Ultrasound is the recommended and preferred modality for fetal assessment. The umbilical artery vessels are assessed at the anomaly scan as per departmental protocols. Assessment is completed by using colour Doppler in the transverse plane of the fetal pelvis to visualise the two umbilical arteries branching laterally to the urinary bladder. The arteries can also be assessed by visualising a transverse section of the umbilical cord. Figure 1 demonstrates a typical three vessel cord visualised in a transverse section of the umbilical cord. Figure 2 and 3 demonstrate a single umbilical artery in the transvserse plain of the umbilical cord and branching at the fetal urinary bladder.

To assess the impact of identifying and performing growth surveillance of 2VC’s, a retrospective review of ultrasound scans that report a single artery umbilical cord and fetal outcomes was completed over a 9 month period. All routine anomaly scans and subsequent growth scans in pregnancies with single artery umbilical cords were reviewed, as were the final fetal birthweight at delivery (if available). The centiles of the birthweight were then assessed to identify if the 2VC made an impact on the fetal growth and outcome of the pregnancy.

The hospital being audited follow the Growth Assessment Protocol (GAP) and programme created by the Perinatal Institute. It is a standardised protocol for growth surveillance in pregnancy. GAP is aligned with Saving Babies Lives and the RCOG ‘small for gestational age’ guidelines. A personalised GROW chart (customised chart showing optimal estimated size/weight for each individual fetus) is created as per the GAP programme. The chart is adjusted based on maternal height, weight, parity and ethnic origin. Factors such as diabetes and smoking are excluded in order to predict the growth potential of the fetus. The estimated fetal weight and birth weight plotted on the personalised GROW chart were assessed to establish ‘normal’, ‘large’, or ‘small’ fetuses.

Over the 9 month period reviewed, 3947 anomaly scans had been performed. A total of 13 2VCs were identified. Five birthweights were not available (due to ongoing pregnancies or noncompleted birth details) leaving eight accessible for evaluation. 37.5% were delivered small for gestational age. 25% were large for gestational age. And 37.5% were born at a normal birth centile (findings demonstrated in a pie chart, figure 4). All fetuses were livebirths with no further reported complications.

This study acknowledges that there is a limited sample size and the accuracy of identification of 2VC in the hospital trust was not assessed.