Synopsis
Recognise a time-critical abdominal presentation, use anatomy and physiology to prioritise the differential, and arrange focused investigation, analgesia and surgical or specialist treatment.
- Assess physiological stability and red flags before organising a location-based differential.
- Consider ruptured aneurysm, ectopic pregnancy, bowel ischaemia, perforation and obstructed or strangulated bowel early.
- Offer pregnancy testing when pregnancy is possible, including with apparently nonspecific gastrointestinal or urinary symptoms.
Key red flags
Abdominal or back pain with circulatory collapse requires urgent consideration of a ruptured aneurysm, including when no pulsatile mass is palpable.
Investigation priorities
Identify a pregnancy-related pathway that changes urgency and imaging.
Management branches
Acute abdominal pain is accompanied by collapse, hypoperfusion, peritonism or rapidly worsening physiology.
- Assess ABCs, obtain IV access and relevant samples, provide monitored analgesia and start appropriate resuscitation while urgently contacting the surgical or other responsible specialist team.
- Consider internal bleeding, vascular rupture, perforation and ischaemia explicitly; organise blood components when haemorrhage is suspected rather than relying on routine maintenance fluids.
The patient is haemodynamically stable, without an immediate operative indication, but the cause remains uncertain.
Key medicines
Paracetamol when the oral route is suitableFor an adult weighing at least 50 kg without relevant dose-reduction factors, give 500 mg–1 g orally per dose, at least 4 hours apart, up to 4 g in 24 hours; review ongoing need and stop when pain resolves.Check all combination products and reduce the dose when low body weight, liver disease or other risk factors require it. Oral treatment is unsuitable with unsafe swallowing or significant vomiting, and severe pain needs additional monitored analgesia.