Some women worry about pregnancy even after a tubal ligation. On the other hand, some women find themselves wanting to get pregnant again after previously deciding to have the surgery. Is it possible to have a pregnancy after tubal ligation? 

Tubal Ligation

Ligation of the tubes is a surgical procedure where each fallopian tube is permanently blocked by means of surgery. The fallopian tube is a long, narrow tube that connects the ovary to the womb or uterus. It carries the egg towards the uterus and also carries the sperm towards the ovaries. Tubal ligation therefore mechanically blocks the fallopian tubes to prevent the sperm from fertilizing the egg so that a woman becomes ‘sterile' and cannot get pregnant. 

It can be done in the hospital or in a clinic at anytime, usually after a woman gives birth. The fallopian tubes are permanently blocked by tying them together, clipping or banding, cutting or burning (cauterized) them shut. Tubal ligation is also referred to as female sterilization, tubal occlusion, tube tying, or tying the tubes.

Chances of Failed Tubal Ligation

Tubal ligation is one of the most effective contraceptive methods if performed correctly. Generally, the risk of pregnancy after tubal ligation is low. Failure of tubal ligation occurs when a woman becomes pregnant after the surgery is done.

Causes of Failed Tubal Ligation. There are several causes of failed tubal ligation. It can be classified as failure before or after tubal ligation. Failure before tubal ligation occurs when pregnancy, called luteal-phase pregnancy, was not detected before the procedure is done. Failure after tubal ligation represents technical errors done in performing the surgery. This is called true failure of tubal ligation.

The causes of true failure of tubal ligation are incomplete or inadequate closure of the tube, misidentifying a different structure for a fallopian tube, development of a fistula or recanalization, and a misplaced device used in occlusion the fallopian tube.

Failure to identify the fallopian tube maybe due to poor lighting or presence of scarring (adhesions). Scarring results when a patient has had conditions that required surgery in the abdomen, for example, endometriosis or pelvic inflammatory disease. A fistula or an abnormal opening called tuboperitoneal fistula develops between the abdominal (peritoneal) space due to incomplete healing of the ligated end of the fallopian tube. Recanalization occurs when the ends of the fallopian tube regenerates and form slit-like spaces and pouches or the ends of the tubes meet and re-establish the patency of the tube.   

Pregnancy after Tubal Ligation

Tubal pregnancy.  The risk of pregnancy in women who had tubal ligation is much lower than women who did not have tubal ligation. If pregnancy occurs following tubal ligation, the pregnancy will most likely be ectopic. When an egg is fertilized and gets implanted anywhere but the uterus, an ectopic pregnancy is said to occur. In many cases, the egg implants in one fallopian tube, called a tubal pregnancy. Other locations are the ovary, cervix, or abdominal cavity.

In the CREST study, the 10-year cumulative risk of ectopic pregnancy from all methods of tubal ligation was less than 1%, that is, 7.3 ectopic pregnancies per 1,000 procedures. The highest rate of pregnancy occurred among women who had bipolar electrocoagulation, 17.1 ectopic pregnancies per 1,000 procedures, while the lowest was among women who had partial salpingectomy, 1.5 per 1,000. It was also found that women, 30 years of age and younger were more at risk for ectopic pregnancy and that ectopic pregnancy may occur even at 10 years or more after tubal ligation.

A woman who becomes pregnant after tubal ligation needs to see a doctor immediately. Ectopic pregnancy will not proceed to full-term and is a life-threatening condition. In tubal pregnancy, the fetus grows inside the fallopian tube, which may cause the tube to expand and eventually rupture. Rupture will lead to significant bleeding and lead to shock, which is a surgical emergency.  

Tubal ligation is a permanent procedure but women may often feel regret at having been sterilized. Regret is most commonly because of divorce, remarriage, death of a child, or the desire to have more children. According to the CREST study, this occurs more commonly among younger women who have remarried or wanted another child.

Tubal re-anastomosis. Women who desire to be pregnant can undergo a procedure called tubal re-anastomosis to reverse tubal ligation. Tubal re-anastomosis is a surgical procedure where the severed ends of the fallopian tubes are rejoined. The chances of successful pregnancy are reported to be 50% and are higher among women who are in their 20s and among those who have had Hulka clip tubal ligation.

Scientific Proof. A study, the U.S. Collaborative Review of Sterilization or CREST, is the largest study done to find out the risk of pregnancy after tubal ligation with use of different methods. This was a study conducted up to 14 years on more than 10,000 women. In this study, the 10-year cumulative rate of failure of tubal ligation was 1.85% for all types of ligation methods.

The rates were highest with the use of Hulka clips (36.5 per 1,000 procedures), followed by silicone bands or rings (17.1 per 1,000), partial salpingectomy and unipolar coagulation (7.5 per 1,000). Partial salpingectomy involves cutting a piece of the fallopian tube, which is done on both tubes. Coagulation involves applying electrical current to cauterize or burn a segment of the fallopian tubes. The study also reported that the 10-year pregnancy rate was higher among younger women aged 28 years and younger.