Does umbilical cord milking result in higher measures of systemic blood flow in preterm infants?

Abstract

Commentary on: Katheria AC, Truong G, Cousins L, Oshiro B, Finer NN. Umbilical cord milking versus delayed cord clamping in preterm infants. Pediatrics. 2015 July;136(1):61–69; doi:10.1542/peds.2015-0368. The American Congress of Obstetricians and Gynecologists recommends a 30–60 s delay in umbilical cord clamping for all preterm deliveries, though limited data regarding outcomes by mode of delivery exists 1. Umbilical cord milking (UCM) is a method to auto-infuse blood into the neonate in a shorter amount of time. A 2011 study comparing UCM with delayed cord clamping (DCC) in infants <33 weeks’ gestation found no major clinical differences between the groups, though the trial did not stratify outcomes by mode of delivery 2. The reviewed study (Katheria et al.) is the first trial to compare UCM and DCC at Caesarean delivery and to evaluate DCC for more than 30 seconds in preterm infants. The authors hypothesised that UCM after Caesarean delivery would improve systemic blood flow and be associated with decreased morbidities compared with DCC. The study was unique in its use of delayed consent, in which parents were informed and consented after delivery. Delayed consent was used because antenatal consent requirements would exclude a subset of newborns, and because UCM and DCC are both standard practices at these institutions. This method of consent may raise ethical concerns; however, others have praised it as a strategy to increase enrolment of high risk infants 3. The study was adequately blinded and used advanced techniques to measure neonatal hemodynamics. The primary outcome of superior vena cava flow was chosen as a marker of neonatal transition that is not affected by foetal shunts. Right ventricular output was lower in the DCC group, which previous studies have shown to be associated with increased oxygen requirement, severe intraventricular haemorrhage (IVH) and death 4. There was no difference in left ventricular output (LVO), but LVO may be confounded by a left to right shunt across a patent ductus arteriosus and thereby overestimate systemic blood flow. The authors argue that given the markers suggestive of improved organ perfusion, UCM may stabilise fluctuations in systemic blood flow and therefore prevent IVH, although the study did not have adequate power to assess this outcome. Despite not being statistically significant, the different rates of IVH appear to be clinically relevant. With an absolute risk difference of 6/100, it is difficult to dismiss the potential decreased risk of IVH associated with UCM. Another limitation of the study is the lack of a control group to undergo immediate cord clamping (ICC). Given improved clinical outcomes associated with placental transfusion, the authors state that they did not have clinical equipoise to assign ICC. Lastly, the study was limited by only including 94/197 infants who were <29 weeks’ gestational age. It remains uncertain if and how the present study will influence clinical practice. Larger trials involving smaller, more premature neonates are needed in addition to long-term assessment of neurodevelopmental outcomes. The authors confidently state that ‘UCM should no longer be considered experimental…[but] a beneficial option for preterm infants delivered by Caesarean delivery’. With the growing body of evidence supporting the safety of UCM, we concur with the authors in advocating for this intervention. https://ebneo.org/2015/12/does-umbilical-cord-milking-result-in-higher-measures-of-systemic-blood-flow-in-preterm-infants/ None. None.