A 70-year-old woman comes to the office for worsening constipation. The patient has chronic constipation for which she takes over-the-counter fiber supplements and stool softeners; however, for the past 3 months, the patient has had to push 2 fingers into her vagina to defecate. She has had increased bloating but no nausea, diarrhea, or abdominal pain. The patient has 1 son. Medical history includes hypothyroidism and type 2 diabetes mellitus for which she takes levothyroxine and metformin. A colonoscopy last year was normal. BMI is 32 kg/m². Vital signs are normal. The abdomen is soft and nontender with normoactive bowel sounds. On rectal examination, the resting sphincter tone is normal and there are no palpable masses. With Valsalva maneuver, the posterior vaginal wall extends outside the hymenal ring. There is no fecal incontinence with Valsalva maneuver. Anocutaneous reflex is intact bilaterally. TSH is 3.9 mU/L and serum hemoglobin A1c is 7.5%. Fecal occult blood testing is negative. Which of the following is the most likely underlying cause of this patient's presentation?

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11ec25c8_d97d_a6a1_bc81_bdb5c4576f86_MD0003_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 extending past the hymen while straining), which cause further difficulty with defecation. Therefore, some patients apply digital pressure against the prolapse (ie, splinting) to help improve bowel movements. Treatment is with pelvic floor muscle exercises, vaginal pessary placement, or possible surgical correction. (Choice A) Diabetic autonomic neuropathy can occasionally cause constipation but is more commonly associated with gastroparesis and chronic diarrhea (usually due to decreased rectal sphincter tone). This patient has a normal rectal sphincter tone, making this diagnosis unlikely. (Choice B) External anal sphincter dysfunction can occur with prior perineal laceration, a common complication of vaginal delivery. In contrast to this patient, those with external anal sphincter dysfunction typically have decreased sphincter tone and anal incontinence (ie, involuntary loss of flatus or fecal material). perineal laceration (Choice D) Fiber supplementation is used to help treat constipation, and overuse can cause abdominal bloating and flatulence but typically not worsening constipation. (Choice E) Hypothyroidism can cause chronic constipation; however, this patient's TSH level is normal, making subtherapeutic levothyroxine dosing an unlikely cause of this patient's symptoms. 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 70-Year-Old Woman Comes to the Office for Worsening Constipation