Malignant bowel obstruction — Rapid

Synopsis

Recognise mechanical and functional bowel failure in advanced cancer, resuscitate and exclude perforation or ischaemia, define level and multiplicity on CT and select surgery, stenting, decompression or symptom-focused medical care.

Malignant bowel obstruction may be a single intraluminal stricture, external compression, multifocal peritoneal encasement or diffuse functional ileus; treatment depends on the mechanism.
Colicky pain, vomiting, distension and reduced flatus or stool are typical, but partial obstruction can still pass stool and high small-bowel obstruction can vomit before marked distension.
First-line definitive imaging is contrast-enhanced CT abdomen and pelvis, which identifies level, transition, multiplicity, tumour burden, closed loop, ischaemia and potential stent or surgical target.
Initial care is nil by mouth, reassessed intravenous fluid and electrolyte replacement, antiemetic and analgesia, with nasogastric decompression for persistent vomiting or major gastric distension.
Peritonism, continuous severe pain, shock, rising lactate, closed loop or poor bowel-wall enhancement requires immediate senior surgical assessment regardless of cancer prognosis.
A single operable obstruction in a fit patient may benefit from resection, bypass or stoma; selected left-sided malignant colonic obstruction may be treated with an endoscopic self-expanding metal stent.
When surgery or stent will not provide worthwhile benefit, octreotide reduces gastrointestinal secretion, anticholinergic therapy reduces colic and a venting gastrostomy can replace prolonged nasogastric drainage.
Use metoclopramide only in selected partial obstruction without colic; avoid prokinetic treatment in complete mechanical obstruction because it can worsen painful contractions and risk.

Key red flags

Continuous rather than intermittent pain, guarding, rebound or pain out of proportion raises strangulation, ischaemia or perforation.

Fever, hypotension, oliguria, confusion, raised lactate or metabolic acidosis indicates sepsis or compromised bowel and needs urgent surgical review.

Closed-loop configuration, reduced wall enhancement, pneumatosis, portal venous gas or free intraperitoneal gas on CT requires immediate escalation.

Persistent high-volume vomiting causes aspiration, severe chloride and potassium loss and acute kidney injury even without peritonism.

Recent opioid escalation, anticholinergic medicine, electrolyte disturbance and faecal impaction can worsen functional obstruction and must be assessed alongside tumour.

Ischaemic conversion

Pain becoming continuous, peritonism, fever, tachycardia, acidosis or shock indicates threatened bowel and needs urgent surgical action.

Investigation priorities

First-line contrast CT abdomen and pelvisFirst stepFirst line

Locate and characterise obstruction and identify ischaemia, perforation, multiplicity and procedural options.

Management branches

InitialResuscitate and define anatomy

A person with cancer develops vomiting, colicky pain, distension or failure to pass stool or flatus.

Use ABCDE, keep nil by mouth, establish intravenous access, correct fluid and electrolyte loss, provide analgesia and antiemetic and decompress persistent vomiting with a nasogastric tube.
Obtain contrast CT abdomen and pelvis promptly and repeat examination and lactate while looking for peritonism, closed loop, poor enhancement, free gas or shock.
Call senior surgery immediately for ischaemia, perforation or sepsis and involve acute oncology and palliative care early for cancer context and symptom support.

Key medicines

OctreotideStart octreotide 300 micrograms by continuous subcutaneous infusion over 24 hours for persistent vomiting and high gastrointestinal secretion, titrating within the current specialist palliative-care protocol according to output and symptom response.Monitor abdominal symptoms, glucose, heart rate and injection site; longer use can cause biliary effects. It does not reverse ischaemia or perforation and should not delay surgical reassessment when pain changes.

Hyoscine butylbromideGive 20 mg subcutaneously as needed for colic and, when recurrent, 60 mg by continuous subcutaneous infusion over 24 hours, titrating to the palliative-care protocol and response.Can worsen dry mouth, urinary retention, glaucoma and delirium and may oppose a desired prokinetic strategy; continuous severe pain requires renewed ischaemia assessment rather than more antispasmodic alone.

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