Investigation into the Effects of Dried Blood Spot Quality on Newborn Blood Spot Screening Results and Recommendations for an Effective Sample Acceptance Criteria for Scotland

Abstract

Repeating newborn blood spot samples causes anxiety for parents, therefore, the requirements for repeating samples must be kept to a minimum. The most common reason for repeating samples is because the original sample was poor quality and may not give accurate results.
To understand why poor quality samples occur, midwives were interviewed to understand the barriers to producing good quality blood spots. Additionally, the consequence to the analyte levels recovered from blood spot samples were investigated in three ways; using historical data, using laboratory manufactured samples, and using samples received by the Scottish Newborn Screening Laboratory.
The results showed that midwives understand how to take a good quality blood spot, but poor blood flow can mean this is not possible, therefore poor quality samples will always occur. Poor quality samples have a predictable consequence to analyte levels, with small blood spots and compressed blood spots reducing analyte levels, whilst layered samples, samples where blood is applied to both sides of the card, and large blood spots cause increased levels. The outcome to multi-spotted samples could not be predicted. One major factor that influenced analyte levels was the haematocrit of the blood. The newborn screening programme is required to be effective for all babies regardless of the haematocrit of the blood, and the most effective way to ensure the analyte level was accurate at different haematocrit levels was to ensure the blood spot size was 10mm in diameter.
Sample acceptance criteria appropriate for the current screens performed in Scotland are: samples that reduce analyte levels (small spots and compressed spots) or those where the consequence to the analyte level cannot be predicted (multi-spotted samples) should be repeated, and those that increase results (layered spots, large spots and where blood is applied both sides of the filter paper) do not need repeating.

Date of Award	2 Mar 2025
Original language	English
Awarding Institution	University of Portsmouth
Supervisor	Simon Kolstoe (Supervisor) & Suzannah Helps (Supervisor)