Open versus minimally invasive surgical techniques for displaced abomasum in dairy cattle: A systematic review and meta-analysis.

Minimally invasive surgery for abomasal displacement is reasonable, but survival and milk-yield benefits remain unconfirmed by RCT evidence.

This systematic review and meta-analysis compared open versus minimally invasive surgical (MIS) techniques for abomasal displacement (AD) in dairy cattle, evaluating mortality, recurrence, milk yield, complications, and operative time across 10 studies (3 RCTs, 7 nonrandomized) involving 2,900 cows. Using PRISMA guidelines and a random-effects model, pooled analysis across all studies found MIS associated with lower mortality (RR = 0.65; p = .001) and higher postoperative milk yield (MD = 1.76 kg/day; p < .00001) compared to open surgery. However, critical sensitivity analyses revealed significant limitations: the mortality advantage disappeared when restricted to RCTs only (RR = 1.27; p = .69), indicating the benefit was driven by nonrandomized studies with inherent selection bias. The milk yield advantage was similarly dependent on a single large observational study at serious risk of bias, though the directional effect persisted after exclusion. No statistically significant differences were identified for operative time, recurrence rates, or postoperative complication rates, though the recurrence estimate was unstable in sensitivity analyses. Notably, abomasal volvulus was excluded, limiting generalizability to that condition. The authors conclude that while MIS remains a clinically reasonable option for AD management, the evidence base is predominantly observational, and a definitive survival or production advantage over open techniques cannot yet be considered established without higher-quality RCT data.

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