Hiatal hernia size predicts abnormal pH testing: a retrospective cohort study

Hiatal hernia (HH) disrupts the anti-reflux barrier and contributes to gastroesophageal reflux disease (GERD), which is defined objectively by abnormal pH testing. Ambulatory 96-h wireless pH monitoring is widely used for objective GERD assessment, yet the relationship between HH size and abnormal pH results remains ambiguous. We evaluated the association between HH size and pH study positivity in a surgically evaluated cohort.

Patients with HH identified on imaging or endoscopy who underwent preoperative pH monitoring between January 1, 2009 and January 1, 2026 were identified from a prospectively maintained institutional database. Patients with prior HH repair or incomplete pH data were excluded. Abnormal pH study was defined according to Lyon Consensus criteria as acid exposure time (AET) ≥ 6% on at least two monitoring days. DeMeester score was analyzed as a secondary measure of reflux severity. HH size was analyzed across predefined strata. Multivariable logistic regression assessed independent predictors of abnormal pH study.

A total of 363 patients were included; 65.8% were female and the mean age was 60 ± 14 years. Overall, 79.3% had abnormal pH testing. Abnormal pH prevalence increased with HH size (p = 0.002), rising from 60.0% in hernias < 1.0 cm to 95.2% in 5.0-5.9 cm hernias. In contrast, prevalence decreased to 68.4% in hernias ≥ 6.0 cm. In multivariable analysis, HH size remained independently associated with abnormal pH testing, with adjusted odds ratios increasing from 3.71 (95% CI 1.17-11.80) in the 2.0-2.9 cm group to 17.44 (95% CI 2.33-130.67) in the 5.0-5.9 cm group compared with hernias < 1.0 cm. Hernias ≥ 6.0 cm were not independently predictive. Increasing HH size was also associated with higher AET%, DeMeester scores, and moderate-to-severe esophagitis.

Intermediate-to-large sliding hernias are strong anatomic predictors of abnormal reflux and may inform anatomy-guided preoperative evaluation.