Originally published by Harvard Health.
What is the test?
Percutaneous transhepatic cholangiography is an x-ray test that can help show whether there is a blockage in the liver or the bile ducts that drain it. Since the liver and its drainage system do not normally show up on x-rays, the doctor doing the x-ray needs to inject a special dye directly into the drainage system of the liver. This dye, which is visible on x-rays, should then spread out to fill the whole drainage system. If it does not, that means there is a blockage. This type of blockage might result from a gallstone or a cancer in the liver.
How do I prepare for the test?
Tell your doctor if you have ever had an allergic reaction to lidocaine or the numbing medicine used at the dentist’s office, or to x-ray dye. Also tell your doctor if you could be pregnant, since x-rays can harm the developing baby. If you have diabetes and take insulin, discuss this with your doctor before the test.
Most people need to have a blood test done some time before the procedure, to make sure they are not at high risk for bleeding complications. If you take aspirin, nonsteroidal anti-inflammatory drugs, vitamin E or other medicines that affect blood clotting, talk with your doctor. It may be necessary to stop or adjust the dose of these medicines before your test.
You will be told not to eat anything on the morning of the test so that your stomach is empty. This is a safety measure in the unlikely case you have a complication, such as bleeding, that might require surgery.
What happens when the test is performed?
You lie on a table wearing a hospital gown. An IV (intravenous) line is inserted into a vein in case you need medicines or fluid during the procedure. An area over your right rib cage is cleaned with an antibacterial soap. Then the radiologist may take a picture of your abdomen with an overhead camera. Medicine is injected through a small needle to numb the skin and the tissue underneath the skin in the area where the dye is to be injected. You may feel some brief stinging from the numbing medicine.
A separate needle is then inserted between two of your ribs on your right side. The needle is advanced into your liver. A small amount of x-ray dye is injected, and some pictures are taken that are visible on a video screen. Your doctor adjusts the placement of the needle until it is clear that the dye is flowing easily through the ducts (drainage tubes) inside your liver.
Because taking the x-ray pictures sometimes requires a significant amount of time, the doctor replaces the needle with a softer plastic tube. First, the syringe holding the dye is detached from the top of the needle, leaving the needle in place. The doctor then gently pushes a thin wire through the needle and into the duct where the needle has been sitting. Next the needle is pulled out, sliding over the outside end of the wire. The wire is left with one end inside the liver to hold the position where the needle had been. The doctor then slides a thin plastic tube similar to an IV line along the wire, like a long bead on a string, until it is in the same place where the needle was. The wire is then pulled out, and the syringe with the dye is reattached to the tube.
Then more dye is injected through the plastic tube, and pictures are taken with the video camera as the dye spreads inside the liver. If there is no blockage, the dye drains out of the liver through the bile ducts and begins to show up on the x-ray in your small intestine. Once all of the needed pictures have been taken, the plastic tube is pulled out, and a small bandage is placed over your side. The whole test usually takes less than an hour.
What risks are there from the test?
It is possible to have serious bleeding from this test. In some cases, blood leaks to the outside surface of the liver and causes a buildup of blood there. In other cases, blood can leak directly into the liver’s drainage system, in which case it might start showing up in your intestine, causing a bloody bowel movement. It is possible that you could develop an infection after the test, although this is rare. The only soreness you are likely to have is at the skin surface where the needle went in. This should last for only a day or two.
In rare cases, the dye used in the test can damage your kidneys. This kidney effect is almost always temporary, but some people have permanent damage.
Because x-rays are used, there is a small exposure to radiation. In large amounts, exposure to radiation can cause cancers or (in pregnant women) birth defects. The amount of radiation from the video x-ray in this test is very small—too small to be likely to cause any harm. (The people performing the test will wear lead shields, since they would otherwise be exposed to this radiation over and over.)
Must I do anything special after the test is over?
Call your doctor right away if you have pain in your right abdomen or shoulder, fever, dizziness, or a change in your stool color to black or red.
How long is it before the result of the test is known?
You may be told a few early results of your test as soon as the test is done. It takes a day or two for the radiologist to review the x-rays more thoroughly and to give your doctor a full report.