Port (medical) - How IT Works

How It Works

A port consists of a reservoir compartment (the portal) that has a silicone bubble for needle insertion (the septum), with an attached plastic tube (the catheter). The device is surgically inserted under the skin in the upper chest or in the arm and appears as a bump under the skin. It requires no special maintenance and is completely internal so swimming and bathing are not a problem. The catheter runs from the portal and is surgically inserted into a vein (usually the jugular vein, subclavian vein, or superior vena cava). Ideally, the catheter terminates in the superior vena cava, just upstream of the right atrium. This position allows infused agents to be spread throughout the body quickly and efficiently.

The septum is made of a special self-sealing silicone rubber; it can be punctured hundreds of times before it weakens significantly. To administer treatment or to withdraw blood, a health professional will first locate the port and disinfect the area. Then he or she will access the port by puncturing the overlying skin with a 90° Huber point needle although a winged needle may also be used. (Due to its design, there is a very low infection risk, as the breach of skin integrity is never larger than the caliber of the needle. This gives it an advantage over indwelling lines such as the Hickman line.) Negative pressure is created to withdraw blood into the vacuumized needle, to check for blood return and see if the port is functioning normally. Next, the port will be flushed with a saline solution. Then, treatment will begin. After each use, a heparin lock is made by injecting a small amount of heparinized saline (an anticoagulant) into the device. This prevents development of clots within the port or catheter. In some catheter designs where there is a self-sealing valve at the far end, the system is locked with just saline. The port can be left accessed for as long as required. The port is covered in a dressing to protect the site from infection and to secure the needle in position.

If a port is used infrequently, it may be necessary to access the port, flush it with saline, and inject a new heparin lock every month to prevent clotting between uses.

The surgery itself is considered minor, and is typically performed under both local anaesthesia and conscious sedation. Patients sometimes have a little discomfort after the procedure, and can be managed with a narcotic, such as demerol for 24–48 hours.

A port is most commonly inserted as a day surgery procedure in a hospital or clinic by a surgeon or an interventional radiologist, under conscious sedation. When no longer needed, the port can be removed in the operating room.