Newborn Blood Spot
Explaining repeat blood spot screening samples to
parents
Information sheet for health professionals November 2013 (v1.1)
Occasionally the newborn screening laboratories need to ask for a repeat blood spot
sample. This can be for a variety of reasons, and a repeat sample must be taken as soon as
possible or as directed by the laboratory.
‘Avoidable repeat’ samples are required when there is something unacceptable with either
the card or the blood sample on the card (e.g. missing information, inadequate sample).
‘Unavoidable repeat’ samples are usually requested for clinical reasons (e.g. borderline or
inconclusive result).
This information sheet has been developed to assist health professionals when you have
been requested to take a repeat blood spot sample. It is important that parents are fully
informed of why the repeat is required as research has shown that parents who are told the
true reason for the repeat sample feel more satisfied with the screening process [1].
Parents should be told the reason for a repeat sample. Your communication should include:
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The reason you have been asked to take a second blood spot
A repeat blood spot card is required so that the screening test can be completed
When the parents can expect to receive the result
Whom to contact if they do not receive the result
If there is thought to be any problem with their baby they will be contacted as soon as
the result is available
If the family has changed address and no longer lives in your area you should handover this
request to the responsible health professional according to local procedures (including
copies of any ‘request for repeat sample’ documentation). It is essential to also inform the
screening laboratory that you have been unable to complete the screening and provide any
contact information. This must be done immediately.
When completing the blood spot card, ensure that the ‘repeat sample’ box is ticked on the
card and the reason for the repeat sample is entered into the comments box.
Avoidable repeats
A good quality blood spot sample is one that is taken at the right time, contains sufficient
blood to perform all tests, is despatched to the laboratory in a timely manner
and has not been contaminated.
Public Health England is responsible for the NHS Screening Programmes
Parents can expect to receive the result by the time their baby is 6 – 8 weeks old, either by
letter or via the health visitor. If the baby screens positive for a condition the parents will be
contacted sooner.
Avoidable repeats are requested when the previous sample was either:
 An insufficient sample
 An unsuitable sample
 Taken when the baby was too young
Insufficient samples
This is when there is:
 Not enough blood on the card, e.g. the blood spot has not soaked through to the
back of the card, therefore the laboratory cannot analyse to ensure an accurate result
 Compression of the blood spot. Applying pressure to the spot to try to spread the
blood to fill out the circle reduces the density of blood on the sample and can lead to
a ‘suspected’ result being missed as the blood is spread too thinly
Unsuitable samples
This is when there is an issue with the card:
 Layering of blood. This is when more blood has been dropped on top of another
blood spot and may lead to an invalid result
 Incorrect or incomplete labelling of the sample, e.g. no date of sample recorded, no
date of birth. All data is required by the laboratory to ensure correct interpretation of
the results, the baby has had the sample taken at the correct age, any necessary
follow-up arranged and the result can be returned to the parent
 No NHS number (or UK equivalent) on the card. This is a mandatory requirement in
England. The NHS number is the unique identifier for every baby, and is very
important for blood spot screening as many babies either are un-named or change
their names within the first few weeks of life. If a baby is nursed away from their
home hospital or are visiting family at the time of screening, the address may delay
the result being returned to the correct child health record department
If you do not have the NHS number, it can usually be obtained from any of the
following:
- Child health record departments
- Newborn hearing screeners
- GP practice
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Bar-coded label not complete. This can be due to misalignment of the label printer or
some of the information being missing. With an incomplete label the laboratory is
unable to confirm the identity of the baby
Delay in laboratory receiving the sample. The sample must be posted on the day it
was taken (or within 24 hours) to ensure the laboratory receives the sample as soon
as possible. Laboratories will reject samples if received 14 or more days after the
sample was taken
Contamination of the sample card. This can be with faeces from the baby’s foot, from
laying the card on a wet surface, and very rarely with blood not from the baby.
Contamination may lead to an invalid result
Taken when the baby was too young
This is when a sample is taken before the baby is five days old. This may give rise to a falsepositive result for congenital hypothyroidism. It is imperative that the baby’s age is calculated
using the day of birth as day 0. Sample takers should be aware that some IT systems record
the day of birth as day 1, and this may result in the sample being taken too early.
Unavoidable repeats
Repeat samples may be required from a few babies due to:
 Prematurity
 Borderline thyroid stimulating hormone (TSH) results
 Inconclusive cystic fibrosis (CF) screening
 Blood transfusions
When a parent is informed that a repeat sample is required they may be very anxious and
concerned that their baby is at an increased risk of one of the conditions, and you must be
able to clearly explain the reason for the repeat sample to allay their anxiety.
Parents will receive the result as soon as it is available, either via a letter or from the health
visitor. The results are usually available within 14 days after taking the sample (although
every effort is made to complete the test and release the result within 7 days). It is important
that parents/families are reassured about normal results for the other screening tests as
soon as possible.
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Prematurity. Prematurity can mask congenital hypothyroidism (CHT), so babies born
at less than 32 weeks (equal to or less than 31 weeks + 6 days) require a second
blood spot sample to be taken in addition to the day 5 sample. These babies are to
be tested when they reach 28 days of age or on the day of discharge home from the
hospital specialist unit, whichever is the sooner. This is to ensure a valid sample for
CHT screening is obtained. Fill two circles on the card with blood and mark the card
‘CHT preterm’.
The explanation to be given to parents is that in babies born at less than 32 weeks
of pregnancy, the routine day 5 test may not pick up congenital hypothyroidism. It is
advised to have another test at either 28 days of age or immediately before the
baby is discharged home, whichever comes first.
Prematurity can also mask sickle cell disease (SCD), therefore some very premature
babies who show no haemoglobin A (HbA) need repeat testing to check for the
presence of sickle cell disease. This is to ensure all babies have a valid screen for
SCD
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Borderline thyroid stimulating hormone (TSH) results. This is when the result is
unclear or borderline for congenital hypothyroidism (CHT). Another sample is
required to confirm the result. The repeat sample should be collected urgently, but an
interval of 7 days after the first blood spot sample was collected is required to allow
time for the TSH levels to normalise.
Fill four circles on the card with blood and the blood spot card should be marked as
‘CHT borderline’.
There are two possible outcomes from this repeat test and parents must be made
aware of them:
1.
Normal – CHT not suspected. In this case the midwife/health visitor should
inform the baby’s parents directly and as soon as possible to relieve anxiety
(this can be by telephone). A normal result requires no further action
2.
CHT suspected – If CHT is suspected (this is an unlikely outcome) then the
baby will be referred by the newborn screening laboratory directly to a
paediatrician. If the result is another ‘borderline’ then the baby will also be
referred
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Inconclusive for cystic fibrosis (CF). This is when the result of the initial blood spot
screening test for CF immunoreactive trypsinogen (IRT) is inconclusive and requires
follow up. A repeat blood spot sample is therefore required so that the screening test
can be completed. This further (second) blood spot sample should to be collected
when the baby is between 21 and 28 days of age, ideally as close to 21 days as
possible. If the baby is already more than 28 days of age the repeat blood spot card
should be collected as soon as possible. The blood spot card should be marked as
‘Second IRT’.
However, if the baby is already more than 8 weeks of age (56 days) the repeat blood
spot card should not be collected. In this situation inform the screening laboratory
immediately so that appropriate arrangements can be made for the baby to be
followed up. There are three possible outcomes from this repeat test and parents
must be made aware of them:
1.
The repeat test will be normal and there is no need for further follow up
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2.
The baby is a healthy carrier of cystic fibrosis and will not need any further
follow up – however a health professional will visit the family to discuss the
result
3.
There is a small possibility that the baby may be affected with cystic fibrosis in
which case the baby will be referred by the newborn screening laboratory
directly to a CF specialist
Blood transfusions. When a baby has had a blood transfusion, in the newborn period,
before the day 5 blood spot, another sample (four circles) is needed 72 hours (3
days) after the last blood transfusion. This is to enable the metabolite concentrations
to return to pre-transfusion levels. The date of the last blood transfusion before the
blood spot must be recorded on the card and on discharge / transfer notifications
When taking a repeat sample, you should follow the Guidelines for Newborn Blood Spot
Sampling 2012, available at www.newbornbloodspot.screening.nhs.uk/bloodspotsampling.
The NHS Newborn Blood Spot Screening Programme monitors the avoidable sample rates.
It is expected that the avoidable repeat rate is less than or equal to 2% (i.e. one in fifty
samples), but health professionals should be aiming to achieve a rate of equal to or less
than 0.5% (i.e. one in two hundred samples).
To support health professionals, the programme has developed several resources, including
Guidelines for Newborn Blood Spot Sampling 2012, an ‘interactive newborn blood spot card’
and a short film on how to take a good quality sample. These resources, and more
information to support you when taking a blood spot sample, can be found at
www.newbornbloodspot.screening.nhs.uk/professionals.
1.
Kai, J., et al., Communication of carrier status information following universal
newborn screening for sickle cell disorders and cystic fibrosis: qualitative study of
experience and practice. Health Technol Assess, 2009. 13(57): p. 1-82, iii.