Hum. Reprod. Advance Access originally published online on August 29, 2007
Human Reproduction 2007 22(11):3044-3045; doi:10.1093/humrep/dem162
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Letters to the Editor |
Reply: Antiphospholipid antibodies in serum and follicular fluid: is there a correlation with IVF implantation failure?
1 Department of Obstetrics and Gynaecology, University of Auckland, Private Bag 92019, Auckland 1001, New Zealand 2 Fertility Plus, Greenlane Clinical Centre, Private Bag 92189, Auckland, New Zealand
3 Correspondence address. Tel: 64 9 578 1928 or 027 296 8635; Fax: 64 9 631 0728; E-mail: karen{at}onlinecom.co.nz
Thank you for the opportunity to respond to Matsubayashi's letter. As they observed, despite >25 studies looking at antiphospholipid antibodies (aPLs) in infertile/IVF patients, only 4 studies have analysed aPLs in follicular fluid. There are considerable difficulties in comparing studies due to the differing populations studied, the aPL types screened for and the definitions of a ‘positive result’ used. Of these studies, Matsubayashi is the only one to find a significant reduction in fertilization rates in patients who were aPL positive (using a cutoff of >95th centile). We wonder if their significant findings would still apply if a cutoff of >99th centile was used. We analysed our own data at both the 95th and 99th centiles and despite finding a greater prevalence of positive aPL patients when the 95th cutoff was used, there were no significant differences in fertilization and pregnancy rates (Buckingham et al., 2006
).
As can be seen from Matsubayashi's table, subject numbers in each study are small. We agree that a multi-centre trial might be the only way to recruit the large number of patients that would be needed to answer the question of whether aPL contribute to implantation failure once and for all (as pointed out by Matsubayashi our own study indicated at least 1250 participants would be required). Before such a study was undertaken, however, agreement would have to be reached as to which aPL types to test for and how to define a positive result. Since all studies were essentially in agreement that aPL are not selectively concentrated in follicular fluid, there would seem little point in measuring the levels of antibodies in anything other than blood. However, it might be that to lay that question to rest once and for all, it may be of value to measure aPL levels in both blood and follicular fluid.
Reference
Buckingham K, Stone P, Smith J, Chamley L. Antiphospholipid antibodies in serum and follicular fluid – is there a correlation with IVF implantation failure? Human Reprod (2006) 21:728–734.
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