We discussed a case of an elderly woman with hx of CAD c/b MI, hx of recent PEA arrest due to high-grade AV block s/p PPM, HFrEF, and afib, who presented with acute diffuse abdominal pain, not passing gas, and large volume bright red blood per rectum, found to have severe constipation causing fecal impaction & rectal perforation.

LGIB ddx

• Structural:  diverticulosis, hemorrhoids, post-polypectomy bleeding, polyps, malignancy, anal fissure, colonic / rectal ulcers
• Vascular:  ischemic colitis, angiodysplasias, colonic / rectal varices, congenital or systemic diseases causing vascular anomalies (HHT, CREST), tumors (hemangiomas, Kaposi sarcoma)
• Inflammatory:  IBD, infectious, radiation

Management of constipation & laxatives

• PO hydration, exercise, fiber
• Bulking:  psyllium, wheat dextrin, cellulose
• Osmotic:  miralax, lactulose, magnesium citrate
• Stimulant:  senna, bisacodyl
• Stool softeners / enemas:  colace, tap water, soap suds, Fleet (glycerin, mineral oil, sodium phosphate)
• Opioid antagonists:  methylnaltrexone, naloxegol