Risk factors for inguinal hernia in women: a case-control study. The Coala Trial Group.

Potential risk factors for inguinal hernia in women were investigated and the relative importance of these factors was quantified. In women, symptomatic but nonpalpable hernias often remain undiagnosed. However, knowledge on this subject only concerns hernia and operation characteristics, which have been obtained by review of case series. Virtually nothing is known about risk factors for inguinal hernia. The authors performed a hospital-based case-control study of 89 female patients with an incident inguinal hernia and 176 age-matched female controls. Activity since birth with two validated questionnaires was measured and smoking habits, medical and operation history, Quetelet index (kg/m2), and history of pregnancies and deliveries were recorded. Response for cases was 81% and for controls 73%. Total physical activity was not associated with inguinal hernia (univariate odds ratio (OR) = 0.8, 95% confidence interval (CI) 0.6-1.1), but high present sports activities was associated with less inguinal hernia (multivariate OR = 0.2, 95% CI 0.1-0.7). Obesity (Quetelet index > 30) was also protective for inguinal hernia (OR = 0.2, 95% CI 0.04-1.0). Independent risk factors were positive family history (OR = 4.3, 95% CI 1.9-9.7) and obstipation (OR = 2.5, 95% CI 1.0-6.7). In particular, smoking, appendectomy, other abdominal operations, and multiple deliveries were not associated with inguinal hernia in females. The protective effect of present sports activity may be explained by optimizing the resistance of the abdominal musculature protecting the relatively small inguinal weak spot in the female. The individual predisposition for inguinal hernia may be quantified by these risk factors, and, with this in mind, the authors advise that further evaluation might be needed for the patient with unexplained inguinal pain.