Reference ranges for the intra-amniotic umbilical cord vein diameter, peak velocity and blood flow in a regional NSW population.

AIM

To construct gestational age (GA)-related reference ranges of the intra-amniotic umbilical cord vein (UCV) diameter, peak velocity (PV) and blood flow (Qucv) using a Central West New South Wales population.

MATERIALS AND METHODS

This was a prospective, quasi-experimental study of low risk, singleton pregnancies (n = 321) between 16 and 42 weeks of gestation. Participation was voluntary following informed consent. The UCV diameter and PV were measured using B mode and duplex Doppler respectively, and Qucv calculated. Percentile values and reference range graphs were established using quantile regression modelling in R statistical software. Intraclass correlation coefficients (ICCs) were calculated to assess the intra and intersonographer reliability.

RESULTS

Reference ranges for the UCV diameter, PV and Qucv were established and graphed. All three UCV measurements increased with advancing GA, with both diameter and Qucv exhibiting a decline in the late third trimester. The intrasonographer and intersonographer ICCs for the UCV diameter and PV showed almost perfect agreement within and between sonographers.

CONCLUSION

Gestational age-related reference ranges for the UCV diameter, PV and Qucv were developed using quantile regression from a cohort of low risk, singleton pregnancies in Central West NSW. These reference ranges have the potential to assist in the diagnosis and monitoring of fetal growth restriction.