الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Obstetric ultrasound is the initial imaging method used to evaluate the fetus and monitor growth. It is useful for dating when the last menstrual period (LMP) is uncertain. Studies have shown that about 30% of pregnant women forget the date of their LMP.
When the precise gestational age (GA) is unknown, the outcome of the pregnancy may be unfavorable. 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.
Many biometric parameters such as crown rump length, biparietal diameter (BPD), femur length (FL), abdominal circumference (AC), and head circumference (HC) are used to date pregnancy. When combined all, these parameters agree well with GA to some extent. 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 growth restriction.
Konje et al., (11) reported that fetal kidney diameter and circumference, in addition to kidney length, also give accurate gestational dating. In addition some studies have shown a strong correlation between renal length and GA determined by BPD, FL, and AC, or an average of all three.
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Normal renal parameters knowledge 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. 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. Many abnormalities are minor and have no clinical significance, whereas the frequency of major malfor- mations of the kidney, excluding polycystic kidneys, has been estimated as 4–7 in 1000 fetuses.
Intrauterine growth restriction (IUGR) is defined as a sonographic estimation of fetal weight below the tenth percentile for a given gestational age. IUGR complicates up to 10% of all pregnancies. It is associated with a perinatal mortality rate that is 6 to 10 times higher than that for normally grown fetuses and is the second most important cause of perinatal death after preterm delivery. Usual biometric parameters such as, biparietal diameter (BPD), femur length (FL), abdominal circumference (AC), and head circumference (HC) are not reliable in determination of GA specially in the third trimester.
Studies of kidney size in human fetuses of known gestational age have shown that intrauterine growth restriction is accompanied by decreased kidney volume compared to fetuses with appropriate weight for gestational age, kidney length remained similar to appropriately grown fetuses whereas AP and TS dimensions were significantly decreased.
This prospective study was conducted at department of obstetrics and gynecology at Menoufia University Hospital from December 2019 to December 2020 to determine the strength of
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association of both fetal kidney dimensions measurements with GA in appropriate and small for gestational age in the third-trimester pregnancies. The participants of this study were 150 cases. The cases were subdivided into two groups: group A included 100 patients with appropriate weight for gestational age pregnancy. group B included 50 patients with intrauterine growth restriction.
Statistical analysis of current study showed that third trimesteric ultrasonic assessment of fetal kidney dimensions is an independent parameter in estimation of fetal gestational age in appropriate and small for gestational age fetuses. It is most accurate single parameter for estimating GA than other biometric indices especially in cases when the other parameters like BPD, FL, AC and HC are not reliable for assessing GA in the 3rd trimester of pregnancy.
There was statistically significant positive correlation between gestational age with right and left fetal kidneys dimensions. Multiple comparisons between normal group and IUGR group according to ultrasonic determination and fetal kidney dimensions in GA (wks) showed that the measurement at 38 weeks of gestation had the most accurate results with statistically significant decrease mean in IUGR group compared to normal group according to ultrasonic determination (bi-parietal diameter, head circumference, abdominal circumference, femur length and amniotic fluid index; and fetal kidney dimensions (rt. length (mm), rt. transverse (mm), rt. anteroposterior (mm), rt. volume (cm3), lt. length (mm), lt. transverse (mm), lt. anteroposterior (mm), lt. volume (cm3) compare with other weeks (29 – 37 and 39).