation only proximal to the splenic flexure is an uncommon and poorly characterized disease. This study aimed to identify the characteristics of idiopathic proximal hemimegacolon.

METHODS

Five patients (2 males and 3 females) were diagnosed to have idiopathic proximal hemimegacolon and their radiologic, clinical, and physiological characteristics were reviewed. Hirschsprung's disease and other known causes of bowel dilatation were excluded by the presence of rectoanal inhibitory reflex and reviewing medical records.

RESULTS

Mean age at diagnosis and symptom onset were 50.4 years and 47.2 years, respectively. Four patients presented with constipation, and all five patients showed abdominal distention and abdominal pain. Four patients were successfully treated and maintained only with laxatives and prokinetics without enema. Only one patient underwent surgery for intractable constipation. Mean maximal diameters of each segment of colons measured by computed tomography were 57.5 mm, 69.3 mm, 73.0 mm, 33.3 mm, 24.0 mm, and 27.3 mm for cecum, ascending colon, transverse colon, descending colon, sigmoid colon, and rectum, respectively. Colon transit time was delayed in four patients with mean value of 90.0 h.

CONCLUSIONS

These results indicated that patients with idiopathic proximal hemimegacolon may be treated successfully only with medical therapy in most cases.

Novel concepts in the diagnosis, pathophysiology and management of idiopathic megabowel

A proportion of patients with intractable constipation have persistent dilatation of the bowel, which in the absence of an organic cause is termed idiopathic megabowel (IMB). Whilst uncommon, this condition results in considerable morbidity. Traditional methods of identifying such patients are associated with inherent methodological limitations with anorectal manometry and contrast studies overestimating and underestimating the prevalence of the condition, respectively. Recently, controlled, pressure-based distension during fluoroscopic imaging has allowed more accurate identification of patients on the basis of a rectal diameter > 6.3 cm at the minimum distension pressure. Histopathological abnormalities of all three final effectors of sensorimotor function have been reported, although it remains unclear whether these changes are primary, secondary or epiphenomic. Physiological abnormalities of sensorimotor function, namely impaired perception of rectal distension and delayed colonic transit are well documented in patients with IMB. Further, the recent demonstration of two subgroups of patients, defined on the basis of rectal compliance, suggests the possibility that they differ pathophysiologically, although the clinical relevance of this distinction is uncertain. Surgery is performed when conservative therapy is ineffective or poorly tolerated. Numerous procedures have been attempted with variable success rates and significant mortality and morbidity. Surgery should preferably be performed in specialist centres given the relative infrequency with which such patients are encountered, and that they require comprehensive clinical, psychological and physiological evaluation preoperatively.

Acquired non-Chagas megacolon associated with the use of psychiatric medication: case report and differential diagnosis with Chagas megacolon

A case of acquired megacolon in a 62-year-old man with acute abdomen due to sigmoid volvulus is reported. The case was associated with the use of psychiatric medications. The aim in this report was to emphasize the differential diagnosis with Chagas megacolon. Anatomopathological examination did not show any evidence of denervation, ganglionitis and/or myositis, and the serological test for Chagas disease was negative.

A novel technique to identify patients with megarectum

PURPOSE

Traditional methods of identifying patients with persistent dilation of the rectum, or megarectum, are associated with inherent methodologic limitations. The purpose of this study was to use a barostat to establish criteria for the diagnosis of megarectum and to assess rectal diameter during isobaric (barostat) and volumetric (barium contrast) distention protocols in constipated patients with megarectum on anorectal manometry.

METHODS

During fluoroscopic screening, rectal diameter was measured at minimum distending pressure of the rectum, achieved using a barostat. It was also measured during evacuation proctography (volumetric distention). Having established a normal range in 25 healthy volunteers, 30 constipated patients with evidence of megarectum on anorectal manometry (elevated maximum tolerable volume on latex balloon distention) were studied. A further 10 constipated patients without evidence of megarectum were studied (normal rectum).

RESULTS

Megarectum was diagnosed when the rectal diameter was greater than 6.3 cm at minimum distending pressure. Rectal diameter at minimum distending pressure was increased in 20 patients (67 percent) with megarectum on anorectal manometry, but was normal in the remaining 10 patients (33 percent) and all patients with a normal rectum on anorectal manometry. Rectal diameter was increased at evacuation proctography in only 15 patients (50 percent) with evidence of megarectum on anorectal manometry.

CONCLUSIONS

The prevalence of megarectum is overestimated and underestimated when rectal diameter is assessed using anorectal manometry and contrast studies, respectively. Controlled (pressure-based) distention combined with fluoroscopic imaging allowed accurate identification of patients with megarectum on the basis of a rectal diameter greater than 6.3 cm at the minimum distention pressure. Measurement of rectal diameter at minimum distention pressure may be useful in those patients with an elevated maximum tolerable volume on anorectal manometry when surgery is being contemplated.

Pathophysiology, diagnosis and current management of chronic constipation

Chronic constipation is prevalent in Western countries and is a complaint that is commonly seen in clinical practice. Only a relatively small percentage of constipated patients seek medical evaluation and most can be managed satisfactorily with first-line, conservative therapy. In patients with severe, refractory constipation, additional studies of colonic and anorectal function have clinical utility, as such patients are candidates for therapies not given to most constipated patients. This article reviews the modern principles and therapies used to manage chronic constipation of varying severities.

Massive Fecal Impaction Presenting with Megarectum and Perforation of a Stercoral Ulcer at the Rectosigmoid Junction

A 25-year-old male with lifelong constipation presented to the emergency department with an acute abdomen. Initial resuscitation was performed, and the patient underwent urgent laparotomy. He was found to have feculent peritonitis with megabowel involving the rectum and sigmoid colon and a stercoral ulcer with full thickness erosion, and perforation was also identified on the anti-mesocolic surface at the rectosigmoid junction. Abdominal irrigation and subtotal colectomy with proximal fecal diversion was performed. This case illustrates that recognition of severe, chronic constipation should lead to interventions including disimpaction and aggressive medical management. When indicated, megabowel can be managed surgically in an elective setting based on anatomic findings and physiologic studies. Peritonitis is an ominous late finding in patients with severe constipation.

Colonic manometry as predictor of cecostomy success in children with defecation disorders

PURPOSE

The aim of this study was to define the predictive value of colonic manometry and contrast enema before cecostomy placement in children with defecation disorders.

METHODS

Medical records, contrast enema, and colonic manometry studies were reviewed for 32 children with defecation disorders who underwent cecostomy placement between 1999 and 2004. Diagnoses included idiopathic constipation (n = 13), Hirschsprung's disease (n = 2), cerebral palsy (n = 1), imperforate anus (n = 6), spinal abnormality (n = 6), and anal with spinal abnormality (n = 4). Contrast enemas were evaluated for the presence of anatomic abnormalities and the degree of colonic dilatation. Colonic manometry was considered normal when high-amplitude propagating contractions (HAPC) occurred from proximal to distal colon. Clinical success was defined as normal defecation frequency with no or occasional fecal incontinence.

RESULTS

Colonic manometry was done on 32 and contrast enema on 24 patients before cecostomy. At follow-up, 25 patients (78%) fulfilled the success criteria. Absence of HAPC throughout the colon was related to unsuccessful outcome (P = .03). Colonic response with normal HAPC after bisacodyl administration was predictive of success (P = .03). Presence of colonic dilatation was not associated with colonic dysmotility.

CONCLUSION

Colonic manometry is helpful in predicting the outcome after cecostomy. Patients with generalized colonic dysmotility are less likely to benefit from use of antegrade enemas via cecostomy. Normal colonic response to bisacodyl predicts favorable outcome.

Use of pelvic ultrasound in the diagnosis of megarectum in children with constipation

PURPOSE

It has not been possible so far to differentiate slow transit constipation from functional fecal retention because the existing medical literature lacks data on rectal dimensions for healthy children or children with chronic idiopathic constipation (CIC). We, for the first time, describe the use of pelvic ultrasound (US) to achieve this.

METHODS

A pelvic US was carried out on 82 children with a full or partially full bladder and with no history of bowel problems and on 95 children with CIC. The rectal crescent seen behind the bladder was measured. All children also had documentation of their age, weight, and height.

RESULTS

The median age, weight, and height for the healthy children were comparable with those of the children with CIC. The median rectal crescent size in children with constipation was 3.4 cm (range, 2.10-7.0; IQR, 1.0), as compared with 2.4 cm (range, 1.3-4.2; IQR, 0.72) in the healthy children, and this difference is statistically significant on multiple regressions of log for rectal diameter, adjusted for height, weight, and age (P value< .001).

CONCLUSION

Pelvic US is a quick child-friendly investigation, which can be used to document the presence of megarectum. It should be the first line investigation for all the children with CIC.

Decreased density of interstitial cells of Cajal and neuronal cells in patients with slow-transit constipation and acquired megacolon

BACKGROUND

The pathophysiology of constipation is not clearly identified as yet, and the interstital cells of Cajal (ICC), known to generate the slow wave activity and to be involved in intestinal neurotransmission and the enteric nervous system (ENS), are suspected to play an important role. The aims of the present study were to assess the distribution of ICC and neuronal cells of ENS in patients with slow-transit constipation and acquired megacolon.

METHODS

Sigmoid colon specimens were obtained from patients who underwent colectomy due to slow-transit constipation (n = 10), acquired megacolon (n = 9) and non-obstructive colon cancer (n = 10) as a control group. The ICC were visualized by c-Kit immunohistochemistry and neuronal cells of the ENS were demonstrated by protein gene product (PGP) 9.5. Density of cells stained by c-Kit and PGP 9.5 was calculated as percent area (area stained/area of X-Y plane) x 100, when images were collected at a magnification of x40 objective, with maximum area examined in the horizontal X-Y plane of 400 microm x 400 microm using an image analyzer.

RESULTS

The densities of ICC and PGP 9.5 reactive neuronal structures were significantly decreased in all layers of sigmoid colon specimens in patients with slow-transit constipation and acquired megacolon, compared with that of the control group. However, there was no statistically significant difference in either the density of ICC or that of neuronal structures between the patients with slow-transit constipation and acquired megacolon.

CONCLUSIONS

Slow-transit constipation and acquired megacolon were associated with alteration of ICC and neuronal cells of ENS in the sigmoid colon.

Magnetic resonance imaging of the rectum during distension

PURPOSE

A knowledge of the relationships between the rectum and its surrounding structures during distention may improve our understanding of the results of studies assessing rectal sensory-motor responses to distention. This magnetic resonance imaging study was designed to assess the shape of the rectum and the degree of distention at which the surrounding structures are compressed.

METHODS

Nine healthy patients underwent magnetic resonance imaging of the rectum under resting conditions and after the inflation of a plastic bag to volumes of 50, 100, 150, 200, and 250 ml. The thickness of the rectovesical space was assessed as a measure of the compression of the perirectal structures, and the perception of sensations were recorded.

RESULTS

The shape of the rectum changed from being quasicylindrical at distention volumes of <100 ml to bean-shaped at larger volumes. The thickness of the rectovesical space at a distention volume of 50 ml was the same as when the bag was not inflated, but it progressively decreased until the difference became statistically significant at distention volumes of > or = 200 ml, corresponding to a mean +/- standard deviation rectal radius of 2.66 +/- 0.37 cm. Statistically significant compression of the rectovesical space was recorded when the sensations of gas, desire to defecate, and urgency were perceived.

CONCLUSIONS

The shape of the rectum changes during distention; it significantly compresses the extrarectal structures in the tested range of distention that induces non-painful sensations. Magnetic resonance imaging is a useful means of assessing the morphologic changes in the rectum during distention.

Rectal intussusception in symptomatic patients is different from that in asymptomatic volunteers

Background

Rectal intussusception is a common finding at evacuation proctography in both symptomatic and asymptomatic individuals. Little information exists, however, as to whether intussusception morphology differs between patients with evacuatory dysfunction and healthy volunteers.

Methods

Thirty patients (19 women; median age 44 (range 21–76) years) with disordered rectal evacuation, in whom an isolated intussusception was seen on proctography, were studied. Various morphological parameters were measured, and compared with those from 11 asymptomatic controls (six women; median age 30 (range 24–38) years) found, from 31 volunteers, to have rectal intussusception. Intussusceptum thickness greater than 3 mm was designated as full thickness. Intussuscepta impeding evacuation were deemed to be occluding.

Results

Twenty-two patients had full-thickness intussusception, compared with two controls (P = 0·003). Intussusceptum thickness was significantly greater in the symptomatic group (anterior component: P = 0·004; posterior: P = 0·011). Twenty patients in the symptomatic group, but only three subjects in the control group, had a mechanically occluding intussusception (P = 0·043), although only three patients demonstrated evacuatory dynamics outside the normal range.

Conclusion

Rectal intussusception in patients with evacuatory dysfunction is more advanced morphologically than that seen in asymptomatic controls; it is predominantly full thickness in patients and mucosal in controls. However, caution is required when selecting patients for intervention based solely on radiological findings.

Systematic review of surgical options for idiopathic megarectum and megacolon

OBJECTIVE

A subgroup of patients with intractable constipation has persistent dilatation of the bowel, which in the absence of an organic cause is termed idiopathic megabowel (IMB). The aim of this systematic review was to evaluate the published outcome data of surgical procedures for IMB in adults.

METHODS

Electronic searches of the MEDLINE (PubMed) database, Cochrane Library, EMBase, and Science Citation Index were performed. Only peer-reviewed articles of surgery for IMB published in the English language were evaluated. Studies of all surgical procedures were included, providing they were performed on 3 or more patients, and overall success rates were documented. Studies were critically appraised in terms of design and methodology, inclusion criteria, success, mortality and morbidity rates, and functional outcomes.

RESULTS

A total of 27 suitable studies were identified, all evidence was low quality obtained from case series, and there were no comparative studies. The studies involved small numbers of patients (median 12, range 3-50), without long-term follow-up (median 3 years, range 0.5-7). Inclusion of subjects, methods of data acquisition, and reporting of outcomes were extremely variable. Subtotal colectomy was successful in 71.1% (0%-100%) but was associated with significant morbidity related to bowel obstruction (14.5%, range 0%-29%). Segmental resection was successful in 48.4% (12.5%-100%), and recurrent symptoms were common (23.8%). Rectal procedures achieved a successful outcome in 71% to 87% of patients. Proctectomy, the Duhamel, and pull-through procedures were associated with significant mortality (3%-25%) and morbidity (6%-29%). Vertical reduction rectoplasty (VRR) offered promising short-term success (83%). Pelvic-floor procedures were associated with poor outcomes. A stoma provided a safe alternative but was only effective in 65% of cases.

CONCLUSIONS

Outcome data of surgery for IMB must be interpreted with extreme caution due to limitations of included studies. Recommendations based on firm evidence cannot be given, although colectomy appears to be the optimum procedure in patients with a nondilated rectum, restorative proctocolectomy the most suitable in those with dilatation of the colon and rectum, and VRR in those patients with dilatation confined to the rectum. Appropriately designed studies are required to make valid comparisons of the different procedures available.

Medium-term results of vertical reduction rectoplasty and sigmoid colectomy for idiopathic megarectum

Background

Vertical reduction rectoplasty (VRR) was devised specifically to address the physiological abnormalities present in the rectum of patients with idiopathic megarectum (IMR). This study evaluated the medium-term clinical and physiological results of VRR.

Methods

VRR and sigmoid colectomy was performed in ten patients with IMR and constipation (six women). Patients were evaluated before and a median of 60 (range 28–74) months after surgery by assessment of symptoms using scoring systems and anorectal physiological measurements. Independent, detailed postoperative evaluation of rectal diameter, compliance, and sensory and evacuatory function was performed.

Results

There were no deaths or late complications. Symptoms recurred necessitating permanent ileostomy formation in two patients. Median (range) constipation scores improved from 22 (18–27) before to 10 (0–24) after surgery (P = 0·016). Median (range) bowel frequency increased from 1·5 (0·2–7) to 7 (0·5–21) per week (P = 0·016). Rectal diameter, compliance and sensory function were normal in seven of eight patients after surgery. Evacuatory function and colonic transit were each normalized in two of eight patients after VRR.

Conclusion

VRR corrected rectal diameter, compliance and sensory function in most patients, and clinical benefit was sustained in the medium term. The procedure was associated with a low morbidity, and no mortality and should be considered in the surgical management of IMR.

Treatment of constipation in adults associated with idiopathic megarectum by behavioural retraining including biofeedback

BACKGROUND

Constipation in adults associated with a grossly dilated rectum and recurrent faecal impaction, idiopathic megarectum, is rare. The aetiology of idiopathic megarectum is unknown, but may involve neuromuscular or behavioural factors. It is unknown whether the condition is reversible. This study aimed to determine the efficacy of behavioural therapy, including biofeedback, in such patients.

METHODS

Six patients (4 female; median age 27) with a history of rectal faecal impaction and a grossly dilated rectum on radiological examination were evaluated by structured questionnaire before, immediately after biofeedback therapy, and on follow-up. Physiological testing was performed before treatment, and 2 patients were evaluated by repeat physiological testing and contrast radiology on follow-up.

RESULTS

On median follow-up of 18 months (range 11-27), five patients felt major and one patient minor improvement in symptoms, including two with complete symptom relief. Four patients came off laxatives without recurrent faecal impaction. In the 2 studied patients rectal size did not appear to decrease.

CONCLUSION

Behavioural retraining, including biofeedback, improved symptoms in most patients with idiopathic megarectum. In some patients symptoms completely resolved, without the need for laxatives. Although further studies are necessary in terms of both larger number of patients and longer follow-up period, behavioural treatment may be useful for such patients.

Idiopathic slow transit constipation and megacolon are not associated with neurturin mutations

Chronic idiopathic slow-transit constipation (ISTC) and idiopathic megacolon (IMC) are early-onset gastrointestinal motility disorders of unknown aetiology. The gene encoding the neurotrophic factor neurturin may be a candidate for these disorders, as neurturin-deficient mice have a similar enteric phenotype. In the present study, we tested this hypothesis. Genomic DNA from 26 cases of chronic idiopathic STC [with a family history of constipation in 15 (58%) and Hirschsprung's disease in two (8%)], and five cases of IMC [two familial (40%)] was screened by direct DNA sequencing using the fluorescent dideoxy terminator method. Results were compared with published sequence data and 24 control DNAs. Our results revealed several previously unreported common sequence polymorphisms, but overall frequencies were comparable between patients and controls. We conclude that mutation of neurturin is not a frequent cause of ISTC or IMC.

Vertical reduction rectoplasty: a new treatment for idiopathic megarectum

BACKGROUND

The aetiology of idiopathic megarectum is unknown and the results of surgery are often unsatisfactory. Rectal hyposensation is common and poor perception of rectal filling may contribute to the poor evacuatory function. By reducing the capacity of the rectum, it was hypothesized that sensory thresholds to rectal distension and perception of urge to defaecate would be improved.

METHODS

Vertical reduction rectoplasty (VRR) and concomitant sigmoid colectomy was performed on six patients with idiopathic megarectum. Patients were evaluated before and after operation by detailed questionnaire and anorectal physiology. Postoperative rectal compliance was also studied by means of a programmable electronic barostat. Where appropriate, physiological data were compared with those obtained in eight healthy volunteers.

RESULTS

Bowel frequency increased from a preoperative median of 2.5 to 16 per month after operation. Four patients reported improved rectal perception of the urge to defaecate. Thresholds for defaecatory urge and maximum tolerated volume were significantly reduced following VRR (P<0.05). Post-VRR rectal compliance was no different from that in healthy volunteers. Colonic transit time decreased significantly after VRR (P<0.05) and evacuation on proctography increased from a median of 30 per cent to 50 per cent. At a median of 57 weeks' follow-up five of the six patients expressed continued satisfaction with the results.

CONCLUSION

VRR is a new approach to the treatment of idiopathic megarectum. Clinical and physiological studies confirm that it can improve sensory feedback and defaecation. The procedure needs further evaluation as the number of patients undergoing the procedure increases.

Megarectum in constipation

BACKGROUND

Faecal impaction is frequently observed in children with chronic constipation. The term megarectum is often used to describe this finding.

AIM

To evaluate rectal functioning and rectal measures in constipated children with a filled rectum, in order to define the terms faecal impaction, enlarged rectum, and megarectum.

METHODS

All children underwent radiological investigation, colonic transit time study, anorectal manometry, and rectal volume and rectal wall compliance measurements. Patients with faecal impaction were compared with controls, who had an empty rectum on digital rectal examination.

RESULTS

A total of 31 patients and six controls were included in the study. The mean duration of complaints was 4.2 years and all had faecal incontinence. The colonic transit times in the patients showed a distinct delay in the rectosigmoid segment. Anorectal manometry was not significantly different between patients and controls. The rectal width in patients was 0.68 and in controls 0.52 with an upper limit of 0.61. The pressure-volume curve in patients showed significant less relaxation at a distension of 50 ml. The slope of the curve (corresponding with rectal wall compliance) was comparable for patients and controls.

CONCLUSIONS

We suggest that faecal impaction is a filled rectum found on digital rectal examination; an enlarged rectum is defined by a rectopelvic ratio greater than 0.61; and megarectum is defined in those with significant abnormalities found with anorectal manometry, pressure-volume curves, or rectal compliance investigation. A diminished relaxation of the rectum on rectal distension could be the first sign of megarectum in children with chronic constipation.

Nitric oxide production is diminished in colonic circular muscle from acquired megacolon

PURPOSE

Nitric oxide modulates human colonic smooth muscle function. To determine whether nitric oxide production is altered in colon from acquired megacolon, we measured cholinergic nerve-mediated contractions in vitro before and after inhibition of nitric oxide synthase.

METHODS

Intramural nerves in circular smooth muscle from histologically normal colon (n = 12) and acquired megacolon (n = 3) were activated by electrical field stimulation.

RESULTS

In controls blockade of nitric oxide synthase by N(G)-Nitro-L-Arginine induced increases (P < 0.05) in amplitude of contractions; these increases in amplitudes were blocked by L-Arginine (analysis of variance; P < 0.05). By contrast, blockade of nitric oxide synthase did not increase amplitudes of contractions with circular smooth muscle from acquired megacolon. An immediate phasic contraction was blocked by atropine sulfate.

CONCLUSIONS

The results support the concept that nitric oxide production modulates cholinergic nerve-mediated contractions in normal colonic circular muscle, whereas acquired megacolon is associated with altered release of this inhibitory neurochemical. Potential explanations include depletion of tissue L-Arginine, decreased capacity to recycle citrulline to arginine, or decreased release of vasoactive intestinal peptide from circular smooth muscle in acquired megacolon.

Interstitial cells of Cajal in slow transit constipation and megabowel

OBJECTIVE

Disordered gut motor activity is a feature of patients with chronic idiopathic constipation. Interstitial cells of Cajal (ICC) are thought to modulate gut motility. The aim of this study was to test the hypothesis that there is an abnormality of the density of distribution of ICC in slow transit constipation and megabowel.

PATIENTS AND METHODS

ICC were identified by immunohistochemistry using an anti-c-kit antibody. Six patients (slow transit constipation n=3; megabowel n=3) were compared with normal controls. The density of distribution of ICC was assessed in the longitudinal and circular muscle layers, and in the intermuscular plane of the colon. Statistical analysis was performed using Fisher's exact test and χ(2) test.

RESULTS

No consistent pattern of difference in the density of ICC could be identified between the constipated and control groups.

CONCLUSION

The density of ICC in the constipated patients was not significantly different from normal colon. The results in these patients suggest that if ICC have a role in the causation of slow transit idiopathic constipation or megabowel then an abnormality of function rather than distribution is implicated.

Megacolon: Acute, Toxic, and Chronic

Megacolon refers to cecal dilatation above the dimension of 12 cm and above 6.5 cm of the sigmoid colon, measured at the pelvic brim. Dilatation of the colon can be broadly categorized into three clinical entities: In acute megacolon (Ogilvie's syndrome), colonic dilatation is attributed to a sympathetically mediated reflex response to a number of serious medical or surgical conditions in elderly patients. The initial tasks are to exclude mechanical obstruction (with a hypaque enema), to discontinue enabling medications, and to correct metabolic disturbances. Dilatation of the cecum to greater than 12 cm diameter is a cause for grave concern. The rectum should be decompressed with an indwelling tube and tap water enemas. Intravenous neostigmine is generally effective and safe for patients with colonic distention unresponsive to such conservative therapies. Endoscopic decompression is necessary for patients who do not respond to, or relapse after neostigmine, or in whom neostigmine is contraindicated. Signs of peritonitis may imply colonic perforation, and surgery will be needed, often on an emergent basis. Toxic megacolon is secondary to an identifiable inflammation of the colon. Therapy is directed toward specific treatment for the underlying disorder, inflammatory bowel disease, or infectious colitis. Bowel rest and close monitoring of the clinical status is vital. Colectomy may be needed under emergency circumstances. Chronic megacolon may be congenital (due to Hirschsprung's disease) or may represent the end-stage of any form of refractory constipation (slow transit constipation or pelvic floor dysfunction). The initial treatment for Hirschsprung's disease is surgery, while pelvic floor dysfunction and encopresis respond to biofeedback therapy. In chronic idiopathic megacolon, medical measures, such as colonic evacuation with enemas, fiber supplementation, and laxatives may suffice. If severe motor dysfunction is confined to the colon, a subtotal colectomy with an ileorectal anastomosis, or an ileostomy may occasionally be necessary.

Physiology of refractory chronic constipation

OBJECTIVE

Investigators suggest three distinct pathophysiologies for patients with constipation symptoms: 1) slow colon transit, 2) irritable bowel syndrome (IBS), and 3) pelvic floor dysfunction (PFD). Our aim was to determine the prevalence of the three types of constipation pathophysiology, the degree of overlap, and what interactions exist between pathophysiologies.

METHODS

Constipated patients refractory to fiber (n = 131) underwent regional colon transit studies, anorectal manometry/EMG, measurement of rectal compliance, and rectal sensory testing. Correlations were performed examining interactions between the above measures.

RESULTS

Visceral hypersensitivity (typical of IBS) was found in 58%, slow colonic transit in 47%, PFD in 59%, and no physiological abnormalities were detected in 24%. Slow transit and visceral hypersensitivity overlapped in half of each group. PFD physiology was found in approximately half of each of the subgroups. There was no correlation between PFD physiology and rectosigmoid transit, total colon transit, or any other physiology. There were no correlations between slow transit and visceral hypersensitivity. Visceral hypersensitivity did correlate with increased rectal compliance, suggestive of increased accommodation reflexes in IBS.

CONCLUSIONS

At a tertiary center, slow transit physiology and visceral hypersensitivity typical of IBS are equally common and overlap heavily in constipated patients. PFD physiology does not correlate with slower rectosigmoid colon transit, and is seen equally in all subgroups. No abnormalities were found in 24% of patients. We therefore identify four subgroups in constipation: IBS, slow transit, both, and neither.

Minimizing recurrence after sigmoid volvulus

BACKGROUND

This study was a retrospective review of a series of patients with sigmoid volvulus to identify risk factors for recurrence and recommend appropriate treatment.

METHODS

Thirty-five patients with sigmoid volvulus were treated over 8 years.

RESULTS

Six patients had emergency surgery for peritonitis. Twenty-eight of the other 29 patients had successful endoscopic decompression; 15 of these patients had elective surgery during the same admission. Twelve of the 14 patients who refused operation after endoscopic decompression developed recurrent volvulus, a median of 2.8 months later. Eight subsequently agreed to surgery and underwent elective operation following repeat decompression. Of 29 patients who had surgery, 27 had sigmoid colectomy (two were initial Hartmann procedures) and two had subtotal colectomy. Six patients who had sigmoid colectomy developed recurrent volvulus. Concomitant megacolon and megarectum at the time of initial surgery were significant predictors of recurrence.

CONCLUSION

Subtotal colectomy, carried out as the primary procedure if there is concomitant megacolon or megarectum, might reduce the risk of recurrent sigmoid volvulus.

Altered contractile proteins and neural innervation in idiopathic megarectum and megacolon

AIM

The aetiology of idiopathic megarectum and idiopathic megacolon is unknown. We postulated that biochemical or ultrastructural abnormalities may be pathologically important, as has been observed in patients with chronic idiopathic intestinal pseudo-obstruction.

METHODS AND RESULTS

Resection specimens from five patients with idiopathic megarectum or megacolon were processed for paraffin wax-embedded tissue histology (haematoxylin and eosin, Gomori trichrome and picrosirius stains, phosphatase activity and periodic acid-Schiff staining), and frozen tissue for histochemistry and electron microscopy. The antibodies used in the immunohistochemistry were to myosin light chain kinase, smooth muscle myosin, alpha and beta actins, filamin, tropomyosin, phosphorylated and dephosphorylated neurofilaments and N-CAM. Variable hypertrophy of the muscularis mucosae and externa, no atrophy, and a variable nerve density decrease in longitudinal muscle and increase in the lamina propria was seen. In one patient beta actin and myosin light chain kinase immunoreactivity was reduced.

CONCLUSION

Variable changes in innervation, and an abnormal contractile protein immunoreactivity pattern in one patient, may be of pathogenic importance. These clinically homogeneous conditions are likely to be due to a range of underlying pathogenic abnormalities. A search for further specific biochemical abnormalities is justified.

Colonic transit time in constipated children: does pediatric slow-transit constipation exist?

In adults, slow-transit constipation is a well-established form of constipation with abdominal pain and an empty rectum on examination. Marker studies in these patients, mainly women, show a markedly slowed transit time in all colonic segments. No studies in constipated children are available that assess the existence of slow-transit constipation. In a prospective study, a total of 94 referred constipated pediatric patients, 63 boys and 31 girls (median age, 8.0 years), underwent colonic-transit-time measurements using radioopaque markers to evaluate the pattern of transit. In addition, orocecal-transit-time measurements using the hydrogen breath (lactulose) test, anorectal manometry, and behavior studies using the Child Behavior Checklist were performed in all children. Based on the upper limit (mean + 2 SD) of total colonic transit time (CTT) in constipated children, we arbitrarily separated patients into two groups. Children with CTTs > 100 h were said to have pediatric slow-transit constipation (PSTC), while patients with CTTs < 100 h were said to have normal- or delayed-transit constipation (NDTC). In 94 constipated children, PSTC was found in 24 children; in 70 children, total CTT was < 100 h (NDTC). Total and segmental CTTs were significantly prolonged in PSTC (median, 189 h; range, 104.4-384) versus NDTC (median, 46.8 h; range, 3.6-99.4) hours. No significant differences were found in orocecal transit time. Significant clinical differences in children with PSTC versus those with NDTC existed regarding nighttime soiling (71 vs. 11%); daytime soiling episodes (14 vs. 7 each week, median), and nighttime soiling episodes (5 vs. 0 each week, median); absent urge to defecate (33 vs. 14%); and palpable abdominal (71 vs. 39%) and/or rectal (71 vs. 13%) masses. All manometric parameters were comparable in the two groups, except for a significantly lower maximal squeeze pressure with PSTC. Using the Child Behavior Checklist, both groups differed significantly from controls (26 and 43%, respectively), with no significant differences in behavior problems found between the NDTC and the PSTC groups. In conclusion, based on objective marker studies, our findings suggest the existence of pediatric slow-transit constipation. This entity can be recognized by clinical features, most importantly nighttime soiling and a palpable rectal mass. The probability of PSTC with both of these symptoms was 0.82; in the absence of these two symptoms, it was 0.07. It is of interest that CTTs in PSTC are comparable with CTTs in adults with slow-transit constipation, although the clinical presentation is clearly different. Further studies are needed to investigate whether the prolonged CTT characterizes a distinct form of constipation in children or is an epiphenomenon of the underlying constipation itself. The mechanisms responsible for the slow transit in these children and the appropriate therapeutic approach need to be studied.

Gastrointestinal transit in patients with idiopathic megarectum

PURPOSE

In patients with idiopathic megarectum, it is unknown whether abnormality is limited to the dilated large bowel or whether the upper gut is abnormal, as in the various forms of chronic intestinal pseudo-obstruction. This has important implications for treatment, especially surgery.

METHODS

Ten patients (4 females; median age, 18 (range, 17-26) years) with idiopathic megarectum had contrast studies of the upper and lower gut, radioisotope (technetium-99m liquid and indium-111 solid phase) measurement of gastric, small-bowel, and colonic regional transit, and radiopaque marker colonic studies.

RESULTS

All patients had a dilated large bowel. No patient had radiographic evidence of upper gut dilation. Four patients had normal and six patients had abnormally slow gastric emptying. Both the radioisotope scans and radiopaque marker studies showed abnormal colonic transit. Regions of delay corresponded with the region of dilated bowel. Symptoms of abdominal distention and bloating did not correspond to abnormalities of gastric emptying but rather with effectiveness of rectal evacuation.

CONCLUSION

Patients with idiopathic megarectum have abnormal colonic transit, delay occurring predominantly in the dilated gut. Marker studies are less sensitive than isotope studies but provide adequate information for clinical purposes. Although motility abnormalities of the upper gut are common, symptoms correlate with large-bowel abnormalities.

Decreased vasoactive intestinal peptide levels and glutathione depletion in acquired megacolon

We reported decreased vasoactive intestinal peptide levels in acquired megacolon. The origin of altered neuropeptide levels is unknown, but recent work suggested that tissue antioxidants may function as neuroprotectants. Our hypothesis was that altered levels of inhibitory neurotransmitters in human colon are associated with depletion of the tripeptide thiol, glutathione. Normal colon samples (N = 10; from patients 41-80 years old) and acquired megacolon samples (N = 10; from patients 31-98 years old) were obtained at surgery. Vasoactive intestinal peptide levels were decreased in muscularis externa from acquired megacolon (P = 0.01), while there was a modest increase in NADPH diaphorase activity in muscularis externa from megacolon (P = 0.10). Glutathione in acquired megacolon was detectable in muscularis externa from only five specimens (P < 0.05), but was not significantly different (P > 0.05) in the mucosal-submucosal layer. The results supported the presence of vasoactive intestinal peptide and NADPH diaphorase in distinct subpopulations of nerves in human colon. The results also supported the hypothesis that glutathione functions as a neuroprotectant in a subset of patients with acquired megacolon.

The anal sphincter in idiopathic megarectum: effects of manual disimpaction under general anesthetic

PURPOSE

This study was designed to investigate the function and morphology of anal sphincters in patients with an idiopathic megarectum.

METHOD

A total of 17 patients were studied by anal endosonography and manometry when not impacted. Fourteen had previously been manually disimpacted under general anesthetic, and three had not.

RESULTS

Nine of 14 patients in the former group, but none of the latter group, had disruption of one or both anal sphincter muscles on endosonography. Endosonographic changes were characteristic of those identified previously in patients following anal dilation. Low anal resting pressure, indicative of internal sphincter dysfunction, was found in a substantial proportion of patients with either an endosonographically intact or disrupted internal anal sphincter. Voluntary contraction increment, a reflection of external sphincter function, was normal in all patients.

CONCLUSION

Manual disimpaction under general anesthetic appears to be associated with iatrogenic structural injury to the anal sphincters. In some patients, this may contribute to sphincter weakness. This damage may contribute to the incontinence experienced by patients with a dilated rectum.

Idiopathic megarectum in adults. An assessment of manometric and radiologic variables

Outlet obstruction is thought to be one of the major factors responsible for idiopathic constipation. However, outlet obstruction itself may be due to several mechanisms. Among these, the presence of a megarectum is a leading one. Pathophysiological studies in adult patients with idiopathic megarectum are scarce. We studied by manometric and defecographic means 15 adult subjects with idiopathic megarectum and severe chronic constipation. Twenty-five healthy volunteers of both sexes acted as controls. Manometric variables showed significant differences between patients and controls with respect to internal anal sphincter pressure (P = 0.02), minimum relaxation volume (P < 0.001), defecatory sensory threshold (P < 0.001), mean rectal tolerable volume (P < 0.001), and rectal compliance (P < 0.001). An altered response to straining was observed in 46.6% of patients and in 12% of controls (P < 0.04); the ability to expel a 50-ml balloon per anum was 13.3% in patients and 100% in controls (P < 0.001). Although all patients opened the anorectal angle and had descent of the pelvic floor, thereby confirming an adequate expulsion effort, evacuation of contrast material appeared extremely difficult. In fact, no subject was able to expel more than 30% of the rectal contents during fluoroscopic screening. These results confirm previous hypotheses that idiopathic megarectum displays features of a neuropathic process as an underlying mechanism. Further studies are needed that also take into consideration the muscle tone component of the rectum in these patients.