Hey, Hey, What Do You Say…What’s the Difference Between These “Ks”

Historically, the final shot, or the “trigger” shot, in an IVF cycle was almost always a fixed amount. While there was variability in what medication was given (hCG/novarel vs. ovidrel), the dosage was pretty standard. Both medications when administered correctly were pretty good at achieving egg maturation. Their differences were in many ways limited to cost and prep time. (hCG must be mixed, and ovidrel is a pre-filled syringe). Who got what was frequently based on insurance coverage and cost. Nothing to shake your pom-poms about! Fast-forward to about 2008, and the game got more interesting with the introduction of a new player, a.k.a. Lupron (leuprolide).

It was discovered around this time that Lupron could not only achieve egg maturation but also eliminate the risk of the dreaded ovarian hyperstimulation syndrome (OHSS). Have we found ourselves both the rookie of the year as well as an MVP in one shot?

Yes and no. While Lupron is really good at avoiding OHSS for almost all, it falls short in achieving egg maturation for some. It requires the endogenous production of good amounts of LH (hormone made in the hypothalamus) to be effective. Without it, it really won’t work. Simply stated, it needs a teammate. Cue hCG or ovidrel. Giving two medications in combination (hCG + Lupron OR ovidrel + Lupron) is like drafting your dream team…dribble, shoot, score! Together, these medications (in the correct “K”) can achieve egg maturity without causing significant OHSS.

The tricky part about hCG, and where some of the confusion comes in (#most common on-call phone call for a fertility doctor!), is when we start to modify the dosage from the traditional 10,000 (a.k.a. 10K) down to 5K and then to 1K. In certain instances, we even modify it more to doses such as 2K or 3K. Why this can become so tricky is the mixing that the various “Ks” require. How you get from a 10K to a 1K dose is all about the water.

If you inject 1cc or mL of water (saline) into the powder and then give yourself a 1cc or mL injection, you have yourself a 10K shot of hCG. Not a problem if you are not cooking several dozen eggs. If you want a LOWER dose of hCG to reduce your risk of OHSS, you would increase the amount of water you inject into the powder to dilute the medication.

It would go something like this: 10 cc or mL of water into the same powder (rather than 1cc). However, you would ONLY give yourself a 1cc or mL injection of the water/powder solution. The more water = the more dilution = the less potent. Ovaries with a ton of potential that are being given Lupron alongside hCG don’t need so much oomph from the hCG. The combo is enough to get their system going without getting them sick.

While ovidrel is no slacker in terms of egg maturity, it is harder to play with the dose. Because the syringe is pre-filled it’s hard to manipulate the dosage. For this reason, many clinics have moved away from using ovidrel in exchange for hCG. It’s VERY important to discuss the trigger medication and what would be best for you and your ovaries before starting the cycle. It can be a huge bummer when you spent your hard-earned cash on a trigger medication that you can’t or don’t want to use. Also, make sure to get the playbook before you leave your doctor’s office on the morning of the planned trigger shot. Getting new instructions only a few hours before the big game can be incredibly overwhelming.

As physicians, we are here to be your cheerleaders and guide you in this “Hey, hey, what do you say?” chant as you throw the final pass. The trigger medication is the grand finale of a whole lot of plays. It’s important to get the medication and the dose right to ensure that your cycle ends on a touchdown and not on a fumble!