Twisting of bowel on its mesentery → closed-loop obstruction with risk of ischemia; sigmoid most common in elderly, cecal in younger adults.
Epidemiology
Sigmoid volvulus accounts for ~60-75% of colonic volvulus and occurs in older, institutionalized, debilitated patients with chronic constipation; common in Africa, the Middle East, and South America. Cecal volvulus accounts for ~25-40% and affects younger adults (30-60 yr), women > men. Overall, volvulus causes 5-10% of large bowel obstruction in the US.
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Question 1GastrointestinalMedium
A 34-year-old woman who is 28 weeks pregnant presents with 12 hours of acute periumbilical cramping pain, bilious vomiting, and abdominal distention. She underwent a screening colonoscopy 3 weeks ago. On exam her abdomen is markedly tympanitic and the rectal vault is empty. An abdominal radiograph shows a dilated, comma-shaped loop of bowel displaced into the left upper quadrant. Vital signs are stable and lactate is normal. Which of the following findings on CT of the abdomen best confirms the suspected diagnosis?
- APericolic fat stranding with abscess
- BTarget sign of layered bowel wall edema
- CWhirl sign of the twisted mesentery
- DPneumatosis with portal venous gas
Reveal answer & full explanation
Correct answer: C — Whirl sign of the twisted mesentery
- APericolic fat stranding with abscess
- BTarget sign of layered bowel wall edema
- CWhirl sign of the twisted mesentery✓
- DPneumatosis with portal venous gas
Why Whirl sign of the twisted mesentery is correct
- This vignette describes cecal volvulus: a younger pregnant woman, recent colonoscopy, acute periumbilical pain with early bilious vomiting, and a comma/kidney-bean-shaped loop displaced to the left upper quadrant (the embryonic position).
- The CT hallmark of any volvulus is the whirl sign, the swirl of twisted mesenteric vessels around the rotational axis. It directly demonstrates the torsion that creates the closed-loop obstruction and confirms the diagnosis.
Why the others are wrong
- Pericolic fat stranding with abscess is the CT picture of diverticulitis, not the mesenteric twist of volvulus.
- Target sign of layered bowel wall edema reflects nonspecific mural stratification seen with intussusception or ischemia; it can accompany many obstructions and does not confirm torsion.
- Pneumatosis with portal venous gas signals established bowel necrosis, a late complication; here lactate is normal with no peritoneal signs, so it is neither expected nor the confirmatory finding.
Question 2GastrointestinalMedium
A 76-year-old nursing-home resident with Parkinson disease and chronic constipation is brought in for 2 days of progressive abdominal distention, cramping, and obstipation. Temperature is 37.1°C (98.8°F), heart rate 88/min, and blood pressure 132/78 mm Hg. The abdomen is markedly distended and tympanitic but soft and nontender, with no rebound or guarding. The rectum is empty on digital examination. Lactate is normal. Abdominal radiograph shows a massively dilated loop of bowel forming a "coffee bean" with its apex pointing toward the right upper quadrant, and CT confirms a sigmoid mesenteric twist without bowel-wall thickening or pneumatosis. Which of the following is the most appropriate initial management?
- ALaparoscopic sigmoidopexy with mesenteric fixation
- BEndoscopic detorsion and rectal tube placement
- CIntravenous neostigmine with cardiac monitoring
- DEmergent sigmoidectomy with Hartmann procedure
Reveal answer & full explanation
Correct answer: B — Endoscopic detorsion and rectal tube placement
- ALaparoscopic sigmoidopexy with mesenteric fixation
- BEndoscopic detorsion and rectal tube placement✓
- CIntravenous neostigmine with cardiac monitoring
- DEmergent sigmoidectomy with Hartmann procedure
Why Endoscopic detorsion and rectal tube placement is correct
- This is sigmoid volvulus (older, institutionalized, chronically constipated patient; "coffee bean" with apex toward the RUQ; mesenteric twist on CT) with NO signs of ischemia — normal lactate, soft nontender abdomen, no peritoneal signs, no bowel-wall thickening or pneumatosis.
- For viable, non-ischemic sigmoid volvulus, flexible sigmoidoscopic detorsion with rectal tube placement is first-line, decompressing the closed loop with an ~80% success rate and converting an emergency into a planned procedure.
- Because recurrence after detorsion alone is high (~50-70%), elective sigmoidectomy is then scheduled during the same admission after bowel preparation — but detorsion is the initial step.
Why the others are wrong
- Emergent sigmoidectomy with Hartmann procedure — reserved for sigmoid volvulus with ischemia, perforation, or failed endoscopic detorsion; this stable patient with no ischemic findings should first undergo detorsion rather than emergency resection.
- Laparoscopic sigmoidopexy with mesenteric fixation — an operative fixation occasionally used for recurrent volvulus in patients who cannot tolerate resection; it does not relieve the acute closed loop, which should first be untwisted endoscopically in this stable patient with a viable colon.
- Intravenous neostigmine with cardiac monitoring — treats acute colonic pseudo-obstruction (Ogilvie syndrome), which lacks a true mechanical twist; here CT shows a mechanical mesenteric torsion, so a prokinetic will not relieve the closed-loop obstruction.
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Risk factors
- Sigmoid: chronic constipation, redundant sigmoid (long mesentery), neuropsychiatric disease (Parkinson, schizophrenia), high-fiber diet, institutionalization, prior abdominal surgery
- Cecal: long mobile cecum (congenital fixation failure), pregnancy, prior abdominal surgery, recent colonoscopy
- Both: laxative abuse, dysmotility, hospitalization with prolonged ileus
Pathophysiology
A redundant mobile loop with a narrow mesenteric base rotates around its axis, producing a closed-loop obstruction at the twist. Venous outflow is impaired first, leading to edema, then arterial inflow is compromised, producing ischemia, gangrene, and perforation. Cecal 'bascule' is a variant in which the cecum folds anteriorly without true rotation.
Clinical presentation
Symptoms
- Sigmoid: gradual onset cramping abdominal pain, abdominal distention, obstipation, vomiting (late)
- Cecal: more acute presentation with RLQ or periumbilical pain, distention, vomiting (earlier and more bilious than sigmoid)
- Tympanic distention out of proportion to systemic symptoms early on
- Late: signs of ischemia — severe pain, fever, peritonitis
Signs / physical exam
- Massively distended, tympanitic abdomen
- Bowel sounds high-pitched then absent
- Tenderness, peritoneal signs suggest ischemia or perforation
- Empty rectum on DRE
Classic findings
Sigmoid: 'coffee bean' or 'bent inner tube' sign on abdominal radiograph, with the apex pointing toward the RUQ. Cecal: dilated cecum displaced to the LUQ ('embryonic position'), with a 'kidney bean' or 'comma' shape.
Differential diagnosis
- Colorectal malignancy with obstruction — Older adult with weight loss, progressive constipation, anemia; mass on CT or colonoscopy
- Pseudo-obstruction (Ogilvie syndrome) — Massive cecal dilation without mechanical obstruction; postoperative or critically ill patients; rectal tube and neostigmine
- Diverticulitis with stricture — LLQ pain, fever, history of diverticulosis; CT shows pericolic inflammation
- Inflammatory bowel disease with stricture — Younger patient with chronic diarrhea, bloody stools
- Adhesive small bowel obstruction — Prior abdominal surgery, dilated small bowel loops with transition point
- Fecal impaction — Hard stool in rectum on DRE; relieved by disimpaction
Diagnostic workup
Diagnostic criteria
Imaging demonstration of closed-loop colonic obstruction with mesenteric twist and characteristic radiographic appearance.
Labs
- CBC, BMP, lactate (elevated in ischemia), coagulation studies, type and crossmatch
Imaging
- Abdominal radiograph — often diagnostic for sigmoid (coffee bean sign) or cecal (LUQ kidney bean)
- CT abdomen/pelvis with IV contrast — confirms diagnosis ('whirl sign' of twisted mesentery), identifies ischemia (pneumatosis, portal venous gas, bowel wall thickening), and excludes alternatives
- Water-soluble contrast enema — 'bird's beak' tapering at the point of torsion (sigmoid)
Complications
- Bowel ischemia and necrosis
- Perforation and feculent peritonitis
- Septic shock, multiorgan failure
- Recurrence (sigmoid: high without surgery; cecal: lower if resected)
- Anastomotic leak, surgical site infection, stoma complications
PANCE pearls
- Sigmoid volvulus in a chronically constipated nursing home patient — picture the coffee bean pointing to the RUQ.
- Cecal volvulus in a younger pregnant patient or after recent colonoscopy — picture the dilated cecum displaced to the LUQ.
- Endoscopic detorsion is appropriate ONLY for sigmoid volvulus without ischemia — NEVER for cecal volvulus as primary therapy.
- Recurrence after detorsion alone is high — definitive sigmoidectomy should be done during the same admission.
- Cecal bascule is an anterior folding of the cecum without true rotation; same clinical presentation and management.
References
- ASCRS 2016 — American Society of Colon and Rectal Surgeons clinical practice guidelines for the management of colonic volvulus (Vogel et al., Dis Colon Rectum 2016)
- WSES 2018 — World Society of Emergency Surgery (WSES) guidelines on colon and rectal obstruction