Key Facts

Volvulus is a surgical emergency involving rotation of the bowel on its mesenteric axis, causing closed-loop obstruction and compromised blood supply. Sigmoid volvulus is the most common type in Western countries.

Epidemiology

Volvulus accounts for ~5% of large bowel obstruction in the UK and 20-50% in parts of Africa and Asia (the "volvulus belt"). Sigmoid volvulus: peak age 60-80 years, male predominance (3:1), associated with institutionalisation and neuropsychiatric disease. Caecal volvulus: younger patients (30-50 years), female predominance.

Aetiology

Sigmoid volvulus:

• Redundant sigmoid colon with a long, narrow mesenteric pedicle
• Chronic constipation → sigmoid megacolon
• Institutionalisation: nursing homes, psychiatric facilities (medication-related constipation: antipsychotics, opioids)
• Chagas disease (megacolon — South America)
• High-fibre/high-residue diet (African/Asian populations)

Caecal volvulus:

• Mobile caecum (congenital incomplete peritoneal fixation — ~10% of population)
• Previous surgery (adhesions altering caecal mobility)
• Pregnancy
• Marathon running (rare)

Pathophysiology

Rotation creates a closed-loop obstruction with progressive bowel dilatation proximal to the twist. Mesenteric vessel compression causes venous congestion, then arterial compromise, leading to ischaemia, gangrene, and perforation. Sigmoid volvulus typically twists anticlockwise. The closed-loop mechanism means that, unlike simple obstruction, decompression cannot occur proximally, and pressure rises rapidly — high perforation risk, especially if caecal diameter >12 cm.

Sigmoid Volvulus

• Elderly patient, often from care home
• Progressive abdominal distension (often massive)
• Colicky lower abdominal pain
• Absolute constipation
• Vomiting (late)
• History of chronic constipation, previous episodes
• On examination: massively distended abdomen, tympanic; rectum often empty on DRE

Caecal Volvulus

• Younger patient
• Acute onset colicky abdominal pain (often RIF initially)
• Distension
• Vomiting (earlier than sigmoid)
• May mimic SBO

Red Flags

• Peritonism (ischaemia/gangrene)
• Sepsis (fever, tachycardia, hypotension)
• Absent bowel sounds
• Bloody PR discharge (mucosal ischaemia)
• Raised lactate

Bedside

• AXR: often diagnostic
  • Sigmoid: coffee bean sign (inverted U), large dilated loop arising from pelvis, no haustral markings, overlap sign
  • Caecal: dilated caecum displaced to LUQ, SBO features
• Observations: sepsis screen

Bloods

• FBC: leucocytosis (strangulation)
• U&Es: dehydration, electrolyte disturbance
• Lactate: raised = ischaemia
• VBG: metabolic acidosis (ischaemia)

Imaging

• CT abdomen/pelvis: gold standard — whirl sign (twisted mesentery at the twist point), dilated bowel, transition point; identifies ischaemia (poor wall enhancement, pneumatosis) and perforation
• AXR: may be sufficient for classic sigmoid volvulus presentation in known patient

Special Tests

• Flexible sigmoidoscopy: diagnostic AND therapeutic for sigmoid volvulus — mucosal assessment for viability + flatus tube insertion
• Contrast enema (water-soluble): "bird's beak" at the twist point — rarely needed with CT availability

Non-pharmacological

• Sigmoid volvulus (no peritonitis): endoscopic decompression first-line
  • Rigid sigmoidoscope or flexible endoscope passed through twist → dramatic decompression of gas/liquid
  • Flatus tube inserted and left in situ for 24-48 hours (prevents early recurrence)
  • ~80% success rate for initial decompression
• NBM, IV fluids, NG decompression if SBO component

Pharmacological

• IV fluids: aggressive resuscitation
• IV antibiotics: if signs of ischaemia/perforation (piperacillin-tazobactam 4.5 g TDS)
• VTE prophylaxis
• Correct electrolyte imbalances

Surgical/Interventional

• Sigmoid volvulus — definitive:
  • Elective sigmoid colectomy: recommended after successful decompression (recurrence rate ~60% without surgery); laparoscopic preferred
  • If patient unfit for surgery: percutaneous endoscopic colostomy (PEC) — emerging option
• Sigmoid volvulus — emergency surgery: if gangrenous, perforated, or failed endoscopic decompression
  • Hartmann's procedure (sigmoid resection + end colostomy) — commonest emergency operation
  • Primary anastomosis ± defunctioning ileostomy in selected patients
• Caecal volvulus: endoscopic decompression usually unsuccessful (~10-20%)
  • Right hemicolectomy: definitive treatment
  • Caecopexy: alternative in selected cases (higher recurrence)

Referral Criteria

• Emergency surgical review for all volvulus
• Urgent endoscopy for sigmoid volvulus decompression
• Colorectal surgical review for definitive management after decompression

Sigmoid volvulus: endoscopic decompression successful in ~80%, but recurrence without surgery is ~60%. Elective sigmoid colectomy has <5% mortality. Emergency surgery for gangrenous sigmoid volvulus has 15-30% mortality. Caecal volvulus: emergency right hemicolectomy mortality is ~10-15%. Overall mortality for volvulus is ~10-15%, rising to 30-40% with gangrene/perforation.

Sigmoid vs Caecal Volvulus

Volvulus Management Algorithm