Sonographic estimation of gestational age from 20 to 40 weeks by fetal kidney lengths' measurements among pregnant women in Portharcourt, Nigeria

Evaluation of fetal kidney length as a marker for fetal biometry

BACKGROUND

The precise determination of gestational age is essential for effectively managing and prognosis of all pregnancies. Through careful biometry, timely interventions can be implemented, leading to positive outcomes for both the mother and fetus. In routine fetal biometry, parameters such as biparietal diameter (BPD), femur length (FL), head circumference (HC), and abdominal circumference (AC) have been traditionally used. This study aims to evaluate the usefulness of fetal kidney length (FKL) as a marker for fetal biometry.

METHODOLOGY

This prospective, observational, and cross-sectional study was conducted in the Radiodiagnosis and Obstetrics and Gynaecology departments, including a diverse group of pregnant women from various socio-economic backgrounds, with adherence to ethical standards. Women with singleton pregnancies between 22 and 40 weeks of gestation who met the inclusion and exclusion criteria were examined through ultrasound. The data collected were subsequently analyzed.

RESULT

In the current study, 280 participants with an average age of 26.71 ± 3.6 years were included. The agreement between the mean fetal kidney length and standard biometry parameters was almost perfect, with a strength of agreement exceeding 0.99. A strong and statistically significant positive correlation existed between fetal kidney length and the estimated gestational period calculated using DLMP/standard biometric measurements.

CONCLUSION

Fetal kidney length is a reliable indicator of gestational age and can supplement standard biometric measurements to provide a more precise estimation of gestational age, especially in the later stages when obtaining such standard measurements may be challenging.

Ultrasound Measurement of Foetal Kidney Length during Healthy Pregnancy: Relationship with Gestational Age

Background

Foetal kidney length (FKL) measurements and comparisons to normal charts can be used to assess the development of the foetal kidneys throughout the entire course of pregnancy. This study was designed to assess FKL between 20 - 40 weeks' gestation, establish reference ranges for FKL and determine the relationship between FKL and gestational age (GA) in normal pregnancy.

Methods

This descriptive, cross-sectional study was conducted between March-August 2022, at the Obstetric Units and Radiology Departments of the two tertiary health facilities, one secondary facility and one radio-diagnostic facility in Bayelsa State, Southern Nigeria. Transabdominal ultrasound scan was used to evaluate the foetal kidneys. The relationship between foetal kidney dimensions and GA was explored using Pearson's correlation analysis. Linear regression analysis was done to define the relationship between GA and mean kidney length (MKL). A nomogram predicting GA from MKL was constructed. Level of significance was set at p<0.05.

Results

There was a very strong significant correlation between foetal renal dimensions and GA. The correlation coefficient between GA and mean FKL, width and anteroposterior diameter were 0.89 (p=0.001), 0.87 (p=0.001) and 0.82 (p=0.001), respectively. A unit change in mean FKL corresponded to a 79% change in GA (ɼ2), showing a very strong association between mean FKL and GA. The regression equation: GA = 9.87 + 5.91 x MKL, was derived for estimation of GA for a given MKL.

Conclusions

Our study revealed a significant relationship between FKL and GA. The FKL can therefore be reliably used to estimate GA.

The Sonographic Evaluation of Gestational Age: A Comparative Study Utilizing Different Biometric Measurement Indices and Fetal Kidney Length

Objective:

Various indices have been introduced for estimating sonographic gestational age and have demonstrated varied diagnostic accuracy. The aim of this study was to evaluate the correlation of fetal kidney length (FKL) with some other traditional measurement parameters in determining an accurate gestational age.

Materials and Methods:

In this prospective study, healthy pregnant women, who had completed a scheduled and routine obstetrical sonogram, were included. During the sonogram, the measurement indices, biparietal diameter (BPD), abdominal circumference (AC), crown rump length (CRL), head circumference (HC), femur length (FL), and FKL were analyzed. The obstetrical measurements had been taken every 4 weeks from the 20th week of the pregnancy, until the end of the pregnancy (e.g., 20th, 24th, 28th, 32nd, 36th, 40th weeks). After data collection, the measurement data were analyzed with SPSS software.

Results:

There were significant ( P < .05) high strength of associations between FKL and the routine measurements of BPD ( r = 0.668), AC ( r = 0.770), CRL ( r = 0.792), HC ( r = 0.791), and FL ( r = 0.803).

Conclusion:

These results suggest possible significant positive relationships between FKL and BPD, AC, CRL, HC, and FL. It can be assumed that FKL might be a suitable index for determining gestational age especially in the late second and third trimester, when other measurement indices are less accurate.