The Leeds Teaching Hospitals NHS Trust

Tissue Samples

Reasons for Referral:

  • Spontaneous pregnancy loss
  • Intrauterine and neonatal death
  • Termination of pregnancy following an abnormal ultrasound scan
  • Phenotype suggestive of chromosome abnormality
  • Confirmation or diagnosis of mosaic chromosome abnormalities
  • Sudden unexplained death in infancy / childhood
  • Cultures can also be established for the study of genetic and metabolic diseases in other laboratories. These samples must be accompanied by a covering letter from the referring clinician to identify where the sample is to be sent, and for what test. A contact name and address for invoicing purposes should also be provided.
  • Storage of DNA or of frozen cell cultures

The laboratory no longer requests confirmation samples from pregnancies which have been terminated due to a cytogenetic abnormality.

Sample Requirements

Pregnancy losses: Ideally a sample of cord and/or placenta; post-mortem samples of skin, lung, cartilage etc (foetal samples). Products of conception may be sent if there is no alternative but please note that the results may be less accurate due to maternal cell contamination. If sending placental tissue or products of conception, please also send a small (2-3ml) sample of maternal blood in EDTA if possible; this will enable exclusion of maternal cell contamination and ensure that the result is reported appropriately.

Live patients (for mosaicism / enzymes / cell storage etc): A full thickness skin biopsy.

Please note that, due to the restrictions of the Human Tissue Act, whole foetuses cannot be accepted by the laboratory and will be returned to the referrer without processing. Products of conception containing recognisable foetal parts will be returned for burial / disposal once appropriate material has been processed.

Samples collected into formalin, those that are obviously infected, and samples which are excessively delayed in transit are unsuitable for cytogenetic studies and no attempt will be made to test such specimens.

A fully completed referral form must accompany all samples. Download a referral card.

Sample Transport

Whole foetuses are not accepted by the laboratory and, if sent, will be returned.

Samples should be collected into a sterile Universal container containing culture medium (Ham’s F10) and antibiotics. A supply of suitable transport medium can be obtained from the laboratory on request.

If no transport medium is available it is possible to send the tissue in sterile isotonic saline, or in a dry sterile vessel. These samples should be sent to the laboratory without delay.

Samples must not be frozen, exposed to excess heat or stored in formalin.

Samples should be addressed to: YNEGLH, Central lab. Please see laboratory contact page for address and contact details.

Some of the testing performed requires living cells. Please ensure that the sample reaches us as quickly as possible (within 48 hours). First class post is satisfactory.

If there is a delay in transit please store the sample at 4°C (in a refrigerator).

Please try to avoid sending samples at weekends or bank holidays.

When sending samples by post a secure container should be used to conform to current postal regulations, i.e. P650 and UN3373 applicable.

Testing Pathways

Obstetric samples (pregnancy loss / TOP / IUD / stillbirth):

From 1st October 2016, all obstetric samples will be tested by QFPCR (Elucigene QST*R-PLTM) for chromosomes 13/15/16/18/21/22/X/Y to identify those aneuploidies which are most commonly found in pregnancy losses.

From the 1st February 2021 a subset of those with normal QFPCR results will then be tested by SNP Array instead of CNV sequencing. SNP arrays can identify significant copy number imbalances including, but not limited to, whole chromosome aneuploidy, which are likely to have contributed to the pregnancy loss and/or fetal abnormality.

Samples which will receive the additional SNP array test are:

  • Pregnancy losses at or before 12 weeks
  • Pregnancy losses / TOP at any gestation where there is a fetal abnormality
  • Where there is a history of 3 or more recurrent miscarriages

Audit data suggest that other referrals have a very low incidence of clinically significant copy number abnormalities detectable by SNP Array but not by QFPCR.

Please include as much information as possible on the referral form so that the sample is processed in the correct workstream.

Sudden infant deaths and skin biopsies from live patients:

These samples will continue to be cultured for karyotype analysis/ SNP Array / DNA storage / cell storage / metabolic testing as appropriate.


All QFPCR results will be issued in the form of a written report with a 42 calendar day reporting time target. SNP Array results will be issued separately and may take up to a month longer since, due to batching requirements, we will only be performing a run every few weeks.

For SNP Array results the reporting criteria will be similar to those presently in use for prenatal SNP array, so that only those copy number variants which are thought to be directly relevant to the referral reason (i.e. likely to be a cause of the pregnancy loss or fetal anomaly) will be reported. Incidental findings and variants of uncertain significance will usually not be reported.

Results are sent by post to the referring clinician and / or pathologist. Complex abnormal results may be telephoned prior to the written report being sent and the interpretation and implication discussed.

In response to telephone enquiries, only normal results or those which confirm a previous finding can be given to a clinician’s secretary or the clinic sister. All other results are only given to clinicians or faxed reports are sent to designated contacts. Reports in pdf format can be emailed if a suitable secure email address is supplied.

Please note: Although every effort is made to use suitable material for analysis, it is not always possible to avoid analysing maternal cells where the material used is of extra-embryonic origin (e.g. products of conception, placenta). Samples which are subject to this limitation will be reported with appropriate interpretative comments.