Faculty Bibliography

OBJECTIVE: Pregnancy outcomes in patients with twin pregnancy undergoing second-trimester amniocentesis for fetal karyotype assessment were compared in a case-control study with twin pregnancies undergoing routine ultrasonographic studies at similar gestational ages. STUDY DESIGN: All spontaneous and induced twin gestations that underwent ultrasonographic examination between 14 and 20 weeks were compiled for the period January 1987 through January 1992. Patients having undergone multifetal reduction or chorionic villous sampling and those with fetal anatomic or chromosomal anomalies, discordant growth (> 20%), death, or a monoamniotic sac detected at ultrasonography were excluded. RESULTS: The mean (+/- SD) maternal age was significantly higher among the 101 cases than among the 108 controls (35.2 +/- 3.5 vs 30.4 +/- 5.3 years, respectively; p < 0.01). No differences were noted in gravidity, parity, number of prior spontaneous losses, or gestational age at ultrasonography between the two groups. The fetal loss rate was similar among cases and controls (seven of 202 [3.5%] vs seven of 216 [3.2%], relative risk 1.07, 95% confidence intervals 0.3 to 3.5). No losses occurred within 3 weeks of the procedure. Gestational age at delivery, birth weight, mean Apgar scores at 1 and 5 minutes, and length of neonatal stay were not significantly different between cases and controls. CONCLUSIONS: Second-trimester amniocentesis in twin pregnancies is apparently not associated with excess pregnancy loss.

This study was conducted to determine whether fetal blood sampling during the second trimester is associated with changes in circulating fetal beta-endorphin (BE) concentrations. We measured BE concentrations in 68 paired fetal and maternal blood samples obtained between 18 and 28 weeks' gestation. Patients were divided into a control group (n = 50), if the fetal blood samples were obtained by a single umbilical cord puncture, or multiple insertion group (n = 18), if multiple cord punctures were required to obtain a sample. The mean (+/- SE) fetal BE value for the multiple insertion group was significantly higher than BE levels from the control group (771.2 +/- 79.2 pg/ml versus 107.1 +/- 11.7 pg/ml; p < 0.001]. This elevation did not appear to be related to acidosis, since no differences in fetal umbilical pH were observed between the two groups. Fetal BE levels from the control but not from the multiple insertion group significantly correlated with maternal values (Spearman rank r = 0.59; p < 0.001 vs r = -0.08; p > 0.5). In neither group did fetal BE levels correlate with gestational age. These findings indicate that multiple cord punctures at the time of fetal blood sampling are associated with significant increases in BE release. Furthermore, although a maternal or placental contribution to steady state circulating fetal BE cannot be excluded, it would seem that the fetus itself is the primary source of elevated circulating BE levels following multiple cord punctures.

OBJECTIVE: The aim of our study was to determine whether the reported increased morbidity associated with failed attempted vaginal birth after cesarean section is attributable to the presence of a uterine scar alone or to labor preceding a cesarean section. STUDY DESIGN: Primiparous women (N = 237) who underwent repeat cesarean section after a failed trial of vaginal birth after cesarean section were retrospectively compared with 1582 nulliparous women who underwent a primary cesarean section after a failed trial of labor. RESULTS: There were no significant differences in maternal or neonatal morbidity between the two groups except for an increase in the prevalence of thin meconium in patients undergoing primary cesarean section. CONCLUSION: Our results suggest that the presence of a previous cesarean section scar does not increase the overall baseline morbidity associated with cesarean section after labor.

OBJECTIVE: Endogenous opiates may play a role in both fetal physiologic functions and the adaptation to intrauterine stress. However, our understanding of this role is hampered by an absence of data on circulating levels of these substances during fetal life. STUDY DESIGN: We measured serum beta-endorphin values with a radioimmunoassay in 81 paired fetal and maternal blood samples and 24 neonatal cord specimens. The former samples were uneventfully obtained from uncomplicated pregnancies between 18 and 39 weeks of gestation at the time of cordocentesis for prenatal diagnosis. RESULTS: Mean fetal beta-endorphin concentrations were significantly lower than beta-endorphin values from neonates (90.5 pg/ml [+/- 59.4] vs 228.4 pg/ml [+/- 166.2]; p less than 0.001), but significantly higher than mean maternal values (70.5 pg/ml [+/- 48.8]; p less than 0.02). Although fetal beta-endorphin levels decreased between 18 and 28 weeks' gestation, the correlation between fetal beta-endorphin values and gestational age was not significant (r = -0.193; p = 0.07). However, fetal beta-endorphin concentrations were significantly correlated with maternal values (Spearman's rank r = 0.47; p less than 0.001). CONCLUSION: These findings suggest that delivery or fetal adaptation to an extrauterine environment is associated with significant increases in beta-endorphin release. Moreover, although the fetal pituitary may be the primary source of circulating fetal beta-endorphin, a maternal or placental contribution cannot be excluded. Our data identify a physiologic range for fetal beta-endorphin concentrations.

Treatment of obstetric hemorrhage by the selective embolization of damaged pelvic vessels under fluoroscopy holds promise as an alternative to surgical intervention. Unfortunately, the effectiveness of selective embolization is often compromised by its use in emergent settings following the failure of primary operative approaches. Therefore we compared the efficacy of prophylactic versus emergent catheter placement for selective embolization in nine patients with or at risk for obstetric hemorrhage. In four patients with acute obstetric hemorrhage catheterization and embolization was carried out following the failure of initial medical and surgical approaches. In five patients determined to be at risk for intrapartum hemorrhage based on sonographic findings, catheters were inserted into the hypogastric vessels prior to elective cesarean delivery. Three of these five patients subsequently required selective embolization. In comparison to patients undergoing selective embolization following prophylactic catheter placement, patients in the emergent group all had a coagulopathy at the time of embolization, sustained substantially greater blood loss, and had an increased rate of postpartum complications. Finally, there was a significant reduction in total embolization time and therefore in radiation exposure in patients undergoing prophylactic catheter placement prior to selective embolization. These data support the conclusion that in patients determined to be at risk for intrapartum or postpartum hemorrhage the prophylactic placement of catheters allows for selective embolization in a hemodynamically intact patient with stable coagulation indices, theoretically reducing the risk of maternal morbidity and possibly mortality.

Hydrops caused by isoimmune hemolytic anemia is frequently associated with fetal death following intrauterine intravascular transfusion. To identify possible predictors of procedure-related fetal death, we examined changes in fetal blood volume and hematocrit resulting from the initial transfusion performed on 19 severely anemic, hydropic fetuses. Seven fetuses (36.8%) died at 24-72 hours after transfusion, but in no case was the procedure associated with fetal distress. There were no significant differences between fetuses who died and those who survived in terms of total volume of blood transfused, volume transfused as a percentage of total fetoplacental blood volume, hematocrit of transfused blood, post-transfusion hematocrit, umbilical vein pH, or gestational age at transfusion. Significant differences were noted between hydropic fetuses who died compared with those who survived in the mean pretransfusion hematocrit, 6.7% (+/- 2.0) versus 8.7% (+/- 1.6) (P = .03), and the relative increase in post- over pre-transfusion hematocrit, 5.5-fold (+/- 1.4) versus 3.5-fold (+/- 0.8) (P = .001). Stepwise logistic regression analysis confirmed that only the relative increase in hematocrit was predictive of fetal loss. Moreover, six of seven fetal deaths occurred when the relative increase in hematocrit was greater than fourfold, whereas ten of 12 surviving fetuses had relative increases of less than fourfold. We conclude that large, acute increases in fetal hematocrit following intrauterine transfusion are associated with substantial mortality in hydropic fetuses.