Résumé : Background: Gynaecological laparoscopic surgery outcomes can be compromised by the formation of de novo adhesions. This randomized, double-blind study was designed to assess the efficacy and safety of 4 icodextrin solution (Adept ®) in the reduction of de novo adhesion incidence compared to lactated Ringers solution (LRS). Methods: Patients undergoing laparoscopic surgery for removal of myomas or endometriotic cysts were treated with randomized solution as an intra-operative irrigant and 1l post-operative instillate. De novo adhesion incidence (number of sites with adhesions), severity and extent were independently scored at a second-look procedure and the efficacy of the two solutions compared. The effect of surgical covariates on adhesion formation was also investigated. Initial exploratory analysis of individual anatomical sites of clinical importance was progressed. Results: Of 498 patients randomized, 330 were evaluable (160 LRS 75 myomectomy/25 endometriotic cysts; 170 Adept 79 myomectomy/21 endometriotic cysts). At study completion, 76.2 LRS and 77.6 Adept had <1 de novo adhesion. The mean (SD) number of de novo adhesions was 2.58 (2.11) for Adept and 2.58 (2.38) for LRS. The treatment effect difference was not significant (P=0.909). Assessment of surgical covariates identified significant influences on the mean number of de novo adhesions regardless of treatment, including surgery duration (P 0.048), blood loss in myomectomy patients (P=0.019), length of uterine incision in myomectomy patients (P < 0.001) and number of suture knots (P < 0.001). There were 15 adverse events considered treatment-related in the LRS patients (7.2) and 18 in the Adept group (8.3). Of 17 reported serious adverse events (9 LRS; 8 Adept) none were considered treatment-related. Conclusions: The study confirmed the safety of Adept in laparoscopic surgery. The proportion of patients with de novo adhesion formation was considerably higher than previous literature suggested. Overall there was no evidence of a clinical effect but various surgical covariates including surgery duration, blood loss, number and size of incisions, suturing and number of knots were found to influence de novo adhesion formation. The study provides direction for future research into adhesion reduction strategies in site specific surgery. © 2011 The Author Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved.