Tubal Ligation Failure – Causes of Pregnancy After Sterilization

A tubal ligation, when performed properly and with all due precautions, gives nearly 100% protection against pregnancy, with failure rates almost negligible. Although it is a very effective method of contraception it can, in extremely rare cases, fail to prevent pregnancy. In these instances, the tubal ligation procedure may need to be repeated.

Causes of Tubal Ligation Failure

Tubal ligation failure can occur due to a number of reasons, some preventable but others unavoidable. Most of the causes are related to shortfalls of the tubal ligation method employed.

  • Sometimes, conception occurs before a sterilization procedure but is diagnosed only afterwards. It is not really a failure of tubal ligation since the woman was already pregnant before the procedure.
  • Spontaneous reanastomosis or fistula formation where the cut ends of the tube sometimes grow back together when the gap between them is not large enough. A Falope ring used for tubal ligation can fall off or a clamp can get loose. All these conditions result in re-establishing continuity of the fallopian tubes, thus making pregnancy possible. A fistula formation or a passageway into the tube, sometimes seen in unipolar electrocoagulation method of tubal sterilization, can also result in entry of ovum into the tube and subsequent fertilization, resulting in an unintended pregnancy.
  • Ectopic pregnancy is a possibility following tubal ligation. The highest risk seems to be in those women who had bipolar electrocoagulation done for sterilization.
  • Improperly done procedure – the tube was not cut off completely or blocked totally, or the occluding device may not have been placed in the correct position.
  • Sometimes, the round ligaments are mistakenly tied in place of the fallopian tubes when care has not been taken to identify the fallopian tubes. Here, since the wrong tubes are tied, sterilization has not been done at all.
  • Slipping of a ligature or any other occlusive device.
  • Pelvic adhesions or obesity could have made the procedure difficult to perform.
  • Inability to complete a procedure effectively, such as a laparoscopic tubal ligation, either due to inefficiency of the surgeon or equipment problem.
  • Tubal ligation failure rate usually depends upon the technique used to perform the procedure – techniques that cause least damage to the tubes (such as clips and clamps) have the highest failure rates. There is less of a chance of pregnancy where maximum damage to the tubes has been done (electrocoagulation methods) or where a large portion of the tube has been excised (postpartum partial salpingectomy).
  • With hysteroscopic techniques of tubal sterilization such as Essure or Adiana, pregnancy may occur if an alternate method of contraception is not used for 3 months or till the time it takes for total tubal occlusion by scar tissue to occur.

Prevention of Tubal Ligation Failure

While tubal ligation failure cannot be totally prevented, certain precautions can go a long way in reducing the possibility of an unintended pregnancy.

  • To make sure that a woman undergoing a tubal ligation procedure is not already pregnant, same day testing on the day of the operation with an ELISA-type pregnancy test can eliminate this risk to a large extent.
  • Use of some form of contraception before tubal ligation and till the next period can reduce the risk of pregnancy.
  • Postpartum tubal ligation or performing the procedure during the periods can eliminate the chance of pregnancy.
  • If an IUD is being used, it may be left intact till the next period following the tubal ligation procedure.
  • Women undergoing the hysteroscopic method of tubal sterilization (Essure or Adiana), should understand the reason why it is important to use an alternate method of contraception. This is necessary until it can be confirmed by a hysterosalpingogram that the tubes have been totally blocked by the growth of scar tissue.

Facts Regarding Tubal Ligation Failure

Women undergoing a tubal ligation procedure should be aware of the possibility, however rare, of a pregnancy occurring in the future. It can be utterly devastating for a woman, secure in the knowledge that she is fully protected against pregnancy, to be confronted with the alarming prospect of an unwanted and totally unexpected pregnancy.

  • Sterilization failure may occur immediately or many years after a tubal ligation procedure.
  • Although tubal ligation failure may occur at any time after the procedure, it has been seen that the pregnancy rate following tubal ligation goes up slightly after 10 years.
  • The younger the woman at the time of tubal ligation, the greater the chance of ligation failure. This could possibly be due to the fact a younger woman is likely to be more fertile than a woman who is older in age.
  • If pregnancy occurs due to tubal ligation failure, chances of an ectopic pregnancy are very high. If a woman misses her periods any time after a tubal ligation, she should get a pregnancy test done immediately. If pregnancy is confirmed, she must consult her doctor and undergo an ultrasound to rule out an ectopic pregnancy.