Achieving enteric continence: principles and applications

Fatigue rate index as a new measurement of external sphincter function

PURPOSE

Assessment of sustained voluntary contraction of the external sphincter is helpful in evaluating the patient who has a defecation disorder on presentation. A new index of external sphincter function is described.

METHOD

A prospective registry of patients referred for computerized anal manometry using standard protocols was reviewed. Patients were grouped by primary symptoms; those with overlapping complaints were excluded. The rate of fatigue, defined as the change in stationary squeeze over a 40-second period of voluntary contraction, was calculated by linear regression analysis. Fatigue rate index, a calculated measure of time necessary for the external sphincter to become completely fatigued, was determined to permit comparison of external sphincter fatigue in patients with different complaints.

RESULTS

Twenty-six healthy volunteers (15 women; mean age, 45 years), 33 patients with a primary complaint of anal seepage (13 women; mean age, 53 years), 75 patients with gross incontinence (61 women; mean age, 53 years), and 49 patients with severe constipation (41 women; mean age, 45 years) were evaluated. Mean resting and squeeze pressures were 55 mmHg and 107 mmHg for volunteers, 37 mmHg and 97 mmHg for patients with seepage, 30 mmHg and 49 mmHg for incontinent patients, and 56 mmHg and 93 mmHg for constipated patients. Pudendal neuropathy, as evidenced by a prolonged pudendal nerve terminal motor latency (> 2.4 ms), was identified in 13 percent of volunteers, 32 percent of patients with seepage, 54 percent of incontinent patients, and 38 percent of constipated patients. Mean fatigue rate index was 3.3 minutes for volunteers, 2.3 minutes for seepage patients, 1.5 minutes for incontinent patients, and 2.8 minutes for constipated patients. Compared with volunteers and patients with seepage, the incontinent patients had a significantly shorter fatigue rate index (P < 0.05; Student's t-test), which was independent of the variations in resting pressure (P < 0.05; two-way analysis of variance).

CONCLUSION

The external anal sphincter is normally subject to fatigue. Patients with worsening degrees of incontinence have a predictably lower fatigue rate index. Fatigue rate index is a simple measure of external sphincter integrity, which may be used in assessment of sphincter function and future treatment protocols.

Factors influencing bowel function following total abdominal colectomy

PURPOSE

The purpose of this study was to determine which factors influenced bowel function following total abdominal colectomy.

METHODS

Thirty-two patients who had undergone total abdominal colectomy were studied with regard to factors that are classically thought to influence bowel function, namely, residual stump length, transit time, and rectal stump manometry. In a limited subset of patients, anal manometry was done also.

RESULTS

Transit time was the best predictor of bowel function following total abdominal colectomy. This was followed by stump length. If transit time was short, then stump length became important in predicting the occurrence of diarrhea following total abdominal colectomy.

CONCLUSIONS

Two factors have an important influence on bowel function following total abdominal colectomy: transit time and rectal stump length. Rectal stump length is an anatomic factor that can be controlled by the surgeon. In total abdominal colectomy, rectal stump length of at least 20 cm is necessary if the patient is to have satisfactory postoperative bowel function. This may not always be possible. In these patients, modification of diet to influence transit time and methods to increase rectal compliance will be necessary.

Simple radiographic evaluation of ileoanal pouch volume

PURPOSE

Total colectomy and mucosal protectomy with ileal reservoir and anal pull-through is used in the treatment of ulcerative colitis or familial polyposis, with one complication being frequent bowel movements. A simple radiographic test to predict frequency of bowel movements and measure spasticity was evaluated.

METHODS

Fourteen patients underwent evaluation after ileal reservoir and anal pull-through J-pouch construction. Barium sulfate suspension was instilled into the pouch via the anus in the standing position until reflux flowed into the small intestine proximal to the pouch and patients felt the urge to defecate. Total volume infused (VOLtot), volume to reflux (VOLrflx), and volume voided (VOLvoid) were measured.

RESULTS

VOLvoid and the "voiding efficiency" (VOLvoid/VOLtot) correlated significantly with stool frequency (R=-0.744, P<0.002 and R=-0.754, P<0.002, respectively). Time from operation was correlated with VOLvoid and stool frequency (R=-0.723, P<0.003 and RO.573, P<0.032, respectively).

CONCLUSIONS

The addition of quantitative measurements to this radiographic test gives useful information about pouch performance. Furthermore, the data imply that spasticity, as measured by voiding quantum and efficiency, rather than actual pouch volume is a major determinant of bowel movement frequency.

Physiology of ileal pouch-anal anastomosis. Current concepts

PURPOSE

Increasing experience with ileal pouch-anal anastomosis (IPAA) associated with increasing knowledge about anorectal physiology has lead to a large number of publications. The purpose of this review is to evaluate the current understanding of fecal continence as revealed by the evolution of the ileoanal procedure.

METHODS

Review of the literature covering the most important physiologic parameters involved in fecal continence was undertaken.

RESULTS

Rectoanal inhibitory reflex is probably absent after IPAA but is preserved when distal anorectal mucosa is spared. Anal resting pressure decreases but is less affected when the internal anal sphincter is less traumatized. Squeeze pressure is not importantly affected, and the importance of reservoir function as a determinant of stool frequency is emphasized. IPAA does not affect the coordination between pouch and anal canal motility in the majority of cases. Normal continence is preserved, even during the night, by preserving a gradient of pressure between the pouch and anal canal.

CONCLUSIONS

Physiologic concepts are well established, but controversies about the continence mechanism related to IPAA remain. The IPAA procedure has allowed discrimination of details about the function of multiple structures involved in fecal continence.

The two-chamber ileal pelvic reservoir--an alternative design

A new ileal pouch design, combining an upper triplicate ileum with a lower duplicate ileum, is described. The physical characteristics of this two-chamber reservoir would lead to better functional results by delaying the filling time of the reservoir.

Contribution of imaging to the understanding of the female pelvic fasciae

According to the ultrasound and MRI findings, supported by planned dissections, the female perineum is organised around the musculofascial system converging towards the fibrous structure of the central perineal tendon (CPT). Behind the CPT the fascial layers form part of a fibrous assembly extending from the ventral surface of the sacrum to the anal complex, prolonging the direction of the sacral concavity downwards and forwards. On the other hand, in front of the CPT the fasciae fuse to form two aponeurotic bands circumscribing the urogenital fossa. The fascial system is reinforced cranially by the structures of the hypogastric sheath and the uterosacral ligaments. The weak point of the urogenital fossa is partly filled by the urethral-clitoridal-vulvar complex. The perineum so formed plays a cardinal role in stabilising the pelvic viscera. Stress is placed on the firmness of the posterior perineum, a key element in pelvic stability. The posterior perineum is often involved in pathological conditions and a good acquaintance with these structures is essential in defining therapeutic indications.

The effect of stool consistency on rectal and neorectal emptying

Although stool consistency is considered to be an important component of anorectal continence, its effect on rectal emptying has never been quantitated. In 12 healthy volunteers and 12 patients after ileal pouch-anal anastomosis (IPAA) (46 +/- 5 months after the operation; mean +/- SEM), perfused anal manometry was performed; movements of the anorectal angle were quantitated scintigraphically; and rectal capacity and compliance were measured by air insufflation of an intrarectal balloon at three infusion rates. The efficiency of rectal evacuation of three consistencies (5 percent, liquid; 7.5 percent semisolid gel; 11.25 percent solid gel; w/w) of Tc99m labeled artificial stool (aluminum magnesium silicate gel) was quantitated by gamma camera imaging. No abnormalities of pelvic floor function were demonstrated in either controls or patients. The mean neorectal capacity and compliance of patients with IPAA did not differ from control, (capacity; IPAA: 215 +/- 22 ml vs. control; 245 +/- 29 ml; compliance; IPAA: 5.5 +/- 0.7 ml/cm H2O vs. control; 6.6 +/- 0.7 ml/cm H2O; P greater than 0.05). In controls, the percentage of the 7.5 percent consistency evacuated (81 +/- 5 percent, mean +/- SEM) was significantly more than the percentage evacuation of either the 5 percent consistency (67 +/- 7 percent) or the 11.25 percent consistency (77 +/- 2 percent) (P less than 0.05). After IPAA, the mean overall percent evacuation of the three stool consistencies was significantly less than control (52 +/- 6 percent after IPAA; 75 +/- 5 percent control, P less than 0.05). However, there was no significant difference in neorectal emptying between the liquid, the semisolid gel and the solid gel (56 +/- 6, 55 +/- 6, 51 +/- 9 percent, respectively, P greater than 0.1). We concluded that in healthy subjects but not in patients after IPAA, stool consistency affected the efficiency of evacuation of enteric content.

Scintigraphic assessment of the anorectal angle in health and after ileal pouch-anal anastomosis

To determine whether the anorectal angle was preserved after ileal pouch-anal anastomosis, a simple, safe, low-radiation, real-time method of imaging the anorectum was developed. A cylindrical balloon was placed in the neorectum and anal canal and filled with a solution of 99mTc in water. A gamma camera then imaged the angulation of the balloon while the subject was at rest, during sphincteric squeeze, and during a Valsalva maneuver. Thirteen healthy volunteers and six patients were studied after ileal pouch-anal anastomosis. An angle was identified in all controls and patients. In the lateral decubitus position at rest, the mean anorectal angle in controls (102 +/- 18 degrees; SD) and anopouch angle in patients (108 +/- 19 degrees) were similar (p = 0.3). Sitting straightened the angle in both groups (p less than 0.03), whereas sphincteric squeeze and a Valsalva maneuver sharpened the angle in both the sitting and standing positions (p less than 0.03). In the lateral decubitus position, however, the pouch group was less able to sharpen the angle than were the controls (p = 0.04). In controls, the anorectal junction descended during sitting and elevated during squeeze (p less than 0.03), but this did not occur in the pouch group. In conclusion, maneuvers favoring or stressing continence (squeeze, Valsalva) sharpened the anorectal angle and elevated the pelvic floor, whereas a maneuver favoring defecation (sitting) straightened the angle and caused the pelvic floor to descend. After ileal-anal anastomosis, the angle and its movements (except those while lying) were similar to controls. Elevation of the pelvic floor during squeeze, however, was decreased, indicating a decreased mobility of the pelvic floor after operation.

[Intrapelvic reservoir with direct anal anastomosis]

To reduce the frequency of bowel movements following colectomy and proctomucosectomy today three major types of ileoanal reservoirs are in use: the S-, J- and H-pouch. Approximately 2000 such operations have been performed throughout the world. Although only one postoperative death has been recorded, postoperative morbidity remains high. Our own results as well as a review of the literature confirms: 1) satisfactory sphincter control on continence; 2) retained discrimatory sensitivity; 3) reduction of daily bowel movements 4-7; 4) social rehabilitation. The difficulties of the procedure call for the referral of patients to centers specializing in these techniques.

Enteric continence and the ileal pouch-anal procedure

The ileal pouch-anal procedure maintains enteric continence by preserving critical physiological mechanisms. The reservoir, although possessing somewhat different physiologic characteristics than the rectum, provides sufficient storage capacity to enable the patient to resume most daily activities. The intact anorectal angle continues to perform its pivotal role in the maintenance of gross fecal continence, while the functioning anal sphincter muscles fine-tune the system. The success of the procedure has shown that certain widely held "principles" of continence may be less important than previously believed. These include the requirement for a long rectal stump, the preservation of the rectosphincteric inhibitory reflex, and the maintenance of sensation to the upper half of the anal canal. Yet, results are not perfect, and it is possible that while these mechanisms are not required for gross fecal continence, their transgression results in a subtle reduction in function from that of the normal state. When one considers, however, that the only other curative procedure for patients with familial polyposis is total proctocolectomy with permanent ileostomy, the ileal pouch-anal operation represents an important advance. The disease is removed, yet reasonably effective control of enteric continence is restored such that quality of life appears to be enhanced when compared to that achieved after proctocolectomy and Brook ileostomy.