Forest plot of meta-analysis of non-randomized studies

a Duration of operation. b Estimated blood loss. c Overall complication rate. d Clavien–Dindo grade I–II complication rate. e Clavien–Dindo grade III–V complication rate. f Duration of hospital stay. ND, no drain; PD, pelvic drain; IV, inverse-variance method; MH, Mantel–Haenszel method.