MKSAP: 36-year-old woman with refractory constipation

Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.

A 36-year-old woman is evaluated for a 12-year history of refractory constipation. Her symptoms began after a difficult childbirth. She has constipation marked by straining, bloating, and a constant sensation of incomplete emptying. She sometimes has 4 or more days between bowel movements. When she does have a bowel movement, the stool is soft-formed. Trials of several fiber supplements, lactulose, milk of magnesia, docusate, bisacodyl, polyethylene glycol, and lubiprostone have provided only transient relief for no more than 4 weeks before the gradual return of symptoms. There is no family history of gastrointestinal malignancies or inflammatory bowel disease. Medications are polyethylene glycol, psyllium, and bisacodyl.

On physical examination, vital signs are normal. BMI is 17. Tenderness to palpation is noted in the lower abdomen. No masses are noted. Rectal examination reveals normal resting tone, an increase in external anal sphincter tone, and poor relaxation of the pelvic floor when bearing down. Soft stool is noted in the rectal vault.

Anorectal manometry confirms paradoxical muscle contraction during the Valsalva maneuver consistent with pelvic floor dyssynergia.

Which of the following is the most appropriate management?

A. Increase polyethylene glycol
B. Increase psyllium
C. Start biofeedback therapy
D. Start enema therapy.

MKSAP Answer and Critique

The correct answer is C. Start biofeedback therapy.

The most appropriate management is to refer for biofeedback therapy. The cause of this patient’s refractory constipation is dyssynergic defecation. Dyssynergic defecation is characterized by the inability to coordinate the relaxation of the puborectalis and external anal sphincter muscles while increasing intraabdominal pressure that results in normal evacuation of stool. Dyssynergic defecation is believed to be an acquired behavioral disorder, resulting from causes such as sexual abuse, obstetric trauma, pelvic/abdominal surgery, or traumatic injury to the pelvis/abdomen. The mechanisms underlying this condition can include some combination of the following factors: inability to contract the abdominal wall musculature, deficient relaxation or paradoxical contraction of the puborectalis muscle, impaired rectal contraction, paradoxical anal contraction, and/or inadequate anal relaxation. These abnormal muscle actions of the pelvic floor and anorectum can be detected by asking the patient to bear down during a digital rectal examination (DRE). The inability to relax the puborectalis and external anal sphincter when instructed or with bearing down is indicative of dyssynergia. The positive predictive value of such findings on DRE is 97%. Dyssynergia generally responds poorly to laxative therapy. Biofeedback therapy, also termed neuromuscular re-education, entails a program of neuromuscular training utilizing visual and verbal feedback to restore coordinated muscle activity involved with defecation and improve rectal sensory function. Biofeedback therapy is commonly provided by a physical therapist with this specialized training. Biofeedback therapy is superior to all forms of laxative therapy because it corrects the underlying pathologic mechanisms responsible for dyssynergic defecation.

This patient’s stool is already soft, so further softening with more polyethylene glycol is unlikely to be of any sustained benefit.

Psyllium bulks the stool, which is likely to worsen symptoms in the presence of an underlying problem with stool evacuation.

Enema therapy may promote further dyssynergia by providing an artificial means of emptying the rectal vault, leading to progressive pelvic floor weakness and dysfunction.

Key Point

  • Biofeedback therapy is superior to all forms of laxative therapy for dyssynergic defecation because it corrects the underlying pathologic mechanisms.

This content is excerpted from MKSAP 17 with permission from the American College of Physicians (ACP). Use is restricted in the same manner as that defined in the MKSAP 17 Digital license agreement. This material should never be used as a substitute for clinical judgment and does not represent an official position of ACP. All content is licensed to on an “AS IS” basis without any warranty of any nature. The publisher, ACP, shall not be liable for any damage or loss of any kind arising out of or resulting from use of content, regardless of whether such liability is based in tort, contract or otherwise.

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