Hypothesis / aims of study
Faecal incontinence (FI) is a common problem, with an important impact on quality of life. The aetiology of FI in multifactorial and not completely understood. Several systems have been developed for classifying FI, including system based on pathophysiology (bowel disturbances, anorectal dysfunctions), type of leakage (urge, passive or combined), isolated or combined with obstructive defaecation symptoms (ODS), or symptom severity scale (1,2). There is also a variation in approaches to diagnosis and among pelvic floor tests available, no one seems to be superior to the others and able to drive patients’ treatment (3). The aim of this study was to assess symptoms related to FI among patients referred to a tertiary referral centre for pelvic floor disorders and correlate them with diagnostic tests.
Study design, materials and methods
Patients referred to our pelvic floor unit with various degree of faecal incontinence as a main complaint and underwent to pelvic floor tests over a period of 4 years (2013-2017) have been included. All patients underwent a dedicated telephone triage assessment clinic (TTAC), where symptoms severity scores were assessed and completed using ICIQ-BS (International Consultation on Incontinence Modular Questionnaire-Bowel Symptoms) and St Mark’s faecal incontinence grading system. All patients had comprehensive anorectal physiologic tests with rectum unprepared. The following tests have been done:
1. Station pullthrough anal manometry with a water-perfused catheter system. This provided measurements of anal resting tone (lower limit of normal 50 cmH2O) an anal squeeze increment pressures (lower limit of normal 50 cmH2O).
2. Assessment of rectal sensation. Three sensory thresholds were determined via ramp distension of a latex balloon positioned 10 cm from the anal verge: threshold volume (upper limit of normal, 150 mL); defaecatory desire volume (upper limit of normal, 190 mL); and maximum tolerable volume (MTV; lower limit of normal 80 mL, upper limit of normal 320 mL). Subjects were stratified as having rectal hyposensitivity (RH) when 1 or more sensory thresholds were greater than normal, or for rectal hypersensitivity when MTV was lower 80 mL. All subjects in between were defined as having normal rectal sensation.
3. Endoanal ultrasound two transducer, one sagittal and one axial). The internal and external anal sphincters were categorized as intact or abnormal by two independent reviewers.
4. Evacuation proctography. A standard mixture of porridge oats, water, and barium, with similar consistency to soft stool, was instilled using a calibrated large syringe into the unprepared rectum to a maximum of 180 mls. Patient was then transferred to a commode and defaecation assessed under fluoroscopy. Complete defaecation was defined as ≥ 90% of instilled past expelled, subjects repeated the evacuation attempts three times if unable to empty at first attempt with additional manoeuvres, like vaginal splinting for women. Grading of intussusception has been reported according to Oxford internal rectal prolapse grading system. Low grade are grade I (descent to proximal limit of rectocoele) and grade II, descends into the level of rectocoele (but not onto the anal canal). High grade of intussusception are grade III (descents onto anal canal), grade IV (descents into anal canal). External rectal prolapse is grade V, with prolapse protrudes from the anus. Rectocoele has been defined as an outpouching of the rectal wall on defaecation and measurements have been calculated as the distance between the maximal anterior out bulge and the extrapolated line of the anterior rectal wall.
A total of 574 patients have been assessed in our tertiary referral pelvic floor unit between 2013 and 2017. There were 16% males and 84% females. The mean age at presentation was 57 years old (Male median age 55, range 17-85; Female, median age 58, range 20-93).
81% had pelvic floor tests, out of which 98% had endoanal US, 97% had anorectal manometry and rectal sensation assessed and 82% had proctography. Results of endoanal ultrasound, anorectal manometry and rectal distension are summarized in table 1.
On endoanal ultrasound, 21% females and 32% males had internal anal sphincter defect; 40% of females and 7% of males had external anal sphincter defect.
On anorectal manometry, low resting pressure was present in 65% females and 35% males (p<0.05). Low incremental squeeze pressure has been detected in 67% females and 43% of males (p<0.05). Rectal distension has highlighted the following values in term of hypersensitivity 32% for females and 17% for males. Hyposensitivity as present in 13% of females and 27% of males.
There was a significant association between the number of vaginal deliveries and having low resting pressures on the anorectal manometry test. There was also significant association between the low squeeze pressures and the history of a traumatic instrumental vaginal delivery that was observed in 52% of women. 75% of patients with an abnormality of the external anal sphincter on EAUS had low resting pressure on the manometry (p<0.05). On the contrary, there wasn’t a significant association between the anatomical internal anal sphincter defect on EAUS and the presence of low resting pressure.
On proctography, 66% had low grade intussusception (Oxford grade I-II, 67% females and 63% males), 22% had moderate grade o intussusception (Oxford grade III, 23% female and 20% male), high grade of intussusception was 9% Oxford grade IV (9% female and 12% male) and 3% Oxford grade V (2% female and 4% male). Women with small and physiological rectocoele (less than 2 cm) was reported in 46%, moderate (2-3 cm) in 35% and large (≥ 4 cm) in 19%. Leakage of paste at rest was observed in 51% (55% in women, 26% in men, p<0.05), while an anismic pattern in 11% (33% in men, 8% in women, p<0.05).
There was no significant association between moderate or high grade intussusception on proctography and ODS. On the contrary, we found have found that rectocoeles larger than 4 cm were correlated with ODS (41%, p<0.05). There wasn’t a significant association with the number of vaginal deliveries and the risk of having a large rectocoele.
Interpretation of results
The aetiology and characteristics of FI are different between males and females. The incidence of external anal sphincter abnormalities was greater in women, and this was associated with lower resting anal sphincter pressures. Women have significantly more hypersensitivity on rectal sensation test and leakage at rest on proctography. On the contrary, males have higher presence of internal anal sphincter defect on EAUS, more hyposensitivity on rectal distention and are more anismic on proctography. This information can help tailor individual treatment options.