Association of esophageal hiatus size with reflux esophagitis and type I hiatal hernia in patients with obesity

Abstract

BACKGROUND

Chinese surgeons often rely on intraoperative exploration of the esophageal hiatus to determine the need for concurrent type I hiatal hernia (HH) repair during laparoscopic sleeve gastrectomy. However, no standardized criteria for the esophageal hiatus size or indications for exploration exist in China.

AIM

To investigate normal anatomical parameter ranges of the esophageal hiatus in patients with obesity.

METHODS

A total of 158 patients, aged 20-49 years, was analyzed from January 2020 to June 2024. The patients were classified into the no reflux esophagitis (RE) no HH group (HHG), RE group, and type I HHG. The transverse and sagittal diameters and cross-sectional area of the esophageal hiatus were measured using multiplanar reconstruction of the computed tomography images.

RESULTS

Body mass index was positively correlated with area and transverse and sagittal diameters of the esophageal hiatus (r = 0.72, 0.69, and 0.54, respectively; P < 0.01). In the no RE no HHG and RE group, the esophageal hiatus size in the subgroup with obesity was greater than that in the non-obesity subgroup (area: 326.15 ± 78 mm² vs 208.12 ± 64.44 mm², transverse diameters: 15.97 ± 2.06 mm vs 13.37 ± 1.99 mm, sagittal diameters: 15.7 ± 2.08 mm vs 11.73 ± 2.08 mm; P < 0.01). Patients with obesity showed no significant differences in esophageal hiatus size with or without RE or HH.

CONCLUSION

The esophageal hiatus size increased with body mass index and was larger in patients with obesity than in those without obesity.

Key Words: Obesity; Esophageal hiatus; Reflux esophagitis; Hiatal hernia; Laparoscopic sleeve gastrectomy

Core Tip: Given the lack of standardized criteria for esophageal hiatus size in patients with obesity, this retrospective case-control study found that esophageal hiatus size increased with body mass index and was larger in patients with obesity than without obesity. The esophageal hiatus area and transverse and sagittal diameters were 326.15 ± 78 mm², 15.97 ± 2.06 mm, and 15.7 ± 2.08 mm, respectively. Patients with obesity with mild reflux esophagitis or type I hiatal hernia did not exhibit an enlarged esophageal hiatus. Thus, further computed tomography measurements of the esophageal hiatus could provide support for determining the need for intraoperative exploration.

INTRODUCTION

The obesity rate in China exceeds 16.4% and increases annually[1]. Obesity is a high-risk factor for reflux esophagitis (RE)[2] and hiatal hernia (HH), and the incidence of these two diseases increases with weight gain. Individuals with a body mass index (BMI) exceeding 30 kg/m² have a four- to five-times higher risk of HH than normal weight individuals[3]. Weight loss can relieve the symptoms of gastroesophageal reflux disease (GERD). A cross-sectional study reported that with a BMI decrease of 3.5 kg/m², the risk of frequent GERD symptoms decreased by 40% (odds ratio = 0.64)[2]. Bariatric surgery is currently the most effective method for long-term weight control. Laparoscopic sleeve gastrectomy (LSG) accounts for nearly 60% of bariatric surgeries performed globally every year, and its proportion in China is high at 87%[4]. Chinese surgeons generally conduct esophageal hiatus exploration during LSG to diagnose concurrent type I HH and determine the need for HH repair based on the exploration results. However, standardized criteria or guidelines for esophageal hiatus size have not yet been established, which may lead to unnecessary esophageal hiatus exploration and even cause complications.

Because the esophageal hiatus presents a noncircular inclined structure, measuring its diameter in the horizontal direction by computed tomography (CT) cannot fully reflect its actual size. In 2016, Ouyang et al[5] proposed the production of a cross-sectional image of the esophageal hiatus area through multiplanar reconstruction (MPR), facilitating its accurate measurement. Subsequent studies have verified the effectiveness and accuracy of MPR by comparing MPR measurements with actual intraoperative measurements[6,7]. Most existing studies in China have directly measured the esophageal hiatus diameter through horizontal CT scans, and most participants were aged > 60 years. However, the median age of patients receiving bariatric surgery is only 32 years[4].

Thus, our study retrospectively analyzed the data of patients aged 20-49 years. MPR was applied to the CT images to comprehensively measure the cross-sectional area and transverse and sagittal diameters of the esophageal hiatus. Through a case-control study of patients with and without obesity, the normal anatomical parameter ranges of the esophageal hiatus in patients with obesity were derived to provide data support to determine the need for esophageal hiatus exploration during LSG.

MATERIALS AND METHODS

Data sources

A total of 158 patients who underwent gastroscopy and chest/abdominal CT between January 1, 2020 and June 1, 2024 were included in this study. The inclusion criteria were age 20-49 years with a BMI ≥ 30 kg/m² (obesity group) or BMI < 30 kg/m² (non-obesity group). The exclusion criteria were gastrointestinal tumors, history of gastrointestinal surgery, achalasia, Mallory-Weiss syndrome, gastric fundal varices, severe organ dysfunction, abdominal aortic aneurysm, and skeletal dysplasia. The patients in the obesity and non-obesity groups were matched 1:1 or 1:2 based on age, height, weight, and medical history.

Esophageal hiatus measurement method

Chest and abdominal CT scans were performed using a 64-slice spiral CT scanner (Discovery CT750 HD; GE Medical Systems, Waukesha, WI, United States) covering the distal esophagus, diaphragm, and proximal stomach. Scanning was performed at a tube voltage of 120 kV, tube current of 70-260 mA, field of view of 50 cm, 521 × 512 matrix, and slice thickness of 5 mm. Scanning was enhanced with an intravenous bolus injection of 100 mL of the non-ionic contrast agent iohexol at 2.5-3.5 mL/second. The raw scan data were transmitted to a workstation for MPR with a slice thickness of 5 mm. The entire circumference of the esophageal hiatus was revealed using the double-oblique correction plane technique[5]. First, a slice passing through the center of the esophageal hiatus was identified in the sagittal plane. The line representing the axial plane was moved and rotated to intersect the anterior and posterior margins of the esophageal hiatus. This line generally slopes toward the spine. Consequently, the line representing the oblique coronal plane was approximately parallel to the distal esophagus (Figure 1A). The sagittal diameter was obtained by measuring the distance between the anterior and posterior margins. The line representing the axial plane was then moved and rotated on the coronal plane to intersect the left and right margins of the esophageal hiatus. This line generally tilted downward toward the right (Figure 1B). The distance between the left and right margins was measured to obtain the transverse diameter. The resulting double oblique axis plane was the esophageal hiatus plane (Figure 1C). The angle and position were slightly adjusted to maximize the hiatal margins. Finally, a polygonal tool was used to manually define the inner margins of the hiatus, and the cross-sectional area of the esophageal hiatus was measured (Figure 1D). Three researchers performed the measurements independently.

Figure 1 Esophageal hiatus measurement method. A: For reconstructing the sagittal plane, select a slice passing through the center of the esophageal hiatus and move and rotate the locating line representing the axial plane (yellow) to intersect the anterior and posterior margins of the esophageal hiatus. This line generally slopes toward the spine. Consequently, the line representing the oblique sagittal plane (purple) is roughly parallel to the distal esophagus. The sagittal diameter is obtained by measuring the distance between the anterior and posterior margins; B: For reconstructing the coronal plane, move and rotate the yellow line to intersect the left and right margins of the esophageal hiatus. This line generally tilts downward toward the right. Consequently, the line representing the oblique coronal plane (blue) is roughly parallel to the distal esophagus. The transverse diameter is obtained by measuring the distance between the left and right margins; C: For the double oblique axis plane, the image presents a superior view of the esophageal hiatus from a perpendicular vantage point; D: A polygonal tool was used to manually define the inner margins of the hiatus, and the cross-sectional area of the esophageal hiatus was measured.

Criteria for diagnosing RE and HH by gastroscopy

According to the Los Angeles classification[8], RE is classified into grades A-D based on the number, length, continuity, and circumferential involvement of the esophageal mucosal breaks. According to the refined Hill classification[9], HH is classified into grades I-IV based on the degree of tight fit between the mucosal fold of the gastroesophageal junction and the gastroscope.

Diagnostic criteria for GERD

The GERD-Q score[10] was calculated based on the frequency of reflux symptoms (heartburn, regurgitation, pain, nausea, and sleep disturbance) and medication use in the past 7 days, with a score of 8 indicating GERD.

Statistical analyses

All data were analyzed using SPSS 24.0 (IBM SPSS Statistics, Armonk, NY, United States). The measurement data are expressed as the means ± SD. Student’s t-test and Pearson’s correlation analysis were conducted for normally distributed data, whereas the rank-sum test and Spearman’s correlation analysis were performed for non-normally distributed data. Statistical significance was set at P < 0.05. Correlations were categorized as strong (r ≥ 0.9), moderate (0.9 > r ≥ 0.5), or weak (r < 0.5). Count data are presented as percentages (%). All figures were generated using Prism 8.4 (GraphPad Software, Boston, MA, United States) and ProcessOn (Beijing Da Mai Di LLC, Beijing, China).

RESULTS

General information

The initial screening yielded 41957 patients who underwent gastroscopy, and 36146 patients without complete medical records were excluded. Further screening yielded 1949 patients aged 20-49 years. Specifically, 543 patients with gastrointestinal tumors, 221 with a history of gastrointestinal surgery, 69 with gastrointestinal obstruction, 149 with severe disease, and 426 without chest/abdominal CT examinations were excluded based on the exclusion criteria. Ultimately, 541 patients were enrolled in this study. The participants were categorized according to their disease status into the no RE and no HH group (NRNHG), RE group (REG), and HH group (HHG). The NRNHG comprised 50 patients with obesity and 50 without obesity (all patients without obesity: BMI < 28 kg/m²). The REG consisted of 20 patients with obesity and 20 without obesity (2 patients without obesity: 30 kg/m² > BMI > 28 kg/m²). The HHG included 6 patients with obesity and 12 without obesity (only 1 patient without obesity: 30 kg/m² > BMI > 28 kg/m²) (Figure 2).

Figure 2 Patient selection flowchart. Patients were screened and grouped based on the inclusion and exclusion criteria. CT: Computed tomography.

Correlation between age and esophageal hiatus size in the NRNHG

A total of 50 patients with and without obesity in the NRNHG were stratified by age in 10-year intervals. After statistical analyses, the rank-sum test results of multiple groups showed no statistically significant differences in height, weight, or BMI between the different age groups with or without obesity. The esophageal hiatus area and transverse and sagittal diameters were not significantly different between the groups (P > 0.05) (Table 1).

Table 1 Correlation between age and esophageal hiatus size in the no reflux esophagitis and no hiatal hernia group, mean ± SD.

Characteristic	Obese group				Non-obese group
	20-29 (n = 12)	30-39 (n = 30)	40-49 (n = 8)	P value	20-29 (n = 12)	30-39 (n = 30)	40-49 (n = 8)	P value
Age (year)	25.42 ± 2.07	34.5 ± 3.14	41.75 ± 1.67	< 0.01	25.83 ± 2.37	34.57 ± 2.76	41.88 ± 1.46	< 0.01
Height (cm)	165.83 ± 5.1	165.87 ± 7.43	168.75 ± 4.68	0.248	165 ± 9.09	167.67 ± 9.25	168.5 ± 7.09	0.62
Weight (kg)	109.08 ± 13.4	106.65 ± 26.5	108.63 ± 20.03	0.424	53.14 ± 9.13	63.1 ± 10.12	59.19 ± 4.21	0.27
BMI (kg/cm2)	39.72 ± 5.23	38.6 ± 8.03	38.19 ± 7.09	0.498	19.39 ± 1.96	22.34 ± 2.37	20.87 ± 1.27	0.10
Sagittal diameter (mm)	14.95 ± 1.58	15.78 ± 2.38	16.55 ± 1.09	0.075	12.17 ± 2.37	11.72 ± 2.13	11.1 ± 1.44	0.572
Transverse diameter (mm)	15.29 ± 1.51	15.98 ± 2.14	16.97 ± 2.3	0.247	13.93 ± 2.97	13.07 ± 1.61	13.63 ± 1.45	0.538
Area (mm2)	319.77 ± 56.18	315.8 ± 85.6	374.56 ± 63.71	0.075	200.11 ± 86.65	210.22 ± 59.95	212.25 ± 47.21	0.564

BMI: Body mass index.

Correlation between BMI and esophageal hiatus size in the NRNHG

After excluding the effect of age on esophageal hiatus size, the correlation between BMI and esophageal hiatus size in 100 patients in the NRNHG was analyzed. Spearman’s correlation analysis showed a moderate positive correlation between BMI and the esophageal hiatus area and transverse and sagittal diameters (P < 0.01). Patients with a higher BMI had a larger esophageal hiatus area and larger transverse and sagittal diameters than their counterparts (Figure 3A-C).

Figure 3 Spearman’s correlation test between body mass index and esophageal hiatus size. A: Correlation between body mass index (BMI) and esophageal hiatus area with a correlation coefficient of 0.72 (P < 0.01), showing a linear positive correlation of moderate intensity; B: Correlation between BMI and esophageal hiatus transverse diameter with a correlation coefficient of 0.69 (P < 0.01), showing a linear positive correlation of moderate intensity; C: Correlation between BMI and esophageal hiatus sagittal diameter with a correlation coefficient of 0.54 (P < 0.01), showing a linear positive correlation of moderate intensity. BMI: Body mass index.

The effect of obesity on esophageal hiatus size in the NRNHG and REG was analyzed. No statistically significant differences in age or height were observed between the obesity and non-obesity subgroups. Patients with obesity exhibited significantly larger esophageal hiatus area and transverse and sagittal diameters than patients without obesity (P < 0.01). In the NRNHG, patients with obesity exhibited esophageal hiatus area and transverse and sagittal diameters of 326.15 ± 78 mm², 15.97 ± 2.06 mm, and 15.7 ± 2.08 mm, respectively (Table 2).

Table 2 Correlation between body mass index and esophageal hiatus size.

Characteristic	NRNHG			REG
	Obese group (n = 50)	Non-obese group (n = 50)	P value	Obese group (n = 20)	Non-obese group (n = 20)	P value
Age (year)	33.48 ± 5.91	33.64 ± 5.71	0.912	38.4 ± 7.39	38.56 ± 7.61	0.942
Height (cm)	163.15 ± 24.2	167.16 ± 8.83	0.559	171.95 ± 6.55	173.06 ± 10.01	0.684
Weight (kg)	107.55 ± 22.68	60.08 ± 9.97	< 0.01	105.46 ± 25.39	69.94 ± 12.41	< 0.01
BMI (kg/cm2)	38.8 ± 7.2	21.4 ± 2.45	< 0.01	35.54 ± 7.51	23.21 ± 2.72	< 0.01
Sagittal diameter (mm)	15.7 ± 2.08	11.73 ± 2.08	< 0.01	16.11 ± 2.31	15.13 ± 2.59	0.028
Transverse diameter (mm)	15.97 ± 2.06	13.37 ± 1.99	< 0.01	16.77 ± 3.12	14.86 ± 3.59	0.022
Area (mm2)	326.15 ± 78	208.12 ± 64.44	< 0.01	437.77 ± 444.25	259.66 ± 97.8	0.020

BMI: Body mass index; NRNHG: No reflux esophagitis and no hiatal hernia group; REG: Reflux esophagitis group.

Correlation between RE and esophageal hiatus size

No statistically significant differences in age, height, weight, or BMI were noted between the two groups. Patients with obesity were classified as Los Angeles (LA)-A (70%) or LA-B (30%) according to the LA classification for RE, and their GERD-Q scores were 6.7 points. The esophageal hiatus area and transverse and sagittal diameters were larger in patients with RE than in those without RE; however, these differences were not statistically significant (P > 0.05). Patients without obesity were also classified as LA-A (60%) or LA-B (40%) according to the LA classification for RE, and their GERD-Q scores were 7.8 points. The esophageal hiatus area and sagittal diameter showed no significant differences (P > 0.05), whereas the transverse diameter was statistically different between patients with and without RE (P < 0.01) (Table 3).

Table 3 Correlation between reflux esophagitis and esophageal hiatus size.

Characteristic	Obese group			Non-obese group
	RE (n = 20)	Non-RE (n = 20)	P value	RE (n = 20)	Non-RE (n = 20)	P value
Age (year)	38.4 ± 7.39	36.8 ± 5.47	0.524	38.56 ± 7.61	37.05 ± 5.39	0.558
Height (cm)	171.95 ± 6.55	168.2 ± 6.88	0.059	173.06 ± 10.01	168.5 ± 6.54	0.101
Weight (kg)	105.46 ± 25.39	109.8 ± 26.84	0.386	69.94 ± 12.41	61.87 ± 8.57	0.06
BMI (kg/cm2)	35.54 ± 7.51	38.67 ± 8.04	0.094	23.21 ± 2.72	21.71 ± 2.01	0.70
Sagittal diameter (mm)	16.11 ± 2.31	15.92 ± 1.89	0.715	14.86 ± 3.59	13.4 ± 1.45	0.335
Transverse diameter (mm)	16.77 ± 3.12	16.35 ± 2.15	0.839	15.13 ± 2.59	11.25 ± 1.52	0.023
Area (mm2)	437.77 ± 444.25	346.11 ± 70.75	0.935	259.66 ± 97.8	199.43 ± 38.23	0.079

BMI: Body mass index; RE: Reflux esophagitis.

Correlation between HH and esophageal hiatus size

Six patients with obesity complicated HH were included in this study. Among them, 3 patients (50%) were classified as having Hill grade III, with an esophageal hiatus diameter 1.5 times the width of the endoscope, and 3 patients were classified as having grade IV, with an esophageal hiatus diameter twice the width of the endoscope. No statistically significant differences in the esophageal hiatus area, transverse diameter, or sagittal diameter (P > 0.05) were observed between patients with and without HH. In addition, 12 patients without obesity had HH, of whom 7 (58.3%) were classified as having Hill grade III, with the esophageal hiatus expansion width reaching 1.5 times that of the endoscope, and 5 were classified as having grade IV, with the expansion width reaching twice that of the gastroscope. No statistically significant differences were found in the esophageal hiatus area and sagittal diameter, whereas the transverse diameter showed significant differences between patients with and without HH (P < 0.01) (Table 4).

Table 4 Correlation between hiatal hernia and esophageal hiatus size.

Characteristic	Obese group			Non-obese group
	HH (n = 6)	Non-HH (n = 12)	P value	HH (n = 12)	Non-HH (n = 12)	P value
Age (year)	40.17 ± 8.54	38.25 ± 6.72	0.279	41.58 ± 7.03	37.75 ± 5.86	0.68
Height (cm)	173.33 ± 6.62	168.75 ± 6.24	0.155	170.5 ± 7.24	167.25 ± 8.21	0.543
Weight (kg)	97.83 ± 4.54	109.96 ± 22.04	0.574	70.73 ± 8.35	65.45 ± 13.66	0.112
BMI (kg/cm2)	32.64 ± 2.23	38.49 ± 6.51	0.059	24.36 ± 2.71	23.19 ± 3.11	0.248
Sagittal diameter (mm)	15.07 ± 2.96	16.11 ± 1.3	0.349	13.7 ± 3.22	14.16 ± 2.18	0.525
Transverse diameter (mm)	15.91 ± 4.27	16.55 ± 2.25	0.399	15.45 ± 2.51	12.14 ± 2.25	0.005
Area (mm2)	302.45 ± 82.72	346.11 ± 75.85	0.075	276.33 ± 93.42	220.57 ± 51.34	0.106

BMI: Body mass index; HH: Hiatal hernia.

DISCUSSION

The esophageal hiatus is composed of diaphragmatic muscle rather than the more resilient tendinous tissue. A physiological gap exists between the diaphragm and the esophagus, resulting in incomplete closure, which renders the area relatively weak and prone to herniation. The crura of the diaphragm, phrenoesophageal ligament, and esophageal branches of the phrenic nerve collectively form the anatomical basis for antireflux mechanisms and prevention of HH. However, there remains no universally accepted standard for defining the normal size of the esophageal hiatus, particularly in patients with obesity. Obesity is a well-established risk factor for RE and HH. The necessity of performing antireflux procedures or hernia repair concurrently with LSG in patients who do not meet the diagnostic criteria for GERD or have only type I HH remains controversial. Some experts advocate for routine intraoperative exploration of the hiatus during LSG in patients with obesity with preoperative reflux symptoms—even if they fall short of GERD criteria - or endoscopic evidence of any degree of RE, particularly when the Hill classification exceeds grade II. The decision to repair is often based on subjective assessments, such as the size of the anterior cardial depression or the perceived weakness of the hiatal tissues, rather than objective metrics, limiting its generalizability and reproducibility. Domestic studies frequently use a hiatal diameter of 5 cm as the threshold for intervention, while international studies often adopt 4 cm[11,12]. However, the esophageal hiatus is an oblique, noncircular structure, making unidirectional measurements inadequate for reflecting its true dimensions. Thus, establishing normative reference ranges for hiatal size in patients with obesity is of critical importance.

Age and obesity are significant contributing factors to HH. With age, the gradual loss of elastin, collagen, and matrix metalloproteinases that constitute the extracellular matrix causes muscle weakness and decreases diaphragmatic elasticity. Consequently, the function of the structures around the esophagus is weakened, the esophageal hiatus is enlarged, and the gastroesophageal junction moves upward, resulting in HH and reflux symptoms, with pronounced manifestations typically observed between 60 years and 80 years of age[13,14]. In this study, no significant differences in the esophageal hiatus area and transverse and sagittal diameters were observed among the different age groups of patients with and without obesity aged 20-49 years. This finding is supported by a retrospective study of 119 patients in North America that stratified participants aged 20-60 years and identified no correlation between age and esophageal hiatus size[15]. In the young and middle-aged strata, age had no effect on the esophageal hiatus size.

Among the NRNHG, the esophageal hiatus area of patients with obesity was significantly larger than that of patients without obesity, and BMI showed a moderate positive linear correlation with the esophageal hiatus area and transverse and sagittal diameters. In patients with obesity, the esophageal hiatus had sagittal and transverse diameters and area of 15.7 ± 2.08 mm, 15.97 ± 2.06 mm, and 326.15 ± 78 mm², respectively. The maximum and minimum areas were 510.1 mm² and 210.03 mm², respectively. These results are consistent with the trends reported outside China. Boru et al[6] reported that the esophageal hiatus area of patients with normal weight and without HH or RE was 3.69 cm², whereas that of patients with obesity was 3.98 cm². During bariatric surgery, indications for esophageal hiatus exploration should be based on the effect of obesity on the esophageal hiatus. Preoperative CT-based hiatal measurement offers objective data, mitigating the risk of overestimating hiatal size due to pneumoperitoneum-induced artificial expansion during laparoscopy. Proactive hiatal assessment may reduce unnecessary dissection and collateral damage. Quantification of the indicators for exploration requires further research.

No consensus regarding the effects of LSG on the cause and exacerbation of GERD has been established. Studies have indicated that LSG can not only effectively alleviate GERD but may also induce or aggravate GERD, with incidences ranging from 8% to 52%[16,17], the highest being 83.3%[18]. This may be related to the lack of uniformity in the LSG details. The first factor is the integrity of the gastric antrum. The gastric antrum effectively facilitates gastric motility, promotes gastric emptying, and reduces intragastric pressure[19]. The second detail concerns the protection of antireflux anatomical structures at the cardia, such as maintaining the acute angle of His and protecting the integrity of the pharyngoesophageal ligament and esophageal branches of the phrenic nerve at the gastroesophageal junction[20,21]. A 1-year self-controlled study in 2013 reported that routine esophageal hiatus exploration during LSG increased the incidence of HH by 20%[22]. Improper manipulation of the gastroesophageal junction may lead to HH and intrathoracic sleeve migration, and > 40% of patients with intrathoracic sleeve migration developed GERD symptoms[23]. Santonicola et al[24] explored the esophageal hiatus during LSG and conducted concurrent HH repair in 78 patients with concomitant type I HH, and LSG alone in 108 patients without HH before surgery. The results of the 6-month postoperative follow-up showed that 43.3% of patients who underwent concurrent HH repair still had GERD symptoms, and 22.9% developed new GERD symptoms. In the LSG alone group, the percentages of patients with persistent and new GERD symptoms were 22.5% and 17.7%, respectively. Therefore, whether patients with obesity with type I HH but without GERD benefit from bariatric surgery combined with HH repair remains unclear.

In this study, 70% of patients with obesity with comorbid RE were classified as Los Angeles grade A, and all had GERD-Q scores ≤ 6.7, indicating mild RE at this stage. The esophageal hiatus area of patients with obesity with RE was 437.77 ± 444.25 mm², which was larger than that of patients with obesity without RE. However, this difference was not statistically significant. This study included 6 patients with obesity with HH and 12 patients without obesity with HH. All HHs were diagnosed by gastroscopy and all were Hill grade > II. The hiatal width was less than twice the diameter of the endoscope, and no herniation of the stomach or other tissues into the thoracic cavity was observed, consistent with type I HH. No significant difference in esophageal hiatus size was detected between the two groups on CT. In patients with obesity with mild reflux and type I HH, no anatomical hiatal enlargement was observed. Excessive dissection or evaluation under laparoscopic pneumoperitoneum pressure may lead to overestimation of the hiatal area, potentially misleading surgical decision-making.

International guidelines recommend observation for type I HHs in patients without GERD[25], especially for HHs detected by endoscopy, due to the extremely low probability of developing acute obstruction and progressive RE[26]. In the present study, the transverse diameter of the esophageal hiatus significantly increased in patients without obesity in the REG and HHG. This is consistent with the progression of HH, which mainly manifests as an enlarged transverse diameter of the esophageal hiatus, that is, a morphological change from the original elliptical shape to a circular shape[27-29]. These findings offer important reference values for formulating the indications for further related examinations and intraoperative exploration in patients with endoscopic evidence suggestive of RE or HH. Several limitations warrant consideration. First, the retrospective case-control design restricts causal inference, and the absence of longitudinal follow-up precludes assessment of disease progression. Second, the limited sample size - especially in the HH subgroup - may reduce statistical power. Finally, unmeasured confounders (e.g., dietary patterns, geographic disparities) could bias the observed associations.

CONCLUSION

Compared to patients without obesity, those with obesity had a larger esophageal hiatus size, with an esophageal hiatus area and transverse and sagittal diameters of 326.15 ± 78 mm², 15.97 ± 2.06 mm, and 15.7 ± 2.08 mm, respectively. The esophageal hiatus area and transverse and sagittal diameters increased with increasing BMI. Patients with obesity with mild RE or type I HH did not exhibit an enlarged esophageal hiatus. For patients with endoscopic evidence suggestive of RE or HH, further CT measurements of the esophageal hiatus area and transverse and sagittal diameters could provide support for determining the need for intraoperative exploration. The transverse diameter of the esophageal hiatus offers greater reference values.

ACKNOWLEDGEMENTS

We thank Kai-Xuan Yang from the China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, Beijing, China for reviewing the statistical methods used in this study.