6 - Kidney Size in Premature Infants: Time for new percentiles? First Machine Learning Approach Using Natural Language Processing

Poster Number: 6
Publication Number: 6.1415

Background: Ultrasound is a safe modality to measure kidney length in the neonatal period, including in preterm infants. Renal size and volume have been shown to be markers of nephron endowment, which is often compromised in prematurity.

Objective: Given outdated kidney size charts in prematurity, we used natural language processing and a large radiology report repository to calculate new age-based renal length normative values in healthy preterm infants.

Design/Methods: We retrieved abdominal ultrasound reports for children under 1 year of age between 2012 and 2022 in a tertiary academic children’s hospital (Illuminate InSight). Reports were filtered for “normal kidneys,” excluding all types of kidney renal abnormalities (e.g., dysplasia, dilation). Natural language processing using Python was used to extract kidney measurements and identify a subgroup of preterm infants ( < 37 weeks). Phyton was also used to perform descriptive analyses, and further narrow our cohort by excluding additional pathological terms identified after the first data pull. Normative values were established by postnatal age: 0-1 weeks, 1 week to 4 months, 4 to 8 months, and 8 months to 1 year. Gestational age, weight, and height data are being retrieved.

Results: A total of 4564 ultrasound reports were collected and 251 (5.5%) were born preterm (female 43%; median age 22 days, IQR: 3-90.5 days). In the preterm cohort, the median kidney length was 4.3cm, IQR: 3.8-4.9cm. Median (IQR) kidney length by age group was: 0-1 weeks, 4.1cm (3.75-4.36); 1 week to 4 months, 4.25cm (3.55-4.83); 4-8 months, 5.2cm (4.78-5.88); and 8 months - 1 year, 5.75cm (5.45-6.15). When compared to full-term infants (n = 4313), the kidney length was lower across all age groups, although the gap gradually narrowed when approaching 1-year of age (Figure 1).

Conclusion(s): Normative values for preterm infants were established by postnatal age-group. Kidney length in preterm infants tends to approximate kidney length of term infants by 1 year postnatal age. Our sample size, the largest reported to date in preterm infants, validates normative values during postnatal development with increased certainty. We aim to further characterize our preterm cohort by gestational age and anthropometric data.