Defecography: Technique, Interpretation, and Current Use Arden M

9 Defecography: Technique, Interpretation, and Current Use Arden M. Morris and Susan C. Parker Defecography, or evacuation proctography, is the on technique, interpretation, and implications dynamic study of expulsion of radiopaque mate- for specific patient populations. rial from the rectum, in order to assess changing anatomic relationships of the pelvic floor and associated organs during evacuation. In 1952, Indications for Testing Wallden 1 first described enteroceles, sigmoido- celes, and rectoceles, using roentgenogram Constipation techniques developed to evaluate patients with symptoms of obstructed defecation. He postu- Defecography was initially developed to assess lated that such outlet obstruction was due to an patients with complaints of constipation and a abnormally deep rectogenital pouch and could sensation of rectal outlet obstruction. The diag- be corrected surgically. However, performing nostic armamentarium has expanded to include these static studies using rectal, vaginal, and anal manometry, electromyography, and colonic small bowel contrast was a cumbersome, expen- transit time studies, all of which are crucial for sive, and embarrassing process for the patient. distinguishing end-organ versus total organ Recognizing the limitations of these studies, etiologies. Therefore, although the major indi- subsequent authors streamlined the procedure cation for performing defecography continues to over the ensuing three decades. be constipation, other complaints may occasion- Broden and Snellman2 proposed the use of ally warrant defecographic evaluation. Table 9.1 cineradiographic methods and a physiologic demonstrates the primary indications and their position, which contributed enormously to the proportionate prevalence among our referred simultaneous study of function and anatomy. patients. There is considerable overlap in many Several centers built radiolucent commodes with of these symptoms and diagnoses. air and water chamber modifications to optimize image density.3 To more closely replicate stool consistency, investigators varied the texture of Suspected Enterocele or Rectocele barium contrast with materials such as oatmeal (Obstructed Defecation) and potato starch. Technological advance- ments in videography and manufacturing have Patients with symptoms of enterocele or recto- enhanced sophistication, efficiency, and patient cele describe prolonged straining at defecation, comfort during the test. with a sensation of partial or complete blockage Today, defecography can provide an invalu- (frequently a “closed trapdoor” preventing able aid in the diagnosis and treatment planning passage of stool).Defecography can demonstrate for patients with constipation and rectal outlet the presence of a rectocele or enterocele, suggest obstruction issues. This chapter explores the the presence of a peritoneocele, and clarify con- current use of defecography, with a special focus tributing disorders such as a nonrelaxing pelvic 85 86 Constipation Table 9.1. Indication for defecography among patients referred to Pain with Defecation the Minnesota Center for Pelvic Floor Disorders seen over a 12-month period Ill-defined low pelvic pain and painful straining Indication for defecography % (n = 954) at defecation (tenesmus) are frequently difficult Constipation 33 to explain and even more difficult to treat. Suspected enterocele or rectocele (obstructed 11.3 After evaluating for obvious sources, such as defecation) fissure, hemorrhoids, or ulcer, defecography may Incomplete emptying 6.3 Rectal intussusception or prolapse 11.3 help to establish or exclude an anatomic etiology. Fecal incontinence 31.3 For example, paradoxical contraction of pelvic Pain with defecation 3.7 muscles may explain anismus and cramping or Urinary incontinence or uterovaginal prolapse 2.5 spastic pain. Extensive perineal descent may Postoperative evaluation 0.6 result in stretching of the pudendal nerve that can cause a dull, aching sensation after defecation. floor, rectal intussusception or prolapse, and Urinary Incontinence and potentially uterovaginal prolapse. Uterovaginal Prolapse Up to 41% of patients with urogynecologic Incomplete Emptying pelvic floor disorders also have fecal incontinence; therefore, Kelvin et al4 and others have Incomplete emptying refers to a sensation of recommended a complete pelvic floor evaluation stool retained in the rectum after defecation, prior to extensive operative intervention. Alter- coupled with an immediate need to empty again natively, repair of an anterior enterocele or rec- or a need for digital manipulation in order to tocele may uncover previously occult urinary attempt complete evacuation. Incomplete emp- incontinence. Clearly, a careful history and thor- tying is closely related to obstructed defecation ough evaluation are necessary prior to planning and is generally caused by rectal intussuscep- an intervention for patients at risk for both urog- tion, rectocele, or enterocele. ynecologic and anorectal disorders (generally postmenopausal multiparous women). Rectal Intussusception or Prolapse Postoperative Evaluation Internal prolapse or intussusception may be difficult or impossible to diagnose without Follow-up evaluation of postoperative patients is defecography. As intussusception progresses a little-discussed but important indication for toward overt prolapse, patients may complain of defecography. Patients who experience difficult rectal bleeding and a sensation of fullness. Phys- evacuation after an ileal pouch–anal anastomo- ical exam reveals a patulous anus with decreased sis may have a long spout, kinking of the pouch sphincter tone. Anoscopy or rigid proctoscopy or spout, a strictured anastomosis, or another may demonstrate associated conditions, such as mechanical reason for obstruction. Defeco- erythema or a solitary rectal ulcer, thought to be graphy may be helpful for the evaluation of caused by sheer stress on the anterior rectal wall. new-onset evacuation difficulties after a sphinc- teroplasty, prolapse repair, or colon resection. Alternatively, it may help to assess patients with Fecal Incontinence unrelieved symptoms of incontinence after a repair, or to ascertain continence prior to stoma Defecography plays a limited role in evaluation closure. of fecal incontinence, and is most useful among those patients with attendant obstructive symptoms. Defecography can aid in the diagnosis Technique of overflow fecal incontinence, demonstrating retention of stool due to a nonrelaxing puborec- Dynamic defecography, as originally described talis muscle or retained stool within a large by Broden and Snellman2 in 1968, used rectal, rectocele. small bowel, and vaginal contrast. Since that Defecography: Technique, Interpretation, and Current Use 87 initial description, the technique has been prolapse, and potential widening of the recto- further refined, but a consensus still does not vaginal space, which may indicate an enterocele. exist regarding the optimal examination tech- Some authors discourage tampon use, arguing nique.Practitioners may vary the number of cav- that it stents the vagina, thereby obscuring rec- ities or organs that are opacified (small bowel, toceles, enteroceles, and prolapse.7,8 We recom- vagina, bladder, peritoneum), the method of mend opacification of the vagina with 5 to 10cc opacification (ingested or injected contrast, con- of thick barium paste (barium sulfate esophageal trast applied to a sponge or tampon), and even cream, 60% w/w, E-Z-EM, Westbury, NY) the type of contrast used for each anatomic site inserted using a rounded flexi-tip applicator. (liquid, paste, or prepared mixtures). Contrast is slowly injected as the applicator is withdrawn to coat the entire length of the vagina. Contrast The use of bladder contrast is less common and requires sterile bladder catheterization and Options for rectal contrast preparations in- the instillation of 150 to 200cc of water-soluble clude barium suspension, mixtures of barium contrast. Bladder opacification is advocated and starch (oatmeal, potato flakes), and com- for patients with bladder symptoms or a large mercial products formulated specifically for vaginal eversion, and can help to differentiate a defecography. cystocele from an enterocele or rectocele.9 Ikenberry and colleagues5 compared three types of contrast (thin barium liquid, commer- cial paste, and thick prepared contrast paste) in Peritoneal Cavity normal subjects and found that contrast materials and consistency altered their pathologic The small intestine may be highlighted by inges- findings. Increased viscosity resulted in a sig- tion of an oral barium meal given 45 minutes to nificantly increased anorectal angle measure- 1.5 hours before the defecography study, to allow ment. Using thin barium decreased evacuation transit to the distal loops of bowel most likely to time and increased the prevalence of intussu- lie in the pelvis. Although a wide space between ception. The authors found little benefit to the the rectum and vagina filled with air lucency use of elaborate heated mixtures of barium and may indicate an enterocele, the diagnosis is starch but advised against the use of liquid alone made easily if contrast-filled loops of bowel or with other contrasts, particularly when diag- occupy that space. However, a deep pouch of nosing intussusception. Douglas may not fill with small bowel on all Mahieu et al6 also found thin contrast inferior; occasions, resulting in an underinterpretation of among other issues, its rapid passage led to enteroceles. missed pathologic

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