Efficacy of natural cycle endometrial preparation for frozen-thawed embryo transfer in patients with endometriosis

To assess the efficiency of natural cycle(NC) endometrial preparation for frozen-thawed embryo transfer (FET) in women with endometriosis(EMS). Retrospective study This was a retrospective study of the use of the natural cycle for endometrial preparation following FET cycles in patients with endometriosis from March, 2011 to August, 2013. The study groups included 97 patients with stage I-II endometriosis who underwent a total of 120 FET cycles(group A, included cases of mild and minimal endometriosis) and 179 patients with stage III-IV endometriosis who underwent a total of 233 FET cycles(group B, included cases of moderate and severe endometriosis). The control group included 258 patients with tubal factor infertility who underwent a total of 300 FET cycles(group C). In stage III-IV endometriosis , 40 patients (47 FET cycles,groupB1) had endometrial cyst recurrence after laparoscopic or laparotomy treatment. All patients enrolled in the study met the following inclusion criteria: (i) normal uterine cavity as assessed by ultrasonography, hysterosalpingography or hysteroscopy; (ii) high-quality frozen embryos were transplanted. (iii)normal male semen. The exclusion criteria comprised: (i) presence of hydrosalpinges; (ii) presence of adenomyosis and (iii) past history of myomectomy;(iv) polycystic ovary syndrome(PCOS); (v)repeated failed intrauterine insemination (IUI ). For group A , B and C ,we used the natural cycle for endometrium preparation. The patients’ characteristics, including age, duration of infertility, body mass index, number of embryos transferred, average endometrial thickness of ET (mm), basal FSH, serum E2 and P of transplantation day, No. of previous failed embryo transfer cycle, the rates of basal FSH>10 were recorded. Secondary measures included clinical pregnancy rate, live birth rate, ongoing pregnancy rate, implantation rate, and pregnancy complication rate. There were comparable clinical pregnancy rate (43.33% stage I-II, 50.21% stageIII-IV and 45.33% tubal factor )and live birth rate(36.67% stage I-II, 41.63% stageIII-IV and 40.00% tubal factor ) among the three groups, not depending on severity of endometriosis . No differences were found in other pregnancy parameters , in terms of ongoing pregnancy rate(36.67% stage I-II, 41.63% stageIII-IV and 40.00% tubal factor ) , miscarriage rate(14.89% stage I-II, 16.24% stageIII-IV and 10.29% tubal factor ), pregnancy complication rate(7.69% stage I-II, 10.26% stageIII-IV and 12.50% tubal factor ). No congenital birth defects were found in the endometriosis groups. In addition, when high-quality embryos are transferred, the pregnancy results are not affected by endometriomas. Natural cycle endometrial preparation for FET obtains similar pregnancy outcomes in patients with endometriosis compared with tubal infertility, and don’t increase the risk of birth defects and other complications.