Abstract The purpose of this study is to evaluate the reliabil-ity of volume-based fluid balance monitoring in operative hysteroscopy. The actual volume of twenty 3-litre Glycine 1.5 % bags was measured by weighing the contents of each bag and by converting the weight into volume knowing the specific gravity of Glycine 1.5%. The volume of the Serres OY suction canisters that represents the output volume was mea-sured using a calibrated 1000-ml beaker. The volume in the 3-litre Glycine 1.5%bags ranged froma minimum3105ml to a
maximum of 3124 ml with a mean volume of 3115.3 ml. The actual volume of fluid in the Serres OY suction canisters con-taining the plastic liner when the reading is 500 ml was
425 ml, at 1000 ml, it was 900 ml, and at 2000 ml, it was 1850ml. Therefore, a measured 3-litre outflow would have an actual volume of 2750 ml. It is concluded that volume-based
fluid monitoring is not a reliable method in operative hyster-oscopy. Therefore, weight-based fluid management systems should be used to ensure patient safety and prevent fluid
overload.