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Abstract Obstetric ultrasound is the initial imaging method used to evaluate the fetus and monitor growth. Fetal ultrasonography is useful for dating when the last menstrual period (LMP) is uncertain. Decisions regarding obstetric management and subsequent neonatal outcomes are significantly affected by precise knowledge of GA. Prevention of perinatal mismanagement and scheduling the labor date are also guided by knowledge of GA. Lack of a precise GA is associated with high perinatal mortality rates, an increased incidence of low birth weight, and spontaneous preterm delivery (96). Many biometric parameters such as crown rump length, biparietal diameter (BPD), femoral length (FL), abdominal circumference (AC), and head circumference (HC) are used to date pregnancy. When combined, these parameters have higher + ve predictive value. Although they are reliable up to the early second trimester, they are less reliable in the late second and third trimesters, where the error margin becomes wide after 30 gestational weeks. They are also unreliable in late pregnancy in cases of intrauterine restriction (97). Some studies have shown a strong correlation between renal length and GA determined by BPD, FL, and AC, or an average of all three. Knowledge of normal renal parameters is essential for accurate evaluation of abnormal kidneys, because fetal kidney disease is among the most common malformations, and some disorders affect renal size without significantly altering architecture (96). With the increased use of ultrasonography in obstetrics, it has been noted that the incidence of renal disease in the prenatal and neonatal period is approximately 10% of all pregnancies. |