Pelvic floor surgery for the colorectal surgeon

Introduction

Pelvic floor pathology is multifactorial and often multi-compartmental. Pelvic floor dysfunction includes pathology of the anterior, middle and posterior pelvic floor compartments. Posterior pelvic floor pathology includes defaecatory dysfunction with obstructed defaecation (evacuatory difficulties with or without concomitant faecal incontinence) and rectal prolapse.

Pelvic floor defaecatory dysfunction may be caused by anatomical pathologies (rectocele, intussusception, enterocoele, sigmoidocele, rectal prolapse, perineal descent), functional abnormalities (dyssynergy, poor coordination, poor propulsion) or both. Pelvic pain, bowel motility disorders and psychological contributors are also implicated. Patients primarily presenting with bowel related complaints may also have concurrent vaginal and urinary symptoms.

All aspects must be addressed and treatment of urogynaecological pathology in isolation is likely to have an adverse impact on defaecatory function, and vice versa. Careful assessment and treatment planning in a multi-disciplinary team meeting and dedicated pelvic floor clinic are essential. Ideal care involves specialist urologists, gynaecologists and colorectal surgeons, together with allied specialities including radiology, physiotherapy, specialist nursing expertise, physiology, gastroenterology, psychiatry and chronic pain clinics.

Assessment

Patients can be assessed by subjective measures (symptom assessment) and objective measures (assessment of the structure and function of the bowel and anorectum) ( Table 14.1 ).

Symptom assessment

Symptom assessment can be carried out by clinical history, bowel diaries, visual analogue scores and questionnaires. A careful urogynaecological and obstetrical history and assessment of the impact upon the patient’s quality of life must be included.

The Rome IV diagnostic criteria should be fulfilled for a diagnosis of functional defaecation disorder. The Pelvic Floor Consortium, supported by the International Consultation on Incontinence, recommend assessment with both the Patient Assessment of Quality of Life Symptoms (PAC-SYM) questionnaire and Constipation Severity Instrument, as well as an assessment of quality of life, for patients with bowel evacuatory difficulties and constipation. The International Consultation on Incontinence Modular Questionnaire Bowel Score assesses bowel symptoms, the bother they inflict and health-related quality of life ( www.iciq.net ). In addition, the Obstructed Defaecation Syndrome (ODS) score can assess evacuatory difficulties and monitor symptoms post-operatively.

Examination

Careful examination with general, abdominal and anorectal examination should be performed. Rectal examination is useful to rule out any rectal mass as well as the assessment of scarring from previous obstetrical trauma or surgery, concurrent sepsis or fistula, perineal descent and anal tone at rest and voluntary squeeze.

Rigid sigmoidoscopy and proctoscopy examine for masses and a solitary rectal ulcer and may detect intussusception whilst asking the patient to bear down.

Preliminary investigation

Any change in bowel habit or defaecatory difficulties should be investigated by a colonoscopy or computed tomography (CT) colonoscopy to rule out underlying pathology, such as malignancy. Where there is rectal prolapse, a flexible sigmoidoscopy should be performed to exclude any proximal structural abnormality or mass.

Colonic transit studies

Colonic transit studies aim to differentiate between slow transit constipation and evacuatory disorders. Colonic transit time is assessed by the ingestion of radio-opaque markers and sequential abdominal X-rays. There are differing protocols but usually patients who expel 80% of markers on day 5 are labelled with normal colonic transit. Retained markers may be scattered throughout the colon (suggesting slow transit constipation) or accumulated in the rectum or rectosigmoid (suggesting functional outlet obstruction).

Anorectal physiology

Anorectal physiology includes anorectal manometry and the measurement of rectal sensation and compliance.

Anorectal manometry is the use of a catheter in the anorectum to measure pressure along the anal canal. A variety of systems exist to do this with the two most commonly used ones being water perfused systems or solid-state devices, which are described in the previous chapter. Both systems are used to measure the strength of the anal sphincters both at rest (resting tone; predominantly generated by the internal anal sphincter) and on maximal voluntary squeeze (squeeze pressure; generated by the striated components of the anal canal and pelvic floor). Patients with obstructive defaecation may possess concomitant anal sphincter damage and reduced resting and squeeze pressures.

The measurement of rectal and anal pressures during balloon expulsion can be used to evaluate dyssynergy. Dyssynergy is divided into four subtypes; type I – adequate increased rectal pressure with a paradoxical rise in anal pressure, type II – inadequate increase in rectal pressure (poor propulsive forces) with a paradoxical rise in anal pressure, type III – adequate increase in rectal pressure with a failure of reduction in anal pressure and type IV – inadequate increase in rectal pressure (poor propulsive force) with a failure of reduction in anal pressure).

Rectal balloon testing is the most common way of measuring rectal sensation and compliance. Compliance reflects rectal wall distensibility and is the volumetric response of the rectum when subjected to increased intra-luminal pressure. There is conflicting evidence regarding compliance and obstructive defaecation; compliance may be normal or increased with rectocele.

Anal endosonography/endorectal ultrasound

Routine endoanal ultrasound is performed with a transducer (endoprobe) in the anal canal providing either axial or sagittal images along the anal canal. A volume of data is acquired during an automated withdrawal of the endoprobe with the rotating axial scan or the sagittal array, which sweeps through 360 degrees. This volume of data can be interrogated in any plane for assessment of anal sphincter integrity, obstetrical injury and associated repairs, fistulae or sepsis. It is important to appreciate these pathologies before embarking on treatment of defaecatory dysfunction and prolapse. The internal sphincter may be hypertrophied in patients with straining or rectal prolapse. The interpretation of which must take into account that the thickness of the internal sphincter increases with age: the normal width for a patient aged 55 years or younger is 2.4–2.7 mm; in an older patient the normal range is 2.8–3.4 mm.

Integrated total pelvic floor ultrasound

Integrated total pelvic floor ultrasound (TPFUS) is the dynamic assessment of the entire pelvic floor with transperineal, transvaginal and endoanal ultrasound. It is cheap, accessible and can be performed in a one stop clinic alongside anorectal physiology and endoanal ultrasound. TPFUS is routinely used for anterior and middle compartmental dysfunction (e.g., cystocoele). However, it is now also emerging as an alternative to defaecatory imaging for anatomical (rectocele, intussusception, rectal prolapse, enterocoele, sigmoidocele and perineal descent) and functional (changes in the anorectal angle) aspects. The patient is asked to squeeze up and then perform the Valsalva manoeuvre; some specialists routinely instil and encourage expulsion of rectal gel to improve accuracy of detection of intussusception and rectocele.

Transperineal ultrasound ( Fig. 14.1 )

Transperineal ultrasound allows the global assessment of the entire pelvic floor in real time. It is the most useful element of TPFUS for the assessment of the patient with defaecatory dysfunction. It is non-invasive and potentially more acceptable to patients than defaecatory imaging. It allows visualisation of anterior, middle and posterior pelvic floor compartments in the longitudinal and transverse sections and dynamic assessment of cystocoele, vaginal vault prolapse, enterocoele, rectocele, intussusception, rectal prolapse, dyssynergy and perineal descent without contrast. Comparisons with defaecatory imaging have shown than transperineal ultrasound may be a useful screening tool for defaecatory dysfunction and may avoid further imaging in some patients. ^,

Transvaginal ultrasound

Murad-Regadas et al. report on dynamic three-dimensional endovaginal scanning for the near perfect detection of rectocele, enterocoele and intussusception compared to defaecation proctography. There are concerns however that the vaginal probe may prevent the full prolapse of structures or impede the Valsalva manoeuvre.

Proctography – defecography/evacuation proctography

Defaecation proctography (defaecation barium proctography, fluoroscopic evacuatory proctography, defecography) is a dynamic investigation of rectal emptying. A mixture of barium paste and either porridge oats or potato starch to try to simulate the consistency of stool is instilled in the rectum and the subject sits on a commode and evacuates whilst the process is recorded on cineradiography or fluororadiography.

Advantages include the examination of defaecatory dynamics in the upright physiological position. Defaecation proctography, with rectal and oral contrast, allows the visualisation of anatomical abnormalities (namely rectocele, intussusception, rectal prolapse, enterocoele, sigmoidocele and perineal descent) and functional problems (changes in the anorectal angle, the extent and duration of rectal emptying and ‘trapping’ of stool within a rectocele) ( Fig. 14.2 ). Multi-compartmental visualisation is invasive, though possible by contrast opacification of the vagina (dynamic colpoproctography), bladder (dynamic cystoproctography) or peritoneal cavity.

Defaecation proctography has substantial diagnostic and therapeutic benefit regarding diagnosis and determining management. However, there are concerns that pathology may be over-diagnosed. Patient embarrassment may affect defaecatory dynamics (more complete evacuation of rectocele is observed after evacuation in a private bathroom than during defecography ). There is also debate surrounding the association of pathological findings with symptoms and normal proctographic parameters (rectoceles have been found in asymptomatic subjects ^, ). Findings should be interpreted in context and with caution.