The current method of diagnosing and staging disease in patients with obstructive jaundice begins with a thin-section CT III scan of the abdomen, because pancreatic cancer is the most common cause of obstructive jaundice, and CT scan findings consistent with pancreatic lesion characteristics usually provide sufficient information for clinical diagnosis and staging. If the biliary dilatation pattern shows that the biliary obstruction is located at the hepatic portal, MRA and MRCP on MRI are performed after CT. if MRI does not allow adequate imaging over the tumor on the side of the liver to be preserved, then percutaneous transluminal cholangiography is required. Percutaneous percutaneous cholangiography also allows preoperative decompression of the liver on the side to be preserved without access to the other half of the liver.PTC can be obtained by cytobrushing the cells. CA19-9 testing is required. chest CT is also performed. Sometimes the side to be preserved is not cannulated by ERCP, then PTC is still required to determine the upper limit of the tumor. When the tumor is determined to be unresectable by one or more of the following: extent of bile duct lesions, vascular infiltration, and liver atrophy, a histologic diagnosis can be made – cell brush and clamp biopsy via ERCP, EUS biopsy, CT or ultrasound-mediated percutaneous tissue biopsy to obtain tissue. EUS biopsy is required if there is extensive lymph node disease, and if there are extensive lymph node metastases, then the patient is not a candidate for surgery.