Tubal ligation and tubal implants are not 100% effective at preventing pregnancy.
- There is a slight risk of becoming pregnant after tubal ligation. This happens to about 5 out of 1,000 women after 1 year. After a total of 5 years following tubal ligation, about 13 out of 1,000 women will have become pregnant.
- Pregnancy may occur if:
- The tubes grow back together or a new passage forms (recanalization) that allows an egg to be fertilized by sperm. Your doctor can discuss which method of ligation is more effective for preventing tubes from growing back together.
- The surgery was not done correctly.
- You were pregnant at the time of surgery.
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.