Here’s a challenging question from the ASCLS Consumer web forum: “I’m currently on 40 mg of Lovenox daily during my pregnancy. Can that alter the cell-free DNA test in any way? I take my meds at 10 every morning, should i take the blood test after my shot is due? I’m getting different answers from the genetics counselor and OB.
George consulted with colleagues who have expertise and experience with cell-free DNA testing. While there is no conclusive evidence, his colleagues located publications that imply both unfractionated and low molecular weight heparin (LMWH; Lovenox) can interfere with DNA testing, for example, an abstract: Wardrop J, Dharajiya N; Boomer T, et al. Low molecular weight heparin and noninvasive prenatal testing, May, 2016 Obstetrics & Gynecology. While none of the data we reviewed were 100% conclusive, George suggested that, given uncertainty about heparin and the expense and critical nature of cell-free DNA testing, the patient consult with the physician about the safety of discontinuing Lovenox for up to 48 hours (missing two injections) prior to blood collection.