Neonatal outcome and delivery mode in labors with repetitive fetal scalp blood sampling

Abstract

Objective: To investigate if repeat (≥ 3) fetal scalp blood sampling (FBS) is associated with increased risk of caesarean delivery and worse neonatal outcome than occasional (1-2) FBS.

Study design: Prospective cohort study of women undergoing intrapartum FBS at Karolinska University Hospital, Sweden. FBS with lactate analysis was performed if the attending doctor found the cardiotocography (CTG) tracing suspicious or abnormal. Lactate concentration was measured bedside. As a routine in all deliveries, acid-base analyses were performed on umbilical artery and vein blood immediately after delivery. Main outcome measures were metabolic acidemia in umbilical artery at delivery, Apgar score <7 at 5 min and caesarean delivery.

Results: During the study period there were 2134 FBSs performed on 1070 laboring women with a median of two samplings (range 1-8). There were no differences in Apgar score <7 at 5 min or metabolic acidemia in umbilical artery blood at birth between labors with 1-2 FBS and ≥ 3 FBS. Among women who underwent 1-2 FBS, 23% had a caesarean delivery as compared with 42% of those having ≥ 3 FBS. After adjustment for confounders, repeat FBS remained an independent risk factor for caesarean delivery (adj OR 2.05; 95%C.I 1.5-2.8).

Conclusion: Fetal monitoring with repetitive FBS (≥ 3) during labors with CTG changes is safe for the baby, but the rate of caesarean delivery is doubled as compared to labors where 1-2 FBS are needed. Still, more than 50% of women with repetitive FBS will be delivered vaginally, and 1/3 of these spontaneously.

Keywords: Cardiotocography; Fetal blood sampling; Fetal distress; Fetal monitoring; Metabolic acidosis.