BACKGROUND: Severe dengue is a leading cause of serious illness and death, and intensive supportive care is the most important aspect of management. Before fluid resuscitation, a baseline hematocrit is obtained, and frequent monitoring of the complete blood count is needed.

OBJECTIVE: To determine the correlation of ultrasound measurement of inferior vena cava (IVC) to aorta (Ao) diameter ratio with hematocrit levels and severity of shock among children with dengue fever.

METHODOLOGY: This is a prospective study design conducted at the Emergency Room of Philippine Children's Medical Center. Clinical data and hematocrit of the children with dengue fever aged 1 month to 17 years and 364 days old were documented. The Inferior vena cava diameter (IVC)and the Aorta (Ao) diameter ratio was determined using bedside ultrasound.

 RESULTS: The IVC/Ao diameter ratio correlates with high hematocrit and dengue shock in children. There is a significantly higher proportion of subjects with a hematocrit of normal range of age among those with a ratio 1.0.  A ratio of severity of Dengue illness. Sensitivity of IVC/Ao diameter ratio of Measurement of IVC/Ao diameter ratio has high interrater and intrarater reliability.

CONCLUSION AND RECOMMENDATION: IVC/Ao diameter ratio was significantly associated with severity of dengue illness. It should be used to aid decision?making and monitor response to treatments in dengue fever.