Faculty Bibliography

A case of vasa previa in twin pregnancy associated with a sinusoidal heart rate was observed. A review of the world literature revealed eight previously reported cases of vasa previa in twins. No first twin survived, and 62.5% of second twins eventually died from partial or complete exsanguination. This is the first reported case of sinusoidal fetal heart rate in association with vasa previa. Continuous fetal monitoring suggested the diagnosis of funic presentation and of fetal bleeding. A high index of suspicion, use of amnioscopy, ability to detect fetal blood in the vaginal pool, continuous fetal heart rate monitoring and ultrasonography may help in reducing the high perinatal mortality associated with vasa previa

Three hundred thirty-six consecutive cesarean deliveries performed under epidural anesthesia were reviewed. Twenty per cent of mothers suffered at least a 20% fall in blood pressure following administration of epidural anesthesia. An additional 24% required ephedrine, a vasopressor with predominantly beta activity, when other corrective measures failed. Thus, 44% of these patients suffered significant hypotension. Forty-one percent of all elective repeat cesarean sections were treated wih ephedrine because of maternal hypotension. Fifty-one patients delivered by scheduled repeat cesarean section were divided into ephedrine-treated and untreated groups. There were no differences in Apgar scores among infants of both groups. Fetal acidosis was proportional to the severity of hypotension and the ephedrine dose. The metabolic abnormalities were most pronounced when severe hypotension, requiring over 15 mg of ephedrine, was present. Following restoration of blood pressure with conventional measures and ephedrine therapy, lactic acidosis persisted until delivery, whereas PO2 and PCO2 reverted toward normal values. The hypoperfusion of the intervillous space was the most likely cause of the observed significant umbilical venous and arterial lactic acidosis. Maternal hypotension remains a significant problem complicating conduction anesthesia

Umbilical blood was analyzed for pH, pO2, pCO2, HCO3-, base excess, and plasma lactate to evaluate possible errors of fetal scalp blood analysis. Two studies to determine the effect of delayed collection and exposure to air on fetal blood acid-base measurement analyzed anaerobically collected umbilical blood in syringe and capillary samples. In the first study, 37 samples were analyzed and then placed in small droplets on a glass slide and exposed for 30 seconds and 60 seconds respectively. These samples were then collected and reanalyzed. No significant change was noted through 1 minute of exposure in any of the acid-base parameters measured. In the second study, 34 samples were again analyzed and then exposed in droplets for a full 5 minutes. Differences in measurement of pO2, base excess, and plasma lactate remained insignifiicant even up to 5 minutes. The results of this study demonstrate that the occasional slow scalp blood collection or admixture with air do not present a significant obstacle to proper use of fetal acid-base analysis