01OverviewDefinition, clinical context and the essential points that orientate the chapter.
A volvulus forms when a mobile segment rotates around its mesenteric axis. Luminal obstruction develops first, trapping gas and fluid; venous outflow then fails, causing oedema, haemorrhage and ultimately arterial infarction. The sigmoid is the commonest colonic site in the UK. A long redundant sigmoid on a narrow mesenteric base is predisposed, with chronic constipation, megacolon, neuropsychiatric disease and institutionalisation common contexts. Presentation is distension, colicky pain and obstipation, sometimes with vomiting or prior self-resolving attacks. Marked distension with surprisingly little tenderness can still conceal compromised bowel, so physiology and CT enhancement matter more than discomfort alone.
Caecal volvulus includes axial twisting of caecum, terminal ileum and ascending colon or folding as a caecal bascule. It arises from incomplete fixation and may be triggered by surgery, pregnancy or altered motility. Pain can be more acute and right-sided, with small-bowel dilatation because terminal ileum participates. Unlike sigmoid volvulus, it is rarely suited to endoscopic decompression. Other twisting syndromes, such as transverse-colon volvulus, are uncommon and generally require surgery. In every anatomical type, the key question is whether the bowel is viable. Constant pain, guarding, systemic toxicity, lactate rise and CT poor enhancement or pneumatosis make delay hazardous.
Initial care includes fasting, venous access, fluid and electrolyte replacement, nasogastric decompression for vomiting, analgesia and urgent colorectal discussion. CT usually confirms anatomy and excludes obstructing cancer. If sigmoid bowel appears viable and there is no perforation or peritonitis, flexible sigmoidoscopic detorsion converts an emergency into a controlled situation and allows mucosal inspection; a rectal or flatus tube may maintain decompression. Because recurrence after detorsion alone is frequent and another attack may strangulate, definitive sigmoid colectomy should be planned during the same admission or at the earliest safe point. A frail patient unsuitable for resection requires an individual multidisciplinary plan; repeated decompression or percutaneous endoscopic colostomy carries its own perforation, infection and recurrence risks.
Key points
- Volvulus is axial twisting of a mobile bowel segment and its mesentery, creating obstruction with progressive venous congestion, arterial compromise, necrosis and perforation.
- Sigmoid volvulus is associated with a redundant sigmoid, chronic constipation, neurological or psychiatric disease, immobility, institutional care and previous episodes.
- Caecal volvulus reflects abnormal right-colon mobility and often presents as a more acute obstruction in a younger or postoperative patient than sigmoid disease.
- Abdominal radiography may show a coffee-bean or markedly dilated loop, but contrast CT more reliably identifies the whirl, beak, transition, anatomical type and viability.
- Uncomplicated sigmoid volvulus is initially treated by urgent flexible endoscopic detorsion and decompression, usually leaving a decompression tube according to local practice.
- Successful detorsion is temporary source control rather than cure; recurrence is high, so offer definitive sigmoid resection during the same admission or promptly when fitness allows.
- Do not attempt endoscopic detorsion when perforation, peritonitis or non-viable bowel is suspected; these patients need emergency resection.
- Caecal volvulus is managed surgically because endoscopic decompression is unreliable; resection is generally preferred when fitness and viability permit.
02AetiologyUnderlying causes, associations and risk factors, with why each one matters.
Redundant sigmoid and chronic constipation
An elongated mobile sigmoid with a narrow mesenteric base predisposes to twisting, particularly with constipation, immobility and neurological or psychiatric disease.
Mobile caecum
Incomplete embryological fixation leaves the caecum and right colon free to rotate, sometimes after surgery or during major anatomical displacement.
Distension and altered motility
Megacolon, institutional immobility and recurrent episodes promote further elongation and rotation, especially in sigmoid disease over time.
03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.
- 1Axial bowel rotation
A mobile colonic segment twists around its mesentery, closing the lumen at two points and creating a closed-loop obstruction.
- 2Venous congestion and distension
Mesenteric venous outflow fails first, causing oedema, haemorrhage and rapid gas and fluid accumulation within the trapped loop.
- 3Arterial compromise and necrosis
Continued torsion reduces arterial inflow, leading to ischaemia, gangrene, perforation and faecal contamination without prompt detorsion.
04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.
Massive painless or colicky distension, obstipation and a CT twist in sigmoid mesentery without free air, poor enhancement or peritonism supports urgent endoscopic detorsion.
Continuous pain, involuntary guarding, fever, shock, bloody rectal discharge or CT signs of non-enhancement, pneumatosis and free fluid indicates infarction and emergency surgery.
Acute right-sided or central pain, obstruction and a displaced dilated caecum with mesenteric whirl or beak on CT indicates a mobile right-colon twist that normally requires operation.
Anterior folding of a hypermobile caecum can obstruct without the classic axial whirl. CT anatomy and proximal small-bowel dilatation help identify this surgical variant.
05InvestigationsWhat to request, why it matters and how to interpret it.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Contrast CT abdomen and pelvisFirst step - Why
- Confirm the twist and site, distinguish sigmoid from caecal anatomy, identify a tumour and assess bowel viability or perforation.
- Interpretation and limitations
- A whirl of mesentery and converging beak supports volvulus. Poor enhancement, pneumatosis, portal venous gas, free fluid or free air mandates urgent surgery rather than endoscopy.
- 02
Abdominal radiograph - Why
- Rapidly demonstrate a greatly dilated loop and overall obstruction pattern while definitive CT and treatment are organised.
- Interpretation and limitations
- A coffee-bean-shaped sigmoid loop supports the diagnosis but is not always present; a displaced caecum can mimic sigmoid disease. It cannot reliably establish viability.
- 03
Full blood count, renal profile and CRP - Why
- Assess dehydration, kidney injury, electrolyte loss and inflammatory response before decompression or theatre.
- Interpretation and limitations
- Leucocytosis and kidney injury increase concern but are non-specific. Normal blood tests do not exclude early strangulation, especially in an older or immunosuppressed patient.
- 04
Blood gas and lactate - Why
- Detect acidosis and systemic hypoperfusion in suspected ischaemia or severe obstruction.
- Interpretation and limitations
- A rising lactate or base deficit supports advanced compromise, but a normal early result cannot overrule persistent pain, peritonism or CT evidence of threatened bowel.
- 05
Flexible sigmoidoscopy - Why
- Detorse and decompress a viable uncomplicated sigmoid volvulus while directly assessing distal mucosal viability.
- Interpretation and limitations
- Successful passage beyond the twist with gas and stool release confirms decompression. Dusky, black or ulcerated mucosa ends the procedure and triggers immediate surgical management.
- 06
Histology and completion colonic assessment - Why
- Exclude a malignant lead point and define other colonic disease after emergency decompression when clinically safe.
- Interpretation and limitations
- Timing depends on operative plan and bowel preparation. Do not delay definitive resection solely to complete elective diagnostics if recurrence or viability risk is high.
06Differential diagnosisRealistic alternatives and the features that help distinguish them.
Acute colonic pseudo-obstruction
Diffuse functional dilatation without a twist or transition point occurs during illness, surgery or medicine exposure and has a different decompression pathway.
Malignant large-bowel obstruction
A focal tumour and shouldered transition with proximal dilatation favours cancer rather than a mesenteric whirl and beaked twisted loop.
Small-bowel obstruction
Central small-bowel loops, earlier vomiting and a small-intestinal transition point suggest adhesions, hernia or other SBO rather than colonic volvulus.
Additional chapter-specific clues
Diffuse colonic dilatation in a severely ill or postoperative patient without a twist or focal transition supports acute colonic pseudo-obstruction and follows a different decompression pathway.
An annular lesion with an abrupt transition but no mesenteric twist suggests malignant large-bowel obstruction; cancer can also act as a lead point or coexist and must be excluded after detorsion.
07ManagementImmediate care, first-line treatment, alternatives and escalation.
01Suspected twistResuscitate and establish anatomyFirst stepAcute distension, pain and obstipation suggest colonic volvulus.+
- 1Keep fasting, obtain venous access, correct fluid and electrolyte deficits, provide analgesia and antiemetic care, and decompress the stomach when vomiting or small-bowel dilatation warrants it.
- 2Examine for peritonism and rectal findings, send urgent bloods and lactate, and obtain CT with direct radiology discussion about site, direction, viability and perforation.
- 3Call senior colorectal surgery at diagnosis and alert endoscopy or theatre according to viability; begin local antibiotics when ischaemia, perforation or sepsis is suspected.
- 4DefinitiveDo not allow temporary symptomatic improvement or a normal lactate to defer definitive anatomical management.
02Viable sigmoidDetorse then prevent recurrenceCT supports sigmoid volvulus without perforation, peritonitis or non-viable bowel.+
- 1Arrange urgent expert flexible endoscopic detorsion with surgical backup, minimal insufflation and direct inspection for mucosal ischaemia.
- 2Leave a decompression tube when locally practised, continue fluid and electrolyte correction, and monitor for early retorsion, pain or perforation.
- 3DefinitiveDiscuss definitive sigmoid colectomy during the same admission or promptly after optimisation because decompression alone carries substantial recurrence.
- 4If surgery is prohibitively risky, use a documented multidisciplinary frailty plan for repeated decompression or selected fixation, explaining limitations and emergency triggers.
03Caecal or non-viableProceed to emergency operationThe anatomy is caecal volvulus or any volvulus has perforation, peritonism or threatened viability.+
- 1Continue resuscitation and colonic-sepsis antibiotics, involve anaesthesia and critical care, and obtain consent for resection, anastomosis or stoma according to intraoperative findings.
- 2Avoid routine colonoscopic decompression of caecal volvulus and avoid any endoscopic attempt when necrosis or perforation is suspected.
- 3Resect non-viable bowel back to healthy margins; the operative reconstruction depends on contamination, physiology, anatomy and surgeon judgement.
- 4After operation, monitor for sepsis, leak, ileus and nutritional decline and address constipation, mobility and other recurrence-associated factors during recovery.
Key medicines and prescribing safety3 treatments · regimens, roles and cautions+
Intravenous crystalloid
Give reassessed isotonic fluid under the emergency-surgery protocol, replacing measured deficits and accounting for frailty, cardiac function, renal injury and urine output.Avoid unreviewed fluid loading in heart or renal failure. Fluid cannot reverse mesenteric twisting, and temporary blood-pressure improvement must not delay detorsion or resection.
Broad-spectrum intravenous antibiotic
Use the current local enteric-sepsis regimen promptly when bowel ischaemia, perforation, systemic toxicity or emergency resection is suspected, then review against source control.Not every uncomplicated viable detorsion requires prolonged antibiotics. Check allergy and renal function, narrow where possible, and recognise that antimicrobial treatment cannot salvage strangulated tissue.
Analgesia and antiemetic
Titrate hospital-formulary analgesia and antiemetic treatment to comfort and physiology while maintaining serial abdominal examinations and obstruction precautions.Avoid NSAID-related renal or bleeding harm and minimise unnecessary opioid motility suppression. Increasing requirement, sedation or persistent vomiting should trigger reassessment, not automatic repeat dosing.
08ComplicationsImportant consequences, why they occur and why they matter clinically.
Bowel ischaemia and perforation
Strangulation can make endoscopic decompression unsafe and requires urgent resection before necrotic bowel ruptures into the peritoneum.
Sepsis and organ failure
Barrier loss and faecal contamination cause shock, acidosis, kidney injury and death if definitive source control is delayed.
Recurrence
Successful endoscopic detorsion of viable sigmoid bowel does not correct the mobile anatomy, so recurrence is common without definitive surgical planning.
09Monitoring and follow-upTreatment response, safety checks and longer-term review.
- Before and after decompression, record pain, girth or distension, tenderness, flatus, stool, decompression-tube output and recurrence of vomiting.
- Trend pulse, blood pressure, temperature, respiratory rate, oxygen need, consciousness, urine output and fluid balance for shock or abdominal compartment effects.
- Repeat renal function, potassium, white count, CRP and lactate according to severity; a worsening pattern triggers re-imaging or theatre review.
- Inspect for peritonism and recurrent distension in the hours after endoscopic detorsion because retorsion or perforation can occur before planned surgery.
- Track the definitive-operation decision and date; successful decompression must not become an accidental discharge endpoint without recurrence planning.
10Special situationsVariants, exceptions and circumstances that change the usual approach.
Detorsion buys time
Endoscopic sigmoid decompression converts immediate pressure risk into an opportunity for resuscitation and planned resection. It does not correct the redundant mobile anatomy.
Mucosa reveals viability
Endoscopy can expose dusky or necrotic sigmoid mucosa even when external physiology is modest. Such a finding changes decompression into an urgent operative pathway.
Caecum chooses surgery
Right-colon twisting often includes terminal ileum and has low durable endoscopic success. Operative fixation or, more commonly, resection addresses both obstruction and recurrence.
Coffee bean is not anatomy
The classic radiographic silhouette is helpful but imperfect. CT determines which segment twisted, whether another lesion obstructs and whether the bowel still enhances.
Frailty changes method not stakes
A high operative risk may lead to repeated endoscopy or selected fixation, but recurrence and perforation remain real. The compromise needs explicit shared decision-making.
11Common pitfallsFrequent interpretation and management errors.
- 01
Attempting endoscopic detorsion despite peritonism or CT evidence of non-viable bowel.
- 02
Treating successful sigmoid decompression as definitive cure and discharging without a surgery plan.
- 03
Using a coffee-bean sign to assume sigmoid anatomy without reviewing CT.
- 04
Trying routine colonoscopic decompression for caecal volvulus and delaying resection.
- 05
Reassuring from a normal lactate when constant pain and poor mural enhancement persist.
- 06
Failing to inspect mucosal viability during sigmoid detorsion or act on dusky tissue.