Normal ultrasound dimensions of newborn kidneys in Southwest Nigeria

Background/Aim: Accurate classification of renal size as normal and abnormal depends on precise knowledge of acceptable normal range for the population. Ultrasound (US) is an excellent tool for defining the norm and imaging neonates suspected with renal pathology because it is cheap, easy to perform, and harmless. Since the kidneys of neonates are distinct from those of older children and there is a paucity of data on normal renal size in neonatal population in sub-Saharan Africa, this study is to determine the normal range of renal size in a large cohort of Nigerian neonates. Materials and Methods: In a cross-sectional study of 528 apparently healthy neonates from two large hospitals in Ibadan, Nigeria, clinical examination and renal US scans were performed in the first 28 days of life. Renal length and width were correlated with somatometric parameters and chronological age of neonates. Nomograms with point-wise 95% reference ranges were also constructed. Results: Mean renal length and width were 4.31 ± 0.50 and 2.03 ± 0.28 and 4.33 ± 0.52 and 2.01 ± 0.31 on the right and left, respectively. Only the mean renal lengths were significantly different between males and females (P < 0.01) and there was no significant difference between the renal dimensions by sidedness. Body weight, chronological age, and to a minor extent, length were found to correlate positively with all renal dimensions. Conclusions: This study of a large neonatal population has provided the normal range of US renal dimensions for neonates in the study area, using the age and weight in plotting the 95% reference ranges for the renal nomogram.