Cell Salvage and Donor Blood Transfusion during Caesarean Section: A Pragmatic Multicentre Randomised Controlled Trial (SALVO)

Research output: Contribution to journalArticle


  • Khalid S. Khan
  • Philip Moore
  • Matthew J. A. Wilson
  • Richard Hooper
  • Shubha Allard
  • Ian Wrench
  • Lee Beresford
  • James Geoghegan
  • Sue Catling
  • Vicki Clark
  • Paul Ayuk
  • Stephen Robson
  • Matthew Hogg
  • Doris Lanz
  • Julie Dodds

Colleges, School and Institutes

External organisations

  • Women’s Health Research Unit, Barts and the London School of Medicine and Dentistry, Queen Mary University of London
  • Birmingham Women's Hospital
  • University of Sheffield
  • Pragmatic Clinical Trials Unit, Centre for Primary Care and Public Health, Queen Mary University of London
  • NHS Blood and Transplant, London
  • Sheffield Teaching Hospitals NHS Foundation Trust
  • Singleton Hospital, Swansea
  • The Simpson Centre for Reproductive Health, Royal Infirmary of Edinburgh, Edinburgh.
  • Royal Victoria Infirmary; Newcastle Upon Tyne UK
  • Newcastle University
  • Royal London Hospital, Barts Health NHS Trust


Excessive haemorrhage at caesarean section requires donor (allogeneic) blood transfusion. Cell salvage may reduce this requirement.

Methods and findings
We conducted a pragmatic randomised controlled trial (26 obstetric units; June 2013 through April 2016) of routine cell salvage use (intervention) vs. current standard of care without routine salvage use (control) in caesarean section among women at risk of haemorrhage. Randomisation was stratified, using random permuted blocks of variable sizes. In an intention-to-treat analysis, we used multivariable models, adjusting for stratification variables and prognostic factors identified a priori, to compare rates of donor blood transfusion (primary outcome) and fetomaternal haemorrhage ≥2ml in RhD-negative women with RhD-positive baby (a secondary outcome) between groups.
Among 3028 women randomised (2990 analysed), 95.6% of 1498 assigned to intervention had cell salvage deployed (50.8% had salvaged blood returned; mean 259.9 ml) vs. 3.9% of 1492 assigned to control. Donor blood transfusion rates were 3.5% in the control group vs. 2.5% in intervention (adjusted odds ratio [OR] 0.65, 95% confidence interval [CI] 0.42 to 1.01, p=0.056; adjusted risk difference -1.03, 95% CI -2.13 to 0.06; number needed to treat [NNT] 97, at the lower limit of 95% confidence NNT was 47 and at the upper limit the number needed to harm was 1,667). In a planned subgroup analysis, the transfusion rate was 4.6% in women assigned to control vs. 3.0% in the intervention group among emergency caesareans (adjusted OR 0.58, 95% CI 0.34 to 0.99), whereas it was 2.2% vs. 1.8% among elective caesareans (adjusted OR 0.83, 95% CI 0.38 to 1.83) (interaction p=0.46). No case of amniotic fluid embolism was observed. Fetomaternal haemorrhage was higher with intervention (10.5% in control vs. 25.6% in intervention, adjusted OR 5.63, 95% CI 1.43 to 22.14, p=0.013). We are unable to comment on long-term antibody sensitisation effects.

The overall reduction observed in donor blood transfusion associated with the routine use of cell salvage during caesarean section was not statistically significant.

Author summary
Why was this study done?
• Given that caesarean section rates are rising worldwide, the need for promoting alternatives to blood transfusion in caesareans, such as harnessing the patient’s own reserves where feasible, is well recognised.
• While cell salvage in operations outside of obstetrics has been shown to reduce the need for donor blood transfusion, its effectiveness in caesarean section is unclear and based only on two small controlled trials of cell salvage in caesarean section, with imprecise and inconclusive findings.
• Current obstetric guidelines on cell salvage have focused attention on the lack of high quality research, recognising that although there is potentially a place for cell salvage in emergency blood loss during caesarean section its use remains controversial.

What did the researchers do and find?
• We conducted a multicentre randomised controlled trial, including 3028 women at risk of haemorrhage during caesarean section, to test the effect of routine use of cell salvage compared to current standard of care on the need for donor blood transfusion.
• While donor blood transfusion rates were lower in the lower in cell salvage vs control group (2.5% vs 3.5%, meaning that on average, one in every 100 mothers given cell salvage avoided a donor blood transfusion), the difference between the groups was not statistically significant.
• Additionally, the study has shown that in women with RhD-negative blood groups who gave birth to RhD-positive babies, cell salvage was associated with increased maternal exposure to fetal blood.

What do these findings mean?
• These findings indicate that routine cell salvage does not lead to a significant reduction in donor blood transfusion rates in women at risk of haemorrhage during caesarean section.


Original languageEnglish
Article numbere1002471
JournalPLoS Medicine
Issue number12
Publication statusPublished - 19 Dec 2017


  • Intraoperative Blood Cell Salvage, Caesarean Section, Obstetrics

ASJC Scopus subject areas