Recanalization is the restoration of flow in a vessel or duct after it has been blocked in some way. Sometimes, this process occurs naturally and at other times, it happens with the assistance of medical practitioners. There may be cases in which recanalization is actually not desired and is an unexpected outcome. A variety of tests can be used to measure levels of blockage in vessels and ducts and to determine when recanalization has occurred.
An infamous example of recanalization can be seen in some vasectomy patients. In a vasectomy, the vas deferens, a duct that carries sperm from the testes to the penis, is cut. This prevents sperm from entering the ejaculate and renders a man infertile. Sometimes, however, recanalization occurs and the body is able to bridge the gap created during the vasectomy. This allows sperm to once again travel down the vas deferens. Sometimes, a vasectomy fails as a result of recanalization right away, and at other times this may occur years after the procedure has taken place.
The same phenomenon can be observed when blood vessels become blocked with clots. This can be dangerous because it impedes circulation. If the body cannot dislodge the clot, it comes up with another solution, working around the clot to restore the flow of blood. This can also be seen after surgeries where vessels are severed. The body figures out how to remap the network of vessels to keep bloodflow consistent.
Recanalization also occurs in ducts and tubes used to carry everything from lymph to bile. The process takes varying lengths of time, depending on the area of the body involved, the health of the patient, and the level of obstruction. Sometimes doctors may help the body along, as seen in bypass surgeries where vessels are grafted onto the coronary arteries to restore the supply of blood. Medications can also be used for recanalization by forcing clots to break up, and the insertion of a stent is another way to restore flow.
Doppler ultrasound is a technique that can be used to see whether or not body fluids are flowing as expected. The ultrasound generates an image showing which direction fluids are moving in and how quickly they are moving. As recanalization takes place, the flow may move around or increase in speed. This medical imaging technique is used to check up on people who have required medical procedures to treat obstructions and to screen patients presenting with problems that may reflect a blockage in a vessel or duct.