Prenatal Diagnosis

Description: 
Prenatal diagnosis is offered to couples at risk of having a fetus affected by:

Sickle cell disease including Hb SS, Hb SC, Hb Sβ thalassaemia, Hb S/D-Punjab, Hb S/O-Arab, Hb S/Lepore

Beta thalassaemia major

Beta thalassaemia/delta beta thalassaemia

Beta thalassaemia/Hb Lepore

Beta thalassaemia/Hb E

Hb Barts Hyrops Fetalis

Hb Lepore/delta beta thalassaemia

Hb Lepore homozygous
Clinical details: 
Factors affecting results or interpretation: Fetal samples contaminated with maternal blood are at risk of giving false results.

Presence of heparin anticoagulant will inhibit PCR applications.

Samples must be clearly labelled with the patients first name, surname, D.O.B, hospital number and the date the sample was taken. The details on the sample must correspond to the request form. Unlabelled samples will not be accepted.

CVS samples must be cleaned by a cytogenetics department prior to sending.

A signed consent form must accompany the sample. Failure to do so will delay sample processing and reporting.
Sample type and Volume required: 
Prenatal diagnosis are performed on either chorionic villi, amniotic fluid or fetal blood depending on the gestational age of the fetus:

Chorionic villus sampling (CVS) 9-16 weeks

Samples should be sorted at source in order to remove all maternal deciduas prior to placing into RPMI media containing streptomycin, nystatin and fetal calf serum.

Amniotic fluid 16-18 weeks

20 ml of amniotic fluid should be taken and divided between two sterile universals. Approximately 10 ml should be referred to a cytogenetics laboratory for karyotyping and culture. The cultured cells serve as a back up in the event that DNA analysis fails to give a clear result. The remaining 10 ml should be sent directly to the PND Unit for DNA analysis.

Fetal blood sampling 18+ weeks

2 ml of blood anticoagulated with EDTA is required.

All fetal samples MUST be accompanied with maternal and paternal blood samples anticoagulated with EDTA (10-15 mls), which will be tested alongside the fetal sample.

Consent forms for DNA testing must be provided with the samples. Testing will not take place without these.

Please contact the PND unit prior to performing fetal sampling.
Turnaround time: 
3 working days if mutations have been identified. Where mutations are unknown or the partner is unavailable testing will take up to 5 days.
Storage and transport: 
All samples for prenatal diagnosis should be sent at room temperature, ideally to arrive at King’s within the same day of sampling. If this is not possible the sample should be stored at 4°C overnight and then sent immediately the next working day at room temperature. If possible, please complete the request form attached and send as a hard copy (do not send electronically) with the sample. This will ensure all relevant information is available and will aid us in processing your test.
Cost: 
Please contact Business Development for pricing enquiries
Time limit for extra tests: 
5 years
Contacts:
Red Cell Centre - Molecular Diagnostics Laboratory
020 3299 1246 / 2265
kch-tr.pnd@nhs.net
c/o Central Specimen Reception
Blood Sciences Laboratory
Ground Floor Bessemer Wing
King’s College Hospital
Denmark Hill
London SE5 9RS
Mon-Fri, 9.00am-5.30pm
For clinical advice or interpretation of results, please contact the laboratory in the first instance.

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Last updated: 08/01/2020