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The aim of fluid resuscitation is to increase stroke volume, yet this effect is observed in only 50% of patients. Prediction of fluid responsiveness may allow fluid resuscitation to be administered to those most likely to benefit. The aim of this study was to systematically review the test characteristics of respiratory variation in inferior vena cava (IVC) diameter as a predictor of fluid responsiveness in patients with acute circulatory failure.Electronic searches combined with reference review of identified studies. Prospective observational studies of all patient groups and ages that used a recognized reference standard, stratified participants into fluid responders and fluid non-responders, and used summary statistics to describe their results were selected for inclusion. Study design, size, setting, patient population, use of mechanical ventilation and tidal volume, definition of fluid responsiveness, fluid challenge strategy, and summary statistics were abstracted. Quality assessment was performed using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) domains.Seventeen studies involving 533 patients were included, in whom 253 (47%) were fluid responders. The pooled sensitivity and specificity for a positive IVC ultrasound as a predictor of fluid responsiveness were 0.63 (95% confidence interval [CI]: 0.56–0.69) and 0.73 (95% CI: 0.67–0.78), respectively, with a pooled area under the receiver operating characteristic curve of 0.79 (standard error 0.05). In subgroup analysis, respiratory variation in IVC diameter was a better predictor of fluid responsiveness in mechanically ventilated patients.Respiratory variation in IVC diameter has limited ability to predict fluid responsiveness, particularly in spontaneously ventilating patients. A negative test cannot be used to rule out fluid responsiveness. Clinical context should be taken into account when using IVC ultrasound to help make treatment decisions.