Normograms in Prenatal Life of Stomach and Urinary Bladder in the Second and Third Trimesters of Pregnancy.

Aim: The aim of this study was to prepare normograms for the fetal stomach, urinary bladder, and stomach to urinary bladder index in healthy fetuses.

Material and methods: The study was conducted based on the data extracted from the database of our tertiary center in the years 2016-2019. The study group, comprising 867 fetuses, demonstrated normal biometry and normal heart structure, normal heart function, no extracardiac malformations, and no extracardiac anomalies. The stomach to urinary bladder index was analyzed in the study group. The examinations were performed with the use of the following ultrasound machines: Voluson E10, Philips and Voluson Expert, with convex transabdominal transducers. Linear regression analysis based on Microsoft Excel was used for statistical analysis.

Results: The average size of the stomach in healthy fetuses between the 14-40^th week of gestation was 18 mm (8-40 mm), the average urinary bladder measurement was 17 mm (15-42 mm), and the fetal stomach to urinary bladder index was constant: 1.26 (0.09-3.93).

Conclusions: The normograms for the stomach, urinary bladder and the stomach to urinary bladder index prepared based on our study group can contribute to an improvement in the accuracy of examination and provide an unified organization of the description of fetuses. These normograms constitute an additional marker for the assessment of fetal condition. A clear disproportion in the size of the urinary bladder and stomach can be helpful in terms of paying more attention to fetuses with untypical features in screening centers.