Several studies have found a strong association between intra-abdominal aneurysms (IAA) and abdominal hernias, particularly between abdominal aortic aneurysms (AAA) and abdominal wall hernias (AWH).^(1-5) In a meta-analysis of 14 studies (including 39,262 patients), a 2.3 times higher incidence of AAA in patients with AWH was found.⁽⁶⁾ Kontogeorgi et al. confirmed the high probability that patients with AWH would develop AAA, even recommending that AWH should be used as a criterion in AAA screening in addition to age, sex, family history, and smoking.⁽⁷⁾ Hung et al. found an association between AWH, AAA, and thoracoabdominal aneurysms.⁽⁵⁾

Nonetheless, the relationship between aneurysms and hernias remains multifactorial and not fully understood. Beyond possible connective tissue alterations, several epidemiological and environmental factors, such as age, smoking, atherosclerosis, and increased intra-abdominal pressure, are likely to play concurrent roles in the development of both conditions.^(2,8-12)

Important studies have focused on the association between inguinal hernias, AAA, and thoracoabdominal aneurysms, although the findings of some studies were negative.^(3,13-16) In contrast, few investigations have extended this analysis to include other types of abdominal wall or diaphragmatic hernias, such as hiatal hernias (HH), or to aneurysms located in visceral and renal arteries. This knowledge gap limits our understanding of whether the coexistence observed in AAA also applies to aneurysms in other abdominal territories.

In this context, and recognizing the limitations of retrospective imaging-based designs, this study aimed to describe and characterize the pattern of distribution of AWH and HH in patients with IAA, including aortic, visceral, and renal locations, identified through computed tomography angiography (CTA) performed at a tertiary referral center.

Rather than testing a causal relationship, this study sought to delineate the frequency and anatomical distribution of different hernia types in this specific population, contributing to the descriptive mapping of this clinically relevant association.

This study aimed to describe and characterize the pattern of distribution of abdominal wall hernias and hiatal hernias in patients with intra-abdominal aneurysms, including aortic, visceral, and renal locations, identified through computed tomography angiography performed at a tertiary referral center.

This is a retrospective, cross-sectional study based on CTA reports of patients diagnosed with IAA. All data were collected from the radiological information system of a private quaternary hospital in São Paulo, Brazil, between January 2005 and July 2021. This study was carried out in accordance with the Code of Ethics of the World Medical Association (Declaration of Helsinki). The study protocol was approved by the Ethics Committee of the Hospital Israelita Albert Einstein (CAAE: 47103021.0.0000.0071; # 5,081,688), and the requirement for informed consent was waived due to the retrospective nature of the research.

Among 141,836 CTA scans performed between January 2005 and July 2021, 48,953 (34.5%) were excluded for being follow-up or duplicate exams from the same patients. The remaining 92,883 unique scans identified 2,597 patients with IAA, who constituted the final study cohort.

Of the 2,597 patients with IAA, 837 (32.2%) presented with at least one abdominal or hiatal hernia (Table 1). The overall prevalence of hernias did not differ significantly between sexes (32.4% in women versus 32.1% in men; p=0.876). Patients with hernias were significantly older than those without hernias (mean age 72.2±12.0 versus 68.2±14.0 years; p<0.001).

HH was the most frequent type (50.3%), followed by umbilical (27.0%) and inguinal hernias (right: 16.9%; left: 14.3%). HH were significantly more common among women (66.4%, p<0.001), whereas inguinal and epigastric hernias predominated in men (p<0.001 and p=0.031, respectively). The frequencies of other hernia types, paraumbilical, incisional, Spiegelian, and femoral, were low and showed no sex difference (Table 1S, Supplementary Material).

Patients with inguinal hernias were generally older than those with other hernia types, and women with inguinal hernias were significantly older than men (mean age 82.5±6.4 versus 73.3±9.9 years; p<0.01). For all other hernia types, no significant age difference between sexes was observed (Table 2S, Supplementary Material).

Most patients (76.8%) had a single hernia type, while 23.2% had multiple hernias (Figure 1). The most frequent concomitance occurred between right and left inguinal hernias, indicating frequent bilaterality. The second most common association was between hiatal and umbilical hernias. Other less frequent combinations included paraumbilical with umbilical hernias and spigelian with inguinal hernias (Figure 1S, Supplementary Material).

The frequency of hernias according to the aneurysmal artery followed a similar distribution to the overall cohort, except for the hepatic artery and the celiac trunk aneurysms, which showed a higher prevalence of hernias (42.9% and 41.8%, respectively) (Figure 2S, Supplementary Material). HH were particularly common in patients with aneurysms of the hepatic, splenic, and left renal arteries. No significant correlation was found between the number of aneurysmal vessels and the number of hernia locations (r=0.02). A non-significant positive correlation was observed between age and the number of hernia sites (r=0.12).

In this large retrospective cohort, approximately one-third of patients with IAA also presented with abdominal or HH. This prevalence is notably higher than that reported in the general population, suggesting that patients with aneurysmal disease may have a greater predisposition to hernia formation. However, these results should be interpreted with caution, as this study was designed to describe coexistence patterns rather than to infer causal relationships.

The frequencies of AWH (16.0%) and HH (16.2%) found in this cohort were considerably higher than those reported for the general population, in which the prevalence of AWH is estimated at 1.7–4% and of HH at 2–10%, depending on age and clinical condition.^(17,18) Previous studies have also demonstrated that the coexistence of AAA and hernias is common, with meta-analyses reporting a two- to threefold higher incidence of aneurysm in patients with hernias and vice versa.^(3,6,7) Our findings confirm this trend and expand the current evidence by including aneurysms of visceral arteries, a domain for which data remain limited.^(5,11,12)

Consistent with previous reports, inguinal and umbilical hernias were the most frequent AWH among patients with aneurysms.^(17,19-21) We also identified a remarkable proportion of HH, particularly among patients with hepatic, celiac trunk, and splenic artery aneurysms, suggesting a specific pattern of coexistence that deserves further investigation.

The pathophysiological mechanisms underlying this coexistence remain uncertain. Current evidence suggests that both aneurysms and hernias may share alterations in connective tissue metabolism, involving imbalances in collagen synthesis and degradation and overexpression of matrix metalloproteinases.^{(1,8-10,13,22,23)} These enzymes weaken the extracellular matrix and may affect both vascular and fascial integrity. In addition, environmental and systemic factors such as smoking, atherosclerosis, and aging likely contribute to their simultaneous occurrence.^(2,11,12)

Although our findings cannot establish causality, they emphasize that hernias are common among patients with aortic and visceral aneurysms, and that their coexistence may be more frequent than previously recognized. Awareness of this association may have clinical relevance, as the detection of a hernia in an older patient with vascular risk factors could prompt evaluation for possible aneurysmal disease. Similarly, the presence of hiatal or umbilical hernias in patients with known aneurysms may support a more comprehensive surgical and radiological approach.

This study had some limitations. It was based on a retrospective sample of convenience derived from existing CTA reports, without inclusion of a control group. Direct comparison with the general population was therefore not possible. Minor, reducible, or asymptomatic hernias may have been underreported, since data were obtained from finalized radiology reports without manual re-evaluation of images. The study population also represents a quaternary center, which may have led to selection bias toward more complex cases. Furthermore, demographic and clinical variables such as smoking, body mass index, or comorbidities were unavailable, precluding adjustment for potential confounders.

Despite these limitations, this study provides one of the largest descriptive analyses to date of hernia occurrence among patients with IAA, encompassing both aortic and visceral topographies. The high frequency of hiatal, umbilical, and inguinal hernias underscores the need for future prospective studies to confirm these findings and to clarify the biological and clinical mechanisms underlying this coexistence.⁽²⁴⁾

An ideal next step would be a prospective, multicenter case-control study including patients with and without IAA, with systematic and standardized radiological evaluation for hernias, detailed clinical data (including smoking status, body mass index, and comorbidities), and assessment of biochemical markers related to connective tissue remodeling, such as matrix metalloproteinases. Such a design would allow adjustment for confounding variables, more accurate prevalence estimates, and better exploration of potential shared pathophysiological mechanisms.

This study demonstrated a high frequency of abdominal and hiatal hernias among patients with intra-abdominal aneurysms, including both aortic and visceral topographies. The most frequent hernia types were hiatal, umbilical, and inguinal, showing a recognizable pattern of coexistence within this population.

Given the retrospective and descriptive design, these findings should be interpreted as hypothesis-generating rather than causal. These findings highlight a statistical association and should not be interpreted as indicating a causal relationship or as a risk-stratification tool in the absence of prospective, controlled studies. Nevertheless, they provide relevant insights into the distribution of hernias among patients with aneurysmal disease and highlight the need for prospective studies to further explore the biological and clinical mechanisms behind this association.