Where is a PTC drain placed?

A PTC drain, or percutaneous transhepatic cholangiography drainage catheter, is placed into the biliary system to provide internal-external drainage of bile. 

The typical placement of a PTC drain is:

- Access is gained percutaneously (through the skin) into the liver using a thin Chiba needle, usually via an intercostal approach below the right rib cage.

- Under fluoroscopic guidance, the needle is advanced through the liver parenchyma into one of the main intrahepatic bile ducts.

- A guidewire is passed through the needle and manipulated into the biliary system, often across the obstruction.

- The tract is dilated to allow placement of a large-bore sheath into the bile duct.

- The drainage catheter is inserted through the sheath and positioned with the tip in the common bile duct or duodenum. Multiple side holes ensure bile drainage.

- The external end of the catheter exits the body and is attached to gravity drainage or a vacuum system. 

This allows decompression of the biliary system and diversion of bile outside the body to relieve symptoms of obstruction like jaundice, pruritus, and cholangitis. The PTC drain can remain in place until definitive management of the obstruction can be performed. 

So in summary, a PTC drain is inserted through the liver into the bile ducts to provide internal drainage past an obstruction, and external diversion of bile via the catheter. Placement is done minimally invasively under imaging guidance.