A: Having your "tubes tied" (medically called a bilateral tubal ligation or BTL), is one of the most effective methods of birth control. A BTL is a surgical procedure that cuts and separates a portion of each fallopian tube. It can either be done at the time of Cesarean section, shortly after a vaginal delivery, or laparoscopically at a time remote from childbirth. It is 99.9% effective in preventing pregnancy. However, in a small percentage of cases, despite the tubes being severed, they can grow together again during the process of healing and a connection between the two cut ends of the fallopian tube can reform. This can allow an egg and sperm to meet and a pregnancy to develop. If a pregnancy does occur after a tubal ligation, it is more likely to be an ectopic pregnancy (a pregnancy that implants in the fallopian tube instead of in the uterus). If you have had your tubes tied and you are getting a positive urine pregnancy test at home, it is very important that you see your doctor to first confirm that you are in fact pregnant, and second, to make sure you don't have an ectopic pregnancy.