Ovulation-Induction Medications and OHSS

Ovulation induction is a controlled attempt to recruit one or more ovarian follicles, mature an oocyte, and time ovulation or retrieval. The treatment becomes dangerous when ovarian response is excessive: several follicles may mature simultaneously, increasing multiple-gestation risk, and the post-ovulatory ovary may release mediators that make capillaries abnormally permeable. That permeability shifts protein-rich fluid into the abdomen and sometimes the pleural space. The patient may look fluid overloaded because the abdomen is filling, while the circulation is actually depleted. The resulting haemoconcentration, falling urine output, electrolyte disturbance, and thrombotic risk—not simply ovarian enlargement—make OHSS an emergency. The drugs require different safety thinking. Clomiphene increases endogenous FSH and LH by blocking oestrogen feedback. Letrozole lowers oestrogen synthesis and is the preferred first-line pharmacological option for PCOS-related anovulation, although ovulation induction is off-label in Canada. Gonadotropins directly stimulate follicular development and therefore require the closest ultrasound and estradiol surveillance. hCG is the trigger that can initiate or worsen OHSS; it must not be given when the ovarian response is unsafe. For the nurse, the pivotal question is not only whether a...