In a recorded case in which pregnancy occurred after each tube was ligatured in two places, and then divided with a knife, a patent stump was no doubt left.
In order to obviate this danger the peritoneal layer must be opened, and the mucous membrane, which is quite brittle and easily removed, must be torn away for about one quarter of an inch.

A simple cat-gut or silk ligature lightly tied would then be sufficient to insure complete and permanent occlusion.
Nature often performs this operation herself, with the inevitable and irrevocable result, lifelong sterility, with no tittle of positive evidence during life of its occurrence.
Here are a few examples:--A young married woman has a miscarriage; it is not severe, and she is indiscreet enough to be about at her duties in a day or two, but within a few days or so she finds she must return to bed, with feverishness and pelvic pain.

Before a month is past she is up and quite herself again.

But she never afterwards conceives.

What has happened?
To the most careful and critical examination nothing abnormal is detected.