en <p>Background: Echocardiographic indicators may be useful as an alternative method to determine the appropriate time for intervention, especially when Doppler assessment of the middle cerebral artery peak systolic velocity (MCA-PSV) is inconclusive. In this study, arterial duct blood flow and cardiac output of fetuses with Rh alloimmunization-related anemia were compared before and after intrauterine transfusion (IUT).<br /> Methods: Fifty intrauterine blood transfusions were performed on anemic fetuses in this study. All cases were attributed to Rh alloimmunization, detected with MCA-PSV Doppler ultrasound imaging assessments. They all underwent intrauterine blood transfusion and echocardiographic assessments a day before and 24 <em>hr</em> after the procedure. The measured cardiac indices included the velocity time integral (VTI) of the aortic and pulmonary valves, the ductus arteriosus acceleration-to-ejection time (AT/ET) ratio, and the MCA-PSV. Analyses were performed in SPSS v24 (p&lt;0.05) using paired t-tests for mean differences and Pearson&rsquo;s correlation for associations between continuous variables.<br /> Results: Aortic and pulmonary valve VTI, MCA-PSV, and ductus arteriosus AT/ET ratio significantly decreased after intrauterine blood transfusion (p&lt;0.001). The aortic valve VTI and ductus arteriosus accurately detected anemia, with areas under the receiver operating characteristic (ROC) curve of 99.9% and 98.9%, respectively.&nbsp;<br /> Conclusion: All the measured parameters showed significant changes after intrauterine blood transfusion. Aortic valve VTI and ductus arteriosus AT/ET ratio seem to have the highest accuracy in detecting anemia. Echocardiographic assessment can be beneficial in defining the appropriate time for intrauterine blood transfusion in cases where MCA-PSV is inefficient.</p> Ductus arteriosus, Echocardiography, Intrauterine blood transfusion 248 255 https://www.jri.ir/article/140284 https://www.jri.ir/documents/fullpaper/en/140284.pdf BehrokhSahebdelDepartment of Obstetrics and Gynecology, Yas Hospital complex, Tehran University of Medical Sciences, Tehran, Iran122840Mohammad NasirHematianDepartment of Perinatology and Fetal Cardiology, Yas Hospital complex, Tehran University of Medical Sciences, Tehran, Iran122935ZohrehHeidaryVali-E-Asr Reproductive Health Research Center, Family Health Research Institute, Tehran University of Medical Sciences, Tehran, Iran51898FatemehRahimi-SharbafDepartment of Obstetrics and Gynecology, Yas Hospital complex, Tehran University of Medical Sciences, Tehran, Iran122919FatemehGolshahiDepartment of Obstetrics and Gynecology, Yas Hospital complex, Tehran University of Medical Sciences, Tehran, Iran122844MahboobehShiraziDepartment of Obstetrics and Gynecology, Yas Hospital complex, Tehran University of Medical Sciences, Tehran, Iran122847NafisehSaediDepartment of Obstetrics and Gynecology, Yas Hospital complex, Tehran University of Medical Sciences, Tehran, Iran122845FaezehMahdavi OmranDepartment of Medical Education, Faculty of Medicine, Babol University of medical sciences, Babol, Iran122936ZahraMoradiDepartment of Obstetrics and Gynecology, Yas Hospital complex, Tehran University of Medical Sciences, Tehran, Iran122937SodabehRezaeiDepartment of Obstetrics and Gynecology, Yas Hospital complex, Tehran University of Medical Sciences, Tehran, Iransodabe.rezaei80@gmail.com, sodabe.rezaei89@gmail.com122938