Abdominal X-ray
Ileus, loss of psoas shadow, sentinel loop, pancreatic calcification, and calcified gallstones
Chest X-ray
Pleural effusions (usually on left) and pulmonary infiltrates
Chest US
Visualization of pleural effusion; guided drainage for diagnosis or treatment of respiratory failure
Abdominal US
Superior to CT at detecting stones in the gallbladder or biliary duct; may be difficult to visualize pancreas, especially in the presence of ileus; free peritoneal fluid
Endoscopic Ultrasound
Combination of endoscopy and high-frequency US; useful if abdominal US/CT fail to detect CBD stones; useful when CT/MRI are not available/feasible
Renal Tract US
If oliguric, to rule out obstruction/pyelonephrosis
Contrast-Enhanced CT
Contrast deficit indicating necrosis, local pathology, e.g. abscess, acute fluid collections (pseudocysts/abscesses usually form after approximately 4 weeks), haemorrhage, thrombosis, pseudoaneurysm; can guide interventional procedures (FNAB and drain placement)
MRI/MRCP
May be of use in the stable patient in whom CT contrast is contraindicated; can delineate necrotic areas; excellent at assessing biliary tree
Angiography
Haemorrhage localization and guided endovascular management