Hypothesis / aims of study
Identify and characterize the main manometric and ultrasonographic variations presented by patients diagnosed with anal incontinence. Once identified, correlate these findings to recognize risk factors for fecal incontinence in order to work towards prevention. In case incontinence is already present, employ a specific treatment strategy.
Study design, materials and methods
We conducted a descriptive retrospective study gathering data from electronic files of patients diagnosed with fecal incontinence. Between March 2017 to June 2018. Exclusion criteria include patients diagnosed with inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), individuals with rectal or anal canal tumors and patients with congenital or neurological diseases. We look for past history of pelvic floor, anorectal or spinal surgeries, as well as comorbidities such as diabetes mellitus and arterial hypertension. The study was carried out using a Bk medical 400 device, with a 2250 endoanal transductor, 8830 perineal transductor and a 24-channel MMS HR manometry equipment. Statistical analysis, was performed with the statistical package SPSS version 24 (IBM Corp Amonk, NY).
A total of 82 patients were included. 60% were females, 50% had no surgical history, only 4.8% reported previous anorectal surgery, hemorrhoidectomy and fistulotomy being the most frequent procedures. Regarding the loss of continuity in the sphincteric complex; 44% show a defect in the EAS and 46% in the IAS. The most common site of injury was on the posterior wall in 12.19% for the IAS and 11.89% for the EAS, followed by multifragmented lesion in 8.75% and 10%, respectively. Transperineal ultrasonography was performed in 25% of our patients with anal incontinence concomitant with rectal prolapse and cystocele, or a combination of both (70% of the patients). High resolution anal manometry was performed in all patients. 33% showed rectal hypersensitivity, 18% hyposensitivity and 48% had normal findings. One patient showed high resting anal pressures.
A Pearson correlation coefficient was used in endoanal ultrasound and manometry results, finding a significant correlation in patients with alteration in the resting pressure - squeeze, rest - dyssynergia and sensitivity - alteration of the EAS with p = 0.001.
Interpretation of results
Anal incontinence, rather than a single disease, represents a clinical spectrum with diverse manifestations closely related to its wide etiology. It´s a relatively common disorder, which has a major impact on patient´s quality of life. With an incidence of 1 to 7.4% in healthy people. Present predominantly in women. Several risk factors have been identified in anal incontinence pathophysiology, being perhaps the most important ones central nervous system disorders, such as cerebrovascular events, multiple sclerosis, parkinson's disease, spinal cord injuries, autonomic nervous system disorders due to diabetes, ageing, intestinal diseases such as irritable bowel syndrome and inflammatory bowel disease, non-intestinal and intestinal pelvic surgeries, and radiation, among others. Although, most of our patients didn’t have recognizable risk factors.
Only in a minority of cases the cause-effect relationship is clear, as in patients following anorectal surgery. Temporal relationships in most patients are not so evident (e.g. developing symptoms several years after an uneventful vaginal delivery due to a hidden spinchter injury), in which association between the event and the onset of symptoms is less clear, and probably represents just one component of a multifactorial etiology.
Continence is a highly complex physiological function that requires coordination between the brain, the central nervous system, the autonomic and enteric systems as well as an appropriate biomechanical characteristics of the gastrointestinal tract by the hand of an adequate sphincter complex function.
Anal incontinence is a multifactorial disorder of high complexity that demands the adequate and complete knowledge, not only of the pelvic floor, but also of the multiple components involved in the continence system as well as the methods and strategies of diagnostic approach to which we should go to, in order to offer our patients the best alternative to reduce their discomfort and improve their quality of life as much as possible.
The most frequent aetiology for incontinence, according to Pinsk et al, is obstetric injury, followed by lesion secondary to anorectal surgery (46% of hemorrhoidectomies, 27-50% of lateral internal sphincterotomies and 60% of fistulotomies) .
Being a relatively common clinical problem that significantly affects the quality of life of patients, the diagnostic approach is vital for the individualized treatment. Any attempt at managing anorectal disorders such as fecal incontinence, requires a clear understanding of the anatomy and physiologic mechanisms responsible for continence, for which, diagnostic tests like endoanal and transperineal ultrasonography and high resolution anal manometry are helpful, for diagnostic purposes, as well for treatment planning.
There is no correlation in most cases between injury of the sphincter complex and manometric alterations, and fecal incontinence is sometimes associated with alterations in rectal sensitivity.
Rectal sensation assessment should be regarded as one of the most useful parameters, because variations in rectal sensation measured under treatment can be of help in the evaluation of therapeutic effectiveness.
This shows the complexity of the problem and the need for a detailed multidisciplinary approach, in which studies of pelvic floor physiology are imperative, helping us dictate the best behavior to follow between different treatment modalities and their best suitable combinations (surgical repair, surgical augmentation, electrostimulation, biofeedback, etc.).