No decrease occurs in the number of COCs retrieved with repeated IVF cycles
Centre for Reproductive Medicine, Dutch speaking Brussels Free University, Laarbeeklaan 101, B-1090 Brussels, Belgium
Email: stratis{at}easynet.be
Sir,
We read with interest the paper by de Boer et al. (2004)
. The authors examined if the number of cumulus–oocyte complexes (COCs) retrieved decreases across consecutive IVF cycles, by analysing 1980 cycles performed in 330 women. The authors quote in their manuscript the study by Kolibianakis et al. (2002), which also analysed the effect of multiple IVF cycles on the number of COCs retrieved.
The authors' comment (Introduction, second paragraph) regarding the study by Kolibianakis et al. (2002) ‘The available literature concerning ovarian response in repeated IVF cycles is limited, based on small numbers of women or a limited number of treatment cycles’ is incorrect. The study by Kolibianakis et al. (2002) analysed 9379 cycles performed in 3249 patients and is currently the largest series examining the effect of consecutive IVF cycles on ovarian response.
Moreover, the authors' statement (Introduction, second paragraph) that the study by Kolibianakis et al. (2002) ‘suggests that repeated IVF cycles lead to a decrease of the number of retrieved oocytes’ is also incorrect. The study by Kolibianakis et al. (2002) showed that there is no decrease in the number of COCs retrieved across consecutive IVF cycles, controlling for the effect of maternal age. However, an age-independent increase in the number of ampoules required for ovarian stimulation was concomitantly present, pointing towards a decreased ovarian response across consecutive IVF cycles.
Furthermore, we would like to question the authors' suggestion that ‘the ideal study design should include a comparison group of women who had undergone multiple stimulated intrauterine inseminations’. The ovarian stimulation task present in IUI cycles (mono-follicular development) is entirely different from that present during ovarian stimulation for IVF (multi-follicular development). As a consequence, women who have been stimulated for intrauterine insemination cannot be a control group for those subjected to gonadotrophin treatment for IVF.
References
de Boer EJ, Den Tonkelaar I, Burger CW, Looman CW, Van Leeuwen FE and Te Velde ER (2004) The number of retrieved oocytes does not decrease during consecutive gonadotrophin-stimulated IVF cycles. Hum Reprod 19, 899–904.
Kolibianakis E, Osmanagaoglu K, Camus M, Tournaye H, Van Steirteghem A and Devroey P (2002) Effect of repeated assisted reproductive technology cycles on ovarian response. Fertil Steril 77, 967–970.[CrossRef][Web of Science][Medline]
Submitted on August 11, 2003; accepted on May 5, 2004.
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