Imaging of obstructed defecation

Imaging of Gastrointestinal Tract Ailments

Gastrointestinal (GI) disorders comprise a diverse range of conditions that can significantly reduce the quality of life and can even be life-threatening in serious cases. The development of accurate and rapid detection approaches is of essential importance for early diagnosis and timely management of GI diseases. This review mainly focuses on the imaging of several representative gastrointestinal ailments, such as inflammatory bowel disease, tumors, appendicitis, Meckel's diverticulum, and others. Various imaging modalities commonly used for the gastrointestinal tract, including magnetic resonance imaging (MRI), positron emission tomography (PET) and single photon emission computed tomography (SPECT), and photoacoustic tomography (PAT) and multimodal imaging with mode overlap are summarized. These achievements in single and multimodal imaging provide useful guidance for improved diagnosis, staging, and treatment of the corresponding gastrointestinal diseases. The review evaluates the strengths and weaknesses of different imaging techniques and summarizes the development of imaging techniques used for diagnosing gastrointestinal ailments.

Statistical shape modeling of the pelvic floor to evaluate women with obstructed defecation symptoms

Obstructed defecation (OD) is common and may be related to compromised pelvic floor integrity. Magnetic resonance (MR) defecography and statistical shape modeling were used to define pelvic floor shape variations, hypothesizing that State (rest vs peak evacuation) and Group (control vs case) would significantly influence shape. 16 women underwent MR defecography (9 cases vs 7 controls). Midsagittal, 2D pelvic floors were segmented and aligned by corresponding points. Principal component scores were compared using a Two-Way Mixed MANOVA. Three modes described differences between State (p < 0.001) and Group (p = 0.023). The pelvic floor shape differed significantly between women with and without OD and during evacuation.

Rectal axis and enterocele on proctogram may predict laparoscopic ventral mesh rectopexy outcomes for rectal intussusception

BACKGROUND

Laparoscopic ventral mesh rectopexy (LVMR) has become a well-established treatment for symptomatic high-grade internal rectal prolapse. The aim of this study was to identify proctographic criteria predictive of a successful outcome.

METHODS

One hundred and twenty consecutive patients were evaluated from a prospectively maintained pelvic floor database. Pre- and post-operative functional results were assessed with the Wexner constipation score (WCS) and Fecal Incontinence Severity Index (FISI). Proctogram criteria were analyzed against functional results. These included grade of intussusception, presence of enterocele, rectocele, excessive perineal descent and the orientation of the rectal axis at rest (vertical vs. horizontal).

RESULTS

Ninety-one patients completed both pre- and post-operative follow-up questionnaires. Median pre-operative WCS was 14 (range 10-17), and median FISI was 20 (range 0-61), with 28 patients (31%) having a FISI above 30. The presence of an enterocele was associated with more frequent complete resolution of obstructed defecation (70 vs. 52%, p = 0.02) and fecal incontinence symptoms (71 vs. 38%, p = 0.01) after LVMR. Patients with a more horizontal rectum at rest pre-operatively had significantly less resolution of symptoms post-operatively (p = 0.03).

CONCLUSIONS

These data show that proctographic findings can help predict functional outcomes after LVMR. Presence of an enterocele and a vertical axis of the rectum at rest may be associated with a better resolution of symptoms.

Comparison of dynamic magnetic resonance defaecography with rectal contrast and conventional defaecography for posterior pelvic floor compartment prolapse

AIM

This study compared the diagnostic capabilities of dynamic magnetic resonance defaecography (D-MRI) with conventional defaecography (CD, reference standard) in patients with symptoms of prolapse of the posterior compartment of the pelvic floor.

METHOD

Forty-five consecutive patients underwent CD and D-MRI. Outcome measures were the presence or absence of rectocele, enterocele, intussusception, rectal prolapse and the descent of the anorectal junction on straining, measured in millimetres. Cohen's Kappa, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and the positive and negative likelihood ratio of D-MRI were compared with CD. Cohen's Kappa and Pearson's correlation coefficient were calculated and regression analysis was performed to determine inter-observer agreement.

RESULTS

Forty-one patients were available for analysis. D-MRI underreported rectocele formation with a difference in prevalence (CD 77.8% vs D-MRI 55.6%), mean protrusion (26.4 vs 22.7 mm, P = 0.039) and 11 false negative results, giving a low sensitivity of 0.62 and a NPV of 0.31. For the diagnosis of enterocele, D-MRI was inferior to CD, with five false negative results, giving a low sensitivity of 0.17 and high specificity (1.0) and PPV (1.0). Nine false positive intussusceptions were seen on D-MRI with only two missed.

CONCLUSION

The accuracy of D-MRI for diagnosing rectocele and enterocele is less than that of CD. D-MRI, however, appears superior to CD in identifying intussusception. D-MRI and CD are complementary imaging techniques in the evaluation of patients with symptoms of prolapse of the posterior compartment.

Rectal prolapse traumatizes rectal neuromuscular microstructure explaining persistent rectal dysfunction

PURPOSE

Internal rectal prolapse is common and correlates with age. It causes a plug-like physical obstruction and is a major cause of defecation disorder. The progressive distortion of the prolapsing rectum likely causes secondary defects in the rectal wall, which may exacerbate rectal dysfunction. We undertook a prospective observational study to detect and quantify the neurologic and histopathologic changes in the rectal wall.

METHODS

We examined dorsal and ventral rectal wall specimens from consecutive patients with internal rectal prolapse undergoing stapled transanal rectal resection (STARR). We subjected specimens to histopathologic and neuropathologic assessment, including immunohistochemistry. We also recorded patients' clinical and demographic characteristics and sought correlations between these and the pathologic findings.

RESULTS

We examined 100 specimens. The severity of rectal prolapse and the extent of descent of the perineum correlated significantly with age. Concomitant hemorrhoidal prolapse was noted in all male patients and in 79 % of female patients. Muscular and neuronal defects were detected in 94 and 90 % of the specimens, respectively. Only four specimens (4 %) were free of significant structural defects.

CONCLUSION

Rectal prolapse traumatizes the rectum causing neuromuscular defects. The tissue trauma is due to shearing forces and ischemia caused by the intussusception. This initiates a self-reinforcing vicious circle of physical and functional obstruction, further impairing rectal evacuation and causing constipation and incontinence. The correlation between extent of prolapse and age suggests that internal rectal prolapse can be considered a degenerative disorder. Neural and motor defects in the wall of the rectum caused by rectal prolapse are likely irreversible.

Defecating Disorders: A Common Cause of Constipation in Women

Defecating disorders are a common and complex problem. There are a range of anatomical and functional bowel abnormalities that can lead to this condition. Treatment is difficult and needs a multidisciplinary approach. First line treatment for defecating disorders is conservative. For those that fail conservative treatment, some may respond to surgical therapy but with variable results. The aim of this review is to offer an overview of defecating disorders as well as provide an algorithm on how to diagnose and treat them with the help of a multidisciplinary and multimodal approach.

Chronic severe constipation: current pathophysiological aspects, new diagnostic approaches, and therapeutic options

Chronic constipation is a considerable problem because it significantly affects the quality of a patient's life. Constipation can be diagnosed at every age and is more frequent in women and among the elderly. In epidemiological studies, its incidence is estimated at 2-27% in the general population. Chronic constipation may be primary or secondary. However, primary constipation (functional or idiopathic) can be classified into normal transit constipation, slow transit constipation, and pelvic outlet obstruction. In this review we make an attempt to present the current pathophysiological aspects and new therapeutic options for chronic idiopathic constipation, particularly highlighting the value of patient assessment for accurate diagnosis of the cause of the problem, thus helping in the choice of appropriate treatment.

Posterior vaginal prolapse shape and position changes at maximal Valsalva seen in 3-D MRI-based models

INTRODUCTION AND HYPOTHESIS

Two-dimensional magnetic resonance imaging (MRI) of posterior vaginal prolapse has been studied. However, the three-dimensional (3-D) mechanisms causing such prolapse remain poorly understood. This discovery project was undertaken to identify the different 3-D characteristics of models of rectocele-type posterior vaginal prolapse (PVP(R)) in women.

METHODS

Ten women with (cases) and ten without (controls) PVP(R) were selected from an ongoing case-control study. Supine, multiplanar MR imaging was performed at rest and maximal Valsalva. Three-dimensional reconstructions of the posterior vaginal wall and pelvic bones were created using 3D Slicer v. 3.4.1. In each slice the posterior vaginal wall and perineal skin were outlined to the anterior margin of the external anal sphincter to include the area of the perineal body. Women with predominant enteroceles or anterior vaginal prolapse were excluded.

RESULTS

The case and control groups had similar demographics. In women with PVP(R) two characteristics were consistently visible (10/10): (1) the posterior vaginal wall displayed a folding phenomenon similar to a person beginning to kneel ("kneeling" shape) and (2) a downward displacement in the upper two thirds of the vagina. Also seen in some, but not all of the scans were: (3) forward protrusion of the distal vagina (6/10), (4) perineal descent (5/10), and (5) distal widening in the lower third of the vagina (3/10).

CONCLUSIONS

Increased folding (kneeling) of the vagina and an overall downward displacement are consistently present in rectocele. Forward protrusion, perineal descent, and distal widening are sometimes seen as well.

How to interpret a functional or motility test - defecography

Defecography evaluates in real time the morphology of rectum and anal canal in a physiologic setting by injection of a thick barium paste into the rectum and its subsequent evacuation. Because of its ability of structural and functional evaluation, defecography is primarily performed for work up of patients with longstanding constipation, unexplained anal or rectal pain, residual sensation after defecation or suspected prolapse. Technique and interpretation of this examination are outlined in this review.

Assessment of gastrointestinal motor functions by MRI: a comprehensive review

BACKGROUND

Magnetic resonance imaging (MRI) is a useful technique for evaluating gastrointestinal (GI) motor functions because it provides multi-planar imaging capability, high imaging speed, good spatial resolution and excellent soft tissue contrast. Moreover, multiple parameters of GI function can be assessed non-invasively during a single study.

PURPOSE

This critical review of the literature discusses the strengths and limitations of MRI for evaluating GI motor functions.

[Mechanical obstruction as a cause of acute abdomen. Radiological differential diagnosis]

Mechanical obstruction is a common cause of acute abdomen. Besides the diagnosis of the obstruction itself it is crucial to recognize the cause of the obstruction for planning of conservative or operative treatment.This article gives a general overview of the methods available for imaging obstructions in the setting of an acute abdomen. In the second part the differential diagnoses of the most common causes of obstruction will be discussed.

Technical advances in monitoring human motility patterns

Abnormal motor patterns are implicated in many motility disorders. However, for many regions of the gut, our knowledge of normal and abnormal motility behaviors and mechanisms remains incomplete. There have been many recent advances in the development of techniques to increase our knowledge of gastrointestinal motility, some readily available while others remain confined to research centers. This review highlights a range of these recent developments and examines their potential to help diagnose and guide treatment for motility disorders.

Overview of pelvic floor disorders

Disorders of the pelvic floor are common sources of morbidity, decreased quality of life, and are unfortunately increasing in incidence. Owing to their complex and often coexistent nature, a comprehensive, multidisciplinary strategy of testing and care is required. Many nonoperative and operative approaches for management of the symptoms of pelvic floor disorders are available. This article reviews the evaluation and management for these difficult disorders.

Laparoscopic ventral rectopexy for internal rectal prolapse: short-term functional results

OBJECTIVE

Over the last 15 years, posterior rectopexy, which causes rectal autonomic denervation, was discredited for internal rectal prolapse because of poor results. The condition became medical, managed largely by biofeedback. We aimed to audit the short-term functional results of autonomic nerve-sparing laparoscopic ventral rectopexy (LVR) for internal rectal prolapse.

METHOD

Prospectively collected data on LVR for internal rectal prolapse were analysed. End-points were changes in bowel function (Wexner Constipation Score and Fecal Incontinence Severity Index) at 3 and 12 months. Analysis was performed using Mann-Whitney U-test for unpaired data and Wilcoxon signed rank test for paired data (two-sided p-test). Functional outcomes were compared with those achieved previously for external rectal prolapse (ERP).

RESULTS

Seventy-five patients underwent LVR (median age 58, range 25-88 years, median follow up was 12 months). Mortality (0%), major (0%) and minor morbidity (4%) were acceptably low. Median length of stay was 2 days. Preoperative constipation (median Wexner score 12) and faecal incontinence (median FISI score 28) improved significantly at 3 months (Wexner 4, FISI 8, both P < 0.0001) and 12 months (Wexner 5, FISI 8, both P < 0.0001). No patient had worse function. Functional outcomes were similar to those for ERP.

CONCLUSION

Laparoscopic ventral rectopexy for internal rectal prolapse improves symptoms of obstructed defaecation and faecal incontinence in the short-term. This establishes proof of concept for a nerve-sparing surgical treatment for internal rectal prolapse.

Function and dysfunction of the colon and anorectum in adults: working team report of the Swedish Motility Group (SMoG)

Symptoms of fecal incontinence and constipation are common in the general population. These can, however, be unreliably reported and are poorly discriminatory for underlying pathophysiology. Furthermore, both symptoms may coexist. In the elderly, fecal impaction always must be excluded. For patients with constipation, colon transit studies, anorectal manometry and defecography may help to identify patients with slow-transit constipation and/or pelvic floor dysfunction. The best documented medical treatments for constipation are the macrogols, lactulose and isphagula. Evolving drugs include lubiprostone, which enhances colonic secretion by activating chloride channels. Surgery is restricted for a highly selected group of patients with severe slow-transit constipation and for those with large rectoceles that demonstrably cause rectal evacuatory impairment. For patients with fecal incontinence that does not resolve on antidiarrheal treatment, functional and structural evaluation with anorectal manometry and endoanal ultrasound or magnetic resonance (MR) of the anal canal may help to guide management. Sacral nerve stimulation is a rapidly evolving alternative when other treatments such as biofeedback and direct sphincter repair have failed. Advances in understanding the pathophysiology as a guide to treatment of patients with constipation and fecal incontinence is a continuing important goal for translational research. The content of this article is a summary of presentations given by the authors at the Fourth Meeting of the Swedish Motility Group, held in Gothenburg in April 2007.

Defecographic pelvic floor abnormalities in constipated patients: does mode of delivery matter?

BACKGROUND

The aim of this study was to demonstrate the distribution of defecographic pelvic floor abnormalities in constipated female patients and to correlate these dysfunctions with the mode of delivery.

METHODS

Two hundred and fifty-five female patients who underwent defecography for constipation from 2001 to 2008 were reviewed and pelvic floor abnormalities were assessed. The patients were divided into three groups: group I had 50 nulliparous women, mean age 40.2 (+ or - 15.3), group II had 165 vaginally parous women, mean age 57 (+ or - 13.3), and group III had 40 patients delivered by cesarean section, mean age 50.6 (+ or - 11.9).

RESULTS

Significant rectocele was identified in group I (36%), group II (35.8%), and group III (20%) without any statistically significant differences among the groups (p > 0.05). Intussusception was identified in group I (48%), group II (70.3%), and in group III (67.5%; p = 0.014). Intussusception associated with significant rectocele was more common in vaginally parous patients (p = 0.043). Abnormalities on puborectalis relaxation associated or not associated with rectocele were similar among the groups (p = 0.47). Vaginally parous patients had more abnormal exams as compared to other patients (p = 0.005). Significant rectocele was identified in (39%) patients with age > or = 50 years and in (26.3%) patients with age <50 years (p = 0.03).

CONCLUSION

There was no specific correlation between distribution of pelvic floor disorders and mode of delivery in this study. Patients of age greater than 50 years had a higher incidence of significant rectocele.