A 63-year-old woman comes to the office for evaluation of chronic constipation. For the past 8 months, the patient has had increased straining with bowel movements but no abdominal pain or rectal bleeding. She has 2 children, both delivered via forceps-assisted vaginal delivery. BMI is 31 kg/m². On digital rectal examination, there are no masses and rectal tone is normal; pelvic examination shows a visible bulge into the vagina with straining. Sensation around the perineum is intact. Fecal occult blood testing is negative. Which of the following is the most likely cause of this patient's symptoms?

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11ec160b_3574_2d04_9249_77dfc04708e6_MD0001_00 This patient's chronic constipation is caused by pelvic organ prolapse, the herniation of pelvic organs (eg, bladder, rectum) into the vaginal wall due to levator ani muscle complex damage. The levator ani muscle complex forms most of the pelvic floor and functions to hold the pelvic organs in a stable position; when this complex is damaged, such as with increased intraabdominal pressure (eg, pregnancy, obesity) or obstetric trauma (eg, forceps-assisted vaginal delivery), there is increased pelvic floor laxity, resulting in decreased pelvic organ support. The decreased pelvic floor support causes an anatomic change to normal pelvic organ positions; for the rectum, this leads to a change in rectal angle during defecation, which can cause incomplete defecation and constipation. With accumulation of fecal material, the rectum expands and herniates through the rectovaginal septum, causing prolapse of the rectum into the posterior vaginal wall (ie, rectocele). The prolapse is exacerbated by Valsalva maneuvers (eg, vaginal bulge while straining), which cause further difficulty with defecation; therefore, some patients apply digital pressure against the prolapse (ie, splinting) to help improve bowel movements. (Choice A) Hirschsprung disease, the absence of colonic intramural ganglion cells due to failed neural crest cell migration, typically presents in infants. It causes constipation and increased rectal tone due to the inability of the aganglionic segment to relax. (Choice B) Irritable bowel syndrome (IBS) is often associated with chronic irregular luminal contractions and increased gastrointestinal tract sensitivity. It typically presents with recurrent abdominal pain and either diarrhea or constipation. IBS does not affect the pelvic floor musculature and, therefore, does not cause a vaginal bulge. (Choice D) An external anal sphincter defect occurs with a perineal laceration, a common complication of vaginal deliveries; however, patients typically have decreased rectal tone (not seen here) that can result in anal incontinence (ie, involuntary loss of flatus or fecal material). (Choice E) The internal anal sphincter (IAS) is under tonic contraction via sympathetic fibers; contraction is inhibited by parasympathetic fibers. Increased IAS parasympathetic tone would cause sphincter relaxation and an increased urge to defecate rather than chronic constipation. Educational objective: Pelvic organ prolapse, the herniation of pelvic organs (eg, rectum) into the vagina, occurs due to damage to the levator ani muscle complex. Patients with prolapse of the posterior vaginal wall (ie, rectocele) classically have chronic constipation and a vaginal bulge. __________ References: Functional disorders: rectocele. (http://www.ncbi.nlm.nih.gov/pubmed/28144214)

A 63-Year-Old Woman Comes to the Office for Evaluation of Chronic