Williams Manual of Pregnancy Complications, 23 ed.

CHAPTER 29. Transfusion of Blood Products for Obstetrical Hemorrhage

Management of obstetrical hemorrhage is fundamental to obstetrical care. Hypovolemia due to hemorrhage is common—a frequent cause of acute renal tubular necrosis (ATN) and even acute respiratory distress syndrome (ARDS)—and continues to be a leading cause of maternal death in the United States. The purpose of this chapter is to provide a readily useable guide for the management of serious obstetrical hemorrhage. Considerations in the management of hypovolemia are summarized in Table 29-1. An important goal is to prevent overt clinical shock because this will prevent target organ damage. Transfusion of blood products is preferable before, as opposed to after, shock has occurred. It is also emphasized that obstetrical hemorrhage often occurs in patients with endothelial “leaks” due to preeclampsia or sepsis—both circumstances in which circulating plasma is more effective than crystalloid for maintenance of intravascular volume.

TABLE 29-1. Considerations in the Management of Hypovolemia due to Obstetrical Hemorrhage

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PREDICTION OF BLOOD VOLUME

Estimates of total blood volume (TBV) can easily be calculated for pregnant women as well as those who have sustained serious obstetrical hemorrhage. In the latter case, assume that the woman has lost her normal pregnancy hypervolemia and has acutely returned to her calculated (Table 29-2nonpregnant blood volume. In other words, manage the patient based upon her nonpregnant blood volume. Examples of maternal blood volume using this method for calculation of TBV are shown in Table 29-3.

TABLE 29-2. Calculation of Maternal Total Blood Volume (TBV)

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TABLE 29-3. Examples of Nonpregnant and Pregnant Total Blood Volume (TBV) According to Pregnant Weight in a Woman Who Is 64-in. (5-ft 4-in.) Tall Using the Calculation Method Shown in Table 29-2a

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BLOOD PRODUCTS

Whole blood is ideal for management of hypovolemic shock but is seldom available. Blood components commonly used in the management of obstetrical hemorrhage are shown in Table 29-4. The preparation of blood products, beginning with the blood donor, is shown in Figure 29-1 in an effort to better understand transfusion of blood components. Shown in Table 29-5 is a method to estimate fibrinogen requirement when treating serious obstetrical hypofibrinogenemia such as occurs with placental abruption.

TABLE 29-4. Blood Products Commonly Transfused in Obstetrical Hemorrhage

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TABLE 29-5. Calculation of Plasma Volume to Estimate Necessary Fibrinogen Replacement

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FIGURE 29-1 Preparation and storage of blood components from one donor unit of whole blood.

At Parkland Hospital, after determining that the woman does not have circulating antibodies to red blood cell antigens (i.e., her indirect Coombs test is negative), type-specific blood components are administered. This is accomplished by sending a “Group and Screen” blood specimen to the laboratory. This approach avoids the time-consuming cross-match procedure, which requires at least another 30 minutes to perform if the patient’s indirect Coombs test is found to be negative. However, the cross-match requires 4 to 6 additional hours or longer if the indirect Coombs test is positive. Importantly, if the indirect Coombs (“Screen”) is positive, only cross-matched blood components can be given.

It is also important to emphasize that blood type–specific components include not only packed red blood cells, but also fresh frozen plasma (FFP) and platelets. Cryoprecipitate is not type specific. Put another way, an O-positive woman requires O-positive packed red blood cells, O-positive FFP, and O-positive platelets should transfusion of any of these products become necessary.

Determining blood type (“Group”) requires about 5 minutes, and screening (“Screen”) for antibodies takes about 30 minutes. Routinely determining blood type and indirect Coombs on admission in pregnant women with complications permits almost immediate transfusion of blood products should serious obstetrical hemorrhage develop later during labor or delivery. For example, if a “Group and Screen” was previously done and the hemorrhaging woman is blood type O and Rh positive (O+), with a negative indirect Coombs, the blood bank laboratory need only go to the storage refrigerator, obtain O-positive blood products from the shelf and hand them to the obstetrician for immediate transfusion. This has been the procedure at Parkland Hospital for more than 25 years. Type O-negative packed red blood cells (“universal donor”) can be given in serious emergencies while the patient’s “Group and Screen” is being done.

PRAGMATIC TRANSFUSION AT PARKLAND HOSPITAL

Management of ongoing, serious obstetrical hemorrhage can be chaotic without a pragmatic approach for the use of blood products. The approach at Parkland Hospital for many years has been to maintain urine flow at 30 mL per hour or more by infusing blood products sufficient to maintain the hematocrit at 25 to 30 volumes percent. Use of whole blood greatly simplifies transfusion in these difficult clinical circumstances. Component therapy, however, is frequently necessary because whole blood is usually not available. The following case is a prototypical example of transfusion practice at Parkland Hospital. We emphasize that we, as well as others, all too frequently (i.e., regularly) seriously underestimate the volume of blood a woman has lost due to obstetrical hemorrhage. We also emphasize, to ourselves as well as others, that reluctance to transfuse blood products is usually incorrect.

Example: Placental Abruption Severe Enough to Kill the Fetus

In this situation, the woman has typically lost 2000 mL (or more) of whole blood. Moreover, hypofibrinogenemia may already have developed before admission. Not infrequently, no urine (anuria) is found when a Foley catheter is placed. Immediate transfusion (after “Group and Screen” and emergency crystalloid infusion; see Table 29-1) of 4 units of whole blood would be the ideal treatment since this simultaneously replaces both blood volume and fibrinogen. When this is not possible, transfusion should begin immediately with packed red blood cells followed by FFP as soon as possible (when thawed). Ongoing adequacy of transfusion can be estimated by urine flow greater than 30 mL/h, hematocrit of 25 to 30 volumes percent, and bedside clotting tests for fibrinogen adequacy. Preferred use of blood components at the outset in this circumstance is 4 units of packed red blood cells plus 4 units of FFP—thus, in effect, transfusing 4 units (2000 mL) of whole blood.


For further reading in Williams Obstetrics, 23rd ed.,

see Chapter 35, “Obstetrical Hemorrhage.”