Postnatal Cytogenetic Diagnosis at Bristol Genetics Laboratory

Blood samples are used to study the chromosomes of babies, children or adults with a problem that may have a cytogenetic basis. The majority of referrals are from neonatal and infant units (birth defects), paediatric clinics (intellectual or physical handicaps and developmental delay, delayed growth and puberty problems), infertility clinics, obstetric departments (e.g. follow up testing following certain cytogenetic abnormalities found in foetal loss samples), and genetic counselling clinics.

For patients with learning difficulties and/or physical abnormalities, testing is carried out using 

and for all other referrals by high resolution karyotyping 

with additional 

studies on appropriate cases. Rapid aneuploidy screening and gender testing is carried out using 


Blood samples: for information on sample requirements follow link:  Sample requirements

Target reporting time:
Provisional ResultsUrgent confirmation of sex chromosome status and trisomy for chromosomes 13,18 or 21 in neonatal patients for samples arriving before 2.30 pm, within 3 calendar days after receipt of sample (most tests are reported in 1-2 working days, currently Monday to Saturday). Testing is carried out by QF PCR.

Final Results: Urgent samples within 14 calendar days. Non-urgent samples within 42 days. Please contact Bristol Genetics Laboratory to find out current reporting times.

Patients should be advised that:

  •  Occasionally samples fail to grow in culture (chromosome analysis); or extracted DNA is of insufficient quality for testing (microarray CGH and QF PCR).  These occur for <1% of samples.  Repeat samples would be required
  •  A repeat sample may be required should cell culture yield chromosomes of insufficient quality required for the reason for referral (high resolution karyotyping).
  •  Cell suspensions are routinely discarded 4 months after receipt.
  •  DNA is stored indefinitely or discarded on request.

It is important to let Bristol Genetics Laboratory (BGL) know of any recent blood transfusions that the patient may have received and to advise the patient that a repeat sample at a later date may be necessary.    

Last updated: 30th July 2019

Bristol Genetics Laboratory

Bristol Genetics Laboratory
Pathology Sciences
Southmead Hospital
BS10 5NB

Enquiries telephone: 0117 41461680117 41461670117 4146174

MRD Service telephone: 0117 4146173
Email: Professor Rachel Butler, FRCPath, Consultant Clinical Scientist, at