Autologous blood in obstetrics: where are we going now?

Abstract

In developed countries1, pregnancy-related transfusion accounts for about 6 percent of red blood cell (RBC) units transfused. This means that, for example, in the UK as a whole, approximately 70,000 units of RBC are transfused to obstetric patients each year2. The pattern of blood usage is very different in countries in which diagnostic and treatment options are more limited, with 37 percent of transfusions being given to women with obstetric emergencies1. Obstetric haemorrhage is a leading cause of maternal and perinatal mortality3. Placental abruption and placenta praevia/accreta can present as antepartum haemorrhage and are risk factors for post-partum haemorrhage (PPH). Uterine atony, inversion, retained products of conception and genital tract trauma all cause PPH and account for the majority of cases of major haemorrhage. Uterine rupture is an infrequent cause of haemorrhage and maternal death and can occur spontaneously or at the site of previous uterine surgery (caesarean section or retained placenta)3. During the triennium 2006–2008, the rate of deaths from hemorrhage in the UK was 0.39 per 100,000 maternities4. The incidence of severe bleeding in childbirth has been estimated in various surveys and is approximately one in 200 to 250 deliveries4. In developed countries treatment is generally effective with an approximate case fatality rate between 1 in 600 to 800 cases of obstetric bleeding5–7. Various blood conservation techniques can reduce exposure to allogeneic blood. These include pre-operative autologous blood donation (PABD), acute normovolaemic haemodilution (ANH) and intra-operative blood salvage (IBS). PABD may cause anaemia, does not eliminate transfusion risk, cannot be used in an emergency, is not acceptable to Jehovah’s Witnesses and should be reserved for exceptional circumstances8,9. ANH may induce anaemia and cardiac failure, cannot be used in an emergency and may have a limited role in combination with other techniques9. The use of IBS has increased substantially during the last two decades and the re-infusion of shed washed blood is commonplace in many types of surgical operations in which heavy blood loss is anticipated10,11. In this technique, blood shed at the time of surgery is collected and washed, and RBC are returned to the patient as an ongoing process (Figure 1)12,13. In skilled hands, blood salvage can be quickly set up and the final product returned to the patient within minutes of collection. In addition, this technique is also acceptable to some Jehovah’s Witnesses, provided the equipment is set up in continuity with the circulation (Figure 1)14, but consent needs to be obtained on an individual basis. Figure 1 Schematic representation of a blood salvage system with a double suction setup to reduce the possible contamination of the blood suctioned from the surgical field138. In this setup, one suction line is connected to the collection reservoir and used for ... However, the safety of IBS in obstetrics has been questioned and its introduction in this clinical arena has been delayed because of theoretical concerns stemming from the historical and ongoing dispute focused on the risk of maternal-foetal anti-Rh(D) alloimmunisation and the risk of contamination of the cell-saved blood with traces of amniotic fluid (AF)15,16. The objective of this article is to review the role of autologous blood conservation techniques in obstetrics focusing on the currently available evidence regarding IBS. An overview of current European regulatory requirements on IBS will also be provided.