Synopsis
Select abdominal imaging by the anatomical and clinical question, understand contrast, radiation and MRI constraints, and reserve ERCP chiefly for biliary or pancreatic therapy with explicit prevention and recognition of complications.
- Ultrasound is first-line for gallstones, biliary dilatation, ascites and many liver questions; it is dynamic and radiation-free but limited by bowel gas, body habitus and operator dependence.
- Contrast-enhanced CT is fast and broad for acute abdomen, perforation, obstruction, ischaemia, bleeding, sepsis, trauma and cancer staging, but uses ionising radiation and often iodine.
- MRI offers high soft-tissue contrast without ionising radiation; liver protocols and enterography answer focused questions but take longer and require implant, claustrophobia and motion assessment.
Key red flags
Fever or sepsis, right upper-quadrant pain, jaundice and cholestatic tests with obstruction suggest infected biliary pressure. Hypotension, confusion or organ dysfunction requires emergency drainage planning.
Investigation priorities
Assess gallstones, bile-duct calibre, liver texture and lesions, portal or hepatic flow, kidneys, pelvic organs and ascites; guide safe aspiration or drainage.
Management branches
Cholestatic tests, jaundice, biliary pain or ductal concern prompts imaging.
- Assess for sepsis and organ dysfunction, obtain liver tests and ultrasound, and start urgent cholangitis treatment when clinically indicated.
- If ultrasound does not show a duct stone but the duct is dilated or liver tests remain abnormal, use MRCP; consider EUS if MRCP remains non-diagnostic and suspicion persists.
Key medicines
Rectal diclofenac or indometacinA common adult prophylactic regimen is 100 mg rectally immediately before or after ERCP, chosen under the current BSG or local ERCP protocol.
Iodinated contrast mediumAgent, concentration, volume and injection rate are selected by radiology for body size, vascular access, examination and scanner protocol; there is no universal dose.