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Abdominal Emergency Checklist (On-Call)

Checklist for the acute abdomen/pelvis study: appendicitis, diverticulitis (Hinchey stage), small-bowel obstruction with closed-loop signs, mesenteric ischemia, a free-air search pattern, and gonadal torsion. Focuses on the findings that trigger immediate surgical or interventional management.
reviewed 2026-07-01

Appendicitis

  • Dilated appendix >6 mm, non-compressible, with wall thickening/hyperenhancement
  • Periappendiceal fat stranding, fluid, and appendicolith
  • Perforation signs: extraluminal air, abscess, focal wall defect
  • Alternative diagnoses when the appendix is normal (adnexal, diverticular, renal)

Diverticulitis (Hinchey)

  • Colonic wall thickening, diverticula, and pericolic fat stranding
  • Extraluminal air (pericolic vs distant free air) and abscess — sets the Hinchey stage
  • Distant free air / feculent peritonitis (Hinchey III–IV) — surgical emergency
  • Fistula (colovesical → air in bladder), obstruction, and mimics (perforated colon cancer)

Small-bowel obstruction & closed loop

  • Transition point with dilated proximal (>3 cm) and collapsed distal bowel
  • Closed-loop: two adjacent transition points, C-/U-shaped loop, radial mesenteric vessels converging to a point of torsionClosed-loop obstruction risks strangulation — a surgical emergency.
  • Ischemia signs: reduced/absent wall enhancement, wall thickening, mesenteric edema, pneumatosis, portal venous gas
  • Whirl sign (volvulus) and internal/closed hernia
  • Cause: adhesions, hernia, mass, intussusception; the small-bowel feces sign marks the transition zone

Mesenteric ischemia

  • SMA/SMV and celiac patency: arterial embolus/thrombus, venous thrombosis, or non-occlusive (low-flow) pattern
  • Bowel-wall enhancement: decreased (arterial) or hyperenhancement/target (venous/reperfusion)
  • Pneumatosis intestinalis and portomesenteric venous gas — late, ominous
  • Bowel dilation, mesenteric edema/fat stranding, and ascites

Free-air search pattern & torsion

  • Free air: nondependent (anterior) locations — perihepatic, falciform ligament outline, Rigler sign; use lung windowsScroll the most nondependent slices on lung windows to catch small pneumoperitoneum.
  • Trace free air to a perforation source (ulcer, diverticulum, bowel)
  • Testicular torsion (US): absent/decreased intratesticular flow, whirlpool of the cord, heterogeneous echotextureA time-critical diagnosis — communicate immediately for surgical exploration.
  • Ovarian torsion: enlarged edematous ovary, peripheralized follicles, twisted vascular pedicle, ± adnexal mass as lead point
How to assign
  1. 1Hinchey (perforated diverticulitis) — find the single most advanced feature; that stage wins.
  2. 2Stage I: pericolic/mesenteric abscess (confined phlegmon/small abscess adjacent to the segment).
  3. 3Stage II: walled-off pelvic/retroperitoneal/distant abscess.
  4. 4Stage III: purulent peritonitis (free purulent fluid, generalized — without gross enteric contrast leak).
  5. 5Stage IV: feculent peritonitis (free communication with the bowel lumen / gross fecal peritonitis).
  6. 6Report the stage with the free-air burden and abscess size/drainability — Ia/Ib and II are often drainable; III–IV are surgical.

Hinchey classification of perforated diverticulitis (1978)

Stage I

Pericolic abscess or phlegmon confined to the mesentery.

Stage II

Pelvic, intra-abdominal, or retroperitoneal abscess (walled-off, distant from the primary process).

Stage III

Generalized purulent peritonitis.

Stage IV

Generalized feculent peritonitis (free colonic perforation).

Closed-loop / strangulation clues

Two transition points close together

Hallmark of a closed loop.

C- or U-shaped dilated loop

Loop configuration around a torsion point.

Whirl / radial converging mesenteric vessels

Twist of mesentery (volvulus).

Reduced/absent wall enhancement

Ischemia — surgical urgency.

Pneumatosis / portal venous gas

Advanced ischemia/necrosis.

  • Gonadal torsion and closed-loop/strangulating obstruction are time-critical — communicate directly and document.
  • Free air on CT is best detected on lung windows over the most nondependent surfaces; a small volume may be the only clue to perforation.

Sources

  • Hinchey EJ, et al. Treatment of Perforated Diverticular Disease of the Colon. Adv Surg. 1978;12:85-109.
  • Silva AC, et al. Small Bowel Obstruction: What to Look For. RadioGraphics. 2009;29(2):423-439.
  • Furukawa A, et al. CT Diagnosis of Acute Mesenteric Ischemia from Various Causes. AJR Am J Roentgenol. 2009;192(2):408-416.

Educational reference for clinicians — not medical advice. Verify against the primary source before acting on it; guidelines change. Final decisions rest with the interpreting physician and your institution's protocols.