Influence of controlled ovarian hyperstimulation on uterine peristalsis in infertile women.

STUDY QUESTION: Is there a difference in the characteristics of uterine peristalsis in natural and controlled ovarian hyperstimulation (COH) cycles?

SUMMARY ANSWER: COH significantly changed the uterine peristaltic pattern.

WHAT IS KNOWN ALREADY: In natural menstrual cycles, the periodic changes of uterine peristalsis are closely related to the reproductive process.

STUDY DESIGN, SIZE, DURATION: This is a prospective cohort study with a total of 64 subjects involved. The study was performed between May 2011 and August 2011.

PARTICIPANTS/MATERIALS, SETTING, METHODS: Sixty-four infertile women with regular, ovulatory menstrual cycles underwent follicular tracking in one natural cycle and after ovarian stimulation (GnRH-agonist down-regulation) in the subsequent cycle (COH). Three time points were studied in both cycles: at LH surge/HCG plus 1 day, ovulation/oocyte retrieval and 2 days after ovulation/retrieval. The study was performed in an IVF center of the university-affiliated Xiangya hospital.

MAIN RESULTS AND THE ROLE OF CHANCE: Uterine peristaltic wave frequency was 1.31 times higher in the COH than in the natural cycle (P< 0.01). At all three time points in the COH cycle, waves moving from the cervix to fundus dominated, comprising 80-90% of the wave types observed, while 'no activity' was more frequently observed in the natural cycle. The wave frequency was positively correlated with the level of serum estradiol (E(2)) (r= 0.30; P< 0.01) and negatively correlated with the progesterone level (r= -0.48; P< 0.01) for the physiological range of steroid levels. No correlation was found between the wave frequency and supraphysiological concentrations of E(2) or progesterone.

LIMITATIONS, REASONS FOR CAUTION: The two observers were not independent and this was a limitation of the study. Quantitative measurements of wave amplitude in the different cycles should be compared in future research.

WIDER IMPLICATIONS OF THE FINDINGS: Uterine peristalsis was much higher in the COH cycle than in the natural cycle. The endometrial movements did not weaken to the natural level before embryo transfer, even with high levels of progesterone. The wave frequency was positively correlated with serum E(2) level and negatively correlated with that of progesterone within the physiological range. No correlation was found between the wave frequency and supraphysiological concentrations of E(2) and progesterone.