LETTERS TO THE EDITOR Paul G. McDonough, M.D. Associate Editor The empty follicle syndrome is dead! To the Editor: We would like to compliment the investigators with their successful effort to erase the term ‘‘empty follicle syndrome (EFS)’’ from the annals of reproductive medicine (1). Their thoroughly systematic review demonstrates that existence, if any, of follicles without oocytes are even more obscure than previously presumed. Following the first report of EFS by Coulam and collegues (2), a considerable number of studies failed to demonstrate any genuine biologic rational for EFS to occur. As reported by our group, all patients with so-called genuine EFS had at least one previous or subsequent IVF cycle with oocyte recov- ery (3). Various groups repeatedly reported that EFS does not represent a permanent pathophysiologic condition (4), indicating that EFS reflects a rare chance finding phenomenon. The reported oocyte recovery rate in the natural cycles is approximately 80% (5, 6). Assuming that the chance to re- cover one oocyte per follicle is similar in conventional IVF, the mathematic chance for failure to recover any oocyte is considerable. For example, in our report the 14 patients had two to six dominant follicles present before oocyte retrieval. Given this number of dominant follicles, the calculated chance for failure to recover least one oocyte is 0.064&– 4%. Hence, in relation to the reported incidence of EFS, this mathematic coincidence should be considered. The systematic review of Stevenson and Lashen (1) con- firmed our previous report that genuine EFS is virtually non- existent. However, the investigators suggested to institute a register of all cases of genuine EFS to elucidate its etiology. We are unsure if such a register would be helpful to clarify the etiology of genuine EFS, if any, because standardized criteria for diagnosis of genuine EFS are absent. In addition, the meta-analysis clearly showed a lack of basic evidence for the existence of genuine EFS. Hence, we challenge the inves- tigators to provide arguments to justify this proposed register. Alternatively, the absence of evidence for the existence of EFS may be an argument to bury the term EFS. Arne M. van Heusden, M.D., Ph.D. Department of Obstetrics and Gynecology MCRZ location Zuider Rotterdam, the Netherlands Evert J. van Santbrink, M.D., Ph.D. Izaa¨k Schipper, M.D., Ph.D. Division of Reproductive Medicine Department of Obstetrics and Gynecology Erasmus Medical Center Rotterdam, the Netherlands Diederick de Jong, M.D., Ph.D. Division of Gynecologic Oncology Department of Obstetrics and Gynecology Princess Margaret Hospital University Health Network Toronto, Canada December 13, 2007 REFERENCES 1. Stevenson TL, Lashen H. Empty follicle syndrome: the reality of a controversial syndrome, a systematic review. Fertil Steril 2007 Nov 17; [Epub ahead of print]. 2. Coulam CB, Bustillo M, Schulman JD. Empty follicle syndrome. Fertil Steril 1986;46:1153–5. 3. Aktas M, Beckers NG, van Inzen WG, Verhoeff A, de Jong D. Oocytes in the empty follicle: a controversial syndrome. Fertil Steril 2005;84: 1643–8. 4. Quintans CJ, Donaldson MJ, Blanco LA, Pasqualini RS. Empty follicle syndrome due to human errors: its occurrence in an in-vitro fertilization programme. Hum Reprod 1998;13:2703–5. 5. Daya S, Gunby J, Hughes EG, Collins JA, Sagle MA, YoungLai EV. Natural cycles for in-vitro fertilization: cost-effectiveness analysis and factors influencing outcome. Hum Reprod 1995;10:1719–24. 6. Nargund G, Waterstone J, Bland J, Philips Z, Parsons J, Campbell S. Cumulative conception and live birth rates in natural (unstimulated) IVF cycles. Hum Reprod 2001;16:259–62. doi:10.1016/j.fertnstert.2007.12.048 Markov modeling: questionable data in, questionable data out To the Editor: We read with great interest the article by Hsieh and colleagues (1) regarding the cost effectiveness of vasectomy reversal vs. assisted reproductive technologies (ART) for post-vasectomy patients desiring fertility. Although we have no doubt that the use of Markov modeling will prove highly beneficial to individual centers once the Web-based tool is available, we do have concerns regarding the discus- sion points provided, based on the authors’ ‘‘base case values’’. In particular, in reviewing the base case values and their sources, we would like to raise the following issues: 1. Were the couples who underwent reversal in the authors’ previous study unselected, or were they selected according to specific exclusion criteria? For instance, if female fertility issues were uncovered, was the couple then referred to ART? 2. If so, using Society for Assisted Reproductive Technol- ogy summary statistics for IVF pregnancy rates is inappropriate, because those refer to unselected couples. What would be appropriate would be determining IVF success rates with couples using the same inclusion and exclusion parameters. Failure to Fertility and Sterility â Vol. 89, No. 3, March 2008 0015-0282/08/$34.00 Copyright ª2008 American Society for Reproductive Medicine, Published by Elsevier Inc. 746