Oral contraceptives and postoperative venous thrombosis

Abstract

A nationwide surveillance of mortality associated with sterilization led to the identification of the death of a woman who was using oral contraceptives (OCs) prior to operation and died as a result of mesenteric venous thrombosis after tubal sterilization. This case is reported as a reminder of the increased risk of postoperative thromboembolism associated with OC use and to suggest how this risk can be decreased. The patient was a healthy, 24-year-old, white woman with 2 living children. She did not smoke and had no history of thromboembolic disorders. She had been using OCs for several years and continued their use until the time of hospitalization for operation. The specific OC preparation she was using is unknown. The first 48 hours following the operation the patient did well except for some mild to moderate lower abdominal pain. On the 4th day, she developed severe, acute abdominal pain and suffered a cardiovascular collapse for which she required resuscitation. She was considered to be septic and dehydrated; thus, treatment with intravenous fluids and antibiotics was initiated. An echogram obtained on the 5th day after sterilization suggested the possibility of an abdominal mass on the right sight, and an exploratory laparotomy was performed. There was 2000 ml of clear fluid in the peritoneal cavity. The cecum and ascending colon were necrotic with thrombosis of the colic and ileocolic veins. The pelvis and the appendectomy stump appeared normal. A right hemicolectomy and resection of the distal ileum were performed followed by a primary side-to-side ilecolostomy. The patient's condition deteriorated after laparotomy despite vigorous management, and she died the next morning, 7 days after the sterilization operation. Significant findings at postmortem examinations were thrombosis of both the ileocolic vein and the superior mesenteric vein and inflammation in the area of colon adjacent to the anastomosis. The cause of death was determined to be endotoxic shock secondary to large bowel necrosis which resulted from thrombosis of the mesenteric veins. This patient was at increased risk for postoperative venous thrombosis because she continued to use OCs during the month before the operation. 2 carefully conducted case-control studies have shown that OCs increase by more than 3-fold the risk of postoperative thromboembolism. It is unclear how much the knowledge of this risk has altered preoperative management of women having elective operation in the U.S. At least 1 prospective study has found no difference in incidence of idiopathic deep venous thrombosis with increasing estrogen doses, but the risk of postoperative thromboembolism associated with OCs containing a lower estrogen content has not been studied.