AKT · Gastroenterology/Acute abdomen & surgical

Gastrointestinal perforation

Full-thickness breach of the GI tract → peritoneal contamination (free gas)

Overview

A full-thickness breach of the gut wall, spilling contents into the peritoneum and causing peritonitis. Causes by site: perforated peptic ulcer (upper), perforated diverticulitis/appendicitis/cancer/ischaemia (lower), Boerhaave (oesophagus). Presents with sudden severe abdominal pain and a rigid 'board-like' abdomen. The radiological hallmark is FREE intraperitoneal gas — sub-diaphragmatic on erect CXR, or pooling to the non-dependent side on a lateral decubitus film. An emergency: resuscitate and operate.

Recognise

SUDDEN severe abdominal pain, then generalised PERITONITIS — rigid 'board-like' abdomen, guarding, rebound, lies still, shallow breathing, tachycardia/shock
Loss of liver dullness (gas over the liver); absent bowel sounds; rapid deterioration/sepsis
FREE GAS: erect CXR — air under the diaphragm; AXR — Rigler (double-wall) sign, football sign, falciform outline; LATERAL DECUBITUS — free gas rises to the NON-DEPENDENT side

Red flags

Generalised peritonitis with free gas → emergency resuscitation + surgery
Faecal peritonitis/septic shock — high mortality

Differentials & how to tell them apart

Acute pancreatitisepigastric pain to back, raised amylase/lipase — no free gas (but can mimic)

Mesenteric ischaemiapain out of proportion, raised lactate, AF — may progress to perforation

Ruptured AAAback/flank pain, pulsatile mass, collapse — exclude in the older patient

Myocardial infarction (inferior)epigastric pain — ECG/troponin

Pneumoperitoneum — free gas under the diaphragm on an erect chest X-ray (perforation)
Bill Rhodes / CC BY 2.0 — Wikimedia Commons

Investigations

ERECT CXR (air under the diaphragm — the classic film); if the patient can't sit up, LATERAL DECUBITUS film (free gas non-dependent). CT abdomen/pelvis (site/cause). FBC/U&Es/CRP/lactate/amylase, group & save, VBG.

Management

Resuscitate (fluids + antibiotics) + emergency surgery (repair/resection + washout)

1Resuscitate aggressively (IV fluids, broad-spectrum antibiotics, analgesia, NG tube, catheter) and confirm free gas (erect CXR, or lateral decubitus if the patient can't sit up). Urgent surgical referral.Gate: If the erect CXR is equivocal/the patient can't sit up, a LATERAL DECUBITUS film localises free gas to the NON-DEPENDENT side (the side they are NOT lying on) — distinguishing true free intraperitoneal gas (perforation) from bowel gas; free gas = laparotomy
2Emergency laparotomy: repair (omental/Graham patch for perforated ulcer), resect and wash out per cause; ITU/sepsis care.

Resuscitation: IV fluids, broad-spectrum antibiotics, analgesia, NG tube — sepsis management; nil by mouth

Emergency laparotomy / repair — close the perforation (e.g. omental patch for ulcer), resect/wash-out per cause

Key points

Sudden severe pain + board-like rigid abdomen + free gas = perforation → resuscitate and operate. The film: air under the diaphragm on erect CXR, or — if they can't sit up — free gas pooling to the NON-dependent side on a decubitus film (the read that distinguishes free gas from luminal gas).

Monitor & prognosis

Sepsis/lactate; post-op critical care.

Depends on cause/contamination; faecal peritonitis is high-mortality.

Source: RCS; ACPGBI