Oligoovulatory and anovulatory cycles in women with polycystic ovary syndrome (PCOS): what's the difference?

Context: Polycystic ovary syndrome (PCOS) is a heterogeneous disorder. The phenotype may differ between patients who exhibit signs of recent ovulation and anovulatory PCOS patients.
Objective: Our objective was to study differences in clinical and endocrine characteristics and response to ovulation induction (OI) treatment comparing oligoovulatory and anovulatory PCOS patients.
Design and Setting: We conducted a retrospective cohort study at a tertiary hospital.
Patients: PCOS patients (n=1750) presenting with oligo- or amenorrhea were diagnosed according to the Rotterdam 2003 consensus criteria. Arbitrarily, oligoovulatory PCOS was defined by a single random serum progesterone level of 10 nmol/liter or higher.
Main Outcome Measures: We evaluated the incidence of oligo- or amenorrhea, menstrual cycle length, serum androgen levels, follicle count, and OI outcome parameters.
Results: Anovulatory women (n=1541 of 1750, 88.1%) were more often amenorrheic (P<0.001) and presented with a longer cycle duration (P<0.001) compared with oligoovulatory women (n=209 of 1750, 11.9%). Serum levels of testosterone (P<0.001), the free androgen index (P<0.001), and total follicle count (P<0.005) were higher in anovulatory compared with oligoovulatory patients. During clomiphene citrate OI, more oligoovulatory women gained regular menstrual cycles (P<0.05), whereas after second-line treatment with recombinant FSH, more anovulatory women became pregnant (P<0.05).
Conclusions: Oligoovulatory women with PCOS exhibit a milder phenotype of ovarian dysfunction and have a more favorable response to OI treatment using clomiphene citrate compared with anovulatory PCOS patients. However, during second-line treatment with recombinant FSH, anovulatory PCOS patients presented with a higher chance of pregnancy compared with oligoovulatory patients.