Accurate Intrapartum Estimation of Fetal Platelet Count by Fetal Scalp Sample Smear

ABSTRACT

Fetal scalp sampling has been used to determine fetal platelet count in early labor. Because platelet clumping may lead to falsely low platelet counts, this pilot study was carried out to evaluate an improved method of scanning an intrapartum fetal scalp smear for platelet estimation. We report 5 years' experience with the use of scanning of the smear for platelet aggregates instead of direct measurement of platelets. In 22 cases, intrapartum examination of the scalp blood smear at low power revealed the great majority of high-power, dry microscope fields devoid of platelets, whereas isolated fields contained aggregates of more than 10 platelets. In one case, an adequate number of platelets were evenly distributed. Intrapartum fetal platelet estimation by scanning of the smear (using these platelet aggregates) correctly identified an adequate neonatal platelet count in 23 cases (mean, 264,600 ± 15,000; range, 133,000 to 396,000). Cesarean section was avoided in 82.6% of these cases. In this pilot study, platelet estimation on fetal scalp sample was reliably performed by scanning of the smear for platelet aggregates. When aggregates were seen, platelet adequacy was found in all cases.