Dilation of the fetal umbilical vein in rhesus hemolytic anemia: A predictor of severe disease

Abstract

Presented in part at the annual meeting of the American Institute of Ultrasound in Medicine, September, 1980, New Orleans, Louisiana. Reprint requests: Greggory R. DeVore, M.D., Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Southern California, LAClUSC Women’s Hospital, 1240 North Mission Road, Los Angeles, California 90033. fourth week of gestation, the bone marrow begins to produce hematopoietic cells, and the liver and spleen concomitantly decrease their production.’ When Rh antibody-mediated hemolytic anemia develops, however, the fetal liver increases its erythropoietic activity and enlarges. This is associated with decreased synthesis of serum albumin, with resultant low osmotic pressure.z When this is severe, fluid accumulates in the extravascular compartments, and fetal hydrops results. Although the delta optical density (AOD) of amniotic fluid bilirubin at 450 rnp is used to discover those fetuses with severe hemolytic disease in whom intrauterine transfusion (IUT) is mandatory, serial diagnostic ultrasound is a useful adjuvant in the evaluation of fetal well-being. Presented here are the results of a study designed to evaluate, by means of ultrasound, fetal hepatic congestion resulting from increased erythropoiesis in Rh-sensitized pregnancies. The fetal umbilical vein diameter (UVD) in the-amniotic fluid (AF) and the liver (L) were measured from images obtained with a contact B and a realtime linear array scanner (Fig. 1). In a cross-sectional evaluation of 94 normal control fetuses, the UVD in the AF progressively increased from week 18 through week 30 of ges-