To measure the dimensions of the esophageal hiatus in patients with type I hiatal hernia (HH) using multidetector computed tomography (MDCT) with multiplanar reconstruction (MPR) and to investigate their correlations with body mass index (BMI).

Clinical and imaging data from 106 patients with surgically confirmed type I HH at the Affiliated Hospital of Xuzhou Medical University between January 2022 and June 2025 were retrospectively collected and analyzed. The hiatal surface area (HSA), anteroposterior diameter (AP), and transverse diameter (TD) of the esophageal hiatus were measured using MDCT with MPR. According to BMI, the patients were divided into three groups: normal-weight, overweight, and obese groups. The correlations between BMI and HSA, AP, and TD were evaluated.

Comparisons among the three groups showed statistically significant differences in HSA (F=4.54, P=0.013, partial η²=0.08), AP (F=4.43, P=0.014, partial η²=0.08), and TD (F=9.85, P<0.001, partial η²=0.16), indicating medium to large effect sizes for BMI grouping on these esophageal hiatal measurements. No statistically significant differences were observed among the three groups in sex, age, height, systolic blood pressure, diastolic blood pressure, or fasting blood glucose (P>0.05, partial η²<0.04). After adjustment for age, sex, blood pressure, fasting blood glucose, and other factors, multiple linear regression analysis showed that each 1 kg/m² increase in BMI was associated with an increase of 0.46 cm² in HSA, 0.08 cm in AP, and 0.07 cm in TD (all P<0.001). BMI was positively correlated with HSA, AP, and TD.

MDCT with MPR can accurately measure various parameters of the esophageal hiatus. The findings suggest that BMI may be an independent risk factor for type I HH, with higher BMI associated with larger HSA, AP, and TD measurements of the esophageal hiatus.