Abstract
INTRODUCTION: Isolated single umbilical artery (iSUA) is associated with a fivefold increased risk for perinatal mortality, even though placental blood flow is not reduced compared to healthy fetuses. In recent work, the umbilical cord was shown to have a protective effect against intrapartum fetal acidosis, which is reduced in the case of relevant cord anomalies like iSUA. This study aimed to investigate the protective effect of the umbilical cord against fetal acidosis by comparing cardiotocogram (CTG) characteristics of fetuses with iSUA against controls. MATERIAL AND METHODS: In this retrospective, matched case-control study in a tertiary care center in the Netherlands, computerized CTG analyses were performed on intrapartum registrations for 9 iSUA patients and 35 case-matched controls. CTGs were analyzed for stages of hypoxia classification, CTG characteristics of fetal heart rate such as baseline, variability, (late) decelerations, overshoots, FHR recovery duration, and characteristics of uterine contractions. Linear regression analyses were performed for the CTG parameters, adjusted for uterine contraction frequency and average inter-contraction duration. Neonatal outcome parameters were compared between the iSUA group and healthy controls. RESULTS: The prevalence of decelerations followed by an overshoot was two to three times higher in the iSUA group (p = 0.011 for stage 1 and p = 0.001 for stage 2 of labor) and a longer average fetal heart rate recovery duration for stage 1 of labor was found as well (p = 0.001). Furthermore, iSUA was found to have a higher prevalence of late decelerations in stage 1 (p = 0.042) and shorter decelerations (p = 0.046) along with less decelerations exceeding 1 min (p = 0.017) during stage 2. No differences in hypoxia staging or the presence of saltatory patterns were found. Neonatal outcomes indicative of birth asphyxia did not occur in the study population. CONCLUSIONS: These findings support epidemiological findings that term fetuses with iSUA are more susceptible to hypoxia, warranting further research into tailored management strategies.