Fetal middle cerebral artery peak systolic velocity in the investigation of non-immune hydrops

Objective: In some cases of non-immune hydrops there is congenital or acquired fetal anemia. The aim of this study was to investigate the potential value of fetal middle cerebral artery peak systolic velocity (MCA-PSV) in the assessment and management of non-immune hydrops due to anemia.

Methods: Fetal MCA-PSV and fetal hemoglobin concentration, in blood obtained by cordocentesis, were measured in 16 singleton pregnancies referred to our unit for further investigations because of a diagnosis of non-immune hydrops fetalis. In all cases a detailed ultrasound examination demonstrated moderate or severe ascites, with or without skin edema, and pericardial or pleural effusions. Furthermore, there were no obvious malformations to account for the hydrops. In each fetus the measured MCA-PSV and hemoglobin concentration were expressed as delta values (the difference in SD from the normal mean for gestation). Regression analysis was used to determine the significance of the association between delta MCA-PSV and delta fetal hemoglobin concentration. In addition, we searched our database to identify the sonographic features and hemoglobin concentration of fetuses with congenital infection.

Results: In the 16 cases of non-immune hydrops there were seven with parvovirus B19 infection, one each of alpha-thalassemia and primary cardiomyopathy and seven with no obvious explanation for the hydrops. There was a significant association between delta MCA-PSV and delta hemoglobin concentration (delta hemoglobin = (delta MCA-PSV + 0.1437)/-0.4154; R(2) = 0.7202; P < 0.0001). In 10 of the cases the fetal hemoglobin concentration was more than 4 SD below the normal mean for gestation and in all these cases the MCA-PSV was more than 2 SD above the normal mean for gestation. Our computer search identified an additional nine fetuses with parvovirus B19 infection and in all cases the predominant sonographic finding was ascites and the hemoglobin concentration was more than 4 SD below the normal mean. In contrast, only 3/14 fetuses with cytomegalovirus, toxoplasmosis, coxsackie B or Treponema infection had ascites and only 2/14 had a hemoglobin deficit of 4-6 SD.

Conclusion: In the management of non-immune hydrops, measurement of fetal MCA-PSV can help identify the subgroup with fetal anemia.