Ultrasound-derived reference values for neonatal liver and spleen dimensions: a retrospective cohort study

Aims: To determine liver and spleen sizes in preterm and term neonates using ultrasonography during the first week of life, and to examine their associations with gestational age, birth weight, length, gender, and postmenstrual week. Methods: In this retrospective study, 112 neonates (66 preterm, 46 term) admitted to a tertiary NICU between June and December 2020 were included. Only infants with normal liver function and without conditions affecting organ size were analyzed. Liver and spleen dimensions were measured by ultrasonography within the first seven postnatal days. Correlations were assessed using Pearson, Bayesian Kendall’s, and Bayesian Pearson tests. Regression analyses and comparisons with published data were also performed. Results: In preterm infants, liver size correlated strongly with gestational age (r=0.825) and spleen size with birth weight (r=0.777). In term infants, liver size correlated with birth length (r=0.491) and spleen size with birth weight (r=0.495). Each 1-week increase in gestational age was associated with a 1.8 mm increase in liver size in preterm infants, while each 100 g increase in birth weight increased spleen size by 0.8 mm in both groups. Conclusion: Liver and spleen sizes are closely linked to gestational age, birth weight, and length in neonates. Population-specific percentile references are recommended to improve clinical assessment accuracy.