Interobserver Reproducibility of Ultrasound Measurement of Preperitoneal Fat Using a Convex Probe in the First Trimester of Pregnancy: A Prospective Study

OBJECTIVE: To assess the interobserver reproducibility of preperitoneal fat thickness measurement using a convex ultrasound probe in pregnant women at 12 weeks of gestation. METHODS: We conducted a prospective, cross-sectional observational study involving 50 women with singleton pregnancies between 11 + 5 and 12 + 6 weeks of gestation. Preperitoneal fat thickness was measured independently by three observers: one expert in obstetric ultrasound and two experienced obstetricians. Measurements were performed using a standardized protocol with a convex transducer at the midpoint between the xiphoid process and the umbilicus. Reproducibility was evaluated using the intraclass correlation coefficient (ICC) and Bland-Altman analysis. RESULTS: The technique demonstrated excellent interobserver reproducibility. The (ICC) were 0.985, 0.989, and 0.980 for pair comparisons observer 1-observer 2, observer 1-observer 3, and observer 2-observer 3, respectively. Mean difference ranged from -0.0063 to -0.0102 mm, suggesting minimal dispersion and no systematic bias. CONCLUSION: Ultrasound-based measurement of preperitoneal fat using a convex probe is a highly reproducible and reliable technique across different observers. Given its noninvasive nature, accessibility, and excellent reproducibility, this method can be confidently implemented in routine clinical practice for the early identification of pregnant women at increased metabolic and obstetric risk.