Try it
Physiology · Reproduction: emergency contraception
Sample itemA woman takes levonorgestrel 1.5 mg within 24 hours of unprotected intercourse in mid-cycle. What is its main mechanism?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
D. Delay or inhibition of ovulation by blunting the LH surge
Levonorgestrel acts mainly by delaying or preventing ovulation, taken before the LH surge. It is not effective after ovulation has occurred and does not disrupt an established pregnancy.
Option by option
A. Destruction of the corpus luteum
It does not destroy the corpus luteum.
B. Immobilisation of sperm in the cervix
Sperm immobilisation is the mechanism associated with a copper device, not levonorgestrel.
C. Dislodgement of an implanted blastocyst
It does not act on an implanted pregnancy.
D. Delay or inhibition of ovulation by blunting the LH surge (correct)
Correct. Its main effect is to delay or inhibit the LH surge and ovulation.
Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.
More Physiology questions
- Cardiac cycleDuring which phase of the cardiac cycle are all valves closed while ventricular pressure…
- Renal physiologyWhich substance is freely filtered and neither reabsorbed nor secreted, so that its clea…
- RespirationWhich of the following shifts the oxygen–haemoglobin dissociation curve to the right?
- Renal physiologyWhich of the following favours glomerular filtration?