NoBlood

Article

Cell Salvage in Obstetrics: The Time Is Now
Friday, February 11th, 2005
Author: SABM Staff

Cell Salvage in Obstetrics: The Time Is Now

In a recent issue of the International Journal of Obstetric Anesthesia, Dr. Dafydd Thomas from the Swansea NHD Trust, UK, advocates the use of facilities for blood salvage in every obstetric theater as a means to decrease mortality and provide a safe alternative to the use of precious allogeneic stores (Thomas D, Int J Obstet Anesth 2005;14:48-50). In the February issue of BJOG, the journal of the Royal College of Obstetricians and Gynaecologists, Drs. Sue Catling and Lisa Joels from the Singleton Hospital, Swansea, UK, note that although intraoperative cell salvage (ICS) avoids the hazards of allogeneic blood transfusion, is cheap, and is well established in cardiac, vascular, trauma and major urological surgery, it is rarely used in obstetric theaters. The authors suggest two main reasons for this situation: fear of causing iatrogenic amniotic fluid embolus and ignorance of the risks of allogeneic transfusion (Catling S et al., BJOG 2005;112:131-2).

According to the latest report from the UK Serious Hazards of Transfusion (SHOT) hemovigilance system, 61% of serious sequelae of transfusion reported nationally between 1996 and 2001 involved ‘incorrect blood components transfused,� i.e. clerical errors, leading to 11 deaths and 60 major morbidities. Immunological reactions, including transfusion-related acute lung injury (TRALI), accounted for 36% of incidents, with 20 deaths and 49 major morbidities. The overall risks were estimated as follows: wrong blood, 1 in 25,000 components transfused; major complications, 1 in 103,000; and death, approximately 1 in 350,000. Besides, the risks from unidentified infectious agents cannot be estimated.

“Cell salvage,� the authors point out, “carries none of these risks.� Blood is aspirated from the bleeding site through heparinized tubing and a 25-mm ultrafilter into a collecting reservoir. Cells are then separated by centrifugation and washed in 0.9% saline, which removes circulating fibrin, debris, plasma, microaggregates, complement, platelets, free hemoglobin, circulating procoagulants and most of the heparin. Salvage red cells are usually superior to stored blood in terms of red cell survival, morphological changes, 2,3-diphosphoglycerate activity, and potassium content.

However, two relative contraindications to the use of ICS in obstetrics need to be considered: possible rhesus incompatibility and the risk of amniotic fluid contamination. As the cell saver cannot distinguish between fetal and maternal red cells, any aspirated fetal red cells will be retransfused, thereby increasing the dose of anti-D immunoglobulin required to prevent Rhesus immunization of Rhesus negative mothers. “In practice, 2-19 mL of fetal blood may be retransfused requiring 500-2500 IU of anti-D, so Kleihauer test should be performed as soon as practicable,� the authors state.

The other potential risk, namely amniotic fluid embolism, “has never been documented and remains entirely theoretical,� Drs. Catling and Joels point out. The presence of fetal squames in maternal blood was considered as a marker of amniotic fluid embolism until pulmonary artery flotation catheters showed that many healthy parturients apparently had abundant fetal squames in their circulation (Clark SL et al., Am J Obstet Gynecol 1986;154:104-6). In a study of 15 women undergoing elective cesarean section, Dr. Waters and colleagues found lamellar bodies from the developing fetal lung in all the patients at the time of placental separation (Waters JH et al., Anesthesiology 2000;92:1531-6). It therefore appears that the term “amniotic fluid embolism� is a misnomer and that the syndrome it denotes should be regarded as a type of anaphylactic reaction. Nevertheless, it seems reasonable to remove amniotic fluid and placental tissue as far as possible with conventional suction before aspirating to the cell saver, the authors note.

ICS has been used safely in over 400 published obstetric cases. In the authors’ institution, it has been used in cases of placental abruption, laparotomy for severe postpartum hemorrhage, undiagnosed extrauterine placentation, for anticipated blood due to major placenta praevia and massive fibroids, as well as in several Jehovah’s Witness patients. “The risk/benefit ratio is clearly is favor of cell salvage in obstetrics — what are we waiting for?� the authors conclude.

__________________
Mr. Jan B. Wade
Blood Management Consultant
Enhance Outcomes - Control Cost
For Information Call - 360 296-1807
Email