## Clomiphene Citrate Resistance in PCOS This patient demonstrates **CC-resistant PCOS** — failure to ovulate after 3 cycles at an adequate dose (100 mg). The elevated LH:FSH ratio (18:4.2 ≈ 4.3) confirms hyperandrogenic anovulation typical of PCOS. ### Why FSH Monotherapy? **Key Point:** Once CC resistance is established, escalating CC dose beyond 100–150 mg offers no additional benefit and increases risk of ovarian hyperstimulation or cyst formation. The pathophysiology of CC resistance in PCOS involves: - Altered follicle sensitivity to endogenous FSH despite adequate estradiol feedback suppression - Androgen-mediated impairment of granulosa cell FSH receptor expression - Abnormal intra-ovarian signaling **Low-dose FSH step-up protocol** is the evidence-based next step because: 1. Exogenous FSH bypasses the endogenous LH/androgen axis dysfunction 2. Low-dose step-up minimizes risk of OHSS and multiple follicle recruitment 3. Success rates for ovulation in CC-resistant PCOS are 60–80% with FSH 4. Both recombinant (rFSH) and urinary FSH are acceptable; rFSH preferred for consistency **High-Yield:** The ASRM and ESHRE guidelines recommend FSH as first-line for CC-resistant anovulation after confirmation of resistance (typically ≥3 failed cycles at adequate dose). ### Why Not the Other Options? - **Option 0 (Increase CC):** Doses >150 mg do not improve ovulation rates in resistant cases; wastes time and cycles. - **Option 2 (Add metformin):** Metformin is useful for CC-sensitive PCOS or as adjunct to improve insulin sensitivity, but does NOT overcome established CC resistance; adds no benefit here. - **Option 3 (IVF):** Premature escalation; ovulation induction with FSH should be attempted first as it is less invasive and costly than IVF.
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