Diagnostic Accuracy of Foetal Cardio-femoral index as a Predictor of Anemia in Rhesus Alloimmunized Foetuses
Objective: To calculate the diagnostic accuracy of the cardiofemoral index in prediction of neonatal anemia in rhesus alloimmunisation keeping neonatal hemoglobin estimation at birth as the gold standard.
Methodology: This cross sectional validation study was conducted in the department of Radiology, Shifa International Hospital, Islamabad from Jan 2016 to Dec, 2016. A total of 106 pregnant women near term between 32-35 weeks were included. Patients were subjected to Toshiba Nemio XG (Ta312) real time Doppler ultrasound. Using the 3.75 MHz sector transducer, the fetal biventricular outer dimension of heart was obtained. Then the foetal femur length was calculated. The cardiofemoral index was measured by the ratio between the biventricular outer dimension in diastole and femur length (both in centimeters). The neonatal blood was sent for hemoglobin estimation soon after birth to the hospital pathology laboratory. The results of the cardiofemoral index and neonatal hemoglobin were entered into the Performa.
Results: The average age of the patients was 25.93±5.97 years. Sensitivity, specificity, PPV, NPV and accuracy of the cardiofemoral index in detecting hemoglobin were 82.9, 92.3, 87.2, 89.5 and 88.7 % respectively.
Conclusion: Measurement of the cardiofemoral index in foetuses at risk for anemia due to Rhesus alloimmunization provides an accurate and noninvasive radiological test for the prediction of foetal anemia.
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