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:
- Insufficient blood or not filling all circles may mean
there is not enough sample to repeat tests or perform
additional tests (see Figure 2).
- Milking or squeezing the puncture site can cause haemolysis
and mixing of tissue fluids with blood.
- 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.
- 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.
- 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
- Placing the sample in a plastic bag causes sweating
and promotes bacterial growth.
See also Simple Spot Check (courtesy of Whatman, GE HealthCare).