Obstructive jaundice is caused by a blockage of the common bile duct, resulting in high bilirubin levels seen as yellowing of the skin and eyes. It can be caused by gallstones blocking the cystic duct or common bile duct, or by cancers of the pancreas or bile duct. Patients experience jaundice, itching, pain, fever and pale stool. Investigations include blood tests showing elevated bilirubin and liver enzymes, as well as imaging like ultrasound or MRI to identify gallstones or tumors blocking the bile duct. Treatment depends on the cause, with gallstones removed through ERCP or surgery, while malignant tumors may require Whipple's procedure.