In the lying position, one-third showed dyssynergia and one-half could not expel artificial stool. Whereas when sitting with distended rectum, most showed normal defecation pattern and ability to expel stool. Thus, body position, sensation of stooling and stool characteristics may each influence defecation. Defecation is best evaluated in the sitting position with artificial stool.

This study represents the most comprehensive age- and gender-controlled assessment of anorectal function using solid state technology. Gender influences some parameters of anorectal function. Our results could serve as a valuable resource of normative data.

Background-Ingestion of a meal stimulates colonic motility. It is unclear whether the nutrient composition of a meal aVects colonic motor response. Aims-To investigate and compare the eVects of a predominantly fat or carbohydrate meal on colonic motility. Methods-In 18 healthy subjects, ambulatory colonic manometry was performed by placing a six sensor, solid state probe from the mid-transverse colon to the rectum. In a randomised, crossover design, 10 and 27 hours after probe placement, subjects received 4.18 MJ meals containing 60% calories from fat or carbohydrate sources. Preprandial and postprandial pressure activity and motor patterns were evaluated. Results-Both meals induced phasic activity with a greater area under the curve (p<0.03) in the first postprandial hour, compared with the control period. Fat induced motor activity persisted longer (p<0.05) than that of the carbohydrate meal, but the onset of motor response was slower (p<0.001). Although both meals induced more (p<0.001) propagating pressure waves, only the fat meal induced more (p<0.05) simultaneous and retrograde waves. After both meals, 50% of subjects exhibited high amplitude (more than 103 mm Hg), prolonged duration (more than 13 seconds) propagating waves. Both meals induced greater activity (p<0.05) in the transverse/descending colon than in the rectosigmoid colon. Conclusions-Carbohydrate meals induce colonic motor response, but the eVects are short lived when compared with fat meals. The prolonged, segmental, and retrograde phasic activity induced by the fat meal may delay colon transit. Thus meal composition influences colonic motor response.

OBJECTIVE: To conduct a prospective audit of all patients presenting with anal fistula at St. Mark's Hospital during one calendar year and to compare the presentation and outcome of this cohort with previous reports from this institution. PATIENTS AND METHODS: All patients undergoing examination under anaesthetic (EUA) for anal fistula during 1997 were studied. All fistulae were anatomically classified and operative procedures recorded. During a mean follow-up period of 14 months details of healing, recurrence and function were gathered. RESULTS: 98 patients with a mean age of 43.7 years were assessed. 86 (88%) patients had fistulae of cryptoglandular (idiopathic) origin. Fistulae were superficial in 11 (11%) patients, intersphincteric in 30 (31%) patients, trans-sphincteric in 52 (53%) patients, suprasphincteric in 3 (3%) patients and extra-sphincteric in 2 (2%) patients. 49 (50%) fistulae were classified as complex. Eradication of fistulae with preservation of function was achieved in 89 (91%) patients. Fistula recurrence occurred in 4 (4%) cases. Ten (10%) patients had some degree of incontinence, 9 (9%) of whom had undergone previous fistula surgery. Nine (9%) patients still had setons in situ at the end of the follow-up period. CONCLUSIONS: A greater proportion of difficult fistulae was seen during the year compared with previous studies from St. Mark's. Despite this a satisfactory outcome was achieved in the vast majority with a relatively low rate of disturbed function. Previous fistula surgery is a risk factor for incontinence, which can usually be managed conservatively.