Overview
Sigmoid Volvulus
Topic Overview
Summary
Sigmoid volvulus is torsion of the sigmoid colon on its mesentery, causing large bowel obstruction. It is characterized by massive abdominal distension, constipation, and the classic "coffee bean" sign on abdominal X-ray. It is more common in the elderly, institutionalised patients, and those with chronic constipation. First-line treatment is endoscopic decompression (flexible sigmoidoscopy with rectal tube placement). Surgery is required for failed decompression, perforation, ischaemia, or recurrence.
Key Facts
- Demographics: Elderly, nursing home residents, psychiatric patients, chronic constipation
- Presentation: Abdominal distension, constipation, vomiting (late), abdominal pain
- Diagnosis: AXR — "coffee bean" or "bent inner tube" sign; CT if uncertain
- Treatment: Endoscopic decompression first-line (80-90% success); surgery if failed or complicated
- Recurrence: 40-60% without definitive surgery
- Surgery: Hartmann's or primary anastomosis depending on bowel viability
Clinical Pearls
The sigmoid colon in volvulus can become massive (reaching the diaphragm) — don't underestimate the degree of distension
Empty rectum on DRE + massive distension = mechanical LBO (volvulus high in differential)
Successful decompression does NOT mean the patient is "fixed" — recurrence is common without surgery
Why This Matters Clinically
Sigmoid volvulus is a common cause of large bowel obstruction, especially in certain populations. Non-operative management (endoscopic decompression) can be life-saving but many patients ultimately need surgery. Delayed treatment leads to ischaemia, perforation, and death.
Visual Summary
Visual assets to be added:
- AXR showing coffee bean sign
- CT showing sigmoid volvulus
- Endoscopic view of twisted sigmoid
- Treatment algorithm flowchart
Epidemiology
Incidence
- Third most common cause of LBO (after cancer and diverticular disease)
- More common in Africa, South America, Middle East (due to high-fibre diet)
- In Western countries: peak in elderly institutionalised patients
Demographics
- Age: Peak 70-80s
- Sex: Male predominance
- Setting: Nursing homes, psychiatric institutions
Risk Factors
| Factor | Mechanism |
|---|---|
| Chronic constipation | Sigmoid elongation and redundancy |
| High-fibre diet | Associated with longer sigmoid |
| Psychiatric illness | Neuroleptics cause constipation |
| Nursing home residence | Immobility, dehydration, constipation |
| Chagas disease | Megacolon |
| Previous abdominal surgery | Adhesions, altered anatomy |
| Parkinson's disease | Reduced motility |
| Dementia | Reduced mobility, impaired bowel habits |
Pathophysiology
Mechanism
- Long, redundant sigmoid colon with narrow mesenteric base
- Sigmoid twists on its mesentery (usually counterclockwise)
- Closed-loop obstruction develops
- Venous then arterial occlusion → ischaemia
- If untreated → necrosis, perforation, peritonitis
Why the Sigmoid?
- Sigmoid is the most mobile segment of colon
- Long mesentery creates a narrow point of fixation
- Faecal loading adds weight
Consequences of Delay
- Bowel wall necrosis
- Perforation
- Faecal peritonitis
- Sepsis and death
Clinical Presentation
Symptoms
Signs
Red Flags Suggesting Ischaemia/Perforation
| Finding | Significance |
|---|---|
| Peritonism | Perforation — needs laparotomy |
| Shock (hypotension, tachycardia) | Sepsis, ischaemia |
| Fever | Necrosis, infection |
| Bloody PR | Ischaemic bowel |
| Rapid deterioration | Impending perforation |
Progressive abdominal distension (can be dramatic)
Common presentation.
Absolute constipation (no flatus or stool)
Common presentation.
Abdominal pain (often less severe than the distension suggests)
Common presentation.
Nausea, vomiting (late sign in LBO)
Common presentation.
Clinical Examination
Abdominal Examination
- Distension (often asymmetric — "omega" shape)
- Tympanic percussion
- Variable tenderness (minimal unless ischaemia)
- Peritonism (if perforated)
- Visible peristalsis (rarely)
Digital Rectal Examination
- Often empty rectum (obstruction proximal)
- Ballooning of rectum (air dilated above)
- No impacted faeces
Assess for Signs of Ischaemia
- Tachycardia, hypotension
- Fever
- Abdominal guarding, rigidity
- Acidosis on blood gas
Investigations
Abdominal X-ray (First-Line)
| Finding | Description |
|---|---|
| Coffee bean sign | Massively dilated sigmoid loop pointing towards RUQ |
| Bent inner tube sign | Loop arising from pelvis |
| Point to right upper quadrant | Classic orientation |
| Lack of haustrations | Large bowel distension |
| Air-fluid levels | If erect |
CT Abdomen/Pelvis (If Uncertain or Suspected Complication)
| Finding | Notes |
|---|---|
| Whirl sign | Twisted mesentery |
| Dilated sigmoid | Confirms diagnosis |
| Ischaemic changes | Wall thickening, poor enhancement, pneumatosis |
| Free air | Perforation |
Blood Tests
| Test | Purpose |
|---|---|
| FBC | WCC (infection), Hb |
| U&E | Dehydration, electrolytes |
| Lactate | Ischaemia |
| ABG/VBG | Acidosis |
| Group & Save | Pre-operative |
Classification & Staging
By Viability
| Category | Management |
|---|---|
| Viable (no ischaemia) | Endoscopic decompression |
| Ischaemic (no perforation) | Urgent surgery |
| Perforated | Emergency laparotomy |
By Recurrence
- First episode — trial of endoscopic decompression
- Recurrent — usually requires elective resection
Management
Initial Resuscitation
- IV access, IV fluids
- NBM
- NG tube (if vomiting or upper GI distension)
- Catheter (urine output monitoring)
- Correct electrolytes
Endoscopic Decompression (First-Line if No Peritonism)
| Step | Details |
|---|---|
| Flexible sigmoidoscopy | Advance gently; visualise twist |
| Decompression | Massive release of gas and liquid stool |
| Rectal tube | Leave in situ to prevent re-torsion |
Success rate: 70-90%
Contraindications: Peritonitis, perforation, ischaemic mucosa
Surgical Management
Indications:
- Failed endoscopic decompression
- Signs of ischaemia or perforation
- Recurrent volvulus
- Frail patient — definitive surgery to prevent recurrence
Surgical Options:
| Procedure | Indication |
|---|---|
| Sigmoid resection + primary anastomosis | Viable bowel, elective setting |
| Hartmann's procedure | Ischaemic/perforated bowel, emergency |
| Sigmoid colectomy + end colostomy | Contaminated field, unstable patient |
Prevention of Recurrence
- Elective sigmoid colectomy after successful decompression
- Recurrence rate 40-60% without surgery
Complications
Of Volvulus
- Bowel ischaemia → necrosis
- Perforation
- Faecal peritonitis
- Sepsis
- Death
Of Decompression
- Perforation (rare)
- Re-torsion
- Recurrence (common)
Of Surgery
- Anastomotic leak
- Stoma complications
- Wound infection
- Recurrence (rare after resection)
Prognosis & Outcomes
Mortality
- Non-gangrenous: 5-10%
- Gangrenous/perforated: 30-50%
Recurrence
- After decompression alone: 40-60%
- After surgical resection: Under 5%
Factors Associated with Poor Outcome
- Delayed presentation
- Ischaemia or perforation
- Elderly, frail patients
- Comorbidities
Evidence & Guidelines
Key Guidelines
- No specific national guideline; management based on consensus and case series
Key Evidence
- Endoscopic decompression is safe and effective first-line in uncomplicated cases
- Elective surgery after decompression reduces recurrence
- Hartmann's is safe in emergency/contaminated setting
Patient & Family Information
What is Sigmoid Volvulus?
Sigmoid volvulus is when part of the bowel (the sigmoid colon) twists on itself, causing a blockage. This stops stool and gas from passing through.
Symptoms
- Very swollen tummy
- Not being able to pass gas or stool
- Tummy pain
- Feeling sick or vomiting
Treatment
- A camera (sigmoidoscopy) can untwist the bowel without surgery
- Sometimes surgery is needed, especially if the bowel is damaged
What Happens Next?
- Volvulus can come back, so some people need an operation to prevent this
Resources
References
Key Studies
- Vogel JD, et al. Clinical Practice Guideline for the Management of Sigmoid Volvulus. Dis Colon Rectum. 2016;59(6):479-492. PMID: 27145301
- Atamanalp SS. Sigmoid volvulus: a 10-year experience of 550 cases. Tech Coloproctol. 2013;17(5):561-569. PMID: 23519984
- Halabi WJ, et al. Sigmoid volvulus: epidemiology, treatment, and outcomes. Am Surg. 2014;80(4):407-411. PMID: 24887670