Prenatal
Prenatal testing
The Synnovis Genetics laboratory at Guy’s Hospital is the hub laboratory of the SE GLH.
For accredited tests refer to the UKAS website here UKAS: Search Accredited Organisations – UKAS number 8688. The laboratory works closely with Clinical Services throughout Guy’s and St Thomas’ NHS Foundation Trust (GSTT) and St George’s Hospital Foundation Trust. With our partner laboratories, the SE GLH provides a comprehensive genetics service for a population of 8 million.
In addition, the laboratories receive a large number of national and international referrals for an increasing number of highly specialised genetic tests.
As well as providing a comprehensive diagnostic service, the Synnovis Genetics Laboratory has an active research and development programme. The laboratory works collaboratively with other groups such as GSTT Biomedical Research Centre, GSTT Genetics Innovation Unit and the GSTT Assisted Conception Unit for Preimplantation Genetic Diagnosis.
Tests offered
QF-PCR rapid aneuploidy detection for chromosomes 13, 18, 21. Testing for sex chromosome aneuploidy if clinically indicated. Commonly requested indications include:
- R401.1 Common aneuploidy testing – prenatal
- R320.1 Invasive prenatal diagnosis requiring fetal sexing
- R22.1 Fetus with a likely chromosomal abnormality – PCR
- R21.1 Fetal anomalies with a likely genetic cause – PCR
Targeted G-banded karyotype follow-up of abnormal PCR results.
More information about this QF-PCR testing is available on the Synnovis website.
Array analysis if clinically indicated (e.g. NT >3.5mm before 14 week gestation, nuchal fold >6mm between 14-20 week gestation, fetal ultrasound anomalies). Commonly requested indications include:
- R22.2 Fetus with a likely chromosomal abnormality – microarray
- R21.3 Fetal anomalies with a likely genetic cause – microarray
More information about this array testing can be found on the Synnovis website.
PND targeted analysis for carriers of balanced chromosome rearrangements or known familial imbalances where clinically indicated.
Cell culture and DNA extraction for indicated monogenic disorder testing and/or fetal whole exome sequencing [WES]. Some monogenic tests, and all cases referred for fetal WES, will require DNA to be sent to another GLH for testing.
- R21.2 Fetal anomalies with a likely genetic cause – WES
Please refer to the NHSE National Genomic Test Directory for further indications available and information regarding clinical criteria.
Requirements
Sample types accepted:
- 20ml amniotic fluid in a dry sterile container
- 20mg chorionic villus sample in transport medium (contact the laboratory for provision of sample containers)
- Fetal blood samples
- DNA samples
Please notify the laboratory before sending prenatal samples by e-mailing gst-tr.viapathgeneticsadmin@nhs.net
Testing of low volume samples may need to be prioritised. If direct DNA extraction is not possible, testing will be performed on cultured cells which may delay the turnaround time.
Please send maternal blood with bloodstained amniotic fluid samples for maternal cell contamination (MCC) testing. Samples with a high level of MCC will not be suitable for testing.
If samples are unlabelled the referring clinician will be contacted to complete a disclaimer form for consent to process the sample.
Turnaround times
Rapid aneuploidy by QFPCR – 3 days
Prenatal testing for monogenic disorders – 3 days (known familial variants)
Prenatal targeted G-banded karyotype (follow up of abnormal PCR) – 14 days
Prenatal Array analysis – 14 days
SE GLH: Non-WGS Genetic test request form
Please send an accompanying full ultrasound scan report with all prenatal samples.
Please note that any errors made when completing the form may result in delays in processing.
It is the referring clinician’s responsibility to ensure that the patient/carer knows the purpose of the test and that the sample may be stored for future diagnostic testing.
SE GLH: Record of Discussion form
The Record of Discussion form can be downloaded and used to guide and record the patient’s consent. This should be saved in local patient records and does not need to be sent with the request form.
Fetal WES service
Prior to referral, all fetal WES requests should be discussed with your local Clinical Genetics team at either Guy’s and St Thomas’ NHS Foundation Trust (GSTT) or St George’s University Hospitals Foundation Trust.
If the pregnancy is going to continue please request a rapid WES on teh fetal sample, if the pregnancy is not going to continue please request a non-urgent WES on the fetal sample.
Parental blood samples are required for testing (5ml in EDTA).
Further documentation to be completed:
Rapid WES
- R21 Exome Request Form
- Completed Record of Discussion regarding prenatal exome sequencing for each parent
Non-urgent WES
- R412 Exome Request Form
- Completed Record of Discussion regarding prenatal exome sequencing for each parent
- R412 guidance document
For fetal exome queries please email gst-tr.viapathprenatalgenetics@nhs.net
Lab address and opening hours
Genetics Laboratory
5th Floor Tower Wing
Guy’s Hospital
London
SE1 9RT
Mon-Fri 9:00-17:00
Tel: 020 7188 2582
Key contacts
Service Delivery Manager – Keeley Monsen-McCann
Operations Lead – Emma Fowler
For any clinical or scientific queries please contact the laboratory on 020 7188 1713 between the hours of 9am to 5pm, Monday to Friday. Alternatively contact Emma Fowler on 020 7188 1712.
For complaints
For complaints, please visit the Synnovis complaints page for the policy and procedure.