Umbilical cord coiling index for the prediction of adverse pregnancy outcomes: a meta-analysis and sequential analysis.

PURPOSE: To evaluate the potential association of abnormal cord coiling with adverse pregnancy outcomes.

MATERIALS AND METHODS: We used the Medline (1966-2018), Scopus (2004-2018), Clinicaltrials.gov (2008-2018), Embase (1980-2018), Cochrane Central Register of Controlled Trials CENTRAL (1999-2018), and Google Scholar (2004-2018) databases. The date of last search was set on 31 May 2018. Language, country, or date restrictions were not applied during the literature research to prevent bias. All observational (both prospective and retrospective) studies that reported maternal and neonatal antenatal and perinatal outcomes based on the umbilical coiling index (UCI) status were considered as eligible for inclusion. Meta-analysis of the risk ratio (RR) and mean differences (MD) among hypocoiled/hypercoiled and normocoiled cases was performed with RevMan 5.3 software. Univariate metaregression and leave-one-out meta-analysis was performed with Open Meta-Analyst statistical software. Trial sequential analysis was performed with the trial sequential analysis (TSA) software.

RESULTS: Twenty four studies were finally included that involved 9553 pregnant women. Umbilical cord coiling was evaluated with the use of the umbilical coiling index (UCI). Values of the UCI below the 10th percentile were evaluated as hypocoiled and above the 90th percentile as hypercoiled. Hypocoiled cords were significantly associated with increased prevalence of preterm birth < 37 weeks, need for interventional delivery due to fetal distress, meconium stained liquor, Apgar scores < 7 at 5 min, small for gestational age (SGA) neonates, fetal anomalies, need for admission in the neonatal intensive care unit (NICU), fetal heart rate abnormalities, and fetal death. Hypercoiled cords were significantly associated with increased prevalence of preterm birth < 37 weeks, need for interventional delivery due to fetal distress, meconium stained liquor, Apgar scores < 7 at 5 min, small for gestational age (SGA) neonates, fetal anomalies, fetal growth restriction fetal heart rate abnormalities, fetal acidosis, and fetal death.

CONCLUSIONS: The findings of our meta-analysis underline the correlation of UCI abnormalities with antenatal and perinatal pathology. More studies are needed, however, to elucidate whether antenatal assessment of the UCI can be used as routine in clinical practice as well as its value in uncomplicated pregnancies.