Sterilization failures and their causes.

To say that a sterilization failure rate is expected does not answer why. Forty-seven cases of repeat sterilization have undergone such surgical and pathologic scrutiny. Resection methods failed most frequently because of spontaneous reanastomosis or fistula formation. Fimbriectomy was particularly vulnerable to reanastomosis because the fimbria ovarica was not removed. Mechanical devices failed when the device was defective, placed improperly, or placed in an improper location. Tissue damage was evident but incomplete when the bipolar electrocoagulation method failures were reviewed, and the endosalpinx remained viable. Unipolar method injuries, in contrast, were complete; they failed by fistula formation. Thus bipolar method failures may occur because of the limited range of electrical power available when using bipolar generators. Some sterilization failures are preventable, but many are not. When medicolegal questions arise, these findings may help answer the question, Why?