Does pre-transfusion washing of red blood cells for preterm babies improve their health outcomes?

Background: Babies born preterm or with a low birth weight may be given blood transfusions for a number of reasons. For example, they are sometimes unable to make their own blood well yet; they may need several blood tests to monitor their condition; or they may need extra blood if they become critically unwell.

Studies in older children and in adults have found that a process of ‘washing’ blood cells before transfusion improved short- and longer-term outcomes. Washing blood removes almost all plasma proteins and most white blood cells, which may help reduce the side effects of a blood transfusion. We wanted to learn if preterm babies might experience these same positive effects.

Review question: We wanted to learn whether washing blood cells before transfusion reduces the chance of illnesses that tend to occur in preterm babies. Some of the outcomes that we looked at were illnesses affecting eyes (retinopathy of prematurity), lungs (chronic lung disease), brain (intraventricular haemorrhages or cysts), and long-term developmental problems. We also wanted to look at other outcomes like length of hospital stay and acute transfusion reactions.

Key results: This review found only one study that evaluated the effects of washing blood cells before transfusion in preterm babies. This study included small numbers of babies. The outcomes the study reported that were relevant to our review were mortality, duration of mechanical ventilation, and length of initial hospitalisation. The results for all these outcomes were very uncertain. Washing blood cells might be helpful or harmful, but we cannot make a determination.

Quality of the evidence: It was hard from the available evidence to draw any conclusions about whether washing blood would be helpful or not for preterm babies. As of now, there is no strong evidence showing that washing blood makes any difference to the outcomes of preterm babies.

Authors' conclusions: 

We identified a single small study. The results from this study show a high level of uncertainty, as the confidence intervals are consistent with both a large improvement or a serious harm caused by the intervention. Consequently, there is insufficient evidence to support or refute the use of washed RBCs to prevent the development of significant neonatal morbidities or mortality. Further clinical trials are required to assess the potential effects of pre-transfusion washing of RBCs for preterm or very low birth weight infants, or both, on short- and long-term outcomes.

Read the full abstract...

Infants born very preterm often receive multiple red blood cell (RBC) transfusions during their initial hospitalisation. However, there is an increasing awareness of potential adverse effects of RBC transfusions in this vulnerable patient population. Modification of RBCs prior to transfusion, through washing with 0.9% saline, may reduce these adverse effects and reduce the rate of significant morbidity and mortality for preterm infants and improve outcomes for this high-risk group.


To determine whether pre-transfusion washing of RBCs prevents morbidity and mortality in preterm infants.

Search strategy: 

We used the standard search strategy of the Cochrane Neonatal Review Group to search the Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 7), MEDLINE via PubMed (31 July 2015), EMBASE (31 July 2015), and CINAHL (31 July 2015). We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials.

Selection criteria: 

Randomised, cluster randomised, and quasi-randomised controlled trials including preterm infants (less than 32 weeks gestation) or very low birth weight infants (less than 1500 g), or both, who received one or more washed packed RBC transfusions.

Data collection and analysis: 

Two review authors independently assessed the eligibility of the trials. We identified four studies from the initial search. After further review of the full-text studies, we found one study meeting the selection criteria.

Main results: 

We included a single study enrolling a total of 21 infants for analysis in this review and reported on all-cause mortality during hospital stay, length of initial neonatal intensive care unit (NICU) stay (days), and duration of mechanical ventilation (days). There was no significant difference in mortality between the washed versus the unwashed RBCs for transfusion groups (risk ratio 1.63, 95% confidence interval (CI) 0.28 to 9.36; risk difference 0.10, 95% CI -0.26 to 0.45). There was no significant difference in the length of initial NICU stay between the washed versus the unwashed RBCs for transfusion groups (mean difference (MD) 25 days, 95% CI -21.15 to 71.15) or the duration of mechanical ventilation between the washed versus the unwashed RBCs for transfusion groups (MD 9.60 days, 95% CI -1.90 to 21.10).