Acoustic radiation force impulse elastosonography of placenta in maternal red blood cell alloimmunization: a preliminary and descriptive study.

Abstract

Maternal red blood cell alloimmunization is an important cause of fetal morbidity and mortality in the perinatalperiod, despite well-organized prophylaxis programs. The objective of the study was to evaluate placental elasticity by usingAcoustic Radiation Force Impulse (ARFI) in Rhesus (Rh) alloimmunized pregnant women with hydropic and nonhydropicfetuses and to compare those with healthy pregnant women. This case-control and descriptive studycomprised twenty-eight healthy pregnant women, 14 Rh alloimmunized pregnant women with nonhydropic fetuses, and 16 Rhalloimmunized pregnant women with hydropic fetuses in the third trimester of pregnancy. Placental elasticity measurementswere performed by ARFI elastosonography at the day of delivery. The maternal characteristics and neonatal outcomes of thepatients were also noted. The highest mean placental ARFI scores were observed in Rh alloimmunized pregnantwomen with hydropic fetuses (1.13 m/s) (p=0.001). Healthy controls and Rh alloimmunized pregnant women with nonhydropicfetuses had similar mean placenta ARFI scores (0.84 m/s, 0.88 m/s, respectively) (p<0.05). Based onthe present findings, the placenta becomes stiffer in Rh alloimmunized pregnancies complicated with hydrops fetalis. Theincreased placental ARFI scores may be a supplemental marker for adverse pregnancy outcomes, additional to Doppler evaluationof middle cerebral artery. This data should be confirmed with a large sample size and prospective studies by using serialmeasurements of ARFI elastosonography in maternal red blood cell alloimmunization.