B. M. Sibai

Correlation between Bleeding Times and Platelet Counts in Women with Preeclampsia Undergoing Cesarean Section

Platelet count and bleeding time and the correlation between these two variables in women with preeclampsia who received epidural or general anesthesia for cesarean section were evaluated. The study included 106 women with preeclampsia who were undergoing cesarean section and 94 healthy, term parturients receiving epidural anesthesia for labor analgesia or for cesarean section. Platelet counts were measured using an automated Coulter Counter, and bleeding times were measured using the modified Ivy bleeding time technique. Platelet count was significantly lower and bleeding time significantly prolonged in patients with preeclampsia compared with the control group (P less than 0.0001). In the preeclampsia group, eight patients (7.5%) had thrombocytopenia (platelet count less than 100,000/mm3), whereas in the control group, all women had a normal platelet count (greater than 150,000/mm3). All but one patient with thrombocytopenia had prolonged bleeding time. In addition, 34% of those women with severe preeclampsia and 13% with mild preeclampsia had prolonged bleeding time, although their platelet count was adequate. In the control group, 2% had abnormal bleeding time in the presence of a normal platelet count. There was good correlation between bleeding time and platelet count only when platelet count was lower than 100,000/mm3 (r = -0.76, P less than -0.02).

Nifedipine does not adversely affect uteroplacental blood flow in the hypertensive term-pregnant rat.

The short-term effect of the calcium channel blocker, nifedipine, on maternal hemodynamics and organ perfusion was investigated in 12 hypertensive term-pregnant, spontaneously hypertensive rats by means of the radioactive-labeled microsphere technique. The normal fall in blood pressure during pregnancy was prevented by reducing litter size to two conceptuses on day 7 of gestation. Nifedipine (200 micrograms/kg) effectively lowered mean arterial pressure 25% by decreasing total peripheral resistance 38%. Cardiac output was increased 15%. Blood flows to the splanchnic region and the reproductive organs were increased after nifedipine administration. The increase in blood flow to the reproductive organs was the result of increased ovarian and uterine wall perfusion caused by large reductions in vascular resistances. Placental blood flow was not significantly altered, but resistance was decreased. Thus, the use of nifedipine to lower maternal blood pressure in pregnancy complicated by extreme hypertension does not necessarily decrease uteroplacental perfusion.

Labetalol does not decrease placental perfusion in the hypertensive term-pregnant rat

Summary The acute effect of labetalol hydrochloride, a combined nonspecific s-adrenergic and postsynaptic α 1 -adrenergic blocker, on maternal hemodynamics and organ perfusion was investigated in 10 hypertensive, term-pregnant, spontaneously hypertensive rats with the use of the radioactive-labeled microsphere technique. The normal fall in blood pressure during pregnancy was prevented by the reduction of litter size to two conceptuses on day 7 of gestation. Labetalol (1 to 6 mg/kg) effectively lowered mean arterial pressure 22% by decreasing cardiac output 16%; total peripheral resistance was not significantly decreased. Thus, the blood pressure lowering effect of labetalol was due primarily to its s-adrenergic blocking effect. Regional flows to the carcass and splanchnic circulation were decreased 19% and 15%, respectively, after labetalol administration. Uterine wall and ovarian perfusion were significantly reduced, but placental perfusion was not significantly altered. Because labetalol lowers blood pressure without reducing placental perfusion, it may be a useful alternative to hydralazine for the treatment of hypertensive emergencies in pregnancy. (Am J Obstet Gynecol 1989;160:480-4.)

Pregnancy Complicated by Cardiac Disease: Maternal and Perinatal Outcome

We report maternal and perinatal outcome in pregnancies complicated by maternal cardiac disease. A retrospective review of 54 women with cardiac disease, managed through 71 pregnancies from February 1981, through July 1991, was conducted. Tricuspid atresia and pulmonary hypertension were associated with a 50% maternal mortality rate and a 67% incidence of intrauterine growth retardation. Cardiomyopathy was associated with prematurity and low birthweight. Atrial or ventricular septal defects and stenotic lesions of the outflow tracts were generally not associated with adverse maternal or perinatal outcome. Women with previous myocardial infarction, corrected tetralogy of Fallot, aortic or mitral insufficiency, and mitral valve prolapse generally tolerated pergnancy, labor, and delivery without adverse sequelae in this review. Although peripartum cardiomyopathy was associated with low birthweight, pregnancies were successfully managed with intensive monitoring. Tricuspid atresia and pulmonary hypertension r...