Background There is no perfect method to assess level of dehydration in children. There are studies with conflicting results, where point-of-care ultrasound (POCUS) measurement of diameter ratio of the inferior vena cava to the aorta (IVC/Ao) was used to predict degree of dehydration.

Objective To systematically review the diagnostic accuracy of POCUS measurement of IVC/Ao ratio in predicting dehydration in children.

Methods MEDLINE, EMBASE and Cochrane databases were searched. The primary outcome was the diagnostic accuracy of IVC/Ao ratio. The pooled sensitivity and specificity were calculated. Quality analysis was conducted using Quality Assessment of Diagnostic Accuracy Studies-2.

Results Eleven studies (2679 patients) were included. The most numerous group (five studies) used percentage weight change as a reference standard; the pooled sensitivity, specificity of POCUS in this group were: 0.7 (95% CI: 0.67 to 0.73), I²: 82%; 0.53 (95% CI: 0.5 to 0.53), I²: 84%. In the remaining studies, different comparator tests were used: Clinical Dehydration Scale (two studies, 0.8 (95% CI: 0.72 to 0.86), I²: 0%; 0.56 (95% CI: 0.48 to 0.65), I²: 0%; clinical judgement (three studies, 0.78 (95% CI: 0.73 to 0.83), I²: 95%; 0.82 (95% CI: 0.77 to 0.86), I²: 93% and one study used the Dehydration: Assessing Kids Accurately score model.

Conclusion This systematic review and meta-analysis showed that POCUS has a moderate sensitivity and specificity for identifying dehydration in children. Its use as a complementary diagnostic tool could be promising but needs to be validated in randomised controlled trials.

PROSPERO registration number CRD42022346166.