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Image-Guided Drainage

The ability to drain infected fluid collections (abscesses) percutaneously (through the skin) has represented one of the most significant developments in medicine in recent years. Prior to the development of percutaneous abscess drainage, it was invariable necessary for the patient to undergo major surgery in order that the infected fluid cavity be removed. With the ready availability of ultrasound and CT, most percutaneous abscess drainages are performed using one of these modalities for guidance of the needle and subsequently catheter into the fluid collections.

What are the indications?

Despite the widespread use and availability of antibiotics, most infected fluid collections that are within the abdominal cavity need to be treated actively either by percutaneous drainage or by surgery. Nowadays we have such sophisticated imaging available that most intra-abdominal or intra-pelvic abscesses can be drained percutaneously. The abcesses themselves may be within an organ such as the liver, or may be free within the pericorneal cavity.

What preparation is needed?

Once the diagnosis of an abscess has been made, essentially no preparation is required. If the procedure is to be performed using ultrasound for guidance it is possible to perform the procedure portably on the floor or on the intensive care unit by the patients bedside, where if CT is to be used the patient has to be transported down to the CT scan suite.

How is the procedure performed?

The procedure is explained in detail to the patient with associated possible complications and once the patient agrees to the procedure, written and informed consent is obtained. Ultrasound or CT is used to locate the abscess and to provide guidance for the site of needle insertion. In the case of ultrasound, direct visualization of the needle being inserted into the abscess is performed. If CT is used for guidance, CT scans are obtained intermittently to ensure that the needle is in the correct location. Once the needle is in the fluid collection this is exchanged for a wire and subsequently a drainage catheter which is a long thin plastic tube which coils in the abscess and this in turn is connected to provide free drainage of the infected fluid collection. The imaging can confirm correct placement of the catheter and subsequently over the next few days ensure that the abscess is being drained satisfactorily.

What happens after the procedure?

The catheter remains in the abscess cavity and exits through the patients skin usually into the abdominal wall where it is connected to free drainage. The patient is asked to observe carefully the catheter to ensure that is does not displaced although this rarely happens. Once drainage from the catheter reduces to a minimum confirmation of resolution of abscess with subsequent image will follow, followed by the removal of the catheter itself.

What are the complications?

As with any interventional procedure and the placement of needles within the abdominal cavity there is a risk of infection, bleeding or perforation of bowel. However, with sophisticated imaging equipment and appropriate expertise these risks are very small and the benefits of percutaneous drainage of abscess cavities significantly outweigh any risk of complication.