Anal endosonography in healthy subjects and patients with idiopathic fecal incontinence

Brain responses to mechanical rectal stimulation in patients with faecal incontinence: an fMRI study

AIM

Continence is dependent on anorectal-brain interactions. Consequently, aberrations of the brain-gut axis may be important in the pathophysiology of faecal incontinence (FI) in certain patients. The aim of this study was to assess the feasibility of recording brain responses to rectal mechanical stimulation in patients with FI using functional magnetic resonance imaging (fMRI).

METHOD

A prospective, cohort pilot study was performed to assess brain responses during rectal stimulation in 14 patients [four men, mean (SD) age 62 (15) years]. Blood oxygen level dependent (BOLD) signals were measured by fMRI during rest and mechanical distension, involving random repetitions of isobaric phasic rectal distensions at fixed (15 and 45 mmHg) and variable (10% above sensory perception threshold) pressures.

RESULTS

Increases in BOLD signals in response to high pressure rectal distension (45 mmHg) and maximum toleration were observed in the cingulate gyrus, thalamus, insular cortex, inferior frontal gyrus, cerebellum, caudate nucleus, supramarginal gyrus, putamen and amygdala. Additionally, activation of the supplementary motor cortex and caudate nucleus with inconsistent activity in the frontal lobe was observed.

CONCLUSIONS

This study has demonstrated the feasibility of recording brain responses to rectal mechanical stimulation using fMRI in patients with FI, revealing activity in widespread areas of the brain involved in visceral sensory processing. The observed activity in the supplementary motor cortex and caudate nucleus, with relative paucity of activity in the frontal lobes, warrants investigation in future studies to determine whether aberrations in cerebral processing of rectal stimuli play a role in the pathogenesis of FI.

Endoanal ultrasound in perianal fistulae and abscesses

Endoanal ultrasound is a technique that provides imaging of the anal sphincters and its surrounding structures as well as the pelvic floor. However, endoanal magnetic resonance imaging (MRI) is preferred by most physicians, although costs are higher and demand easily outgrows availability. Endoanal ultrasound is an accurate imaging modality delineating anatomy of both cryptoglandular as well as Crohn perianal fistula and abscess. Endoanal ultrasound is comparable with examination under anesthesia and equally sensitive as endoanal MRI in fistula detection. When fistula tracts or abscesses are located above the puborectal muscle, an additional endoanal MRI should be performed. Preoperative imaging is advocated in recurrent cryptoglandular fistula because a more complex pattern can be expected. Endoanal ultrasound can help avoid missing tracts during surgery, lowering the chance for the fistula to persist or recur. It can easily be performed in an outpatient setting and endosonographic skills are quickly incremented. Costs are low and endoanal ultrasound has the potential to improve outcome of patients with both cryptoglandular and fistulizing Crohn disease; therefore, it values more attention.

Endosonographic evaluation of anal sphincters in healthy children

PURPOSE

To describe the endosonographic anatomy of anal sphincters in healthy children and to evaluate the reproducibility of sphincter thickness measurements.

METHODS

Forty-five healthy children with median age of 3.6 years (range, 1.0-14.5 years) were studied while under general anesthesia for minor surgery. Anal endosonography was performed with a 7- to 10-MHz rotating transducer with a diameter of 19 mm. The internal anal sphincter (IAS) and the external anal sphincter (EAS) were assessed by 2 independent observers.

RESULTS

IAS and EAS were identified in all children. The mean thickness of IAS and EAS were 1.3 mm and 5.3 mm, respectively. Identification of the inner and outer border of IAS was difficult, especially in children younger than 3 years. The thickness of EAS was easier to assess, and the interrater reliability for EAS thickness measurements was excellent. EAS thickness was positively correlated with the children's age. Reflectivity varied within the EAS with frequent hyporeflective areas.

CONCLUSIONS

Anal endosonography provided visualization of the IAS and EAS in children. Assessment of exact IAS thickness was difficult, especially in the youngest children. Mean EAS thickness was 5.3 mm, increasing with age. Hyporeflective areas of the intact EAS should not be misinterpreted as sphincter defects.

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.

Endoanal ultrasound in benign anorectal disorders: clinical relevance and possibilities

Endoanal ultrasound is a well-established technique used to evaluate benign anorectal disorders. The technique is easy to perform, has a short learning curve and causes very little discomfort. Reconstruction of 3D images is possible. The clinical indications for endoanal ultrasound in benign anorectal diseases are fecal incontinence and peri-anal fistula. Sphincter defects can be depicted with precision and correlate perfectly with surgical findings. Furthermore, an impression of sphincter atrophy can be established. With perianal fistula the tracts can be visualized. Introducing hydrogen peroxide via the external fistula opening improves imaging. Endoanal ultrasound and MRI have comparable results in diagnosing anorectal disorders.

Rectal augmentation: short- and mid-term evaluation of a novel procedure for severe fecal urgency with associated incontinence

BACKGROUND

Rectal augmentation (RA) with or without electrically stimulated gracilis neosphincter (ESGN) was developed to address the physiologic and anatomic abnormalities present in a subset of patients with incapacitating fecal urgency and associated urge fecal incontinence (UFI). This study evaluated the short- and medium-term clinical and physiologic results.

METHODS

Eleven patients with fecal urgency and UFI underwent RA, 6 with concomitant ESGN formation. Patients were evaluated preoperatively, and at a median of 12.5 and 54 months after surgery.

RESULTS

At 4.5 years, 7/11 patients had avoided stoma construction. Symptoms recurred leading to permanent stoma formation in 1 patient, whereas one other developed evacuatory difficulty with overflow incontinence. Median ability to defer defecation improved from seconds preoperatively to 10 minutes at 1 year (P = 0.0002), and 15 minutes at 4.5 years (P = 0.002). Median Wexner incontinence scores improved from 15 preoperatively to 3 at 1 year (P = 0.002), and 4 at 4.5 years (P = 0.02). At 1 year, 2 of the rectal sensory thresholds (DDV: P = 0.008; MTV: P = 0.008) and compliance were normalized (P = 0.008), whereas at 4.5 years, all sensation thresholds improved (FCS: P = 0.002; DDV: P = 0.002; MTV: P = 0.002), but changes in compliance were not significant.

CONCLUSION

RA with or without ESGN improved reported symptoms and normalized rectal sensation. Improvements were sustained in the medium term. The procedure had no associated morbidity or mortality, and should be considered in the surgical management of a select group of patients presenting with severe urgency and UFI.

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.

Anorectal ultrasound for neoplastic and inflammatory lesions

Accurate staging of rectal and anal carcinoma is crucial for planning surgery and indicating adjuvant therapy. Although, computed tomography and magnetic resonance imaging are very sensitive in detecting metastatic disease, the local staging of rectal cancer with these techniques has been disappointing. Endorectal ultrasound (ERUS) and anal endosonography (AE) remain the most accurate methods for staging rectal and anal cancer. Anal endosonography is also of value in evaluating perianal sepsis: it can assist the surgeon in planning the surgical strategy by delineating the anatomy of fistula tracts, and can aid in puncturing abscesses in the operating room. Continued research and development has made the instrumentation for ERUS and AE more accurate and user-friendly. New techniques that have contributed significantly to the evolution of ERUS include three-dimensional ERUS, high-frequency miniprobes, transrectal ultrasound-guided biopsy techniques and hydrogen peroxide-enhanced endosonography. Further improvements can be expected from contrast enhancement with microbubbles and colour Doppler imaging. In this new millennium, new developments in ERUS and anal endosonography, such as tri-dimensional ERUS and anal endosonography and radial electronic probing, widen the role of ERUS in the staging of rectal and anal carcinoma, as well as for perianal inflammatory conditions.

The Colorectal Development Unit: impact on functional outcome for the electrically stimulated gracilis neoanal sphincter

OBJECTIVE

A Colorectal Development Unit (CDU) was established to treat patients with end stage faecal incontinence with the electrically stimulated gracilis neoanal sphincter (ESGN). The aim of this study was to investigate the impact of the CDU on functional outcome and complications.

METHODS

From March 1997 to March 2003, 53 patients underwent ESGN formation. Results were compared with 65 patients undergoing ESGN surgery prior to the establishment of the unit (pre-CDU) between 1988 and 1997, which were similar with regard to age, sex, aetiology and follow-up.

RESULTS

Thirty-three (70%) CDU patients had a good functional outcome defined as continence to solid and liquid stool, a significant improvement when compared to the pre-CDU group, successful in 29 (45%) (P = 0.01). Episodes of technical complications leading to stimulator replacement were significantly reduced, from 25 to 3 over time (P < 0.001). Severe septic episodes were significantly reduced from 21 to four (P = 0.003) but there was no significant change in the incidence of postoperative evacuatory dysfunction.

CONCLUSION

Since setting up a CDU, a successful outcome has been achieved in 33 (70%) of 47 patients undergoing ESGN surgery, which represents a significant improvement over time. This is probably related to improved patient assessment and selection, more reliable equipment and increased operative and peri-operative experience that come with a multidisciplinary team approach.

Fecal incontinence related to pregnancy

Fecal incontinence related to pregnancy is an underreported and debilitating physical problem that has psychosocial ramifications. Disruption of the external and internal anal sphincters, which may occur during vaginal delivery, is the most common etiologic factor. Endoanal ultrasound is a minimally invasive, simple, and accurate diagnostic tool used to confirm and guide management of sphincter complex disruption.

Endosonography in anorectal disease: an overview

Anorectal endosonography (AE), which was introduced 20 years ago, derives from the study of urology. It was first used to evaluate rectal tumours and later also to investigate benign disorders of the anal sphincters and pelvic floor. The technique is easy to perform, it has a short learning curve and causes no more discomfort than a routine digital examination. A rotating probe with a 360 degrees radius and a frequency between 5 and 16 MHz is introduced to the rectum and then slowly withdrawn so that the pelvic floor and subsequently the sphincter complex are seen. Recently, it has become possible to reconstruct three-dimensional images. AE has been used for almost every possible disorder in the anal region and has increased our insight into anal pathology. The clinical indications for AE are: 1. Faecal incontinence in patients when surgery is an option. AE can show sphincter defects with excellent precision. There is a perfect correlation with surgical findings. Studies comparing AE with endoanal magnetic resonance imaging (MRI) have shown that both methods are equally good for demonstrating defects in the external anal sphincter; the internal anal sphincter is better visualized with AE. After sphincter repair, the effect is directly related to the decrease in the sphincter defect. 2. Perianal fistulae. AE has been shown to be accurate in staging perianal cryptoglandular fistulae and fistulae in Crohn's disease. When there is an external fistula opening, H2O2 can be introduced with a plastic infusion catheter. The tract then becomes visible as a hyperechoic lesion ("white"). It has been shown that this corresponds well with surgical findings. It is equally sensitive as endoanal MRI. Since recurrent cryptoglandular fistulae are complex in 50% and Crohn's fistula in 75%, it is mandatory to perform AE preoperatively in these patients to avoid missed tracts during surgery and subsequent recurrences. 3. Rectal tumors. In low tubulovillous adenomas or malignant polyps considered removable locally, confirming the local resectability (T0 or T1) is mandatory. Although larger rectal and more advanced tumours can be evaluated with AE, MRI is more sensitive in staging nodal involvement. 4. Anal carcinoma for staging. AE has been shown to stage better than the classical TNM classification for both local extension and prognosis. In conclusion, AE images the internal and external anal sphincter with high accuracy. It is easy to perform and is of particular value in the diagnosis of anal incontinence and perianal fistulae. It is excellent in staging anal carcinoma and can also be used in staging rectal carcinoma, especially very low large malignant polyps.

Contribution of the pudendal nerve to sensation of the distal rectum

Background

Anal and rectal sensory mechanisms and pudendal nerve function are important in the control of faecal continence. The contribution of the pudendal nerve to sensation of the distal rectum was investigated.

Methods

Heat thresholds in the anal canal, distal and mid rectum were measured using a specially designed thermoprobe. Rectal sensory threshold volumes were measured using the balloon distension method. Needle electrodes were inserted into the external anal sphincter. Pudendal nerve block was performed through a perineal approach, and completeness assessed by loss of electromyographic activity. Heat and rectal volume thresholds were measured again following unilateral and bilateral pudendal nerve block.

Results

The technique was successful in four of six volunteers. Bilateral pudendal nerve block produced complete anaesthesia to heat in the anal canal (P = 0·029), but had no effect on heat thresholds in the distal or mid rectum. Rectal sensory threshold volumes were also unaffected by pudendal nerve anaesthesia.

Conclusion

Anal canal sensation is subserved by the pudendal nerve, but this nerve is not essential to nociceptive sensory mechanisms in the distal or mid rectum. The transition between visceral control mechanisms in the lower rectum and somatic mechanisms in the anal canal may have functional importance in the initiation of defaecation and the maintenance of continence.

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.

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.

Rectal intussusception: characterization of symptomatology

PURPOSE

Rectal intussusception is a common finding at evacuation proctography; however, its significance has been debated. This study was designed to characterize clinically and physiologically a large group of patients with rectal intussusception and test the hypothesis that certain symptoms are predictive of this finding on evacuation proctography.

METHODS

A total of 896 patients underwent evacuation proctography from which three groups were identified: those with isolated rectal intussusception (n = 125), those with isolated rectocele (n = 100), and those with both abnormalities (n = 152). Multivariate analyses were used to identify symptoms predictive of findings by evacuation proctography.

RESULTS

The symptoms of anorectal pain and prolapse were highly predictive of the finding of isolated intussusception over rectocele (odds ratio, 3.6, P = 0.006; odds ratio, 4.9, P < 0.001) or combined intussusception and rectocele (odds ratio, 2.9, P = 0.02; odds ratio, 2.4, P = 0.03). The symptom of "toilet revisiting" was associated with the finding of rectoanal intussusception (odds ratio, 3.55, P = 0.04). Although patients with mechanically obstructing intussuscepta evacuated slower and less completely (P < 0.001) than those with nonobstructing intussuscepta, no symptom was predictive of this finding on evacuation proctography.

CONCLUSIONS

Although certain symptoms are predictive of the finding of rectal intussusception, there is a wide overlap with symptoms of rectocele, another common cause of evacuatory dysfunction. Furthermore, the observation that "obstruction to evacuation" made on proctography had no impact on the incidence of evacuatory symptoms suggests that beyond simply demonstrating the presence of an intussusception, analysis of proctography and subclassifying intussusception morphology seems of little clinical significance, and selection for surgical intervention on the basis of proctographic findings may be illogical.

External pelvic rectal suspension (the Express procedure) for full-thickness rectal prolapse: evolution of a new technique

OBJECTIVE

The Délorme's operation for rectal prolapse is a safe procedure but has a high recurrence rate. We aimed to develop an operation akin to it, but designed to reduce this deficit.

PATIENTS AND METHODS

Thirty-one consecutive patients with rectal prolapse were included in the study. Initially, a conventional Délorme's procedure was performed and sutures or strips of Gore-Tex were attached circumferentially to the apex of the prolapse, tunneled subcutaneously, and anchored to the external surface of the pelvis. Subsequently, the procedure was modified. Acellular porcine collagen strips were used and buried within the apex without plication of the denuded rectal musculature. Patients were formally assessed preoperatively and four months postoperatively by symptom and quality of life questionnaires and subsequently by regular clinical review.

RESULTS

In the Gore-Tex group (N = 11; males:females = 10:1; mean age, 61 years) three patients underwent suture repair and eight had strip fixation. All suture repairs developed sepsis and one patient had a recurrence. Seven of the strip fixations (88 percent) developed sepsis that resulted in implant extrusion. There was one full-thickness and one mucosal recurrence after a median follow-up of 25 months. In the collagen group (N = 20; males:females = 2:18; mean age, 63 years), sepsis occurred in four patients, requiring surgical intervention in one patient (5 percent) (cf Gore-Tex group, P = 0.002). There was one mucosal and three full-thickness (15 percent) recurrences after a median follow-up of 14 months (cf Gore-Tex group, P = not significant). Significant improvements in symptom and quality of life scores were recorded in both groups at four months.

CONCLUSION

A new, minimally invasive perineal procedure for rectal prolapse has been developed and initial data testify to its relative safety provided collagen is used. It remains to be seen whether long-term recurrence rates will be lower than those of conventional perineal procedures.

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.

Rectal hypersensitivity worsens stool frequency, urgency, and lifestyle in patients with urge fecal incontinence

PURPOSE

Rectal sensory mechanisms are important in the maintenance of fecal continence. Approximately 50 percent of patients with urge incontinence have lowered rectal sensory threshold volumes (rectal hypersensitivity) on balloon distention. Rectal hypersensitivity may underlie the heightened perception of rectal filling; however, its impact on fecal urgency and incontinence is unknown. This study was designed to investigate the impact of rectal hypersensitivity in patients with urge fecal incontinence.

METHODS

Prospective and retrospective audit review of all patients (n = 258) with an intact native rectum referred to a tertiary colorectal surgical center for physiologic investigation of urge fecal incontinence during a 7.5-year period. Patients with urge fecal incontinence who had undergone pelvic radiotherapy (n = 9) or rectal prolapse (n = 6) were excluded.

RESULTS

A total of 108 of 243 patients (44 percent) were found to have rectal hypersensitivity. The incidence of anal sphincter dysfunction was equal (90 percent) among those with or without rectal hypersensitivity. Patients with urge fecal incontinence and rectal hypersensitivity had increased stool frequency (P < 0.0001), reported greater use of pads (P = 0.003), and lifestyle restrictions (P = 0.0007) compared with those with normal rectal sensation, but had similar frequencies of incontinent episodes.

CONCLUSIONS

Urge fecal incontinence relates primarily to external anal sphincter dysfunction, but in patients with urge fecal incontinence, rectal hypersensitivity exacerbates fecal urgency, and this should be considered in the management and surgical decision in patients who present with fecal incontinence.

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.

Endosonography of anal canal diseases

Anal endosonography became a valuable imaging method for diagnosis of anal diseases because of its accessibility, relative simplicity of performance, and low cost. It is used most often to detect anal sphincter defects, to classify anal fistulas and perianal abscesses, and to stage anal tumors. This review presents a normal anatomy of the anal canal, examination technique, and normal endosonographic anatomy of anal sphincters. The endosonographic findings of anal sepsis, malignancy, trauma, abnormalities in Crohn disease, and ulcerative colitis, as well as the role for anal endosonography among other imaging modalities, are discussed.

General geriatrics and gastroenterology: constipation and faecal incontinence

The incidence of constipation increases with age but no consistent changes of colonic or anorectal motility have been shown in elderly people. Instead, neurological diseases, constipating drugs, bedriddenness and weak straining ability may explain this increased prevalence of constipation. The amount of dietary fibre in the diet may be reduced because of poor chewing ability. Parkinson's disease is accompanied by both slow colonic transit and impaired relaxation of the anal sphincter. Drug-induced constipation is particularly likely with anti-parkinsonism drugs (either anti-cholinergic or dopaminergic) and also with tricyclic anti-depressants, opiates, iron, anti-convulsants and aluminium- or calcium-containing antacids. The prevalence of faecal incontinence is also increased in elderly people. About half of frail bedridden institutionalized patients are incontinent. Anal sphincter pressures tend to be lower, but variables of sensitivity are not. In bedridden people faecal impaction may occur. The ensuing rectal distension leads to relaxation of the internal sphincter and hence to faecal soiling. The condition is often overlooked though correct diagnosis is rather simple, being made with a digital rectal examination.

Measurement of anal sphincter muscles: endoanal US, endoanal MR imaging, or phased-array MR imaging? A study with healthy volunteers

PURPOSE

To compare endoanal ultrasonography (US), endoanal magnetic resonance (MR) imaging, and phased-array MR imaging for anal sphincter muscle measurement.

MATERIALS AND METHODS

Sixty healthy volunteers underwent 1.5-T phased-array MR, endoanal MR, and endoanal US examinations. Sphincter muscle thicknesses were measured. Measurement reliability was analyzed, and correlations among the imaging methods were calculated. Multivariate analysis was performed to assess the influence of age, weight, height, sex, parity, and obstetric trauma on sphincter dimensions.

RESULTS

Both MR methods had good reliability for measurements of all sphincter components, whereas endoanal US was reliable for internal sphincter measurement only. There was little correlation between the techniques, except between the two MR techniques, with a strong correlation for total sphincter and perineal body thickness. The internal sphincter thickened significantly (P =.002) with age at endoanal US and endoanal MR imaging but not at phased-array MR imaging. There were small sex-based differences in sphincter muscle measurements at phased-array MR imaging only.

CONCLUSION

Endoanal US enables reliable measurement of only internal sphincter thickness, whereas both MR imaging methods enable reliable measurement of all sphincter components. Sphincter measurement with phased-array MR imaging is as reliable as that with endoanal MR imaging.

Anal sphincters defects--verification of the anal ultrasound diagnosis in 'bimanual' examination

The aim of this is to evaluate the diagnostic value of anal endosonography performed during pressing anterior wall of anal canal with a finger introduced into the lumen of vagina for the identification of anal sphincter defects. Anal ultrasound (AUS) with a finger introduced into the lumen of vagina was performed in a group of 55 women with anal sphincter defects recognized initially in standard AUS. This technique prevented false positive diagnoses of sphincter defects in 12 out of a group of 55 women (21.8%).

Endosonography for assessment of anorectal changes in patients with fecal incontinence

Our aim was to evaluate the anorectal changes in patients with fecal incontinence by using different endoultrasound techniques. Eighteen females with fecal incontinence and 14 healthy controls (females) were examined. Rigid linear transducer and 10 MHz radial scanning miniprobe were used. Statistically significant difference was found in the mean percentage of decreasing of the anorectal angle during contraction between healthy subjects (21.4%) and incontinent patients (7.5%). The mean percentage of shortening of the puborectal muscle length during squeezing was significantly lower in patients (9.6%) than in controls (17.9%). By means of miniprobe the anal sphincter defects were clearly demonstrated. Endosonography with a radial scanning miniprobe and rigid linear transducer ensures complex morphological and functional assessment of the anorectal region.

Surgical treatment of constipation and fecal incontinence

Fecal incontinence is a disabling and distressing condition. Many patients are reluctant to discuss the condition with a physician. A thorough history, good physical examination, and detailed anorectal physiologic investigations can help in the therapeutic decision-making algorithm. Patients with isolated anterior sphincter defects are candidates for overlapping repair. In the presence of unilateral or bilateral pudendal neuropathy, the patient should be counseled preoperatively regarding a [table: see text] lower anticipation of success. If the injury occurred shortly before the planned surgery and neuropathy is present, it may be prudent to wait because neuropathy sometimes can resolve within 6 to 24 months of the injury. Pudendal nerve study may help determine surgical timing. An anterior sphincter defect combined with a rectovaginal fistula can be approached by overlapping sphincter repair and a concomitant transanal advancement flap. Patients who had undergone multiple such procedures may benefit from concomitant fecal diversion at the time of repeat sphincter repair. Patients with global or multifocal sphincter injury may be candidates for a neosphincter procedure. The stimulated graciloplasty and artificial bowel sphincter are reasonable options. In the absence of the availability of these techniques or because of financial constraints, consideration could be given to bilateral gluteoplasty or unilateral or bilateral nonstimulated graciloplasty. The postanal repair still serves a role in patients with isolated decreased resting pressures with or without neuropathy or external sphincter injury with minimal degrees of incontinence. Biofeedback and the Procon device may play a role in these patients. Lastly, fecal diversion must be considered as a means of improving the quality of life because the patient can participate in the activities of daily living without the fear of fecal incontinence.

Rectal augmentation and stimulated gracilis anal neosphincter: a new approach in the management of fecal urgency and incontinence

PURPOSE

The aim of this study was the development of a procedure which would successfully treat selected patients presenting with incapacitating urgency and fecal incontinence. Some patients presenting with urgency and fecal incontinence, with an intact anorectum but deficient sphincter mechanism, have low rectal compliance. Management is problematic, because correction of the sphincter defect does not abolish the incapacitating urgency caused by rectal hypersensitivity.

METHODS

This was a prospective study of three female patients with urgency and fecal incontinence who underwent combined rectal augmentation using a segment of distal ileum and stimulated gracilis anal neosphincter. All patients had low rectal volumes and two exhibited a temporal relationship between high-amplitude (>60 mmHg) rectal pressure waves and urgency on prolonged ambulatory anorectal manometry.

RESULTS

Urgency was abolished and continence restored in all individuals. When the level of stimulation was not optimal or had been discontinued, patients experienced only passive incontinence with no urgency. Postoperative physiology revealed elevated thresholds to rectal distention and a reduction in the number of high-amplitude rectal pressure waves in all cases.

CONCLUSIONS

Combined rectal augmentation with stimulated gracilis anal neosphincter may be of benefit to some patients with distressing urgency and fecal incontinence not previously helped by current techniques.

Transperineal ultrasonography: new method to image the anorectal region

PURPOSE

The aim of this preliminary study was to present an alternative method to assess the anal sphincters by ultrasonography using a conventional ultrasound surface probe by transperineal approach.

METHODS

Transperineal ultrasonography was performed in 20 asymptomatic volunteers to assess the anal sphincters. Ultrasonographic findings were compared with conventional anal endosonography pictures available in the literature.

RESULTS

Images of the anal sphincters obtained by transperineal ultrasound were found to be similar to those produced by conventional anal endosonography. Internal and external anal sphincters were easily demonstrated in addition to mucosal and submucosal layers.

CONCLUSIONS

Transperineal ultrasonography is a new technique that enables imaging of anal sphincters and anal canal structures with potential application in functional and inflammatory anorectal disorders.

Correlation of endoanal sonography with cross-sectional anatomy of the anal sphincter

BACKGROUND

Anal endosonography has become an important imaging method in the diagnosis of anorectal disorders. However, little information exists as to whether anal endosonography reliably defines pelvic floor structures. The aim of this study was to correlate endoanal sonography with cross-sectional anatomy and histology.

METHODS

Endosonographic tomograms were obtained from 9 human cadavers before fixation and cross-sectioning at identical levels. Muscular layers were defined by visual inspection, histology, immunohistology, and morphometry using three-dimensional sphincter reconstructions.

RESULTS

Endosonography visualized only two muscular layers, whereas anatomic sections always revealed three. Comparisons revealed identical findings with regard to internal sphincter volumes and asymmetries. However, due to its failure to identify the longitudinal muscle, endosonography largely overestimated external sphincter volumes. In contrast to current beliefs, anatomic studies failed to detect striated muscle fibers within the longitudinal muscle and did not show an intersphincteric space. However, anatomic cross sections demonstrated "anterior bands" as newly described anchoring mechanisms for the anal sphincters.

CONCLUSIONS

Anal endosonography supplies accurate information with regard to internal anal sphincter dimensions, but does not reliably outline deeper muscular layers. However, despite these drawbacks, comparisons of modern imaging techniques with cross-sectional anatomy may enhance our understanding of pelvic floor anatomy.

Endosonography in benign anorectal disease: an overview

BACKGROUND

Endosonography may be used for diagnosing various anorectal disorders. This review addresses its technique and clinical use in benign anorectal disease.

METHODS

The English literature available on anal endosonography was reviewed. The different modalities, the endosonography technique itself and its value in benign anorectal disease were described.

RESULTS

Anal endosonography is easy to perform, has a short learning curve and causes less discomfort than routine digital examination. Anal sphincters can be clearly visualized and distinction is possible between the internal (hypoechoic) and external (hyperechoic) anal sphincters. Other pelvic floor structures, like the puborectalis muscle, can also be visualized. Endosonography is mostly used in the assessment of faecal incontinence; it has brought new insight into the pathophysiological mechanisms of this disorder and can select patients with traumatic incontinence for sphincter repair. It has replaced electromyographical sphincter mapping, which is a painful and time-consuming procedure. In perianal sepsis, endosonography assists in defining fistula tract anatomy. The use of contrast agents has significantly increased the accuracy of endosonography in the assessment of perianal fistulae. In addition, endosonography is an excellent alternative to expensive MRI. Besides its use in incontinence and perianal sepsis, with anal endosonography surgical possibilities can be evaluated in individual patients, for example, to decide whether a sphincter repair or a lateral sphincterectomy is preferable. Finally, endosonography may occasionally identify internal sphincter myopathy in patients with intractable constipation or proctalgia.

CONCLUSION

Anal endosonography images the internal and external sphincters with high accuracy. It is easy to perform and is especially valuable in the diagnosis of anal incontinence and perianal sepsis.

Postoperative anal canal length predicts outcome in patients having sphincter repair for fecal incontinence

PURPOSE

Controversy exists in regard to the prognostic value of clinical data and physiological tests in patients undergoing sphincter repair for fecal incontinence. The aim of this study was to identify prognostic factors.

METHODS

Between 1986 and 1996, 405 consecutive patients had a sphincter repair for fecal incontinence. Preoperative and postoperative manometric data were available on 51 of these patients, and these patients' charts were reviewed retrospectively. Preoperative and postoperative continence was scored using the four-level scale of Browning and Parks. Mean follow-up was 16.2 (median, 6; range, 1-96) months. Mean age was 41 (median, 36; range, 21-80) years, and 46 (90 percent) patients were female.

RESULTS

Twenty-three (45 percent) patients had perfect continence postoperatively, whereas 41 (80 percent) patients demonstrated improvement in continence score after sphincter repair. Using univariate analysis, various clinical and anal physiologic data were analyzed for an association with postoperative continence score. Postoperative mean resting pressure and postoperative anal canal length were both significantly related to postoperative continence (r(s)B for Spearman correlation coefficient to differentiate from r for the Pearson coefficient. = 0.442; P = 0.0012; and r(s) = 0.440; P = 0.0012, respectively), whereas postoperative mean squeeze pressure was not (r(s) = 0.273; P = 0.0529). Postoperative mean resting pressure and anal canal length were entered into a logistic regression model. Postoperative mean resting pressure was not significant (P = 0.6643), and when it was dropped from the model, postoperative anal canal length was highly significant (estimated odds ratio, 3.2; 95 percent confidence interval, 1.1-9.3; P = 0.0047) in predicting postoperative continence.

CONCLUSIONS

No preoperative data predicted functional outcome, and in contrast to other studies, postoperative anal canal length provides the best prediction of postoperative continence.

Intraobserver and interobserver agreement in anal endosonography

BACKGROUND

The aim of this study was to determine intraobserver and interobserver agreement for sonographic measurements of anal canal structures using anal endosonography (AES), and to determine interobserver agreement for the diagnosis of anal sphincter disruption.

METHODS

Fifty-one consecutive patients referred for AES for the investigation of possible sphincter abnormality were examined. Studies were reviewed by two observers who measured anal canal structures at defined levels and locations, and recorded an opinion on sphincter integrity. Repeated measurements made by each observer were compared to determine intraobserver agreement, and measurements and diagnoses were compared between observers to determine interobserver agreement.

RESULTS

Intraobserver agreement was better than interobserver agreement for measurements of anal canal structures. Interobserver limits of agreement for external sphincter measurements spanned 5 mm, whereas those for the internal sphincter spanned 1.5 mm. Interobserver agreement for diagnosis of sphincter disruption and internal sphincter echogenicity was very good (kappa = 0.80 and 0.74 respectively).

CONCLUSION

The limits of agreement for intraobserver and interobserver measurements of anal canal structures on AES have been defined. Interobserver assessment of sphincter disruption is very good.

Hydrogen peroxide-enhanced transanal ultrasound in the assessment of fistula-in-ano

Appropriate classification of the fistulous tracts in patients with fistula-in-ano may be of value for the planning of proper surgery. Conventional transanal ultrasound has limited value in the visualization of fistulous tracts and their internal openings. Hydrogen peroxide can be used as a contrast medium for ultrasound to improve visualization of fistulas.

PURPOSE

This prospective study evaluates hydrogen peroxide-enhanced ultrasound in comparison with physical examination, standard ultrasound, and surgery in the assessment of fistula-in-ano.

METHODS

Twenty-one consecutive patients (4 women; mean age, 42 years) with fistula-in-ano were evaluated by local physical examination (inspection, probing, and digital examination), conventional ultrasound, and hydrogen peroxide-enhanced ultrasound before surgery. Ultrasound was performed using a B&K Diagnostic Ultrasound System with a 7-MHz rotating endoprobe. Hydrogen peroxide (3%) was infused via a small catheter into the fistula. The results of physical examination, ultrasound, and hydrogen peroxide-enhanced ultrasound were compared with surgical data as the criterion standard. The additive value of standard ultrasound and hydrogen peroxide-enhanced ultrasound compared with physical examination was also determined.

RESULTS

At surgery, 8 intersphincteric and 11 transsphincteric fistulas and 2 sinus tracts (without an internal opening) were found. During physical examination, probing was incomplete in 13 patients, the diagnosis being correct in the other 8 patients (38%) as a low (intersphincteric or transsphincteric) fistula. With conventional ultrasound, the assessment of fistula-in-ano was correct in 13 patients (62%); defects in one or both sphincters could also be found (n = 8). With hydrogen peroxide-enhanced ultrasound, the fistulous tract was classified correctly in 20 patients, the overall concordance with surgery being 95%. The internal opening was found at physical examination in 15 patients (71%), with hydrogen peroxide-enhanced ultrasound in 10 patients (48%), and during surgery in 19 patients (90%). Secondary extensions, confirmed during surgery, were found in five cases. In two patients, a secondary extension with hydrogen peroxide-enhanced ultrasound was not confirmed during surgery. Both patients developed a recurrent fistula.

CONCLUSION

Hydrogen peroxide-enhanced ultrasound is superior to physical examination and standard ultrasound in delineating the anatomic course of perianal fistulas. It makes accurate preoperative assessment of the fistula possible and may be of value for the surgeon in planning therapeutic strategy.

Accuracy and reliability of transanal ultrasound for anterior anal sphincter injury

INTRODUCTION

Although transanal ultrasound has rapidly become the test of choice for the diagnosis of anal sphincter injury, the accuracy and reliability of this technique are unknown. This study evaluates the accuracy and reliability of transanal ultrasound for anterior (obstetric-related) anal sphincter injury.

METHODS

Sixty-two women underwent transanal ultrasound with hard-copy images obtained at 0.5-cm intervals from the anal verge to 2.5 cm into the anal canal. All transanal ultrasound procedures were also recorded on videotape. Two experienced ultrasonographers blinded as to the patients' clinical history and examination independently reviewed the images and videotape recordings for the presence or absence of anal sphincter injury.

RESULTS

The accuracy of transanal ultrasound in 22 incontinent women with known anal sphincter injury was 100 percent. The accuracy of transanal ultrasound in 20 nulliparous women with intact anal sphincters was only 35 percent but improved to 50 percent after the "real time" videotape was reviewed (P = 0.16) and further improved to 85 percent when interpretation was limited to the distal 1.5 cm of the anal canal (P = 0.004). In these nulliparous women, intact internal sphincters were more accurately predicted than intact external sphincters (95 vs. 85 percent; P = 0.24). Measurement agreement between the two ultrasonographers was 68 percent (fair; kappa, 0.26) but significantly improved to 78 percent (moderate; kappa, 0.48; P = 0.0001) when interpretation was limited to the distal 1.5 cm of the anal canal. Overall clinical agreement (final scan interpretation) was good (81 percent agreement; kappa, 0.61). Agreement was better for the internal sphincter (74 percent; fair; kappa, 0.36) than the external sphincter (61 percent; poor; kappa, 0.17; P = 0.0002).

CONCLUSIONS

Although transanal ultrasound can accurately identify anterior anal sphincter injury when present, transanal ultrasound falsely identifies sphincter injury in at least 5 to 25 percent of normal anal sphincters. Only fair agreement in the interpretation of transanal ultrasound exists between experienced ultrasonographers. Both the accuracy and reliability of transanal ultrasound are significantly improved by limiting transanal ultrasound to the distal 1.5 cm of the anal canal.

Vaginal endosonography of the anal sphincter complex is important in the assessment of faecal incontinence and perianal sepsis

BACKGROUND

Anal endosonography is an established technique in the evaluation of anorectal disease. However, it is sometimes difficult to visualize the anterior part of the sphincter complex and anal endosonography may be impossible when anal pain or stenosis is present. The aim of this study was to evaluate vaginal endosonography in the diagnosis of faecal incontinence and perianal sepsis.

METHODS

Anal and vaginal endosonography were performed in 56 women with faecal incontinence (n = 36) or perianal sepsis (n = 20). The technique and pelvic floor anatomy were described, anal sphincter measurements with anal and vaginal endosonography were compared, and the additive value of vaginal over anal endosonography in the diagnosis of faecal incontinence and perianal sepsis was assessed.

RESULTS

The pelvic floor was clearly imaged with vaginal endosonography. However, after a relatively short learning curve it was still not possible to image the anal sphincters in three of 28 patients. Except for external anal sphincter thickness, which was significantly lower, all anal canal structure measurements were greater with vaginal than with anal endosonography. Concerning the diagnosis of either faecal incontinence or perianal sepsis, vaginal endosonography added important information in comparison with anal endosonography in 14 (25 per cent) of 56 patients.

CONCLUSION

Vaginal endosonography provides reliable images of the anal sphincters in an undistorted fashion, thereby increasing the diagnostic yield of faecal incontinence and perianal sepsis in 25 per cent of patients. Therefore, endosonographists should become acquainted with this technique.

Anal endosonography and manometry: comparison in patients with defecation problems

PURPOSE

Correlations between anal sphincter function as assessed by anorectal manometry and anal sphincter anatomy measured by endoluminal ultrasound have been reported in the literature both for patients and for healthy individuals but have not been confirmed by other authors.

METHODS

For a larger series of patients (152 consecutive patients, mean age 54.1 +/- 15.5 years; female:male ratio, 111:41) with anorectal dysfunctions such as incontinence (n = 92), constipation (n = 37), and other symptoms (n = 23), diagnostic work-up included conventional multilumen anorectal manometry to evaluate internal sphincter pressure at rest, maximum external sphincter squeeze pressure during contraction, and endoanal sonography to determine anal sphincter integrity and to measure dorsal, left lateral, and right lateral diameter of the internal anal sphincter (IAS) and external anal sphincter (EAS) muscles.

RESULTS

Maximum squeeze pressure was significantly correlated to muscle thickness of the EAS (P = 0.001). No association was found between resting pressure and IAS diameter. Women had significantly lower resting and squeeze pressures than men (P = 0.008 and P = 0.003, respectively), but age-related changes of function were only found for resting pressure. Endosonographic values of IAS and EAS did not differ between genders but were significantly correlated with age (P = 0.008 and P = 0.02, respectively). Because all correlations were rather weak, they only can explain a small portion of data variance.

CONCLUSION

Anal manometry and anal ultrasound, therefore, are of complementary value and are both indicated in adequate clinical problems.

Short communication: endoanal ultrasound during contraction of the anal sphincter--improved definition and diagnostic accuracy

Endoanal ultrasound was used in the investigation of 26 patients with faecal incontinence. In each case images of the anal sphincter were taken at rest and during contraction or squeezing (dynamic). Better definition of the normal anal sphincter or anal sphincter defects was obtained in 16 (62%) of the patients with imaging during contraction. In eight of the 13 patients with a sphincter defect there was better definition of the defect and increased separation of the ends of the sphincter during contraction. Imaging during contraction improves diagnostic accuracy and is a useful adjunct with endoanal ultrasound.

Anorectal function and morphology in patients with sporadic proctalgia fugax

PURPOSE

The pathophysiology of sporadic proctalgia fugax remains unknown. This study investigates whether patients with this syndrome exhibit alterations in anal function and morphology.

METHODS

Eighteen patients with sporadic proctalgia fugax and 18 sex-matched and age-matched healthy controls were studied. Manometric studies investigated anal resting and squeeze pressures, the rectoanal inhibitory reflex, rectal compliance, and smooth muscle response to edrophonium chloride administration. External and internal sphincter thickness was measured endosonographically.

RESULTS

Patients had slightly higher (P = 0.0291) anal resting pressures (65.5 +/- 11.4 mmHg) than controls (56 +/- 9.9 mmHg). However, anal squeeze pressure, sphincter relaxation during rectal distention, and rectal compliance were similar in both groups, and no alterations were detected in external and internal anal sphincter thickness. Edrophonium chloride administration was followed by sharp postrelaxation contractions in two patients, whereas anal function remained unaltered in controls. Acute episodes of proctalgia, which occurred in two patients while under study, were associated with a rise in anal resting tone and an increase in slow wave amplitude.

CONCLUSIONS

In the resting state, patients with proctalgia fugax have normal anorectal function and morphology. However, they may exhibit a motor abnormality of the anal smooth muscle during an acute attack.

Level of highest mean resting pressure segment in the anal canal. A quantitative assessment of anal sphincter function

PURPOSE

Even with the development of new technologies, the mechanism of fecal continence is still not completely understood. This study evaluates the relative position of the highest mean resting pressure (HMRP) in the anal canal and its correlation with function in incontinent patients and in controls.

METHODS

Sixteen incontinent patients (mean age, 47.1 +/- 13.9 (range, 18-63) years; 12 female) and 16 controls (mean age, 35.4 +/- 8.7 (range, 24-58) years; 12 female) were studied using a water-perfused eight-port radial catheter computer-assisted vectromanometry. Position of the HMRP was analyzed in relation to the anal verge (D1) and to the proximal functional border of the anal canal (D2).

RESULTS

Controls had HMRP located more distally in the anal canal, because D2 was significantly higher than D1 (mean, 3.45 +/- 0.75 vs. 1.81 +/- 0.63 cm; p + 0.001). For incontinent patients, D1 and D2 were similar (mean, 1.86 +/- 0.75 vs. 2.08 +/- 1.11 cm; not significant). Comparison of the relative position of the HMRP between patients and controls showed a more proximal location for incontinent patients than controls (mean, 49.1 +/- 12.1 percent vs. 35.4 +/- 10.2 percent; p = 0.002).

CONCLUSIONS

Position of the HMRP is significantly more proximal for incontinent patients than for controls, and measurement of the distance from the anal verge to the HMRP in relation to the full length of the anal canal may represent another way to quantitatively assess anal sphincter function.

Gradient of pressure and time between proximal anal canal and high-pressure zone during internal anal sphincter relaxation. Its role in the fecal continence mechanism

PURPOSE

The normal response to rectal distention is a relaxation of the proximal anal canal (PAC). We hypothesized that this mechanism would require a gradient of pressure and time to preserve continence.

METHODS

Sixteen volunteers (10 male), mean age, 41.5 (range, 24-60) years, were studied using an eight port axial catheter with a compliant balloon at its tip. Relaxation was induced by a small volume of rectal distention (15-30 ml of air) and was recorded until recovery of resting anal pressure (RAP). Duration of relaxation was measured until recovery of RAP. Amplitude of relaxation was determined between RAP before rectal distention (RAP-BR) and pressure at the point of maximum relaxation (RAP-PMR). Gradient of pressure was determined by comparing RAP-PMR in the high-pressure zone (HPZ) and PAC. Contraction in the distal anal canal was interpreted as external anal sphincter contraction (EASC) and was compared with RAP-PMR in the HPZ.

RESULTS

Relaxation was significantly greater in PAC than in HPZ (50 vs. 36 percent; P = 0.001). RAP-PMR was significantly higher in HPZ than in PAC (30.7 vs. 12.6 mmHg; P = 0.001). EASC was observed in six patients and did not show significant difference with RAP-PMR in HPZ (39.7 vs. 36.3 mmHg; not significant). Relaxation began at the same time in all levels but lasted significantly longer in PAC compared with HPZ (13.5 vs. 9.4 sec; P = 0.003).

CONCLUSION

Anal relaxation induced by small volume rectal distention involves a gradient in the pressure and time of relaxation between PAC and the HPZ.

Endosonography of the anal sphincters in solitary rectal ulcer syndrome

Twenty-one patients with histologically proven solitary rectal ulcer syndrome (SRUS) were examined by anal endosonography (AES) in order to determine the frequency of any ultrasound abnormality. Comparison was made with a group of 17 age and sex matched asymptomatic subjects. Four patients with SRUS had anal sphincter defects on AES. All were of the internal anal sphincter (IAS), which appeared fragmented in two patients with complete rectal prolapse. Measurements of internal and external anal sphincter (EAS) diameter and cross-sectional area were taken, excluding the 4 patients with defects. The submucosa was inhomogeneous (P = 0.0016) and thickness increased in patients with SRUS (median 4.0 mm vs 2.0 mm; P < 0.0001). IAS diameter was increased (median 3.8 mm vs 2.0 mm; P < 0.0001), as was cross-sectional area (median 241 sq mm vs 112 sq mm; P < 0.0001). EAS diameter was also increased (median 8.5 mm vs 7.0 mm; P = 0.0173), as was cross-sectional area (median 905 sq mm vs 594 sq mm; P = 0.0052). The ratio of EAS to IAS thickness was reduced in patients with SRUS (median 2.6 vs 4.0; P = 0.0029). The mechanism of these changes is unclear but apparent muscle hypertrophy on ultrasound may diagnose those patients with SRUS in whom defecatory difficulty is a predominant symptom.