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Child and Adolescent Health Service

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Princess Margaret Hospital

WA Newborn Screening Program

When the screening laboratory receives an unacceptable sample it must request a second sample to ensure the reliability of the test results. Poor quality samples cause unnecessary trauma to the infant (and parents), potentially delay the detection and treatment of an affected infant, and could contribute to a missed case. You have a vital role to ensure reliable samples are collected.

Common sampling problems include:

  1. Insufficient blood or not filling all circles may mean there is not enough sample to repeat tests or perform additional tests (see Figure 2).
  1. Milking or squeezing the puncture site can cause haemolysis and mixing of tissue fluids with blood.
  1. Layering or applying successive drops of blood (double collection) in the same printed circle causes caking and/or non-uniform concentrations of blood. If blood flow diminishes, such that circles are not completely filled, then repeat the sampling technique in a new circle.
  1. Contamination of the sample during collection, drying, or mailing with water, milk, antiseptic solutions, alcohol, urine, meconium, talc, or soaps, etc may interfere in the testing and render the results unreliable.
  1. Inadequate or inappropriate drying
    • Humidity and moisture adversely affect the quality of sample and analyte recovery.
    • Excess heat or sunlight bakes the sample.
    • Excess cold leads to separation of red blood cells and serum.
    • Placing the sample in a plastic bag causes sweating and promotes bacterial growth.

Figure 2

See also Simple Spot Check (courtesy of Whatman, GE HealthCare).

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