Drainage of fluid collections

A fluid collection is a pocket of fluid that builds up somewhere it should not be. It can form after surgery, after an injury or because of an infection. Some pockets are small and go away on their own. Others cause pain, pressure or fever and need to be drained.

On a CT scan, a fluid collection looks like a smooth, darker gray pocket. An abscess often has a brighter rim and sometimes small bubbles of gas inside.

Many seromas and lymphoceles are found by chance on a scan and cause no problems. The body often absorbs them over weeks to months. We usually suggest drainage when a collection causes symptoms, is growing, may be infected or is pressing on something important, such as a vein, the bladder or a ureter (the tube that carries urine from the kidney).

Interventional radiologists use ultrasound or CT to see the collection and plan a safe path to it. After numbing the skin, we pass a thin needle into the pocket, then slide a soft plastic tube, called a drainage catheter, over a guidewire. The tip of the tube curls inside the pocket so it does not slip out. The tube is held at the skin with a small stitch and a dressing.

Small collections may only need aspiration, which means drawing the fluid out with a needle and leaving nothing behind. Larger ones usually need a drain that stays for a few days to a few weeks. Most people receive moderate sedation, also called twilight sedation, through an IV. You stay awake but relaxed.

Some seromas and lymphoceles keep refilling even with a drain in place. In that case we may recommend sclerotherapy. This means injecting a medicine, called a sclerosant, through the drain into the pocket. Common choices are alcohol, the antibiotic doxycycline or povidone-iodine (Betadine). The medicine irritates the lining of the pocket so the walls stick together and the space closes.

Sclerotherapy may be repeated a few times over one to two weeks. It can sting or ache for a short time. It avoids another operation for many people, but it does not work for everyone.

If you go home with a drain, we will teach you how to empty it, flush it and record how much comes out each day. That daily number, plus your temperature, tells us when the drain can come out. Most drains are removed in the clinic in a few seconds, without sedation, once the output is below about 20 mL a day (less than 1.5 tablespoons) and the fluid looks thin and clear.

Step-by-step instructions are on how do I manage my drain. If fluid keeps building up for months, for example from cancer in the chest or belly, a long-term tunneled drain may make more sense. Read about the PleurX catheter.

Before I place a drain, I study the scan to find a path that stays away from bowel, blood vessels and organs. I also ask what the fluid is likely to be, because an abscess, a seroma and a lymphocele behave differently. I tell patients that the drain is only half of the treatment. Your daily log is how we know when it has done its job.

Fabio Komlos, MD, interventional radiologist · About Dr. Fabio Komlos

Image guidance keeps the risk low, but no procedure is risk-free. There is a small chance of bleeding or injury to nearby organs or bowel. When an abscess is first drained, you may have fever and chills for a few hours as bacteria are stirred up. Collections can come back and may need another drain or sclerotherapy. If contrast dye is used for a CT, there is a very small risk of allergy or kidney strain.