FMF Certification of Biochemical Laboratories
The requirements for certification are:
1. Compliance with the FMF Good Laboratory Guidelines (see below) and a signed
Declaration of Conformity to the GLP guidance.
2. Satisfactory laboratory Standard Operating Procedure (SOP) for prenatal screening.
3. Your UKNEQAS Laboratory number. This is to confirm satisfactory participation and
monitoring of your ongoing performance; it will be kept solely by the FMF Director of
Biochemical Screening (Prof Kevin Spencer) and will not be given to any other person
inside or outside of the FMF.
Full certification is conditional on the demonstration of acceptable audit results after six months.
Continued certification depends on acceptable external quality assurance performance and
participation in an annual FMF audit. Please note that with the new release of the FMF algorithms
the software will allow calculation of risks only if the operator holds the FMF Certificate of
competence in measurement of nuchal translucency thickness and has carried out regular annual
Recommendations for good laboratory practice
1. All laboratories must participate in the United Kingdom National External Quality
Assessment Service (UKNEQAS) scheme for First Trimester Downs Syndrome Screening.
The performance in this scheme must be such that the analytical bias from the Method
Mean for free ß-hCG and PAPP-A does not deviate by more than 10% on an ongoing basis.
Information on this Program can be obtained from:
UK NEQAS for Peptide Hormones
Clinical Chemistry Department
Edinburgh EH16 4SA
Phone: 44 131 242 6848
Fax: 44 131 242 6882
Web Page: www.ukneqas.org.uk/Directory/CC/dsfirst.htm
2. When appropriate laboratories should be accredited by the Clinical Pathology Accreditation
(UK) Ltd in the UK or by an equivalent body in other countries. Clinics who are not part of
an organised laboratory service providing combined screening using FMF approved
automated systems for the measurement of free ß-hCG and PAPP-A may be exempt from
this accreditation, but should employ an experienced laboratory person as an advisor.
1. Laboratories must ensure that whole blood is received within 48 hours of collection and
serum samples within 72 hours of collection. Measurement of free ß-hCG in samples
collected beyond these limits are unreliable.
2. The samples must be collected between 11 weeks 0 days and 13 weeks 6 days and
accompanied by the following information:
Patient Full name
Date of birth
History of previous trisomy
Blood Sample Date of collection
Ultrasound scan Date
Name of sonographer
Fetal crown – rump – length
Fetal nuchal translucency
Number of live fetuses
Analysis of samples and internal quality control
1. Laboratories must use analytical systems and assays for free ß-hCG and PAPP-A that are
supported by the manufacturer for the purpose of first trimester screening for Downs
syndrome and have proven clinical performance for this use. Please see below for Assay
Systems Specification. At present the FMF algorithm only supports both Kryptor analytical
platforms, Kryptor and Kryptor compact (www.kryptor.net) from Brahms
Aktiengesellschaft, Berlin (www.brahms.de), the PerkinElmer Manual Delfia, Auto Delfia
and Delfia Express analytical platforms (www.perkinelmer.com) and Roche Elecsys and
Cobas E analytical platforms (www.roche.com).
2. Laboratories should perform Internal Quality Control (QC) procedures with each batch of
samples analysed – or on a daily basis. Three level QC should be performed for free ßhCG
and PAPP-A and the between day coefficients of variation (CV) should be as follows:
free ß-hCG conc CV PAPP-A conc CV
Level 1 85 3.0 0.30 3.5
Level 2 20 3.0 1.50 3.5
Level 3 8 3.5 4.0 3.0
3. Prenatal screening laboratories should monitor the overall median MoM for Free ß-hCG
and PAPP-A on a monthly basis. This should be within the limits of 1MoM + 10%.
4. Prenatal screening laboratories should monitor the medians for individual completed weeks
on a 3 monthly basis to ensure they do not deviate from the expected values by more than
Calculation of risk
1. All risk calculations should only be performed using software approved by the Fetal
Medicine Foundation (see 'Registered Software' below) and all laboratories must ensure
that they only take nuchal translucency measurements from sonographers who hold the
FMF Certificate of Competence in the 11-13+6 weeks scan (see 'Certification in the 11-13+6
2. The percentage of total screened cases identified with a risk of 1 in 300 or greater should be
monitored on a monthly basis. The screen positive rate should be between 3% and 6%,
depending upon the age of the population being screened.
3. Laboratories should monitor the variability of the risk derived from a fixed maternal age,
fixed gestational age and fixed NT using results from the Level 1 and Level 2 controls. For a
target risk of 1 in 250 a 10% CV of the risk should be achievable.
4. Laboratories should follow up the outcome of all pregnancies screened or at least those
identified with a risk of 1 in 300 or greater.
Continuing audit and certification
1. Laboratories should supply the Fetal Medicine Foundation with regular audit data. Initially
this is done at six monthly intervals, but once satisfactory results have been demonstrated
will be carried annually.
2. Continued certification depends on acceptable external quality assurance performance and
participation in an annual Fetal Medicine Foundation audit.
3. Laboratories should analyse over 1000 screening samples per year for rigorous quality
Specifications for assay systems in order to meet FMF standards
1. Assays must be supported by the company for use in First Trimester Prenatal Screening.
2. Assays must be standardised against the relevant International Reference Preparation
(IRP) for Free Beta hCG and PAPP-A and be expressed in IU/L and in mass or molar units
3. Within day and between day %CV’s at the following concentrations must be demonstrable:
Free Beta hCG Within Day CV % Between Day CV %
85iu/l 3.0 5.0
20iu/l 3.0 5.0
8iu/l 4.0 6.0
PAPP-A Within Day CV % Between Day CV %
0.30iu/l 4.0 6.0
1.50iu/l 4.0 6.0
4.00iu/l 3.0 5.0
4. Performance must be assessed against both individual methods and the ALTM with the
UKNEQAS scheme for First Trimester Downs Syndrome Screening.
5. A Bias of less than +/- 10% from the ALTM must be demonstrable.
6. Assays should have a minimum working range without need for dilution of 150iu/l for Free
Beta hCG and 6.0iu/l for PAPP-A.
7. Recovery of IRP added to non pregnancy serum must be 100% +/-10% across the whole
8. Dilution recovery of high samples must be within +/-10% of the neat material.
9. Assays should have clearly defined performance in the presence of jaundice, haemolysis and
10. Performance in the presence of excess antigen (hook effect) must be clearly detailed.
11. Manufacturers should provide guidelines for the median levels at 11,12, 13, 14 weeks
gestation. A minimum of 150 samples at each gestational week must be analysed.
12. The manufacturer must provide the distribution parameters for the normal data set as
overall median MoM, log10 MoM and its standard deviation. In addition correlation of log
PAPP-A MoM with log Free Beta hCG MoM must be provided. Item 11 and 12 should be
provided from one single testing center.
13. The manufacturer should provide evidence of acceptable clinical performance of the assays
with a panel of sera from know cases of trisomy 21. A study in one center must comprise of
at least 50 cases of trisomy 21. The T21 cases must come from a routine first trimester
screened population. The manufacturer must state for each cases the reasons for diagnosis
and if identified pre or post delivery.
14. From the above population the manufacturer must provide the median MoM, the mean Log
MoM and its standard deviation and the correlation coefficient between log PAPP-A MoM
and log Free Beta hCG MoM.
15. Using the population parameters for the unaffected population and from the Trisomy 21
population the manufacturer must simulate the detection rate and false positive rate using a
standardised age population such as that in England & Wales (2000). A detection rate
better than 60% at a 5% false positive rate must be demonstrated. If the manufacturer
cannot provide such a simulation from an authoritative source then the raw data must be
made available to the FMF in order for this to be established.
16. The assay minimum detection limit and functional sensitivity should be described.
Further information on the Laboratory Certification process can be obtained from:
Prof Kevin Spencer
Director of Biochemical Screening
Fetal Medicine Foundation