A 76-year-old man comes to the office due to constipation. He has infrequent bowel movements associated with straining during defecation. In addition, the patient has intermittent fecal leakage and hematochezia but no melena or unexpected weight loss. Medical history is notable for prostate cancer treated with external beam radiation and brachytherapy 18 months ago. Follow-up CT scans and prostate-specific antigen levels show no evidence of cancer recurrence. Temperature is 37.5 C (99.5 F), blood pressure is 132/80 mm Hg, pulse is 80/min, and respirations are 12/min. Conjunctival pallor is present. Cardiopulmonary examination is unremarkable. The abdomen is soft and nontender. Colonoscopy reveals rectal pallor with areas of mucosal hemorrhage and telangiectasias; the rest of the colon is unremarkable. Which of the following is most likely contributing to this patient's symptoms?

Question

A 76-year-old man comes to the office due to constipation.  He has infrequent bowel movements associated with straining during defecation.  In addition, the patient has intermittent fecal leakage and hematochezia but no melena or unexpected weight loss.  Medical history is notable for prostate cancer treated with external beam radiation and brachytherapy 18 months ago.  Follow-up CT scans and prostate-specific antigen levels show no evidence of cancer recurrence.  Temperature is 37.5 C (99.5 F), blood pressure is 132/80 mm Hg, pulse is 80/min, and respirations are 12/min.  Conjunctival pallor is present.  Cardiopulmonary examination is unremarkable.  The abdomen is soft and nontender.  Colonoscopy reveals rectal pallor with areas of mucosal hemorrhage and telangiectasias; the rest of the colon is unremarkable.  Which of the following is most likely contributing to this patient's symptoms?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d81b_3057_bc81_53d96f97117f_MD0003_00 This patient has chronic radiation proctitis (RP), presenting with constipation, fecal incontinence, and hematochezia. RP is due to injury to the rectal epithelium from pelvic radiation therapy, most commonly in the treatment for prostate, colon, ovarian, or cervical cancer. RP can have both acute and chronic manifestations: Acute RP typically occurs in the first 8 weeks of therapy; damage to the rectal epithelium causes diarrhea and mucoid discharge. Chronic RP, which develops >3 months after radiation exposure, is characterized by obliterative endarteritis and submucosal fibrosis. Progressive fibrosis in chronic RP can impair rectal compliance and cause anorectal stricture formation. Typical symptoms include constipation, fecal incontinence, and fecal impaction. Chronic tissue hypoxia results in neovascularization, which can lead to hemorrhage and secondary anemia (eg, conjunctival pallor). Colonoscopy is diagnostic and typically reveals mucosal pallor, telangiectasias, mucosal hemorrhages, and tissue friability. (Choice A) Ulcerative colitis causes chronic inflammation of the colonic mucosa and submucosa, leading to tenesmus, hematochezia, and abdominal pain but rarely constipation. Colonoscopy findings include erythema and superficial ulcerations; mucosal pallor and telangiectasias are more consistent with RP. (Choice B) Hypercalcemia can occur in advanced prostate cancer due to bone metastasis or the secretion of parathyroid hormone-related protein but would be unlikely in this patient with no evidence of active malignancy. Although hypercalcemia can cause constipation, it would not explain this patient's hematochezia or colonoscopy findings. (Choices C and D) Parasympathetic dysregulation can cause constipation and fecal incontinence in patients with underlying neurologic disorders (eg, Parkinson disease). Dyssynergic defecation occurs when muscles of the pelvic floor fail to relax during bowel movements, preventing stool expulsion from the rectal vault. However, in these conditions, colonoscopy findings are typically normal, and hematochezia would be unexpected. Educational objective: Chronic radiation proctitis is characterized by obliterative endarteritis and submucosal fibrosis, which leads to anorectal stricture formation, reduced rectal compliance, constipation, and fecal incontinence. Chronic tissue hypoxia results in neovascularization and telangiectasia formation, which can lead to hemorrhage. References: Radiation proctopathy. (http://www.ncbi.nlm.nih.gov/pubmed/26034407)

A 76-Year-Old Man Comes to the Office Due to Constipation