Tubal ligation failure is a fairly rare occurrence, but when it does happen, it is typically the result of one of a few common causes. The procedure may be performed incorrectly, leaving a passage for the egg and sperm to travel through. In certain cases, the ends of the tubes may grow back together. When the fallopian tubes are closed off using clamps or rings, those devices may come loose or slip out of place, re-opening the tubes. Women may also be unable to get pregnant normally but be more prone to ectopic pregnancies after tubal ligation.
One of the most common reasons for this procedure to fail is it being performed incorrectly. If the surgeon is not skilled enough to perform the ligation correctly, or runs into problems with a necessary instrument such a laparascope, the tubes may not be totally closed off. They may be left partially unblocked, or the devices used to hold them closed may be placed in the wrong location. Women with certain physical conditions, like obesity or pelvic adhesions, may also be harder to perform the procedure on correctly. Sometimes, the surgeon may incorrectly tie off the round ligaments near the uterus because they are mistaken for the fallopian tubes.
Another issue that commonly causes failure is re-attachment of the tubes. This process, called spontaneous reanastomosis, can occur if the ends of the severed tube are not separated far enough apart. There may also be issues with the sutures used in the procedure that allow the ends to grow back together. In some cases, a fistula or endometriosis may form where the tubes were cut and create a passageway between them.
Women who have certain types of procedures are more likely to experience a tubal ligation failure than others. Devices like rings, loops, or clamps that hold the tubes closed but do not actually damage them can be placed incorrectly or may slip so they are no longer fully blocking the passage of sperm or eggs. Procedures that do more to damage the tubes by actually cutting, scarring, or burning them are much less likely to fail.
Although the tubal ligation procedure may stop passage of an egg, if there is even a tiny passage left open, smaller sperm may be able to make their way through. This can result in an ectopic pregnancy. Not only is this a failure of the procedure, it can also be potentially life threatening to the woman.