Chapter 3.1(Ii) Defecography: a Swedish Perspective*

Chapter 3.1(ii) Defecography: A Swedish Perspective* Annika López,Jan Zetterström, and Anders F. Mellgren Introduction The dynamics of rectal evacuation may be displayed by defecography (evacuation proctography). The technique has gained importance as an investigatory tool in patients with anorectal disorders, and the method has been evaluated in a series of studies. During recent years, variants of the technique have been described, opening up the possibility to investigate patients with other pelvic floor symptoms primarily located in other pelvic compartments. Historical Background The first publications using cineradiographic techniques for studying the mechanism of defecation were published in the 1960s (1–3). However, the technique was not widely spread until the work of Mahieu et al. (4,5) and Ekberg et al. (6), who increased the global interest in defecography. Defecography is useful in studying anorectal functional and detecting anatomic abnormalities as possible causes of defecation disturbances. Rectocele, enterocele, rectal intussusception, and rectal prolapse can be visualized, and several authors have found defecography useful as a com- plement to the clinical examination (7,8). Kelvin et al. (9) reported that “evacuation proctography” has a useful role in enterocele detection prior to surgery for pelvic prolapse. Hock et al. (10) introduced colpo-cysto-defecography of the female pelvis, and Altringer et al. (11) described “four-contrast defecography” with contrast medium in the small bowel, rectum, vagina, and urinary bladder, finding the method helpful in the planning of prolapse surgery. Adminis- tration of contrast medium intraperitoneally has been used to study normal *Ed note: This chapter should be read in conjunction with Chapter 3.1(i) 199 200 A. López et al. anatomy and in the evaluation of patients with obscure symptoms in the groin or pelvis (12). The use of intraperitoneal contrast medium in combination with defecography is advocated by some authors (13,14). With this technique, the peritoneal outline is directly visualized and a deep pouch of Douglas can be demonstrated for enhanced diagnosis of peritoneocele and enterocele. Indications The most common indication for defecography is constipation presenting as difficult or infrequent evacuation. This issue is extensively discussed in the sections of Chapter 6. Some authors have stressed the role of defecography in incontinent patients with intact sphincters. Defecography may then diagnose a rectal intussusception or identify patients with an obtuse anorectal angle suitable for post-anal repair, as well as patients with large recto- celes who present with a combination of evacuatory dysfunction and incontinence. A clinical examination, including rectal palpation and rigid proctoscopy or flexible sigmoidoscopy, should be performed before defecography. In several patients, a full colonoscopy also is indicated. A gynecological examination is recommended in female patients. Defecography may be useful in patients with symptoms such as pelvic heaviness or discomfort due to a vaginal protrusion. It is important to assess the pelvic floor as one unit because several symptoms may be present and combinations of anatomical weaknesses are common (15). Technical Aspects The techniques of defecography are by no means standardized. Contrast filling of the rectum is universal and contrast medium in the vagina is used by a majority of institutions. Opacification of the small bowel is used only by a few (16), and bowel preparation prior to the investigation is preferred by some (17), but not by others (18–20). If contrast in the small bowel is used, it is administered orally one to two hours prior to the investigation. Oral contrast is recommended to enable detection of an enterocele, especially when no contrast medium is instilled intraperitoneally (2,4–6). Rectal contrast media of varying consistencies are used and both regular barium enema contrast medium and thick barium paste are employed. Some mix the contrast medium with potato starch, potato flakes, or cellulose to achieve a consistency similar to that of feces. The contrast medium usually is injected with a pistol injector with the patient in the left lateral position. The injected amount varies; some inves- tigators instill contrast medium until a strong urge to defecate is provoked, 3.1(ii). Defecography: A Swedish Perspective 201 whereas others use the same volume in all cases. Sometimes liquid contrast is administered prior to the paste to opacify the sigmoid colon in order to detect a sigmoidocele. Contrast medium in the vagina enhances the possibilities for studying enterocele and rectocele. A contrast medium gel or a tampon soaked with contrast medium is used. The use of a gel is preferable, as a tampon might obscure important diagnostic information (21). Some authors place gauze at the introitus to avoid leakage of contrast medium from the vagina in order to improve the image (22). After instillation of contrast medium, the patient is seated on a plastic commode in front of a fluoroscopic unit, and the investigation usually is performed in the lateral view. The patient is asked to strain and empty the rectum. As the investigation is rapid and dynamic, it is documented best with video. Spot films sometimes are added to the investigation; these films usually are taken at key points of the study (e.g., at the start, during straining, and after completion of “defecation”). At some centers, an anterior–posterior spot film is added to reveal the coronal configuration of the rectum to help diagnose intussusception (23) and to lateralize a pro- lapsed organ (15). To minimize the dose exposure, imaging should be inter- mittent if rectal evacuation is prolonged. Newer digital systems allow substantial reduction in dose. The procedure usually is not painful for the patient, but it can be stress- ful, and therefore it is important to explain the procedure thoroughly to the patient beforehand and provide maximal privacy and reassurance for the patient during the procedure. Radiographic Analysis Although defecography is a well-established method, there are no standard definitions of the radiographic findings. Studies with asymptomatic volun- teers have revealed a range of normal values, and some overlap with pathological states (24). Therefore, it is important to evaluate the findings at defecography in relation to the patients’ symptoms, clinical findings, and other functional tests because the anatomical changes found may not always be the cause of the patient’s problems. Rectal Emptying and the Anal Canal Rectal emptying can be studied by defecography.At the start, before straining is initiated, there should be no leakage of contrast medium. Constipated patients often empty the rectum slowly and incompletely.An emptying time of more than 30 seconds is considered pathological. The anal canal should open during emptying of the rectum, close after emptying, and remain closed at rest. 202 A. López et al. Rectal Intussusception and Rectal Prolapse A rectal intussusception starts six to eleven centimeters above the anal verge by formation of a circular indentation, which progressively deepens. Its apex descends towards the anal verge on straining. It sometimes is difficult to differentiate between rectal intussusception and “normal” mucosal folds of the rectum at straining. The size of the intussusception can be graded in different ways, but a commonly used system has the following three grades. When the intussusception remains within the rectum, it is called recto-rectal; when the apex penetrates the anal canal, it is referred to as recto-anal; and an external rectal intussusception that protrudes through the anal verge is equivalent to a rectal prolapse (Figures 3.1(ii).1 and 3.1(ii).2). Mucosal Prolapse Defecography usually can differentiate between a mucosal prolapse and a full-thickness rectal prolapse. However, sometimes the differentiation can be difficult, even on defecography. According to Ekberg et al. (6), mucosal Figure 3.1(ii).1. A 56-year-old woman previously operated for a lumbar disc her- niation with persistent minor loss of sensitivity in her legs. The patient suffers from anal incontinence and rectal emptying difficulty with excessive straining and a need for digital assistance by pressing on the perineum during defecation. Defecography with contrast medium in the rectum, vagina, and small bowel was performed and the examination demonstrates a rectal intussusception reaching down into the anal canal during straining. V, vagina; R, rectum; Ri, rectal intussusception; arrow, the base of the intussusception. 3.1(ii). Defecography: A Swedish Perspective 203 Figure 3.1(ii).2. A 44-year-old woman with a two-year history of a rectal prolapse. Defecography was performed with contrast medium in the rectum, vagina. and small bowel and demonstrates a rectal prolapse during straining. V, vagina; R, rectum; RP, rectal prolapse; SB, Small bowel. prolapse starts three to four centimeters above the anal verge containing only the mucosa [see Figure 3.1(ii).5(b)] (25). Enterocele In females, an enterocele usually is diagnosed as a bowel-filled peritoneal sac located between the posterior vaginal wall and the anterior rectal wall, descending below the upper third of the vagina. It often contains small bowel, but sigmoid colon is sometimes evident. In males, it is diagnosed as bowel within a rectal intussusception or a rectal prolapse (Figure 3.1(ii).3). Rectocele A rectocele is seen at defecography as a bulge outside the projected line of the anterior rectal wall during straining. The size of the rectocele is measured as the distance between the extended line of the anterior border of the anal canal and the tip of the rectocele (Figure 3.1(ii).4). 204 A. López et al. Figure 3.1(ii).3. A 66-year-old woman previously operated on with hysterectomy after which there were worsening symptoms of constipation with infrequent bowel emptying about two times a week. Defecography was performed with contrast medium in the rectum, vagina, and small bowel and demonstrates a rectal intussusception reaching into the anal canal and a large enterocele during straining.

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