10 Dynamic rectal examination (defecography)

Abstract

Dynamic rectal examination (DRE), first described in 1952, is becoming more widely used in the dynamic evaluation of pelvic floor and anorectal motility disorders. It is a minimally invasive investigation which is well tolerated by patients and provides information about the anosphincteric, puborectal and levator muscle in addition to insight in rectal function and structure. DRE is the only investigation of anorectal function that can give detailed anatomical information such as the presence of a rectocele, an enterocele and an intussusception. DRE should be performed in a quiet environment with a minimum number of investigators present. Any technique which attempts to study the defecatory mechanism must be a compromise since the patient is aware of being studied. In order to defecate on command the radiologist must make the patient comfortable before starting the investigative procedures to avoid any possible psychological inhibition. We have not encountered any failures in this regard. The relative value of the radiological findings with respect to symptoms and complaints is insufficiently known. This has been the main incentive to design carefully and carry out a large prospective critical evaluation of various aspects of DRE in particular the correlation with objective findings and symptoms. Moreover an assessment has been made of its overall clinical utility (Wiersma, 1994). It is very likely that DRE is both investigator- and technique-dependent. To ensure that the study is as physiological as possible the contrast medium used to fill the rectum needs to be semi-solid and malleable equivalent in consistency to a normal faecal bolus. For proper anatomical studies in females vaginal opacification is mandatory. The acceptance of vaginal contrast was good. Only 4% of the female patients preferred not to have the vaginal application of contrast. The technique of DRE when performed with small bowel and vaginal opacification provides a sensitive and objective method of detecting enteroceles. A substantial number of female patients related the onset of their complaints to hysterectomy. In female patients with constipation there was a significantly higher incidence of enteroceles in patients with a hysterectomy compared to the group of females without hysterectomy. Because of these findings a series of pre- and postoperative DREs in hysterectomy patients are on their way in our institute. Unlike a rectocele which is usually most obvious during defecation, enteroceles are sometimes appreciated only with repeated straining after evacuation. It is therefore important to instruct the patient to continue to strain after evacuation to maximize the chance for detection of enteroceles at DRE. Chronically increased intra-abdominal pressure from any cause may lead to enterocele formation whether or not the cul-de-sac has been exposed at prior pelvic surgery. We showed that DRE has an important role in enterocele detection prior to the performance for surgery. The term rectal prolapse is not accurately defined in the literature. The most commonly used definition is a condition where the rectal wall protrudes partially or completely through the anal orifice. The introduction of techniques involving radiological visualization of rectal voiding as used in our studies, however, has necessitated a reappraisal of the definition of rectal prolapse. The rectal prolapse used to be considered to be an extraanal intussusception. By using oral contrast routinely in DRE we were able to visualize a spectrum of severity of enteroceles. Four patients showed enteroceles which protruded through the anal canal leading to a rectal prolapse. None of our patients showed an extra-anal intussusception. All rectal prolapses in our series were caused by huge enteroceles. DRE is mandatory in the pre-operative work up to detect the cause of the rectal prolapse (enterocele or intussusception) if a patient is to be surgically treated.