Bowel Obstruction

Bowel obstruction: mechanical blockage causing colicky abdominal pain, vomiting, absolute constipation, abdominal distension. Small bowel obstruction (SBO): usually adhesions, hernia. Large bowel obstruction (LBO): usually malignancy, sigmoid…

ACS / ACPGBI Guidelines — Drip & Suck Protocol

The pathway

1 · Clinical assessment

Abdominal examination: distension, tinkling bowel sounds, tenderness, hernial orifices (incarcerated hernia = surgical emergency)
Absolute constipation = no flatus or stool
PR exam essential (rectal mass, impaction, blood)
Vital signs: fever or peritonism = suspect strangulation

2 · Investigations

AXR: dilated loops, air-fluid levels, gas distribution (SBO vs LBO)
CT abdomen with IV contrast: gold standard — defines level, cause, strangulation (mesenteric oedema, free fluid, pneumatosis), closed loop
Bloods: FBC, CRP, U&E, lactate (raised = strangulation), LFTs, amylase, group & save

3 · Drip and suck — NGT decompression

IV access, NBM
NG tube: wide-bore, free drainage, regular aspiration
IV fluids (Hartmann's 1–2L/hr initially)
Urinary catheter + strict fluid balance
Analgesia: IV morphine
IV antiemetic
This is conservative management — 80% of adhesional SBO resolves without surgery

4 · SBO vs LBO management

SBO adhesional: conservative 24–48h trial
SBO from hernia: emergency surgical repair
LBO: usually needs surgery or stenting
Sigmoid volvulus on AXR (coffee bean sign): flexible sigmoidoscopy first — untwist without surgery in 80%
Caecal volvulus: surgery always required

5 · Strangulation red flags

Temperature >38°C
Peritonism
Severe localised tenderness
Raised WBC
Raised lactate
Free fluid on CT
Pneumatosis intestinalis
All suggest strangulation. Strangulation = emergency laparotomy. Do not delay for further investigations if clinical suspicion high.

6 · Surgical referral thresholds

Early surgical referral for: all LBO
Any hernia-related SBO
Failure to improve by 24–48h conservative
Strangulation
Closed-loop obstruction on CT
Volvulus (except sigmoid)
All cases need colorectal surgical input. Bowel prep and consent for potential stoma formation.

Drugs

Drug	Dose	Route	Notes
Hartmann's solution	1–2L/hr initial resuscitation	IV	Aggressive fluid replacement — patients often severely dehydrated from vomiting.
Morphine	5–10mg 4-hourly PRN	IV/IM	Do not withhold analgesia — it does not mask progression to strangulation.
Cyclizine	50mg 8-hourly	IV/IM	Antiemetic. Ondansetron 4–8mg IV if cyclizine insufficient.
Broad-spectrum antibiotics	As per trust guideline	IV	If strangulation suspected or peritonitis. Piperacillin-tazobactam or co-amoxiclav + metronidazole.

When to escalate

Any sign of strangulation (peritonism, fever, raised lactate) → emergency laparotomy,Closed-loop obstruction on CT → surgical emergency,Caecal volvulus → emergency surgery,LBO not suitable for stenting → surgical resection,Haemodynamic compromise → ITU, senior surgical review urgently

Reference: ACPGBI / ACOI Guidelines for Emergency Bowel Obstruction 2021

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