Investigations

Baseline observations.
Urinalysis and ßhCG in all females of child-bearing age to exclude an ectopic pregnancy.
Bloods including FBC, U&Es, LFTs and amylase.
- A low Hb (especially if microchromic microcytic anaemia) and raised urea may suggest bleeding.
- LFTs may point to differential diagnoses including biliary colic, acute cholecystitis or acute pancreatitis.
Group & Save or cross-match if suspicion of gastrointestinal bleeding.
12-lead ECG to exclude acute coronary syndromes.
Erect chest x-ray looking for pneumoperitoneum (air under the diaphragm) if perforation is suspected. This may also be appropriate if there are risk factors for malignancy.
Consider a bedside USS for older patients with epigastric pain radiating to the back to assess for abdominal aortic aneurysm.