Performing an intrauterine transfusionIntrauterine transfusion A procedure that delivers donor red blood cells to the fetus through the umbilical vein to treat severe anemia caused by HDFN. (IUTIntrauterine transfusion A procedure that delivers donor red blood cells to the fetus through the umbilical vein to treat severe anemia caused by HDFN.) at following 34 weeks’ gestational age (GA) as a treatment for fetal anemiaAnemia A condition that occurs when the body doesn’t have enough healthy red blood cells to carry oxygen to its tissues. In HDFN, anemia occurs when maternal antibodies destroy fetal red blood cells. caused by alloimmunizationAlloimmunization When a person’s immune system develops antibodies against foreign antigens from the same species—such as when an Rh-negative mother’s body forms antibodies against her baby’s Rh-positive red blood cells., including for patients with hemolytic disease of the fetus and newborn (HDFN), appears safe and may enable delivery at a later GA, according to findings from a retrospective study published recently in the journal Prenatal Diagnosis.
It is well recognized that without any appropriate intervention, including the use of IUT, HDFN can lead to fetal anemia, hydrops fetalisHydrops fetalis A serious, sometimes fatal condition in which fluid builds up in a baby’s tissues and organs due to severe anemia from HDFN. and even fetal or neonatal death.
The occurrence of alloimmunization secondary to the Rhesus (RhRh factor A protein or antigen found on red blood cells. When an Rh-negative mother carries an Rh-positive fetus, her immune system may make antibodies that attack the fetus' red blood cells.) D and other red blood cell (RBC) antibodiesAntibody A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigens., which continues to have an affect on pregnancies across the globe, is known to be associated with the development of HDFN. In those situations in which fetal anemia is suspected, IUT of RBCs is provided to the patient, if deemed necessary.
The researchers of the current study sought to delineate procedure-associated complications and GA at delivery among patients who received their final IUT at or older than 34 weeks’ GA compared with those who received their final IUT at younger than 34 weeks’ GA.
On the whole, “IUT is considered safe, with perinatal survival following IUT exceeding 90% in most contemporary studies,” the authors stated. Among the procedure-associated complications of IUT are preterm premature rupture of membranes, preterm delivery, intrauterine infection and emergency cesarean section delivery for instances of fetal distress.
Read more about the prognosis of HDFN
IUTs before and after 34 weeks’ gestational age
The current analysis comprised all patients with pregnancies that were complicated by suspected fetal anemia caused by alloimmunization who underwent IUT at a single center from 2006 to 2022. In these cases, anemia was suspected with or without the presence of coexisting hydrops fetalis.
In total, 94 pregnancies with a total of 237 IUTs were included in the study. Overall, 37.2% of these pregnant women underwent their final IUT at older than or equal to 34 weeks’ GA, whereas 62.8% of these patients underwent their last IUT at younger than 34 weeks’ GA.
There were three procedure-related complications reported in the entire study cohort, leading to a rate of complications of 1.3% among all procedures and 3.2% among all pregnancies—with two of the complications among the pregnancies reported in the group of patients who underwent their last IUT at older than or equal to 34 weeks’ GA.
All of the pregnancies with procedure-related complications led to emergency cesarean section. In fact, one of the pregnancies in which IUT was performed at younger than 34 weeks’ GA was associated with neonatal death. The remaining two procedure-related complications were reported during IUT carried out at older than or equal to 34 weeks’ GA.
Of note, among patients with pregnancies in which the final IUT was performed at older than or equal to 34 weeks’ GA, the babies were delivered at a median of 37.1 weeks’ GA.
“IUT is a safe procedure with few [procedure-related] complications and good prenatal survival,” the authors stated. “Performing IUT at ≥34 weeks 0 days appears to be safe and, in theory, may allow for delivery at a later GA.”
