Patients
In this retrospective study, we included patients who had received in vitro fertilisation (IVF) treatment or intracytoplasmic sperm injection (ICSI) at the Department of Reproductive Medicine at the Third Affiliated Hospital of Zhengzhou University between 1 January 2018 and 31 December 2020 and had undergone a single laparoscopic cystectomy of ovarial endometrioma. Because the goal was to compare the effectiveness of different controlled ovarian hyperstimulation protocols, patients were divided into three groups: a Gn-releasing hormone (GnRH) antagonist group, a microstimulation group, and a progestin-primed ovarian stimulation (PPOS) group.
Inclusion criteria
The inclusion criteria were as follows: 1) age ≤ 40 years; 2) DOR(6), evidenced by the presence of either a) an anti-Mullerian hormone (AMH) level of < 1.1 ng/mL, b) an antral follicle count (AFC) of < 5–7 in both the ovaries, or c) a basal follicle-stimulating hormone (FSH) level of ≥ 10 IU/L in two consecutive menstrual cycles; 3) a history of a single laparoscopic cystectomy of ovarial endometrioma; and 4) first IVF/ICSI-assisted pregnancy cycle.
Exclusion criteria
The exclusion criteria were as follows: 1) endocrine-related diseases, such as polycystic ovary syndrome and hyperprolactinaemia; 2) any chromosomal abnormality in either spouse; 3) uterine malformations; 4) a history of recurrent miscarriage; 5) diagnosis of adenomyosis through surgery, ultrasound, or magnetic resonance imaging; 6) cycles with incomplete data; and 7) cycles involving the preimplantation genetic diagnosis and preimplantation genetic screening.
Controlled ovarian hyperstimulatio protocols
1)GnRH antagonist protocol: Based on the patient’s age, body mass index (BMI), and ovarian reserve, ovulation induction was initiated between the second and fourth day of menstruation by administering Gn. The primary agents used were urinary Gn (Zhuhai Lizhu Group, Lizhu Pharmaceutical Factory) and recombinant FSH (Konafen, Merck, Germany), Procon (MSD, USA), or Lishenbao (Zhuhai Lizhu Group, Lizhu Pharmaceutical Factory). Upon reaching an average follicular diameter of 11 to 12 mm and a serum oestradiol level of > 500 ng/L, the patients were administered GnRH antagonists (Citrek, Merck Serrano, Switzerland) at a dose of 0.25 mg/d.
2)Microstimulation protocol: Between the second and fourth day of menstruation, patients were orally administered 2.5 mg/d of letrozole (Jiangsu Hengrui Pharmaceutical Co., Ltd.) or 50 mg/d of clomiphene citrate (Shanghai Hengshan Pharmaceutical Co., Ltd.). Simultaneously, they were administered an intramuscular injection of human menopausal Gn (urotropin for injection, Zhuhai Lizhu Group, Lizhu Pharmaceutical Factory) at an initial dose of 150 IU/d, which was continued until the human chorionic Gn (hCG) injection day.
3)PPOS: From the second to fourth day of menstruation, patients were orally administered 6–10 mg/d of medroxyprogesterone acetate (Zhejiang Xianju Pharmaceutical Co., Ltd.) and injected 150–225 U/d of Gn until the hCG injection day.
The Gn dosage was maintained or adjusted during treatment based on follicle growth and serum hormone levels. When at least one dominant follicle reached a diameter of ≥ 20 mm or three follicles reached a diameter of ≥ 18 mm, hCG (Zhuhai Lizhu Group, Lizhu Pharmaceutical Factory), recombinant hCG (Aize, Merck Serrano, Switzerland), or Dafirin (Iproxen, France) were administered to trigger ovulation. Egg retrieval was performed after 36 h under vaginal ultrasound guidance.
Embryo transfer
In the GnRH antagonist protocol, given the absence of any contraindications, a fresh cycle transfer was performed first depending on the endometrial thickness and serum hormone levels. Two fresh cleavage-stage embryos or one blastocyst was transferred on day 3 or 5 after oocyte retrieval. If pregnancy was not achieved, frozen–thawed embryo transfer (FET) was performed in subsequent cycles. In the microstimulation and PPOS protocols, vitrification freezing technology was employed for total embryo freezing. Different FET plans were developed based on the specific situation of each patient. Endometrial development or follicle growth and serum hormone levels were continuously monitored, and endometrial preparation was timed accurately. Two frozen–thawed cleavage-stage embryos were transferred 3 days after endometrial preparation or one frozen–thawed blastocyst was transferred 5 days after endometrial preparation.
Pregnancy diagnosis
Blood hCG levels were measured 14 days after transplantation. Clinical pregnancy was considered if an ultrasound examination performed 30 days after transplantation revealed a gestational sac.
Observation indicators
The primary outcome was the cumulative live birth rate. In an IVF/ICSI cycle (which includes one oocyte retrieval cycle, fresh embryo transfer, and subsequent FETs), the number of cycles resulting in the first live birth (defined as ≥ 28 weeks of gestation) was used as the numerator and the number of oocyte retrieval cycles was used as the denominator. The observation was continued until one live birth was observed or all embryos were utilised(7, 8).
The secondary outcomes were patient general characteristics, the number of oocytes retrieved, the oocyte output rate, the number of two pronuclear (2PN) embryos, the viable embryo rate, the high-quality embryo rate, the blastocyst formation rate, and the cumulative pregnancy rate.
Statistical analysis
All statistical analyses were performed using SPSS(Statistical Package for the Social Sciences)version 26.0. Normally distributed quantitative data are presented as the mean ± standard deviation and were compared between groups using an analysis of variance. Quantitative data that were not normally distributed are expressed as the median (interquartile interval) and were compared between groups using a nonparametric rank sum test. Qualitative data are presented as the percentage and were compared between groups using a chi-square test or a corrected chi-square test. For the primary outcome measures, binary meta-logistic regression was performed after adjustment for confounding factors. A P value of < 0.05 was considered statistically significant.