Exaggerated rectal adaptation - another cause of outlet obstruction

Assessing Anorectal Function in Constipation and Fecal Incontinence

Constipation and fecal incontinence are commonly encountered complaints in the gastrointestinal clinic. Assessment of anorectal function includes comprehensive history, rectal examination, and prospective stool diary or electronic App diary that accurately captures bowel symptoms, evaluation of severity, and quality of life of measure. Evaluation of a suspected patient with dyssynergic constipation includes anorectal manometry, balloon expulsion test, and defecography. Investigation of a suspected patient with fecal incontinence includes high-resolution anorectal manometry; anal ultrasound or MRI; and neurophysiology tests, such as translumbosacral anorectal magnetic stimulation or pudendal nerve latency. This article provides an approach to the assessment of anorectal function.

Expert consensus document: Advances in the evaluation of anorectal function

Faecal incontinence and evacuation disorders are common, impair quality of life and incur substantial economic costs worldwide. As symptoms alone are poor predictors of underlying pathophysiology and aetiology, diagnostic tests of anorectal function could facilitate patient management in those cases that are refractory to conservative therapies. In the past decade, several major technological advances have improved our understanding of anorectal structure, coordination and sensorimotor function. This Consensus Statement provides the reader with an appraisal of the current indications, study performance characteristics, clinical utility, strengths and limitations of the most widely available tests of anorectal structure (ultrasonography and MRI) and function (anorectal manometry, neurophysiological investigations, rectal distension techniques and tests of evacuation, including defecography). Additionally, this article provides our consensus on the clinical relevance of these tests.

Evacuation proctography: a reappraisal of normal variability

AIM

Interpretation of evacuation proctography (EP) images is reliant on robust normative data. Previous studies of EP in asymptomatic subjects have been methodologically limited. The aim of this study was to provide parameters of normality for both genders using EP.

METHOD

Evacuation proctography was prospectively performed on 46 healthy volunteers (28 women). Proctograms were independently analysed by two reviewers. All established and some new variables of defaecatory structure and function were assessed objectively: anorectal dimensions; anorectal angle changes; evacuation time; percentage contrast evacuated; and incidence of rectal wall morphological 'abnormalities'.

RESULTS

Normal ranges were calculated for all main variables. Mean end-evacuation time was 88 s (95% CI: 63-113) in male subjects and 128 s (95% CI: 98-158) in female subjects; percentage contrast evacuated was 71% (95% CI: 63-80) in male subjects and 65% (95% CI: 58-72) in female subjects. Twenty-six (93%) of 28 female subjects had a rectocoele with a mean depth of 2.5 cm (upper limit = 3.9 cm). Recto-rectal intussusception was found in nine subjects (approximately 20% of both genders); however, recto-anal intussusception was not observed. Only rectal diameter differed significantly between genders. Qualitatively, three patterns of evacuation were present.

CONCLUSION

This study defines normal ranges for anorectal dimensions and parameters of emptying, as well as the incidence and characteristics of rectal-wall 'abnormalities' observed or derived from EP. These ranges can be applied clinically for subsequent disease comparison.

The physiology of human defecation

Human defecation involves integrated and coordinated sensorimotor functions, orchestrated by central, spinal, peripheral (somatic and visceral), and enteric neural activities, acting on a morphologically intact gastrointestinal tract (including the final common path, the pelvic floor, and anal sphincters). The multiple factors that ultimately result in defecation are best appreciated by describing four temporally and physiologically fairly distinct phases. This article details our current understanding of normal defecation, including recent advances, but importantly identifies those areas where knowledge or consensus is still lacking. Appreciation of normal physiology is central to directed treatment of constipation and also of fecal incontinence, which are prevalent in the general population and cause significant morbidity.

Joint hypermobility and rectal evacuatory dysfunction: an etiological link in abnormal connective tissue?

BACKGROUND

  Previous studies report an association between joint hypermobility (JHM), as a clinical feature of underlying connective tissue (CT) disorder, and pelvic organ prolapse. However, its association with rectal evacuatory dysfunction (RED) has not been evaluated. To investigate the prevalence of JHM in the general population and in patients with symptoms of RED referred for anorectal physiological investigation.

METHODS

Bowel symptom and Rome III questionnaires to detect irritable bowel syndrome were sent to 273 patients with RED. Patients then underwent full investigation, including evacuation proctography. A validated 5-point self-reported questionnaire was used to assess JHM in both the patient group and 100 age- and sex-matched controls [87 female, median age 55 (range 28-87)].

KEY RESULTS

Seventy-three patients were excluded from analysis (incomplete questionnaire or investigation). Of 200, 65 patients [32%: 63 female, median age 52 (range 15-80)] and 14% of controls (P = 0.0005 vs patients) had features satisfying criteria for JHM. Overall constipation score (P < 0.0001), abdominal pain (P = 0.003), need for manual assistance (P = 0.009), and use of laxatives (P = 0.03) were greater in the JHM group than the non-JHM group. On proctography, 56 of JHM patients (86%) were found to have significant morphological abnormalities (e.g. functional rectocoele), compared with 64% of the non-JHM group (P = 0.001).

CONCLUSIONS & INFERENCES

The greater prevalence of JHM in patients with symptoms of RED, and the demonstration of significantly higher frequencies of morphological abnormalities than those without JHM, raises the possibility of an important pathoaetiology residing in either an enteric or supporting pelvic floor abnormality of CT.

Manometric, sensorimotor, and neurophysiologic evaluation of anorectal function

With advances in diagnostic technology, it is now accepted that in the field of functional bowel disorders, symptom-based assessment is unsatisfactory as the sole means of directing therapy. A robust taxonomy based on underlying pathophysiology has been suggested, highlighting a crucial role for physiologic testing in clinical practice. A wide number of complementary investigations currently exist for the assessment of anorectal structure and function, some of which have a clinical impact in patients with functional disorders of evacuation and continence by markedly improving diagnostic yield and altering management. The techniques, limitations, measurements, and clinical use of manometric, sensorimotor, and neurophysiologic tests of anorectal function are presented.

Rectal hyposensitivity

Rectal hyposensitivity (RH) relates to a diminished perception of rectal distension that is diagnosed during anorectal physiologic investigation. There have been few direct studies of this physiologic abnormality, and its contribution to the development of functional bowel disorders has been relatively neglected. However, it appears to be common in patients with such disorders, being most prevalent in patients with functional constipation with or without fecal incontinence. Indeed, it may be important in the etiology of symptoms in certain patients, given that it is the only "apparent" identifiable abnormality on physiologic testing. Currently, it is usually diagnosed on the basis of elevated sensory threshold volumes during balloon distension in clinical practice, although such a diagnosis may be susceptible to misinterpretation in the presence of altered rectal wall properties, and thus it is uncertain whether a diagnosis of RH reflects true impairment of afferent nerve function. Furthermore, the etiology of RH is unclear, although there is limited evidence to support the role of pelvic nerve injury and abnormal toilet behavior. The optimum treatment of patients with RH is yet to be established. The majority are managed symptomatically, although "sensory-retraining biofeedback" appears to be the most effective treatment, at least in the short term, and is associated with objective improvement in the rectal sensory function. Currently, fundamental questions relating to the contribution of this physiologic abnormality to the development of functional bowel disorders remain unanswered. Acknowledgment of the potential importance of RH is thus required by clinicians and researchers to determine its relevance.

Rectal intussusception: a study of rectal biomechanics and visceroperception

OBJECTIVES

Rectal intussusception (RI) is a significant cause of morbidity amongst those with a rectal evacuatory disorder. The pathophysiology is unknown, but may involve abnormal biomechanics of the rectal wall similar to that previously demonstrated in patients with overt rectal prolapse (RP). Using an electromechanical barostat, this study aimed to investigate the biomechanics and visceroperception of the rectal wall in patients with RI.

METHODS

Twenty consecutive patients (12 females, median age 46 yr (range 24-66)) with symptomatic, full-thickness RI were studied. Patients underwent assessment of rectal compliance, visceroperception, adaptive response to isobaric distension at urge threshold, and assessment of the postprandial response. Results were compared with those obtained in 28 asymptomatic volunteers, 10 with RI (6 females, median age 29 yr (range 21-36)) and 18 (9 females, median age 33 yr (range 21-62)) without.

RESULTS

In the absence of the clinical finding of solitary rectal ulcer syndrome (SRUS), patients with symptomatic RI have normal rectal wall biomechanics, as do asymptomatic volunteers with RI (p < 0.05). Patients with the clinical finding of SRUS had reduced compliance and adaptation. In all three groups, there was a linear relationship between rectal pressure and visceroperception. The postprandial contractile response was similar between groups.

CONCLUSIONS

Patients with RI have normal rectal wall biomechanics. This is in contrast to patients with RP, and suggests that while they may represent different stages of the same disease process, they are physiologically distinct. In patients with RI and SRUS, rectal wall inflammation and fibrosis, perhaps arising secondary to the intussusception, may explain the physiological changes observed.

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.

Rectal hyposensitivity: a disorder of the rectal wall or the afferent pathway? An assessment using the barostat

OBJECTIVES

Rectal hyposensitivity (RH) relates to a diminished perception of rectal distension. Diagnosis on the basis of abnormal threshold volumes on balloon distension alone may be inaccurate due to the influence of differing rectal wall properties. The aim of this study was to investigate whether RH was actually due to impaired afferent nerve function or whether it could be secondary to abnormalities of the rectal wall.

METHODS

A total of 50 patients were referred consecutively to a tertiary referral unit for physiologic assessment of constipation (Rome II criteria), 25 of whom had associated fecal incontinence. Thirty patients had RH (elevated threshold volumes on latex balloon distension), and 20 patients had normal rectal sensation (NS). Results were compared with those obtained in 20 healthy volunteers (HV). All subjects underwent standard anorectal physiologic investigation, and assessment of rectal compliance, adaptive response to isobaric distension at urge threshold, and postprandial rectal response, using an electromechanical barostat.

RESULTS

Mean rectal compliance was significantly elevated in patients with RH compared to NS and HV (p < 0.001). However, 16 patients with RH (53%) had normal compliance. Intensity of the urge to defecate during random phasic isobaric distensions was significantly reduced in patients with RH compared to NS and HV (p < 0.001). The adaptive response at urge threshold was reduced in patients with RH compared to NS and HV (p < 0.001), although spontaneous adaptation at operating pressure was similar in all three groups studied (p= 0.3). Postprandially, responses were similar between groups.

CONCLUSIONS

In patients found to have RH on simple balloon distension, impaired perception of rectal distension may be partly explained in one subgroup by abnormal rectal compliance. However, a second subgroup exists with normal rectal wall properties, suggestive of a true impairment of the afferent pathway. The barostat has an important role in the identification of these subgroups of patients.

Clinical and physiological findings, and possible aetiological factors of rectal hyposensitivity

BACKGROUND

Rectal hyposensitivity (RH) relates to insensitivity of the rectum on anorectal physiological investigation and appears common in functional bowel disorders. The clinical significance of this physiological abnormality is unclear.

METHOD

RH was defined as one or more sensory threshold volumes raised beyond the normal range (mean plus two standard deviations) on rectal balloon distension. Clinical information and results of other anorectal physiological investigations were evaluated in 261 patients with RH.

RESULTS

Patients with RH most commonly presented with constipation (48 per cent), constipation and incontinence in combination (27 per cent), or faecal incontinence (20 per cent). Thirty-eight per cent of patients had a history of previous pelvic surgery, 22 per cent a history of anal surgery and 13 per cent a history of spinal trauma. In patients with RH presenting with symptoms of constipation or incontinence, impaired rectal sensation was the only abnormality on physiological investigation in 48 per cent and 31 per cent respectively.

CONCLUSION

Patients with RH display marked heterogeneity in terms of presenting symptoms. The exact causes of RH are unknown, but there is evidence to suggest that pelvic nerve injury and spinal trauma are possible aetiological factors. RH appears important in the aetiology of both constipation and faecal incontinence, and may be useful as a predictor of surgical outcome.