Predictive capacity of fetal pancreatic circumference for gestational diabetes mellitus.

Objective: To assess the capacity of fetal pancreatic size, before standard blood glucose testing for screening and diagnosis, to predict maternal gestational diabetes mellitus (GDM).

Methods: This was a retrospective cohort study of low-risk pregnant women recruited during routine second-trimester fetal anatomical screening at 20-25 weeks' gestation at two ultrasound units in Israel between 2017 and 2020. The predictive performance of fetal pancreatic circumference ≥ 80^th and ≥ 90^th centiles and glucose challenge test (GCT) was examined for the outcome of GDM. The independent-samples t-test was used to compare mean pancreatic circumference centile between pregnancies with GDM and those without GDM. Diagnostic performance was evaluated with 2 × 2 contingency tables and receiver-operating-characteristics (ROC) curves.

Results: Overall, 195 women were selected for statistical analysis. Twenty-four (12.3%) women were diagnosed subsequently with GDM. The mean ± SD fetal pancreatic circumference centile was significantly higher in the GDM group compared with the non-GDM group (82.4 ± 14.6 vs 62.8 ± 27.6; P < 0.001). The pancreatic circumference centile was correlated positively with the estimated fetal weight centile (Pearson's coefficient, 0.243; P = 0.001). The 80^th centile cut-off for pancreatic circumference had the highest sensitivity (70.8%) and positive predictive value (23.3%) for future maternal GDM, with the best trade-off between sensitivity and specificity achieved at the 75^th centile cut-off (sensitivity, 79%; specificity, 60%). The GCT had better specificity (90.2%) and negative predictive value (97.9%) compared with both cut-offs in pancreatic circumference. The area under the ROC curve was higher for pancreatic circumference compared with GCT (0.71 vs 0.64) and only the former was statistically significant (P = 0.001).

Conclusions: Fetal pancreatic circumference has a higher positive predictive capacity compared with GCT. Measuring pancreatic circumference can identify pregnancies at high risk for maternal GDM, thereby promoting earlier diagnosis and treatment, decreasing the time period during which the fetus is exposed to high maternal glucose levels and improving infant outcome. © 2024 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.