Basics of Vasectomy Reversal
After vasectomy, sperm are still made by the testes, but since the vas tubes have been blocked, they cannot exit in the usual way. On each side, sperm can still enter the epididymis (the very long coiled tube behind the testis where sperm normally become mature) and the lowermost portion of the vas tube upstream from the obstruction imposed by the vasectomy. After vasectomy, the very fine tubes of the epididymis can become blocked. There are two possible explanations for this.
In the epididymis, white blood cells in the normal testicular circulation ingest and recycle the trapped sperm. This increased white blood cell activity is a chronic inflammation by definition. Inflammations can lead to scarring, and scarring in a very fine tube like the epididymis can cause obstruction. For example, inflammation of the liver (hepatitis) can cause scarring of the liver (cirrhosis); inflammation of joints (arthritis) can cause scarring with stiffness and decreased range of motion. The longer the duration of the inflammation, the greater the likelihood of scarring and obstruction, and this can occur in the epididymis, just as it can in any organ.
An alternative explanation for obstruction in the epididymis after vasectomy is that pressure increases upstream from the vasectomy site and can cause a "blowout" in the fine tubes of the epididymis, resulting in leakage of sperm and local inflammation and blockage.
Whatever the explanation for the obstruction in the epididymis (scarring or blowout), its likelihood is roughly proportional to the number of years that have gone by since the vasectomy. After an interval of only 1-3 years, the epididymis is rarely blocked, but after an interval of 20 years, the likelihood of secondary obstruction may be over 30%. Fixing the vas where it was divided at the time of the vasectomy (vasovasostomy or "VV") will not correct the secondary obstruction upstream in the epididymis. That requires a more elaborate procedure called a vasoepididymostomy or "VE", in which the portion of the vas tube above or "downstream" from the vasectomy site blockage is connected to the portion of the epididymis "upstream" from the secondary obstruction.
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