The probability of ectopic pregnancy is very low after ligation surgery, which involves cutting both fallopian tubes and ligating each of the two broken ends. After the surgery, the probability of tubal recanalization is very low, so the contraceptive effect can be very good. Ectopic pregnancy after ligation is caused by the recanalization of the fallopian tubes, which are not completely open but obstructed, resulting in ectopic pregnancy due to obstruction of the fertilized egg in the fallopian tubes. Because the probability of tubal reopening is very low, the probability of ectopic pregnancy after ligation is also very low, with a maximum of 1-2 ectopic pregnancies per 100 patients.