31st July 2023

Assessment

Initial assessment of a patient presenting with an acute abdomen should follow the ABCDE approach to establish the severity of their condition and ensure appropriate steps are taken to stabilise them.

Alongside a focused history and thorough abdominal examination, which is generally what yields the key information that guides diagnosis and further management, the following investigations may also be employed:

• Blood tests  – FBC, U&Es, LFTs, CRP/ESR, amylase, blood glucose as routine
• Blood cultures if suspicion of sepsis
• Urinalysis and urine sample for microscopy, culture and sensitivity
• Urinary pregnancy test (and β-hCG, if necessary)  – essential in any person with a uterus of childbearing age to rule out an ectopic pregnancy
• Venous blood gas (or arterial blood gas)  – lactate is a key readout, as indicates tissue hypoperfusion and ischaemia; acidosis or alkalosis associated with certain pathologies
• Abdominal x-ray  – relatively limited, but first line for a suspected bowel obstruction as it can be arranged more quickly than a CT scan
• Chest x-ray  – to assess for bowel perforation (i.e. pneumoperitoneum), generally done as standard in any patient presenting with an acute abdomen
• Ultrasound:
  • POCUS  – in suspected ruptured AAAs
  • Abdomen and pelvis  – especially for liver and gynaecological pathology
  • Testes  – if testicular torsion is suspected
  • Urinary tract  – less accurate than CT, but can be used to assess for stones, obstruction, hydronephrosis, and urinary tract abnormalities which may underlie pathology
• CT imaging:
  • Abdomen  – gold standard for an acute abdomen
  • Urinary tract  – gold standard for suspected renal colic, can reveal stones, as well as assess for obstruction and hydronephrosis
  • Angiogram  – gold standard for aortic pathology, providing the patient is stable
• ERCP/MRCP  – used in the investigation of pancreaticobiliary disease, but generally only when the patient is stable
• Endoscopy  – upper GI endoscopy is done acutely in patients with suspected upper GI bleeds (i.e. perforated ulcers, oesophageal varices)
  • Colonoscopy and other forms of scopes are generally not done acutely, but may be important if bowel pathology is suspected, once the patient has stabilised