From the Guidelines
Intrauterine transfusion is the recommended treatment for fetuses with severe anemia due to alloimmunization. This procedure involves directly transfusing packed red blood cells into the fetal circulation, typically via the umbilical vein under ultrasound guidance. The transfusion volume is calculated based on the estimated fetal weight and desired increase in hemoglobin, usually aiming to raise the fetal hematocrit to 40-45% 1. Initial transfusions may be needed every 1-2 weeks, with intervals potentially extending to 2-3 weeks as pregnancy progresses. The procedure should be performed at specialized centers with expertise in fetal therapy. Prior to the procedure, the mother should receive local anesthesia at the needle insertion site, and the fetus may be given paralytic agents like vecuronium (0.1 mg/kg estimated fetal weight) to prevent movement 1. Monitoring for signs of fetal distress during and after the procedure is essential. This treatment is effective because it directly addresses the underlying pathophysiology by replacing the antibody-destroyed red blood cells, bypassing the maternal immune system, and providing immediate correction of the anemia until delivery, when the newborn can be removed from the maternal antibody environment.
The management of fetal anemia involves a coordinated team effort among individuals familiar with fetal blood sampling and intrauterine fetal transfusion, and referral to a center with expertise in invasive fetal therapy is recommended 1. The middle cerebral artery peak systolic velocity (MCA-PSV) measured by ultrasound Doppler interrogation is used as the primary technique to detect fetal anemia, and fetal blood sampling should be performed with preparation for an intrauterine transfusion if the fetus is deemed at significant risk for severe fetal anemia.
The short-term neonatal outcomes after treatment of fetal anemia include a decreased perinatal mortality rate to less than 10% with the use of intrauterine transfusions, and postnatal management is primarily centered on the treatment of hyperbilirubinemia with phototherapy and exchange transfusions to prevent kernicterus 1. Other short-term complications include neonatal anemia, thrombocytopenia, cholestasis, and respiratory disease.
Key considerations for the procedure include:
- Using O negative, CMV-negative, irradiated packed red blood cells from the blood bank
- Maintaining sterility during the procedure
- Using a coordinated team effort among individuals familiar with fetal blood sampling and intrauterine fetal transfusion
- Referring to a center with expertise in invasive fetal therapy
- Monitoring for signs of fetal distress during and after the procedure
- Providing postnatal management for hyperbilirubinemia and other potential complications.
Overall, intrauterine transfusion is a highly effective treatment for fetuses with severe anemia due to alloimmunization, and its use has significantly improved perinatal outcomes.
From the Research
Treatment for Fetuses with Severe Anemia due to Alloimmunization
- The standard treatment for fetuses with anemia is intrauterine transfusion (IUT) 2, 3, 4, 5.
- However, IUT may have adverse effects or may not be available or possible, and alternative approaches such as therapeutic plasma exchange (TPE) and intravenous immunoglobulin (IVIG) may be used 6, 4.
- A combination of TPE, IVIG, and IUT has been shown to be effective in managing severe red blood cell alloimmunization in pregnancy 4.
Intrauterine Transfusion (IUT)
- IUT is a safe procedure in experienced hands, with a low risk of adverse events 3.
- The rate of decline in fetal hemoglobin following IUT can help determine the timing of subsequent transfusions 2.
- The sensitivity of middle cerebral artery peak systolic velocity (MCA-PSV) in detecting moderate-severe anemia declines with repeat transfusions 2.
Predictors of Perinatal Survival
- Hemoglobin deficit and birth week are significant predictors of perinatal survival in severely anemic fetuses undergoing IUT 5.
- A hemoglobin deficit of ≤6.25 g/dl has been shown to be a sensitive and specific predictor of perinatal survival 5.
PLUTO Trial Conclusion
- There is no direct information available on the PLUTO trial conclusion based on the provided evidence.