HY lecture notes:
87F + coffee bean sign on AXR + obstipated; Dx? → sigmoid volvulus.
Tx for sigmoid volvulus? → answer on surgery NBME = “sigmoidoscopy-guided placement of rectal tube.”
How do you Dx congenital midgut volvulus? → upper-GI series (AXR + contrast follow-through of esophagus, stomach, and duodenum with barium or gastrografin).
Where do most colonic ischemic ulcers occur? → watershed areas → splenic flexure (watershed of SMA and IMA) + sigmoidal-rectal junction (watershed of IMA and hypogastric artery).
72M + advanced CVD + bloody stool; Dx? → ischemic colitis (due to ischemic ulcer).
79M + Hx of atrial fibrillation + severe, acute, diffuse abdo pain; Dx? → acute mesenteric ischemia caused by mural thrombus embolizing to SMA or IMA.
Above 79M; next best step in Mx? → mesenteric arteriography.
Above 79M; Tx? → antibiotics (for necrotic bowel) then laparotomy (to remove necrotic bowel) → they will tell you in last line of vignette that IV Abx are administered and then ask for the next step, which is just laparotomy. It should be noted that the literature mentions various Txs like embolectomy, but the USMLE wants resection of nonviable bowel as the answer.
52F + short episode of ventricular fibrillation + defibrillated + now has severe abdo pain; Dx? → acute mesenteric ischemia due to ischemia caused by VF, not an embolus → antibiotics; CT if stable; if unstable go straight to laparotomy.
55F diabetic + Hx of intermittent claudication + Hx of abdo pain 1-2 hours after eating meals; Dx? → chronic mesenteric ischemia (CMI) caused by severe atherosclerosis of SMA or IMA (essentially angina of the bowel).
55F diabetic + Hx of CABG + Hx of abdo pain 1-2 hours after eating meals; next best step in Dx? → mesenteric arteriography (CMI).
55F diabetic + Hx renal artery stenosis + Hx of abdo pain 1-2 hours after eating meals; Tx? → angioplasty + stenting (CMI) to restore blood flow.
Patient with CMI who has a 2-day Hx of severe abdo pain + fever; Dx? → acute mesenteric ischemia (acute on chronic due to a thrombosis; essentially akin to an “MI” of the bowel) → do mesenteric arteriography to Dx; Tx with Abx + laparotomy to remove necrotic bowel.
69M + LLQ pain + fever = diverticulitis → Dx with CT with contrast of abdomen → Tx w/ Abx (metronidazole, PLUS fluoroquinolone or Augmentin; USMLE won’t ask you the exact Abx, but you should be aware that metro covers anaerobes below the diaphragm) → never do a colonoscopy on someone with suspected diverticulitis, as you may cause perforation. However, after the diverticulitis is fully treated + cleared, patient will need a follow-up colonoscopy to rule out malignancy.
C diff + fever of 104F + tachy + diffuse abdominal pain; next best step in Mx? → AXR → look for toxic megacolon → Tx w/ NPO (nothing by mouth), NG decompression + rectal tube (decompression) + Abx (vancomycin or fidaxomicin) + steroids (if UC) + correct any electrolyte imbalances (sometimes low K) → if patient doesn’t improve with conservative therapy, must do surgery (subtotal colectomy + ileostomy); do not do a colonoscopy on a patient with toxic megacolon as this will cause perforation.
