Sonographic Evaluation of Renal Dimensions and Volume in Normal Pregnancy in Bayelsa State, South-South, Nigeria

Background: Physiological changes in the renal system lead to important modifications in electrolyte, acid-base balance and renal function. Some of these changes occur in the renal dimensions and volume, and to adequately interpret these changes, physiological changes in pregnancy should be well understood.

Objective: To evaluate the renal dimensions and volume, and correlate them with age, parity and trimesters in normal pregnancy in Bayelsa State, Nigeria.

Study Design: Prospective, descriptive, cross-sectional study.

Place and Duration of Study: Departments of Obstetrics and Gynaecology, and Radiology of the two tertiary hospitals in Bayelsa State, Nigeria, from July to December, 2021.

Materials and Methods: Sonographic assessments of the renal dimensions and volume in 400 randomly selected normal pregnant women in both tertiary health institutions were done, after obtaining written informed consent from them. Data were entered into a pre-designed proforma, and analysed using Statistical Product and Service Solutions for windows® version 25, SPSS Inc.; Chicago, USA). Results were presented in frequencies and percentages for categorical variables; mean and standard deviation for continuous variables. Student’s t-test was used to compare sample means; and Chi-square for associations.

Results: A total of 400 pregnant women were scanned. The mean renal bipolar length, mean antero-posterior diameter and mean renal width were 10.9 ± 1.0 cm, 4.7 ± 0.6 cm and 6.4 ± 0.7 cm respectively. Mean renal volume was 174.2 ± 44.8 cm. Renal volume was highest in the left kidney of women > 35 years (186.8 ± 47.3 cm3), and was lowest (162.8 ± 33.6 cm3) in the right kidney of women < 20 years. The mean values of the renal dimensions and volume increased with parity of the women and trimester of pregnancy.

Conclusion: This study produced a mean renal volume in pregnancy for our locality. It was revealed that the renal volume and dimensions were lowest in younger women and highest in older women. The renal volume increased as pregnancy advanced; and with increasing parity.