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Are there factors that affect the accuracy of X or Y?

There are several factors which may affect the accuracy of a X or Y result. Some of these factors can be controlled and minimized by the customer and/or laboratory while others are independent factors that cannot be influenced.

Factors which could affect the accuracy of X or Y and which can be minimized:

  • Not following the directions carefully: improperly handling kit components, improperly washing hands, and not sanitizing the collection area
  • Contaminating the sample: allowing males to handle kit contents or assisting with sample collection.
  • Taking the test earlier than 7 weeks post-conception (if you wish to test earlier at 6 weeks post-conception, sign the authorization waiver for the ultra sensitive X or Y test)
  • Having a recent transfusion, miscarriage or abortion
  • Providing an insufficient blood sample
  • Leaving the sample in a hot environment

Factors which could affect the accuracy of X or Y which cannot be controlled:

  • Having a bone marrow transplant from a male donor, blood transfusions, miscarriages or abortions: our technology can detect DNA from previous male pregnancies or from male blood/marrow donors as contamination in most cases. However, there may be instances where the accuracy of our test is affected by any of these conditions.
  • Miscarriage: Women who have recently experienced a miscarriage must wait at least 3 months before they can use X or Y. If it has been at least 3 months since the miscarriage, then you are eligible to order X or Y.
  • Having naturally low levels of fetal DNA: studies have determined that up to 2.8% of women have naturally low levels of fetal DNA. While X or Y is much more sensitive than the methods used in those studies, there may still women whose levels of fetal DNA are too low even for our test to detect. This is a difficult statistic to measure but we anticipate it is less than 2%.
  • Vanishing Twin: some pregnancies begin with two (or more) fetuses but very early in the pregnancy, one of the fetuses terminates. In many cases, this occurs without the woman’s knowledge. If the “vanishing twin” is male and the remaining fetus is female, the results of X or Y may be incorrect.
  • Previously pregnant with a boy: in very rare cases (less than 1%), fetal cells may remain in the mother’s body several years after birth. Our technology can detect some of this DNA as a form of contamination, however, there may be cases where the accuracy of the test may be affected by this rare occurrence.