What is the transfusion management of a sickle cell patient during pregnancy?

Prophylaxis: There is an ongoing trial in transfusion management in pregnancy, comparing prophylactic red cell exchange to a target HbS or SC < 30% compared to transfusion only when clinically indicated. Interestingly, it does not specify a Hct target. Until that trial is done, I would follow the ASH guidelines (high-risk, severe or frequent complications, demonstrated pregnancy complications) for now. As opposed to the study, however, I think (as we said also in the guidelines) maintaining a Hb S or SC target < 50% is reasonable to start with, and if complications continue, then I would move the target down to < 30%. I would keep the Hct between 25-33% based on previous studies (see Malinowski meta-analysis). 

Acute: I would bring the HbS down to < 30% and increase the Hct to 27-30% based on the initial level of anemia, given the evidence of anemia itself contributing to complications such as stroke/silent infarcts (DeBaun’s work).

Vaginal delivery vs C-section: For C-section, if the patient is already on regular transfusion for pregnancy, bringing the HbS or SC down to < 30% (versus < 50%) seems reasonable. If not already on regular transfusion for pregnancy, I would not transfuse for vaginal but I might bring the Hb to around 10 gm/dL for C-section. Even though I would not transfuse upfront for a vaginal, I would have 2-3 matched units in reserve in case they are needed during or post-delivery. 

Importantly, if one is to institute transfusion and the mother is already red cell alloimmunized, especially to antigens other than Rh and K, I would do extended phenotype matching; if not alloimmunized, I would at least do Rh and K matching, as we recommend in the guidelines.