Tubal ligation, often called “having your tubes tied,” is a surgical procedure designed to be a highly effective, long-term method of permanent contraception. While it is one of the most reliable forms of birth control, no contraceptive method is 100% effective. A woman who has undergone this procedure can, in rare instances, still become pregnant, necessitating awareness of the mechanism and the risks associated with failure.
Understanding Tubal Ligation
Tubal ligation physically obstructs the fallopian tubes, which are the conduits that transport the egg from the ovary to the uterus. Normally, fertilization occurs within the fallopian tube as sperm travel up to meet the released egg. The procedure permanently blocks this pathway, preventing sperm from reaching the egg and stopping the fertilized egg from traveling into the uterus for implantation.
The procedure can be performed using several different techniques, including cutting and tying the tubes, applying specialized clips or rings to pinch them closed, or using an electric current to seal them shut through a process called electrocoagulation. Regardless of the method used, the intent is to create a complete barrier. Tubal ligation only affects the transportation of the egg; it does not interfere with the function of the ovaries, and a woman’s hormones and menstrual cycle continue normally.
The Likelihood and Causes of Failure
Tubal ligation is remarkably effective, with a cumulative failure rate over ten years estimated to be between 7.5 and 54.3 pregnancies per 1,000 procedures, depending on the specific technique used. This translates to a very low chance of failure, yet the possibility means that approximately 1 in 200 women who have the procedure may experience an unplanned pregnancy in the decade following sterilization. The risk of failure varies based on a woman’s age and the type of surgery performed. Younger women generally face a higher failure rate, likely because they have more years of fertility remaining.
Failures occur primarily due to two causes: surgical error, such as incomplete blockage allowing a small passage to remain open, or a spontaneous biological process called recanalization. Recanalization involves the body naturally forming a tiny, new passage through the scar tissue or the blocked segment of the tube. This small channel allows microscopic sperm to travel through and fertilize an egg.
The spontaneous re-opening of the tube can occur many years after surgery, explaining why some failures are not seen immediately. When tubal ligation fails, the fallopian tube is damaged and scarred, creating a high-risk environment for pregnancy. This underlying damage contributes to the most serious complication associated with sterilization failure.
The Critical Risk: Ectopic Pregnancy
The primary danger when a tubal ligation fails is the increased likelihood of an ectopic pregnancy. This condition occurs when a fertilized egg implants outside the main cavity of the uterus, most often in the fallopian tube itself. For women who become pregnant after a failed tubal ligation, the risk that the pregnancy will be ectopic is significantly elevated, with some studies suggesting that 7.7 out of every 100 pregnancies conceived after the procedure are ectopic.
The reason for this disproportionate risk lies in the partial compromise of the tube. The small passage created by recanalization or surgical error is often wide enough for sperm to swim upward to fertilize the egg. However, the subsequent passage is too narrow or the tube is too scarred to allow the larger, fertilized egg to travel back down to the uterus. The egg becomes trapped and implants in the tube, which is not designed to support a growing embryo.
An ectopic pregnancy is a life-threatening medical emergency because the growth of the embryo can cause the fallopian tube to rupture, leading to severe internal bleeding. If left untreated, a ruptured ectopic pregnancy can result in shock and maternal death. This high-risk complication underscores why any woman with a history of tubal ligation who suspects pregnancy must seek immediate medical evaluation.
What to Do If Pregnancy Is Suspected
If a woman who has had her tubes tied misses a period or experiences common early pregnancy symptoms, she should take an at-home pregnancy test immediately. A positive result requires an urgent consultation with a healthcare provider, and it is imperative to inform the medical team about the history of tubal ligation.
Beyond typical signs of pregnancy, specific symptoms signal a potential ectopic pregnancy and require emergency care. These warning signs include severe, sudden abdominal or pelvic pain, especially if localized to one side, or unusual vaginal bleeding that is not a normal period. Another sign is pain that radiates up to the shoulder, which can indicate internal bleeding caused by a ruptured tube.
The healthcare provider will quickly rule out an ectopic pregnancy using blood tests to measure human chorionic gonadotropin (hCG) and a transvaginal ultrasound. These tools determine if a pregnancy is present and whether it is safely implanted within the uterus. Prompt diagnosis and intervention are necessary to address the life-threatening risks associated with a failed tubal ligation.