Surgery · Medical Literature
Prophylactic mesh reinforcement at emergency midline laparotomy: a systematic review and meta-analysis with pre-specified subgroup analysis of contaminated and dirty abdominal wounds (CDC Class III-IV).
Abstract
To evaluate the efficacy and safety of prophylactic mesh reinforcement (PMR) at the closure of emergency midline laparotomy (EML), with a pre-specified subgroup analysis of contaminated and dirty wounds (CDC class III-IV). PRISMA 2020-compliant review (PROSPERO CRD420261324766; OSF 10.17605/OSF.IO/ZX2BG; amendments registered before data extraction). PubMed/MEDLINE, Embase, Cochrane CENTRAL, Scopus and Web of Science were searched (January 2015-March 2026). RCTs and comparative cohort studies reporting incisional hernia (IH) at ≥ 12 months were eligible; bias was assessed with ROB-2/ROBINS-I. Random-effects meta-analysis used the REML estimator with Hartung-Knapp-Sidik-Jonkman correction. A pre-specified Borenstein interaction test compared CDC class I-II with III-IV; trial sequential analysis (TSA) and GRADE were applied. Five studies (4 RCTs; 1 cohort; n = 617) were included. PMR was associated with a reduction in IH (pooled OR 0.221, 95% CI 0.122-0.402 [Knapp-Hartung]; 0.101-0.483 under the conservative truncated variant; I2 = 0%); because control-arm event rates exceeded 10%, this corresponds to an approximate RR of ~ 0.36 (0.28-0.38). The RCT-only analysis was concordant (OR 0.179, 95% CI 0.074-0.435). TSA gave an accrued information size of 617 versus a required ~ 151 (409%), interpreted only as numerical sufficiency, not firm evidence. The CDC interaction was non-significant and underpowered (z = 0.327, p = 0.743). Seroma was significantly increased (k = 4; OR 3.980, 95% CI 1.924-8.234; 1.06-14.94 under the conservative variant), whereas deep SSI was non-significant and underpowered (OR 0.991). LOW to VERY LOW. PMR at EML closure was associated with a consistent IH reduction across CDC classes; however, contaminated-wound evidence is sparse, the subgroup interaction is exploratory, non-significant and underpowered, and the safety profile - particularly deep SSI - remains uncharacterized. Seroma was significantly increased. Given LOW-VERY LOW certainty, these hypothesis-generating findings should not change practice and support an adequately powered multicentre RCT in CDC class III-IV wounds. PROSPERO CRD420261324766 (registered 23 February 2026); OSF Registries https://doi.org/10.17605/OSF.IO/ZX2BG .
Clinical relevance
Incisional hernia (IH) following emergency midline laparotomy (EML) represents a significant source of postoperative morbidity, yet evidence-based closure strategies — particularly prophylactic mesh reinforcement (PMR) — remain poorly defined in urgent and contaminated operative settings. This systematic review and meta-analysis specifically addresses the underexplored subpopulation of CDC Class III–IV (contaminated and dirty) abdominal wounds, where mesh use has historically been avoided due to infection concerns. With EML volumes remaining high globally and IH rates after emergency laparotomy reported to exceed 30–40%, surgeons need current, stratified evidence to guide intraoperative decision-making.
Key findings
1. PMR at EML closure was associated with a statistically significant reduction in IH formation: pooled OR 0.221 (95% CI 0.122–0.402, Knapp-Hartung correction; conservative truncated variant 95% CI 0.101–0.483), with zero statistical heterogeneity (I² = 0%). 2. Given control-arm event rates exceeding 10%, the OR approximates a relative risk of ~0.36 (95% CI 0.28–0.38), indicating roughly a 64% relative reduction in IH with PMR versus primary suture closure. 3. The RCT-only sensitivity analysis (4 RCTs) was concordant with the primary result: OR 0.179 (95% CI 0.074–0.435), reinforcing internal consistency of the IH benefit signal. 4. Trial sequential analysis (TSA) demonstrated an accrued information size of 617 patients versus a required information size of ~151 (409% of required), interpreted as numerical sufficiency but explicitly not as firm confirmatory evidence by the authors. 5. Seroma formation was significantly increased with PMR: OR 3.980 (95% CI 1.924–8.234; conservative variant 95% CI 1.06–14.94; k = 4 studies), representing a clinically important wound morbidity signal. 6. The pre-specified CDC Class III–IV subgroup interaction test was non-significant and underpowered (z = 0.327, p = 0.743), and deep surgical site infection (SSI) with PMR was non-significant and uncharacterized (OR 0.991), leaving the safety profile in contaminated wounds unresolved. Overall GRADE certainty was rated LOW to VERY LOW.
Practice implications
Despite a numerically consistent IH reduction signal, the LOW to VERY LOW GRADE certainty rating means these findings should be considered hypothesis-generating only and should not prompt a change in current practice regarding routine PMR use at EML closure, particularly in CDC Class III–IV contaminated or dirty wounds where deep SSI risk with mesh remains uncharacterized. Surgeons should note that seroma is a statistically and clinically significant complication of PMR (OR ~4.0), which must factor into patient counseling and postoperative monitoring protocols when PMR is considered in elective or trial contexts. An adequately powered, multicentre RCT specifically enrolling CDC Class III–IV emergency laparotomy patients is urgently needed before PMR can be endorsed or contraindicated in contaminated fields; enrollment of such patients into prospective registries or existing trials should be prioritized.