[Clinical significance of intermittent sinusoidal fetal heart rate at third trimester]

To investigate clinical significance of intermittent sinusoidal fetal heart rate at third trimester.

From Jan 2002 to Dec 2010, 48 pregnant women at 33 to 41 gestational weeks undergoing electronic fetal heart rate (FHR) monitoring presented with intermittent sinusoidal FHR in Department of Obstetrics and Gynecology, Second School of Clinical Medicine, Jinan University were enrolled in this retrospective study. Twenty-one cases were categorized into continuous group (i.e. with sinusoidal feature and a constant duration ≥ 10 minutes), while the other 27 cases were categorized into intermittent group (i.e. with a duration < 10 minutes). In the mean time, 76 normal cases were chosen randomly matched as control group. Blood gas and hemoglobin were measured in umbilical artery after fetal head delivery. General neurological system examination were performed in those fetus in hospitalization. The outcome of those fetuses was compared.

(1) Neonatal complications: the rate of asphyxia, meconium-stained amniotic fluid and fetal anemia were 63% (17/27), 33% (9/27) and 63% (17/27) in group of intermittent sinusoidal FHR, which were significantly higher than 1% (1/76), 4% (3/76), 3% (2/76) in control group (P < 0.05). When compared with 67% (14/21), 52% (11/21), 76% (16/21) in group of continuous sinusoidal, the statistical difference were not observed (P > 0.05). (2) Blood gas in neonate: the rates of pH less than 7 were 18% (5/27) in intermittent group, 52% (11/21) in continuous group and 0 in control group, which all reached statistical difference among those three groups (P < 0.05). (3) Brain damage and death: the rates of brain damage and death were 48% (13/27) and 11% (3/27) in intermittent group, 81% (17/21) and 43% (9/21) in continuous group, and 0 in control group, which all showed significant difference between them (P < 0.05).

Intermittent and continuous sinusoidal FHR are typical graphics of severe fetal anemia at third trimester. Intermittent sinusoidal FHR is indicative of serious fetal hypoxia.