To measure the esophageal hiatus area (HSA) and esophageal cross-sectional area (ESA) in healthy adults, establish the normal reference value for HSA, and calculate the ESA/HSA ratio, thereby providing morphological evidence for the diagnosis of hiatal hernia (HH).

This retrospective study analyzed medical records of patients who underwent 24-hour esophageal pH-impedance monitoring at Sir Run Run Shaw Hospital, Zhejiang University School of Medicine from November 2022 to December 2024. Eligible patients completed high-resolution manometry (HRM), upper gastrointestinal endoscopy, and enhanced CT scans of the upper abdomen/chest within six months of monitoring. Exclusion criteria included the presence of typical reflux symptoms, abnormal reflux parameters (acid exposure time >4% or DeMeester score >14.72), diagnosis of HH by endoscopy or imaging, abnormal HRM findings, previous diaphragmatic or HH surgery, and incomplete medical records. HSA and ESA were measured using multidetector computed tomography (MDCT) with multiplanar reconstruction technique, and the ESA/HSA ratio was calculated. An independent samples t-test was used to compare sex differences, and Pearson correlation analysis was used to assess the correlation between age and HSA/ESA. A two-tailed P<0.01 was considered statistically significant.

A total of 39 subjects were included, comprising 13 males (33.3%) and 26 females (66.7%), with a mean age of (52±14) years. HSA was (228.4±52.9) mm², ESA was (140.8±42.1) mm², and the ESA/HSA ratio was 0.61±0.10. No significant sex differences were observed in HSA [males (245.6±48.3)mm² vs females (222.5±54.1)mm²] or ESA [males (145.2±39.8) mm² vs females (135.4±43.5)mm²]. Age was not significantly correlated with HSA (r=0.306, P=0.059) or ESA (r=0.348, P=0.030).

This study reports for the first time the normal reference values for HSA and ESA and the ESA/HSA ratio in healthy adults. The ESA/HSA ratio demonstrates good stability and may serve as a novel morphological indicator for assessing the functional status of the esophageal hiatus, providing a reference for the accurate diagnosis of HH.