Obstetric intra-operative cell salvage and maternal fetal red cell contamination

The significance of fetal red blood cell (RBC) contamination in obstetric intra-operative cell salvage is not fully known. It is unclear if we re-infuse a larger volume of fetal RBCs into the maternal circulation than the amount that occurs secondary to transplacental haemorrhages is unclear. We also do not know if there is a critical volume required to cause alloimmunisation or if larger volumes increase the risk.

The aim of this study is to provide data on the level of fetal RBC contamination in the maternal circulation prior to delivery and immediately post-partum and to compare these levels to those found in processed cell-salvaged blood.

In the first part of this study, we quantified the levels of fetal RBCs circulating in women immediately prior to delivery. This was then repeated with a separate group measuring the levels of fetal RBCs pre- and post-delivery.

We found that 37% of women had fetal cells detected in their circulation, median 0·00 mL (IQR 0-0·24; average 0·3 mL, maximum 4·56 mL). Fetal RBCs were present pre-delivery (maximum 0·66 mL) in 16% of women, increasing to 53% post-delivery (median 0·66 mL; IQR 0·22-2·20, maximum 21·20 mL).

We have shown that fetal RBCs are present in the maternal circulation throughout pregnancy and that the volumes are comparable to that obtained from intra-operative salvage, with contamination amounts of up to 19 mL. At the Royal Cornwall Hospital, our experience and evidence supports offering intra-operative salvage to all women, and we have not noted an increase in antibody formation, compared to allogeneic transfusion.