BACKGROUND Haemorrhage follows surgical intervention, but also fluid substitution may affect the blood loss. Here influence of colloids and lactated Ringer's solution (LR) on coagulation competence and haemorrhage is evaluated during cystectomy. METHODS A meta-analysis, a prospective observational study and three randomized controlled trials were conducted - 17 patients received HES 130/0.4, 19 patients Dextran 70, 19 patients human albumin,
and 54 patients LR - with blinded evaluation of blood loss and outcome while coagulation competence was evaluated by thromboelastography (TEG) and plasma coagulation analyses. RESULTS Administration of HES reduced TEG determined "maximal amplitude" (TEG-MA) from 64+/-6 to 52+/-7 mm associated with a 2181+/-1190 mL blood loss. For Dextran values were 65+/-7 to 49+/-9 mm and 2339+/-1471 mL, respectively, for albumin 62+/-6 to 59+/-6 mm and 1658+/-684 mL compared to 65+/-6 to 64+/-6 mm and 1559+/-976 mL with the use of LR. Furthermore, reduced TEG-MA was independently associated with the perioperative blood loss. A straight postoperative course was seen less often after infusion of synthetic colloids versus albumin/LR (7/36 vs. 31/73), P=0.02. CONCLUSIONS Perioperative bleeding is related to administration of Dextran 70 followed by HES 130/0.4 whereas albumin and LR result in a similar low level of haemorrhage. Furthermore, evaluation of coagulation competence by TEG-MA appears superior to plasma coagulation analyses for predicting the perioperative blood loss and supports that haemorrhage depends not only on the surgical intervention but also on the perioperative fluid therapy of apparent consequence for outcome.