What is a trigger shot IVF?

The trigger injection or ‘trigger shot’ as it is also known, is a hormonal injection used in fertility therapy. Brand names in the UK include Choragon, Ovitrelle, and Pregnyl, among others. A trigger shot usually contains a hormone called human chorionic gonadotropin, or HCG. It is hCG which triggers an ovary to mature and release an egg.

Why do I need a trigger shot?

Women undergoing IVF treatment do a trigger shot so that eggs are matured for collection. Once you have the injection, your ovaries are sent into a cycle of development which allows for egg collection at a specific time which will be outlined by your fertility team.

When should I take the trigger shot?

You will be given careful guidance on this topic by your Apricity advisor. It is important to follow the timing instructions exactly as delays of just a few hours can cause issues with your treatment cycle. Essentially, in most cases the trigger shot needs to be taken 36 hours before egg collection, or a day and a half prior. So if you have a midday appointment for egg collection on Tuesday, you would take the trigger shot at midnight on the Sunday prior. There are some variations to this time window and your advisor will inform you if your case is one of those.

 The trigger shot timing is in line with the development of your follicles, which your clinical team will have been tracking. The trigger shot tends to be done when a good number of follicles have grown to their optimal size. Under or overdeveloped eggs have a lower chance of conception success.

Do I inject trigger shots myself?

Generally yes, especially as the 36 hour window from injection to collection often means the shot is usually taken in the evening and sometimes late in the evening. We ensure that an Apricity advisor is available at the time of the injection in case you have any last minute questions.

I have missed my trigger shot. What do I do?

If you are late taking your trigger shot, it is imperative you let your Apricity advisor or clinic know as soon as possible, as there may be things that they can do to try and salvage the situation. It is not possible to retrieve an egg after the ovary has released it, so it’s important to try and resolve this as soon as possible. In certain circumstances, it may be feasible to adjust your egg collection time.

Will the trigger injection be painful?

There are in fact two ways of administering the trigger injection. It can either be given into the muscle (intramuscular) or under the skin (subcutaneous), which is the most common route. An intramuscular injection will feel the same as getting a vaccine shot at your GP and can cause more bruising than when injecting under the skin. 

Women occasionally report that subcutaneous injections cause the site to become red, inflamed and itchy for a day or two. Either way, the side effects immediately post injection are usually minimal.

Potential trigger shot side effects

Most women do not experience any side effects following the trigger injection, apart from perhaps some local irritation at the injection site, which is usually transient. At this stage of your treatment, it is not uncommon to have been already experiencing some abdominal discomfort or mild bloating due to the combined effect of the treatment hormones and the increase in the size of the ovaries. Following the trigger injection, these symptoms can sometimes increase. As this is not intended to be an exhaustive list of side effects, do not hesitate to seek advice if you are concerned about any new symptoms.

Make sure to monitor any abdominal discomfort or bloating as this can sometimes be associated with Ovarian Hyperstimulation Syndrome. Contact your Apricity advisor if you have any concerns.