Sigmoid volvulus case study
The case
Patient: 68‑year‑old male, retired farmer
Presenting complaint: Sudden onset of abdominal pain and distension for 12 hours.
History of present illness:
- Pain started abruptly in the periumbilical region, now diffuse, colicky, worsening over the last 6 hours.
- No passage of flatus or stool for 10 hours (obstipation).
- Two episodes of non‑bloody, non‑bilious vomiting.
- No fever, chills, or urinary symptoms.
Past medical history:
- Chronic constipation for >10 years, usually managed with over‑the‑counter laxatives.
- Hypertension, on amlodipine 5 mg daily.
- No previous abdominal surgeries.
Social history:
- Low‑fiber diet, limited fluid intake.
- Non‑smoker, occasional alcohol.
Examination:
| Parameter | Finding |
|---|---|
| General | Alert, mildly uncomfortable, afebrile (37.2 °C) |
| Vitals | BP 150/90 mm Hg, HR 102 bpm, RR 20 /min, SpO₂ 98 % on room air |
| Abdomen | Marked distension, tympanic on percussion, diffuse tenderness, no guarding or rebound. Bowel sounds hyperactive initially, now absent. No palpable masses. No visible peristalsis. |
| Rectal exam | Empty rectal vault, no gross blood. |
Initial investigations:
| Test | Result |
|---|---|
| CBC | Hb 13.2 g/dL, WBC 14.5 × 10⁹/L (neutrophils 84 %), platelets 310 × 10⁹/L |
| Serum electrolytes | Na 138 mmol/L, K 3.8 mmol/L, Cl 102 mmol/L, HCO₃⁻ 22 mmol/L |
| Renal function | Urea 28 mg/dL, Creatinine 1.2 mg/dL |
| ABG (room air) | pH 7.32, pCO₂ 38 mm Hg, pO₂ 78 mm Hg, HCO₃⁻ 20 mmol/L |
| Plain abdominal X‑ray (supine & upright) | Dilated sigmoid colon forming an inverted “U” or “coffee‑bean” sign, air‑fluid levels, no free intraperitoneal air. |
| Abdominal CT (contrast‑enhanced) – performed after resuscitation | “Whirl sign” of twisted mesenteric vessels at the sigmoid, markedly dilated sigmoid loop (diameter 9 cm), collapsed distal colon and rectum, no perforation. |
The clinical picture suggests an acute large‑bowel obstruction, most likely due to sigmoid volvulus.
Questions
- What is the most likely diagnosis?
- Which clinical and radiological findings specifically support this diagnosis?
- Outline the initial resuscitation and stabilization steps before definitive treatment.
- What are the definitive management options for sigmoid volvulus, and how do you decide between them?
- Discuss possible complications of sigmoid volvulus and their preventive measures.
Answers
1. What is the most likely diagnosis?
Sigmoid volvulus – torsion of the sigmoid colon around its mesentery causing a closed‑loop obstruction. The patient’s age, chronic constipation, abrupt abdominal pain, obstipation, and the characteristic “coffee‑bean” sign on X‑ray together with the CT “whirl sign” confirm the diagnosis.
2. Which clinical and radiological findings specifically support this diagnosis?
| Finding | Why it points to sigmoid volvulus |
|---|---|
| Sudden colicky abdominal pain | Obstruction from a twisted, closed‑loop segment produces intermittent high‑pressure pain. |
| Obstipation (no flatus or stool) | Complete luminal blockage at the sigmoid level prevents distal passage. |
| Marked abdominal distension with tympany | Accumulation of gas and fluid proximal to the obstruction. |
| Absence of peritoneal signs (no guarding/rebound) | Early presentation before ischemia or perforation. |
| Leukocytosis (WBC 14.5 × 10⁹/L) | Inflammatory response; may herald evolving ischemia. |
| Plain X‑ray “coffee‑bean” sign | Dilated sigmoid loop with apex pointing toward the right upper quadrant; classic for sigmoid volvulus. |
| CT “whirl sign” | Twisting of the mesenteric vessels and sigmoid mesocolon; highly specific (sensitivity ≈ 80‑90 %). |
| No free air on imaging | No perforation yet; important for choosing non‑operative decompression. |
These findings collectively differentiate sigmoid volvulus from other causes of large‑bowel obstruction such as colonic carcinoma or volvulus of the cecum.
3. Outline the initial resuscitation and stabilization steps before definitive treatment.
- Airway, Breathing, Circulation (ABCs): Patient is stable; give supplemental O₂ if SpO₂ < 94 %.
- IV access: Two large‑bore cannulas (≥ 18 G).
- Fluid resuscitation: Isotonic crystalloid (0.9 % NaCl) 20 mL/kg bolus, then titrate to maintain MAP ≥ 65 mm Hg and urine output ≥ 0.5 mL/kg/h.
- Electrolyte correction: Replace potassium if < 3.5 mmol/L; correct metabolic acidosis cautiously.
- Nasogastric tube (NGT): Decompress stomach, reduce vomiting risk, and limit further distension.
- Bladder catheter: Monitor urine output.
- Broad‑spectrum antibiotics: If suspicion of bowel ischemia or perforation (e.g., ceftriaxone + metronidazole) per Surviving Sepsis Guidelines 2021.
- Analgesia: IV paracetamol or low‑dose opioids; avoid masking peritoneal signs.
- Imaging confirmation: After stabilization, obtain CT if not already done to rule out perforation.
Resuscitation aims to correct hypovolemia, electrolyte imbalance, and prepare the patient for either endoscopic or surgical intervention.
4. What are the definitive management options for sigmoid volvulus, and how do you decide between them?
| Management option | Indications | Technique | Success rate | When to proceed to surgery |
|---|---|---|---|---|
| Endoscopic detorsion (flexible sigmoidoscopy or colonoscopy) | No peritonitis, no perforation, hemodynamically stable, early presentation (< 24 h). | Insert scope, locate twisted segment, pass the scope beyond the point of torsion, decompress by suction; may place a rectal tube for 24‑48 h. | 70‑90 % initial success; recurrence 30‑50 % within 5 days. | Failure to decompress, signs of ischemia/perforation, recurrent volvulus, or patient unsuitable for endoscopy. |
| Emergency surgery | Peritonitis, perforation, hemodynamic instability, failed endoscopic reduction, recurrent volvulus after initial endoscopic treatment, or patient with high recurrence risk (e.g., megacolon). | Options: (a) Sigmoid resection with primary anastomosis (if bowel viable, patient stable); (b) Hartmann’s procedure (resection + end colostomy) if contamination or poor perfusion; (c) Laparoscopic sigmoidectomy (in selected stable patients). | Definitive cure; recurrence < 5 % after resection. | Immediate surgery if any sign of gangrene or perforation; otherwise, attempt endoscopic reduction first. |
| Elective surgery (after successful endoscopic reduction) | High‑risk of recurrence (e.g., chronic constipation, redundant sigmoid, previous volvulus). | Elective sigmoid colectomy (open or laparoscopic) with primary anastomosis. | Prevents recurrence; low morbidity in elective setting. | Recommended within 1–2 weeks after successful reduction. |
Decision algorithm (2023 ASCRS guideline):
- Stable, no peritonitis → attempt endoscopic detorsion.
- Successful → observe 24‑48 h, place rectal tube, schedule elective resection.
- Unsuccessful or signs of ischemia/perforation → proceed to emergency surgery (resection with primary anastomosis if feasible, otherwise Hartmann’s).
5. Discuss possible complications of sigmoid volvulus and their preventive measures.
| Complication | Pathophysiology | Clinical clue | Prevention / Management |
|---|---|---|---|
| Bowel ischemia / gangrene | Vascular compromise from torsion > 180°; leads to transmural necrosis. | Persistent severe pain, leukocytosis, metabolic acidosis, peritoneal signs, CT shows lack of wall enhancement. | Early diagnosis, prompt decompression; if suspected, immediate surgery (resection). |
| Perforation | Necrotic wall ruptures; risk rises after > 24 h of obstruction. | Free air on X‑ray/CT, sudden worsening pain, sepsis. | Avoid delayed treatment; limit endoscopic attempts to ≤ 2 times; surgical resection if perforation present. |
| Recurrence | Redundant sigmoid, chronic constipation, underlying megacolon. | Re‑obstruction within days to weeks after successful reduction. | Elective sigmoid colectomy after first episode; bowel regimen (high‑fiber diet, adequate fluids, regular laxatives). |
| Sepsis / peritonitis | Bacterial translocation from ischemic gut or perforation. | Fever, tachycardia, leukocytosis, rising lactate. | Early antibiotics, source control via surgery. |
| Electrolyte disturbances | Vomiting and third‑spacing cause hypokalemia, metabolic alkalosis. | Low serum K⁺, elevated bicarbonate. | Replace electrolytes during resuscitation. |
| Anastomotic leak (post‑resection) | Poor perfusion, tension, infection. | Fever, abdominal pain, tachycardia, rising WBC, drainage of feculent fluid. | Ensure good blood supply, tension‑free anastomosis, peri‑operative antibiotics, consider diverting stoma in high‑risk patients. |
Preventive strategies focus on early recognition, timely decompression, and definitive surgical resection to eliminate the redundant sigmoid segment.
Key learning points
- Sigmoid volvulus is the commonest cause of colonic obstruction in elderly males with chronic constipation and a low‑fiber diet.
- The “coffee‑bean” sign on plain abdominal X‑ray and the “whirl sign” on CT are radiological hallmarks.
- Initial management follows ABCs, aggressive fluid resuscitation, NGT decompression, and correction of electrolytes.
- Endoscopic detorsion is the first‑line definitive treatment in stable patients without peritonitis; success rates are high but recurrence is common.
- Emergency surgery (resection with primary anastomosis or Hartmann’s) is indicated for perforation, gangrene, failed endoscopic reduction, or hemodynamic instability.
- Elective sigmoid colectomy after successful reduction prevents recurrence and is the preferred long‑term solution.
- Complications include ischemia, perforation, peritonitis, sepsis, and recurrence; early detection and appropriate surgical intervention are crucial.
Practice MCQs
1. A 70‑year‑old woman presents with acute abdominal distension and obstipation. Plain X‑ray shows a large, inverted “U”‑shaped gas pattern pointing toward the right upper quadrant. The most appropriate next step is:
A. Immediate exploratory laparotomy
B. Flexible sigmoidoscopic decompression
C. High‑dose intravenous metronidazole
D. Observation and repeat X‑ray in 12 hours
Answer: B — In a hemodynamically stable patient without peritonitis, the first‑line treatment for sigmoid volvulus is endoscopic detorsion.
2. Which of the following CT findings is most specific for sigmoid volvulus?
A. Dilated transverse colon > 6 cm
B. “Whirl” of mesenteric vessels at the sigmoid mesocolon
C. Free intraperitoneal air
D. Thickened rectal wall
Answer: B — The “whirl sign” represents twisted mesenteric vessels and is highly specific for volvulus.
3. After successful endoscopic reduction of a sigmoid volvulus, the patient is scheduled for elective surgery. Which of the following statements is true?
A. Elective surgery can be delayed indefinitely because recurrence is rare.
B. A primary anastomosis is contraindicated after any episode of volvulus.
C. High‑fiber diet and regular laxatives reduce the risk of recurrence.
D. Placement of a permanent colostomy is mandatory after reduction.
Answer: C — Lifestyle modification with a high‑fiber diet and adequate hydration reduces chronic constipation and the risk of recurrent volvulus.
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