Initial investigations aim to establish the diagnosis of hyperbilirubinaemia and to differentiate whether the jaundice is prehepatic, hepatocellular or cholestatic.

The following tests may be performed:

1. Laboratory Test
   • Liver function test
   • FBC/Peripheral blood film
   • Urine for urobilinogen (haemolytic) or bilirubin (cholestatic)
   • Reticulocyte count
   • Serology for viral hepatitis
   • PT/APTT
2. Imaging (Non invasive)
   • Ultrasound hepato-biliary system
     Ultrasound is the primary imaging modality of choice in investigating hepatobiliary system, especially in surgical jaundice patient with suspected gallstone disease. It is less expensive and doesn’t involve radiation. Contrast enhanced ultrasound can further differentiate liver lesions. However it is operator dependent and certain anatomical location may make evalution difficult, such as distal CBD and pancreas.
   • Computerised Tomography (CT) Scan
     Contrast enhanced spiral CT is the gold standard for evaluation of space occupying lesion in hepato-pancreatico-biliary system. It is essential in all patients with suspected tumours, not only for diagnostic and staging purpose, also for presurgical planning. However, it involves radiation and small risk of contrast induced nephropathy.
   • Magnetic resonance cholangiopancreatography (MRCP)/Magnetic resonance imaging (MRI)
     MRI may provide better definition as compared to CT scan and may not require contrast. MRCP can better delineate the biliary and pancreatic ductal system. It is relatively more expensive than CT scan.
3. Invasive procedure- diagnostic and therapeutic
   • Endoscopic retrograde cholangiopancreatography (ERCP)
     ERCP is performed under sedation but its diagnostic role in patient with obstructive jaundice is gradually replaced by MRCP which is non invasive and not operator dependent. However, its therapeutic advantage in ductal stone removal or stent insertion in treating obstructive jaundice due to ductal stricture or malignant compression can not be over emphasized. It can also provide direct visualization of periampullary tumour and tissue biopsy, as well as ductal brushing cytology.
   • Percutaneous transhepatic cholangiography (PTC)
     Its advantage lies in assessing obstructing lesion at or proximal to portal hilum in which ERCP is technically not feasible. Besides diagnostic cholangiography and brushing cytology, as in ERCP, it can be used to insert stent through proximal obstructive lesion.
   • Endoscopic ultrasonography (EUS)
     It is extremely useful for the diagnosis and staging of bile duct and pancreatic pathology. Performed endoscopically, EUS can be used to obtain guided trucut biopsy of suspected ductal, pancreatic lesions as well as adjacent lymph nodes, unlike ERCP which can only provide endothelial cytology.