External Sphincter Defects Research Articles

Pudendal neuropathy and severity of incontinence but not presence of an anal sphincter defect may determine the response to biofeedback therapy in fecal incontinence.

It has been suggested that the severity of fecal incontinence, the presence of pudendal neuropathy, or an external anal sphincter defect does not preclude clinical improvement with biofeedback therapy. A discrepancy, however, is frequently found between subjective improvement and objective results after biofeedback therapy. Our aim was to assess whether severity of fecal incontinence, presence of pudendal neuropathy, or an external anal sphincter defect could influence the results of manometric parameters after biofeedback therapy in patients with fecal incontinence. Biofeedback therapy was used to treat 27 patients with fecal incontinence (25 women; mean age, 53; range, 29-74 years), according to a strict protocol. Manometry, pudendal nerve terminal motor latency, and anal ultrasound were performed in all patients before biofeedback therapy. Manometric evaluation of external anal sphincter function was performed after the biofeedback sessions. Eight of 27 patients had a good clinical response to biofeedback, but with no significant difference in their mean amplitude and duration of squeeze pressure before and after biofeedback. There was no relationship between the clinical results of biofeedback therapy and the initial severity of fecal incontinence, pudendal neuropathy, or external sphincter defect. Patients with severe incontinence (incontinence to solids) and pudendal neuropathy failed to improve the amplitude and duration of their maximum voluntary contraction after biofeedback therapy. Patients with mild fecal incontinence (incontinence to flatus, liquids, or both) (P<0.04), without pudendal neuropathy (P<0.02), or with (P<0.05) and without (P<0.05) external sphincter defect improved their external anal sphincter function after biofeedback therapy. In patients with fecal incontinence, the severity of symptoms and pudendal neuropathy should be considered as two factors of poor prognosis of favorable manometric results after biofeedback therapy. Improvement, on the other hand, may be expected after biofeedback therapy despite an external anal sphincter defect.

Three-dimensional endoanal sonography in assessing anal canal injury.

Instrument design limits endosonography of the anal canal to the axial plane, with no capability for longitudinal imaging or measurement. Using three-dimensional reconstructions, the relationship between the radial and linear extent of an anal sphincter tear has been explored, and sex differences in anal canal and sphincter length have been established. Three-dimensional reconstructions were performed in 20 controls and 24 patients with faecal incontinence found to have 25 external and five internal sphincter defects. The radial and linear extent of any sphincter tear was measured. In controls the length of the sphincters was compared with the total anal canal length, and the maximum and mean internal sphincter thickness was compared. The radial angle of an internal or external sphincter defect was significantly related to its length (R2 = 96.8 per cent and R2 = 84.4 per cent respectively; both P < 0.001). The anal canal was longer in men than in women (mean(s.d.) 32.6(5.3) versus 25.1(3.4) mm; P < 0.001). The internal anal sphincter was also longer in men (25.6(6.3) versus 19.8(4.0) mm; P < 0.02), but the mean internal sphincter length as a percentage of total anal canal length did not differ (78.3 versus 78.7 per cent; P not significant). The anterior external anal sphincter was longer in men than in women (32.6(5.3) versus 15.3(2.8) mm; P < 0.001), and formed a greater percentage of total anal canal length (100 versus 62.9 per cent; P < 0.001). Multiplanar imaging has revealed a direct relationship between the length of a sphincter tear and its radial extent as shown on axial scanning. Marked sex differences in sphincter configuration have been demonstrated. In women the shorter anterior sphincter length highlights the risk of complete sphincter disruption with extensive tears.

Results of repeat anal sphincter repair.

Patients with a poor outcome from anterior sphincter repair may be candidates for dynamic graciloplasty, artificial bowel sphincter implantation or a secondary repair. This study examines the outcome of repeat overlap repairs in these patients. Twenty-six of 235 patients undergoing a sphincter repair (median age 43 (range 23-63) years) underwent repeat repair from May 1994 to April 1997. Twenty-three patients were available for follow-up. Clinical evaluation included a satisfaction scale from 1 to 10, the patient's assessment of percentage improvement, ability to defer defaecation before and after operation, and Wexner continence scores before and after operation. Manometric studies were performed in 21 patients before and 17 patients after operation, and anal ultrasonography was undertaken in 17 patients before and 14 patients after operation. External sphincter defects were present on all preoperative scans. At a median follow-up of 20 (range 5-42) months, 15 patients felt that they were 50 per cent or more improved after operation. On the satisfaction scale of 1-10 the median score was 7 (range 1-10). There was a significant improvement in the Wexner continence score from 19 (range 17-20) before operation to 12 (range 1-20) after operation (P < 0.001). Ability to defer defaecation improved significantly from less than 5 min in all patients before operation to greater than 15 min in six patients after operation. Ultrasonography showed good overlap of the external sphincter muscle in eight of 14 patients. All patients who failed to improve showed a residual defect on ultrasonography. Repeat anterior repair produces a significant improvement in continence score and ability to defer defaecation in patients with obstetric sphincter damage. Clinical improvement correlates closely with an improvement in the appearance on endoanal ultrasonography.

Correlation of pudendal nerve terminal motor latency with the results of anal manometry.

Denervation to the external anal sphincter is commonly found in disordered defaecation. To determine whether a correlation exists between pudendal nerve terminal motor latency (PNTML) and anal manometry and what influence an external sphincter defect (ESD) has on any correlation. Sixty seven consecutive patients (23 constipated, 44 incontinent) were analysed. All had results available for PNTML and anal manometry. Anal ultrasound performed in the later part of the study period was available in 46 patients. A significant negative correlation was found between the mean PNTML and squeeze pressures (SP) for incontinent patients (r = -0.32, P = 0.037). No significant correlation was seen in constipated patients. A coexisting ESD was found in 57% of the 46 patients studied. In those without an ESD a significant negative correlation was found between mean PNTML and SP (r = -0.50; P = 0.026). No correlation was found in patients with an ESD. Age did not significantly affect the PNTML or SP results, but was associated with a reduced resting pressure (r = -0.34; P = 0.005). The PNTML was significantly correlated with SP in patients with incontinence and in the subgroup of patients without an ESD. In the assessment of disordered defaecation PNTML is therefore recommended as an adjunct to anal ultrasound.

Normal values and reproducibility of anal endosonographic measurements

Objective: Endosonographic measurements of anal canal structures are used in the description of various anorectal disorders. This study was designed to determine normal values and reproducibility of anal endosonographic measurements. Methods: Anal endosonography was performed in 40 healthy individuals (18 females, 22 males, mean age 45 (range 25–75) years). The mean internal anal sphincter thickness (IST), external anal sphincter thickness (EST), submucosal thickness (SMT) and puborectal muscle thickness (PRT) were assessed and tested for association with physiologic parameters (age, sex and parity). Furthermore, intra- and inter-observer variability were assessed for anal canal measurements and for detected sphincter defects in 19 patients with anorectal disease (ten females, nine males, mean age 53 (range 24–75) years). Results: In healthy individuals mean IST was significantly lower in males (1.3±0.4 vs. 1.8±0.8 mm, p=0.007), while mean EST was significantly lower in females (6.9±1.1 vs. 8.3±1.3 mm, p=0.001). No significant gender differences were found in mean PRT (8.2±1.9 mm) and mean SMT (2.3±0.5 mm). IST ( r=0.41, p=0.008) and SMT ( r=0.33, p=0.04) increased with age. Parity was not associated with any of the measured structures. Although at least 95% of all repeated measurements was within the limits of agreement, most reliability coefficients were relatively low. (respectively for intra- and inter-observer variability: IST r i=0.60/0.64, EST r i=0.70/0.84, SMT r i=0.65/0.62, PRT r i=0.83/0.71). Kappa values for the reproducibility of sphincter defects varied from moderate (interobserver κ=0.48; intraobserver κ=0.60) for internal sphincter defects to good or very good ( κ=0.79; κ=0.89) for external sphincter defects. Conclusion: We determined normal values of anal canal structure measurements. EST and IST are associated with gender and IST and SMT with age. The reproducibility of anal canal measurements is relatively poor, but not investigator dependent. The reproducibility of sphincter defects is good, external sphincter defects being reproduced better than internal sphincter defects.

Transvaginal versus anal endosonography for detecting damage to the anal sphincter.

We undertook this study to establish the accuracy of transvaginal endosonography for detecting damage to the anal sphincter. Anal endosonography was performed in 47 parous patients and one nulliparous patient using a sonographic scanner, an 1850 endoprobe, and a 10-MHz transducer protected by a water-filled hard plastic cone. This procedure was followed by transvaginal sonography using the same system but with a water-filled balloon in 43 and a dedicated vaginal probe Type 8551 of 10-MHz frequency in five. Axial images were obtained as low in the perineum as possible. The transvaginal images were reviewed with the observer unaware of the findings from anal endosonography and were then compared with the anal endosonograms. The transvaginal images were inadequate for review in three patients. In the remaining 45 patients, anal endosonography showed internal sphincter defects in 18 and external sphincter tears in 21. Transvaginal endosonography showed eight internal and 10 external sphincter defects only, giving a sensitivity of 44% and a specificity of 96% for the detection of internal sphincter defects and a sensitivity of 48% and a specificity of 88% for external sphincter tears. Transvaginal examination is not accurate for assessing the anal sphincter because of the anatomic limitations this approach imposes on axial imaging of the anal canal.

Investigation of fecal incontinence with endoanal ultrasound.

This study was undertaken to audit the results of endoanal ultrasound in patients with fecal incontinence. Endoanal ultrasound was used to investigate 53 patients with fecal incontinence. Data for endoanal ultrasound were collected prospectively. Results were compared with clinical and obstetric history, obtained retrospectively from case notes, and were compared with manometric and operative findings. Sphincter abnormalities were identified in 42 of 53 patients. A total of 28 anterior defects were thought to be obstetric in origin. Fourteen other defects were secondary to anal pathology or surgery. Patients with anterior external sphincter defects either had complete defects (4 patients; mean age, 31 years) or proximal defects (24 patients; mean age, 55 years). For patients with a proximal defect, 38 percent gave a history of obstetric tear, episiotomy, or forceps delivery, and the rest declared having had an apparently normal delivery. Only 50 percent had a sphincter weakness that was evident on clinical examination. Of those studied with manometry, only 21 percent had low squeeze pressures consistent with an external sphincter defect. Sphincter defects seen on ultrasound may not have a history of obstetric trauma or abnormal clinical and manometric findings. Endoanal ultrasound is recommended in all patients with fecal incontinence to detect occult sphincter defects.

Anal sphincter defects in fecal incontinence: correlation between endosonography and surgery.

Endoscopic ultrasound provides accurate information about the anatomy of the anal sphincter. The purposes of this study were to evaluate the use of flexible echo endoscopes to examine the anal sphincters, to validate the diagnosis of internal and external sphincter defects obtained using echo endoscopes by comparison with surgical findings, and to assess the outcome after surgical sphincter repair. Twenty-eight patients (13 women, 15 men, median age 50 years, range 30-83) with fecal incontinence--which was of traumatic origin in all but one (childbirth: n = 8; anorectal surgery: n = 17; biopsy of the prostate: n = 2; no trauma: n =1)--were prospectively investigated by endosonography using an echo colonoscope (n = 14) or an echo gastroscope (n = 14) (CF-UM20, GF-UM20, Olympus Optical). The location and extent of the defects of the internal or external sphincters, or both, were compared with the surgical findings in all patients. The surgical outcome was defined as excellent, improved, or unchanged. At surgery, 25 of the 28 patients had an isolated internal sphincter defect (n = 15) or combined sphincter defect (n = 10). Endoscopic ultrasound identified all of the external anal sphincter defects (n = 10), and correctly excluded a defect in 15 of 18 patients (sensitivity, specificity, and accuracy 100%, 83% and 89%, respectively). All of the internal sphincter defects (n = 25) were detected by endosonography. In three patients, a postulated intact internal sphincter was confirmed by surgery (accuracy 100%). In two patients, the extent of the sphincter defect was underestimated. Despite good visualization of the internal and external anal sphincters, as well as of the puborectal muscle in all patients, the shape, diameter, and full radial image sector (360 degrees) of the echo gastroscope made this instrument more practicable than the echo colonoscope. Nineteen of 25 patients who underwent surgery (76%) with proved sphincter defects experienced improvement, the figure reaching 87% (13 of 15) in patients who received isolated internal sphincter defect repair. Anal endosonography, even using flexible echo endoscopes, is an accurate method for identifying anal sphincter defects, and is the method of choice for preoperative sphincter mapping with special regard to internal sphincter repair, which can be carried out with excellent results.

Unsuspected sphincter defects shown by anal endosonography after anorectal surgery. A prospective study.

Anorectal surgery can lead to fecal soiling and incontinence. Whether surgery changes the anatomy and causes symptoms is unknown. Anatomic changes can be visualized by anal endosonography. We studied 50 patients after hemorrhoidectomy (24), fistulectomy (18), and internal sphincterotomy (8). Symptoms were assessed, and anal endosonography, anal manometry, mucosal electrosensitivity, and neurophysiologic tests were performed. In 23 (46 percent) patients, a defect of the anal sphincter was found (13 patients had an internal sphincter defect, 1 had an external sphincter defect, and 9 had a combined sphincter defect), 3 after hemorrhoidectomy, 13 after fistulectomy, and 7 after internal sphincterotomy. Seven patients had symptoms, and they all had a sphincter defect. In the other 16 of 23 patients (70 percent), the sphincter defect did not produce symptoms. An internal sphincter defect lowered maximum basal pressure and shortened sphincter length. Anal endosonography can reveal sphincter defects after anorectal surgery. Seventy percent of the patients in this group had no complaints; therefore, defects were unsuspected. This has clinical implications in the evaluation of patients with fecal incontinence.

Secondary surgery after failed postanal or anterior sphincter repair.

Secondary surgery after failed postanal repair or anterior sphincter repair was performed in eight female patients. After failed postanal repair in five patients, anterior sphincter plication and levatorplasty was the secondary procedure. In two patients a defect of the anterior external sphincter was corrected and in two patients an extremely thin external sphincter was augmented. This contributed to an excellent result in three and a good result in one patient. No improvement was achieved in one patient without anterior defect. After failed anterior sphincter repair in three patients, postanal repair was the secondary procedure. A good result was obtained in one patient and failure in two. Secondary surgery failed postanal or anterior sphincter repair may have a good result in the majority of patients.

Prospective study of the extent of internal anal sphincter division during lateral sphincterotomy

The aim of lateral internal anal sphincterotomy when treating anal fissure is to divide the distal one-third to one-half of the internal anal sphincter. This study aimed to evaluate prospectively the extent of disruption to the internal anal sphincter following lateral anal internal sphincterotomy and also to establish the prevalence of symptoms of anal incontinence in these patients. Fifteen patients with anal fissure (ten females and five males) had bowel symptoms assessed and anal endosonography performed preoperatively and two months after lateral internal anal sphincterotomy. Anal endosonography was normal preoperatively in all but two females who had anterior external sphincter defects (presumedly from previous obstetric trauma). Postoperatively, apart from one male in whom no defect could be identified, all had an internal anal sphincter defect corresponding to the site of lateral internal anal sphincterotomy. In nine of the ten females, the defect involved the full length of the internal anal sphincter, but in the other four males, the defect involved the distal internal anal sphincter only. All were continent preoperatively, but after lateral internal anal sphincterotomy, three females became incontinent to flatus (two of whom had a preoperative external sphincter defect). In contrast to lateral internal anal sphincterotomy in males, division of the internal anal sphincter in most females tends to be more extensive than intended. This is probably related to their shorter anal canal. In some females, lateral internal anal sphincterotomy may compromise sphincter function and precipitate anal incontinence, particularly in the presence of other sphincter defects. Care should be exercised especially in the presence of previous obstetric trauma, as internal anal sphincter division may further compromise sphincter function.

Third degree obstetric anal sphincter tears: risk factors and outcome of primary repair.

To determine (i) risk factors in the development of third degree obstetric tears and (ii) the success of primary sphincter repair. (i) Retrospective analysis of obstetric variables in 50 women who had sustained a third degree tear, compared with the remaining 8553 vaginal deliveries during the same period. (ii) Women who had sustained a third degree tear and had primary sphincter repair and control subjects were interviewed and investigated with anal endosonography, anal manometry, and pudendal nerve terminal motor latency measurements. Antenatal clinic in teaching hospital in inner London. (i) All women (n = 8603) who delivered vaginally over a 31 month period. (ii) 34 women who sustained a third degree tear and 88 matched controls. Obstetric risk factors, defecatory symptoms, sonographic sphincter defects, and pudendal nerve damage. (i) Factors significantly associated with development of a third degree tear were: forceps delivery (50% v 7% in controls; P = 0.00001), primiparous delivery (85% v 43%; P = 0.00001), birth weight > 4 kg (P = 0.00002), and occipito-posterior position at delivery (P = 0.003). No third degree tear occurred during 351 vacuum extractions. Eleven of 25 (44%) women who were delivered without instruments and had a third degree tear did so despite a posterolateral episiotomy. (ii) Anal incontinence or faecal urgency was present in 16 women with tears and 11 controls (47% v 13%; P = 0.00001). Sonographic sphincter defects were identified in 29 with tears and 29 controls (85% v 33%; P = 0.00001). Every symptomatic patient had persistent combined internal and external sphincter defects, and these were associated with significantly lower anal pressures. Pudendal nerve terminal motor latency measurements were not significantly different. Vacuum extraction is associated with fewer third degree tears than forceps delivery. An episiotomy does not always prevent a third degree tear. Primary repair is inadequate in most women who sustain third degree tears, most having residual sphincter defects and about half experiencing anal incontinence, which is caused by persistent mechanical sphincter disruption rather than pudendal nerve damage. Attention should be directed towards preventive obstetric practice and surgical techniques of repair.

Anal-Sphincter Disruption during Vaginal Delivery

Lacerations of the anal sphincter or injury to sphincter innervation during childbirth are major causes of fecal incontinence, but the incidence and importance of occult sphincter damage during routine vaginal delivery are unknown. We sought to determine the incidence of damage to the anal sphincter and the relation of injury to symptoms, anorectal physiologic function, and the mode of delivery. We studied 202 consecutive women six weeks before delivery, 150 of them six weeks after delivery, and 32 with abnormal findings six months after delivery. Symptoms of anal incontinence and fecal urgency were assessed, and anal endosonography, manometry, perineometry, and measurement of the terminal motor latency of the pudendal nerves were performed. Ten of the 79 primiparous women (13 percent) and 11 of the 48 multiparous women (23 percent) who delivered vaginally had anal incontinence or fecal urgency when studied six weeks after delivery. Twenty-eight of the 79 primiparous women (35 percent) had a sphincter defect on endosonography at six weeks; the defect persisted in all 22 women studied at six months. Of the 48 multiparous women, 19 (40 percent) had a sphincter defect before delivery and 21 (44 percent) afterward. None of the 23 women who underwent cesarean section had a new sphincter defect after delivery. Eight of the 10 women who underwent forceps delivery had sphincter defects, but none of the 5 women who underwent vacuum extractions had such defects. Internal-sphincter defects were associated with a significantly lower mean (+/- SD) resting anal pressure (61 +/- 11 vs. 48 +/- 10 mm Hg, P < 0.001) six weeks post partum, and external-sphincter defects were associated with a significantly lower squeeze pressure (increase above resting pressure, 70 +/- 38 vs. 44 +/- 13 mm Hg; P < 0.001). There was a strong association (P < 0.001) between sphincter defects and the development of bowel symptoms. Occult sphincter defects are common after vaginal delivery, especially forceps delivery, and are often associated with disturbance of bowel function.

Anal Sphincter Defects Correlation Between Endoanal Ultrasound and Surgery

This study was performed to (1) correlate and sphincter defects, identified by endoanal ultrasound with operative findings, and (2) define the appearance of such sphincter defects as seen at operation. Endoanal ultrasonography is a minimally invasive method of imaging the anal sphincter complex and enables identification of anal sphincter defects. Little is known about the accuracy and limitations of endoanal ultrasound in identifying such defects. Furthermore, there are no data about the appearances of these endosonic sphincter defects as seen at operation. Forty-four patients (40 women; age range, 26 to 80 years; mean age, 56 years) with fecal incontinence, undergoing pelvic floor repair, were investigated by endoanal ultrasound before operation. Endosonic findings were correlated with the appearances of external anal sphincter, internal anal sphincter, and intersphincteric space, at operation. Diagnosis of the site and type of defect was made by macroscopic appearances. Uncertainty about the type of sphincter defect was resolved by obtaining muscle biopsies for histology. All external sphincter defects seen by endoanal ultrasound (n = 23) were confirmed at operation. Twenty-one of 22 internal sphincter defects identified by endosonography also were confirmed at operation. In ten patients with a neuropathic anal sphincter complex, the morphology was normal on endosonography, and this was confirmed at operation. (Sensitivity and specificity of 100% for external anal sphincter; 100% and 95.5%, respectively, for internal and sphincter) These data show that endoanal ultrasound is an accurate method of identifying anal sphincter defects.

Risk of sphincter damage and anal incontinence after anal dilatation for fissure-in-ano. An endosonographic study.

Follow-up was performed two to six years after anal dilatation for fissure-in-ano in 32 consecutive patients who had not undergone additional anal surgery. All patients were interviewed and asked specifically about impairment of flatus or fecal control and its possible relation to the anal dilatation. Anal dilatation was followed by minor anal incontinence in 12.5 percent of the patients. Anal endosonographic follow-up was accepted by 20 patients, and sphincteric defects were found in 13 (65 percent) of those. Two patients with anal incontinence had internal sphincter defects. Sphincteric defects were also found in 11 of the 18 continent patients who underwent sonography: internal sphincter defects in nine, external sphincter defect in one, and combined defects of both sphincter muscles in one. In conclusion, anal dilatation results in sphincter damage in more than half of patients, but few of them develop anal incontinence.