4 May 2021

What’s the difference between IVF and IUI?

Vector illustration of intrauterine insemination (IUI)
Medical Director
Cesar Diaz-Garcia
MD PhD Assoc Prof
IVI London


With the ongoing advances in reproductive technology, nowadays there are a lot of options when it comes to fertility treatment. When you first start to explore your options, you may be wondering just what is IUI? What’s the difference between IUI and IVF? Which one should I opt for?

Intrauterine Insemination (IUI) is a form of fertility treatment and one of the most straightforward when it comes to assisted conception. For many patients, the attraction of IUI is that it gives couples a helping hand to maximise their chances of pregnancy while allowing the body to undergo the fertilisation process naturally. As an IUI treatment simply aids the sperm’s journey, it is one of the least invasive and affordable procedures to treat infertility.

In this article, we’ll take a closer look at how IUI works, how it differs to In Vitro Fertilisation (IVF), whether IUI is suitable for you and what you can expect if you undergo an IUI treatment.


What’s the difference between IVF and IUI?

IUI and IVF share a common goal, but the steps to parenthood are very different. During an IUI treatment, experts carefully select the strongest sperm before injecting the specimen directly inside the uterus, where it will hopefully fertilise the egg. From this point, the natural process of pregnancy resumes. On the other hand, IVF facilitates fertilisation in vitro (external to the body), inside a controlled lab environment. Unlike IVF, an IUI treatment does not require any sort of egg collection.

During an IUI treatment, there is also no process of embryo selection. This means that Pre-Implantation Genetic Testing for Aneuploidy (PGT-A) or Pre-Implantation Genetic Testing for Monogenic Diseases (PGT-M) or Structural Arrangements (PGT-SR) is not possible with IUI treatment. If you are considering these treatments, then you will need to undergo IVF.


When is an IUI treatment recommended?

IUI treatment can be particularly beneficial to couples experiencing male factor fertility problems, such as a reduced sperm count or poor sperm motility. This is because it maximises the chances of a healthy sperm fertilising the egg. The treatment is also recommended for couples with unexplained fertility issues, providing that the woman undergoing the insemination procedure has healthy fallopian tubes. An IUI treatment can be carried out using a partner’s sperm or donor sperm, making it a good option for lesbian couples or single women who are using donated sperm and have no known fertility issues.

IUI may also be recommended for:

  • Women with polycystic ovary syndrome (PCOS) or other disorders which disrupt ovulation.
  • Couples who are unable to have sexual intercourse (e.g. due to a physical disability).
  • Couples in which the male partner is HIV positive.


What does the IUI process involve?

The first step of an IUI cycle is for experts to prepare the sperm sample. By doing this, they are able to select the sperm with the best motility. To ensure the highest possible chance of fertilisation, the sperm sample will be placed in a centrifuge. This separates the immotile, or less mobile, sperm. Our experts will make sure that the sperm sample contains a minimum concentration of healthy sperm for best results.

Meanwhile, the female patient will undergo regular transvaginal ultrasounds and blood tests to monitor the development of her follicles. Inside each follicle, an egg will develop. When the egg reaches an optimum size, ovulation is triggered using an hCG injection.

Approximately 24 to 36 hours later, the insemination procedure will take place. During the procedure, a speculum is inserted into the vagina. A cannula is passed through the cervix and into the uterus, where the sample is deposited. This process is no more intrusive or uncomfortable than a regular smear test.

During this time, it’s normal to experience a wide range of emotions. As with all fertility treatments at IVI, emotional and psychological support are important parts of the process. Our friendly in-house counselling team will be there with you every single step of the way.


IUI – natural or stimulated cycle?

An IUI treatment can be performed with or without fertility drugs. The most suitable treatment for you will depend on your personal circumstances and medical history.

A medicated or stimulated IUI cycle, sometimes known as SIUI, may improve the chance of pregnancy because it generates a greater number of follicles. During a normal menstrual cycle, a single follicle produces a single egg. During a stimulated IUI cycle, gentle hormone stimulation is used to generate multiple follicles. This causes more eggs to be released during ovulation. Put simply, more eggs mean a higher likelihood of fertilisation occurring. 

After 10 to 12 days of ovarian stimulation, an hCG injection is used to induce egg maturation and trigger ovulation. You’ll be shown how to carry out this step in the comfort of your own home by our medical team. Within 36 hours, you’ll be ready to undergo insemination. Two weeks later, you will be able to have a pregnancy blood test to confirm the outcome of the treatment.

Ovarian stimulation – while beneficial to improve the chances of pregnancy – does come with its own challenges of which patients should be aware. The main risk is a multiple pregnancy. A multiple pregnancy can pose significant safety risks to both mother and baby, especially those of advanced maternal age. Another complication of a stimulated cycle is ovarian hyperstimulation syndrome (OHSS). OHSS is a rare but potentially serious condition resulting from overstimulation of the ovaries during fertility treatment. Nearly a third of all patients will experience mild OHSS symptoms, however only 2-8% require any sort of medical intervention.

An unstimulated or natural IUI cycle is an IUI treatment without any form of ovarian stimulation and one of the least invasive types of fertility treatment. It’s often recommended for women with regular or predictable menstrual cycles. It is not recommended for patients with irregular periods or ovulation disorders, as it is very unlikely to be effective. In the same way as a stimulated IUI cycle, the follicle growth is monitored with ultrasounds and blood tests. However, only one follicle will be generated.  A hCG injection may be administered to trigger ovulation to ensure the insemination procedure is scheduled at the optimal time.


How successful is IUI?

Many patients prefer the more natural side of IUI. However, it comes with one downside: it is less successful compared to IVF. According to the Human Fertilisation and Embryo Association (HFEA), the success rate for IUI is around a third of that of IVF. This doesn’t mean it should be immediately dismissed in favour of IVF: one retrospective observational study spanning 2012 to 2016 even concluded that IUI success rates, in terms of a live birth, are much closer to IVF pregnancy outcomes than previously reported.

Not only is IUI less intrusive, it’s also a more affordable option. This is because fewer fertility drugs are required, along with fewer lab processes. You can expect to pay four times as much for one cycle of IVF than you would for one cycle of IUI.

For couples with no identified fertility issues, for single women or for same-sex couples, IUI can be a highly effective and affordable treatment. It may not be the most appropriate treatment for those with a significant problem affecting male or female fertility. For older women, IVF treatment may also be more suitable. As egg quality and quantity decrease naturally with age, it can decrease the chances of success with IUI. Studies have determined that women aged 38 to 39 still had a reasonable chance of a successful treatment after two cycles of IUI, but this plummeted for those aged over 40.


Any questions? Get in touch with IVI

At IVI, the first step we take with all of our patients is to discuss your medical history and perform a detailed medical assessment of your fertility. This will enable us to recommend the most suitable treatment for your situation and whether IUI is an option for you. If you’re considering your next steps, you’re welcome to come along to one of our free Virtual Open Evenings where you’ll not only have the opportunity to learn more about the treatments we offer, but also about IVI and our dedication to safe and effective fertility treatments.

Request more information, no obligation

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