Production of prostacyclin and thromboxane during cesarean section

The effect of cesarean section on the production of the antiaggregatory prostacyclin and proaggregatory thromboxane A2 was studied in 12 women by measuring the stable metabolites of prostacyclin and thromboxane A2, 6-ketoprostaglandin F1 alpha and thromboxane B2, respectively, from serial maternal blood samples collected before, during, and after the operation. The plasma 6-keto-prostaglandin F1 alpha concentration was similar to the initial concentrations before the start of anesthesia (mean 121.6 +/- SE 11.5 pg/ml), at the time of skin incision (148.0 +/- 21.0 pg/ml), and at delivery of the infant (136.3 +/- 11.2 pg/ml), but was elevated at the end of the operation (454.8 +/- 56.2 pg/ml) (P less than .001) and one hour later (233.1 +/- 39.5 pg/ml) (P less than .01). These increases were similar whether the patients were operated on under general (N = 6) or epidural (N = 6) anesthesia. The serum thromboxane B2 concentration did not change, indicating no influence of cesarean section on the capacity of the platelets to produce thromboxane B2 during spontaneous clotting. The increased output of prostacyclin may originate from the myometrium and/or intrauterine tissues, which are manipulated during cesarean section. The increased output may play a role in preventing thromboembolic complications during and after cesarean section.