Assessment of the accuracy of blood drawn from peripheral venous cannula used for infusing intravenous fluids/ drugs versus direct venepuncture to analyse full blood counts in febrile children.

Introduction: Blood sampling is a common occurrence in current paediatric practice. Dengue and other febrile illnesses are the main disease entities attributable to admissions. These admissions warrant repeated blood sampling especially with regard to full blood counts. Repeated direct pricking for sampling or having an in-situ cannula for bleeding purposes both have their own disadvantages and undesirable effects.

Objectives: Compare the accuracy of parameters of full blood count of a blood sample taken from a cannula in use against a full blood count from a direct prick.

Method: Nine parameters of the full blood count were compared in 38 paired blood samples from each subject of a cohort of febrile children aged 1-14 years admitted to Professorial Paediatric Unit of Colombo South Teaching Hospital, Kalubowila, Sri Lanka. Samples were taken when medically indicated only.

Results: The mean values of MCV and MCHC from direct venepuncture vs cannula sample were statistically different. Other parameters did not show a statistically significant difference between the samples collected by the two methods.

Conclusion: Blood sampling from a cannula in use for intravenous fluids or medications is favourable for majority of parameters of the full blood count and an advantageous alternative for fresh venepuncture bleeding in febrile children.