Risk Factors for Incarceration in Patients with Primary Abdominal Wall and Incisional Hernias: A Prospective Study in 4472 Patients

_Background_ Incarceration of primary and incisional hernias often results in emergency surgery. The objective of this study was to evaluate the relation of defect size and location with incarceration. Secondary objectives comprised identification of additional patient factors associated with an incarcerated hernia. _Methods_ A registry-based prospective study was performed of all consecutive patients undergoing hernia surgery between September 2011 and February 2016. Multivariate logistic regression was performed to identify risk factors for incarceration. _Results_ In total, 83 (3.5%) of 2352 primary hernias and 79 (3.7%) of 2120 incisional hernias had a non-reducible incarceration. For primary hernias, a defect width of 3–4 cm compared to defects of 0–1 cm was significantly associated with an incarcerated hernia (OR 2.85, 95% CI 1.57–5.18, p = 0.0006). For incisional hernias, a defect width of 3–4 cm compared to defects of 0–2 cm was significantly associated with an incarceration (OR 2.14, 95% CI 1.07–4.31, p = 0.0324). For primary hernias, defects in the peri- and infra-umbilical region portrayed a significantly increased odds for incarceration as compared to supra-umbilical defects (OR 1.98, 95% CI 1.02–3.85, p = 0.043). Additionally, in primary hernias age, BMI, and constipation were associated with incarceration. In incisional hernias age, BMI, female sex, diabetes mellitus and ASA classification were associated with incarceration. _Conclusion_ For primary and incisional hernias, mainly defects of 3–4 cm were associated with incarceration. For primary hernias, mainly defects located in the peri- and infra-umbilical region were associated with incarceration. Based on patient and hernia characteristics, patients with increased odds for incarceration may be selected and these patients may benefit from elective surgical treatment