Umbilical cord coiling: clinical outcomes in an unselected population and systematic review

This study was conducted to determine the frequency of pre-defined clinical outcomes in relation to umbilical cord coiling indices >90th percentile and <10th percentile in an unselected population of >1,000 women with a singleton pregnancy resulting in livebirth delivering at or near term and to report these findings in the context of a systematic review. Placentas of consecutive deliveries from an unselected low-risk population with >15 cm attached umbilical cords were included in the study. Clinical outcomes included interventional delivery, birthweight <10th percentile, Apgar score <7 at 1 min, neonatal acidosis (pH<7.2) and admission to neonatal special care. Standard MOOSE (Meta-analysis of Observational Studies in Epidemiology) guidelines were observed for the systematic review. Umbilical coiling index was determined for 1,082 placentas. Mean maternal age was 30.7 years (standard deviation [SD] =5.7) and 519 women (48 %) were primiparous. Mean cord length was 43 cm (SD=13) and mean cord coiling index 0.20 (SD=0.09). A total of 866 cords were normally coiled, and 108 cases were hypercoiled (>90th centile) and 108 cases were undercoiled (<10th percentile). There were no differences between cases of overcoiled, normally coiled or undercoiled cords for any clinical outcome studied. The systematic review yielded a small number of clinical studies which were too statistically and clinically heterogenous to permit meta-analysis. There is insufficient evidence either from this unselected cohort study or from a systematic review to support the previous suggestion that cord coiling index >90th centile or <10th centile is associated with adverse clinical outcome in an unselected population. Previous studies that draw a link between abnormal cord coiling and clinical outcome are generally too small and/or selective to allow meaningful conclusions or applicability to low-risk populations.