Free Fetal DNA Screening for Fetal RhD Status
(Blood Transfusion)
Investigation : Free Fetal DNA Screening for Fetal RhD Status
Specimen type : EDTA
Spec container : BT Tube Twin 
Volume required : 7.5ml

Turnaround: 2 working days, NHSBT referrals take on average another 5 working days

Request: Specific Free Fetal DNA Screening for Fetal RhD Status NHSBT request form (fully completed)

To be done on one full 7.5ml EDTA sample (special Blood Transfusion tube).

Care must be taken not to cause haemolysis during the phlebotomy as this may result in the sample being unsuitable for use.

NHSBT Requirements:

NHSBT Requirements:

  • Estimated delivery date (from dating scan) must be provided on the request form. Gestation must be at least 11+2 weeks at time of venepuncture or the sample will be rejected.
  • The sample tube must not be opened following blood collection.
  • The sample must not be used for any testing prior to being received at IBGRL.
  • The sample tube should be stored at room temperature.
  • The sample tube must be labelled with the following information:
    • Three unique sample identifiers including: first name and surname, date of birth, and NHS or hospitals number (please note the same number must be on both the sample tube and the request form)
    • Samples MUST be labelled, dated and signed by the person taking them.
    • Labels pre-printed prior to phlebotomy e.g. Addressograph labels are not acceptable on samples.
  • Samples must have handwritten labels.
  • Hand written alterations on either the sample or request form may make the sample invalid for testing. Any minor alterations must be initialled by the person taking the sample to be acceptable for testing.


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