Diagnosis of imminent ovulation is :
**Core Concept**
The diagnosis of imminent ovulation is crucial in fertility management and contraception. Ovulation is a complex process involving the coordinated release of gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH), and estrogen from the pituitary gland and ovaries, respectively. The surge in LH, in particular, is a key indicator of impending ovulation.
**Why the Correct Answer is Right**
The correct answer involves the measurement of LH levels, which typically surge 24-48 hours before ovulation. This surge is mediated by the positive feedback loop of estrogen on the pituitary gland, leading to an increase in GnRH secretion and, subsequently, LH release. LH then triggers the final maturation and release of the oocyte from the follicle. Measuring LH levels can help identify the optimal time for conception or fertility treatments.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because basal body temperature (BBT) only rises after ovulation, making it a poor indicator of imminent ovulation.
**Option B:** This option is incorrect because cervical mucus changes, such as increased moisture and ferning, occur after ovulation, not before.
**Option C:** This option is incorrect because ultrasound can detect the presence of a dominant follicle but cannot predict the timing of ovulation.
**Clinical Pearl / High-Yield Fact**
A common mnemonic to remember the sequence of events leading to ovulation is "GnRH → LH → estrogen → LH surge → ovulation."
**Correct Answer:** D. Measurement of LH levels.