523: Correlation between fetal liver length and reticulocyte count in women undergoing PUBS for alloimmunization

Abstract

To assess the correlation between fetal liver length and reticulocyte count in women undergoing percutaneous umbilical cord blood sampling (PUBS) for alloimmunization. This was a single-center retrospective study. All consecutive singleton gestations with complete data referred to the Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Sidney Kimmel Medical College of Thomas Jefferson University (Philadelphia, PA) from January 2001 to December 2013 for suspected fetal anemia due to maternal alloimmunization (Rh-isoimmunization) were included in the study. Women with suspected fetal anemia were managed with detailed scan, including MCA Doppler and liver length. Only women who underwent PUBS were analyzed. The primary outcome was the correlation between the reticulocyte count at the first PUBS and the liver length at the time of the first PUBS quantified as z-score for gestational age. All fetuses were measured for fetal liver length from the right hemidiaphragm to caudal tip of the right liver lobe on coronal image of the fetal abdomen, using high-resolution real-time ultrasound with a 2- to 4-MHz convex transducer (Voluson E8 or E10). Statistical analysis was performed using Statistical Package for Social Sciences (SPSS) to assess Pearson linear regression and multiple regression analysis. 16 fetuses with red blood cell alloimmunization were analyzed. A positive correlation was found between fetal liver length and reticulocyte count (r = 0.70; p-value = 0.01; Figure 1), and liver length and fetal hemoglobin level (r = 0.67; p-value = 0.03). Liver length measurement may be a useful indicator of the degree of and physiologic response to fetal anemia in isoimmunized pregnancies. This may be useful in timing the need for invasive diagnosis and therapy. Further studies of subsequent PUBS and non-Rh fetal anemia may better elucidate this process.