The most common way a liver sample is obtained is by inserting a needle into the liver for a fraction of a second. This can be done in the hospital with a local anesthetic, and the patient may be sent home within 3-6 hours if there are no complications.
The physician determines the best site, depth, and angle of the needle puncture by physical examination or ultrasound. The skin and area under the skin is anesthetized, and a needle is passed quickly into and out of the liver. Approximately half of individuals have no pain afterwards, while another half will experience brief localized pain that may spread to the right shoulder.
Patients are monitored for several hours after a biopsy to make sure serious bleeding has not occurred. Some patients occasionally have a sudden drop in blood pressure after a biopsy that is caused by a "vagal" reflex and not by blood loss; this is caused by sudden irritation of the peritoneal membrane. The characteristics that distinguish this from a bleeding event are:
- slow pulse rather than rapid
The risk of a liver biopsy is minimal. The primary risk is bleeding from the site of needle entry into the liver, although this occurs in less than 1% of patients. Other possible complications include the puncture of other organs, such as the kidney, lung or colon. Biopsy, by mistake, of the gallbladder rather than the liver may be associated with leakage of bile into the abdominal cavity, causing peritonitis. Fortunately, the risk of death from liver biopsy is extremely low, ranging from 0.1% to0.01%.
A biopsy should not be done if:
- you have taken aspirin in the last 5-7 days
- the hemoglobin is below 9-10 grams/dl
- the platelets are below 50,000-60,000
- the prothrombin time INR is above 1.4
Those with bleeding disorders such as hemophilia which can be temporarily corrected with transfused clotting factors can be biopsied safely.
Most people want to know if a biopsy will hurt. Most doctors will not do percutaneous needle liver biopsies under anesthesia. This is because the liver is directly under the diaphram and moves as you breathe. When the needle is inserted through the skin and body wall, the liver must not be moving or else there is danger of a laceration. To keep the liver from moving, the patient has to stop breathing momentarily. Doctors prefer to have you alert and following directions, but if you are very anxious you may want to ask for a sedative to help you relax.
The injections of the local anesthetic and the actual puncture of the liver capsule itself can be a little painful for some people, but it only takes a second and is over very quickly. Other people feel no pain at all, and don't even realize it's over with until the doctor tells them they're finished.
Occasionally there will be a small to moderate amount of pain afterwards. If you find that you are uncomfortable, your doctor will generally prescribe a light painkiller immediately after the biopsy. The pain may be well away from the biopsy site, possibly in the pit of your stomach or typically in the right shoulder. The liver itself has no pain-sensing nerve fibers, but a small amount of blood in the abdominal cavity or up under the diaphram can be irritating and painful. Very occasionally, small adhesions (scar tissue) may form at or near the biopsy site, and can cause a chronic pain that persists near the liver area after the biopsy.