How does the trigger shot work for IVF?

Gonadotropin Stimulation

The trigger shot is in fact human chorionic gonadotropin (HCG), a hormone that stimulates the follicles to rupture and release an egg. In an ovarian stimulation cycle; gonadotropin hormones including FSH and LH stimulate the ovaries for egg development. The trigger shot should be administered about 36 hours earlier than IVF egg retrieval because the timing is essential for the fulfillment of the whole IVF process. HCG injection makes the egg mature and detach from the cumulus oophorus. This makes the mature egg to float in the fluid which can be easily picked up during aspiration of follicles in IVF.

Maturation of Egg Cell

The aim of the trigger shot in IVF treatment is to send eggs into a reproductive division called meiosis. During meiosis; the goal is to prepare the egg cell for division. It lowers the number of chromosomes in the eggs from forty six to twenty-three prior to egg retrieval or ovulation. Trigger shots expels some of the chromosomes from the egg’s nucleus into a membranous envelope. This so-referred to as the first polar body. This organelle lies below the envelope of the egg in an area called perivitelline space. Embryologists use this polar body to identify a mature egg. Here it appears as though the cells surrounding the egg are eliminated through microsurgery, but they erode on their own under effect of HCG. 

Microscopic visualization

Microscopic visualization of the polar body confirms that the eggs are mature, that means it has gone through meiosis. However, it presents no assurance that there are only 23 chromosomes remaining in the egg’s nucleus. If precisely 23 chromosomes aren’t present then the fertilized egg will create an aneuploid embryo. An Aneuploid embryo is one which has an abnormal quantity of chromosomes (extra or much less than forty six) and is incapable of making a healthy baby. Hence, the dosage, method, and management of the trigger shot have an effect on the ability to yield mature quality eggs. The stated trigger shot elements additionally constitute a rate-limiting step in ovulation induction specifically for the IVF treatment cycle.