The liver is a vital organ that produces a fluid called bile, which aids in the digestion process. Naturally, bile flows from the liver through a system of thin tubes, called bile ducts, into the small intestine. Sometimes, these bile ducts can become blocked. The blockage can be caused by a variety of reasons, the most common being tumors (such as pancreatic cancer or bile duct cancer) pressing on the ducts, or gallstones.

​​

When bile cannot drain freely into the intestine, it accumulates in the liver and bloodstream. This condition leads to jaundice (yellowing of the skin and eyes), intense itching, and in severe cases, a life-threatening infection of the bile ducts called cholangitis, and impairment of liver function. The goal of the percutaneous biliary drainage procedure is to bypass the blockage and allow the bile to drain out, thereby relieving symptoms and preventing complications.

The procedure is performed by an interventional radiologist, a physician specializing in image-guided treatments. The procedure is usually done under deep sedation and local anesthesia of the puncture site.
The physician uses a combination of ultrasound and X-ray fluoroscopy to view the liver and bile ducts in real-time. Under this guidance, a thin needle is inserted through the skin into one of the dilated bile ducts within the liver.

After verifying the location, the physician inserts a catheter (a thin, flexible plastic tube) over a guidewire into the bile ducts. The purpose of the catheter is to pass the area of obstruction. There are two main drainage options: external drainage, where the tip of the catheter remains in the bile ducts above the blockage and the other end is connected to a collection bag outside the body or internal-external drainage, where the catheter manages to pass the blockage and reach the intestine, so that bile drains both into the digestive system and into an external bag (which is often capped at a later stage).