IUI Intrauterine Insemination

IUI: Intrauterine Insemination

written by

Dr. Rebecca Angelica Miscioscia

Fertility Clinic Medical Director


IUI (Intrauterine Insemination) or Artificial Insemination: who needs it, why should you do it and how it works.

IUI - Intrauterine Insemination. Let's find out what are the success rates, if it's the right treatment for you, which sperm to use and much more!

IUI or Intra Uterine Insemination is a low complexity assisted fertilization technique that is often recommended as first treatment when starting an assisted reproduction journey (MAP).

I like to define this fertility technique as “power sex”, this is because an IUI follows all the natural steps of fertilization just like normal sex at home.

So where is the advantage?

First of all, IUI is the technique of choice in all those cases in which there is no real fertility issue, but where there is no “sperm supply” due to the lack of a male partner.

Single women who want to become mothers or lesbian couples can in fact perform IUI using donor sperm.

iui single lesbian

On the other hand, in case of heterosexual couples, IUIs can be useful in overcoming some cases of male infertility, such as light alterations in the quantity or motility of the sperm, as well as sexual problems in the man such as erectile dysfunction or in the woman such as vaginismus.

IUI: when is it done?

Intrauterine inseminations are performed at the best time of the menstrual cycle to favor the encounter between the sperm cells and the egg cell released with ovulation.

All this increases the chances of fertilization of the oocyte in the Fallopian tubes (in vivo fertilization).

The journey that the sperm will have to performed inside the woman’s body is shortened and made easier.


The sperm, in fact, will already find itself comfortably inside the uterine cavity bypassing the steps in the vagina and the cervix.

iui insertion

Once in the uterus it will be able to continue its travel into the 2 Fallopian tubes that will have captured the oocyte released in the abdominal cavity at the moment of ovulation (when the rupture of the dominant follicle occurs).

IUI: how does it work

Intrauterine insemination is a simple, painless and quick procedure that is performed on an outpatient basis without the need for any anesthesia or painkiller medication.

The procedure itself itself takes just 5 minutes, but it cannot be performed on any day of the menstrual cycle and it is not useful in all cases of infertility.

For this reason there are some preparatory steps before the IUI can be performed and obviously there are steps following the technique to see if it worked out or not.

IUI, Phase 1: case evaluation and diagnosis of the cause of infertility

Not all types of infertility can be solved with IUI.

For example, if both your Fallopian tubes are closed or absent, due to a previous infection or surgery, the technique has no chance of working.

iui tubes

Before starting an IUI treatment, the gynecologist must check that at least one tube is patent (i.e. open).

Also, the sperm analysis (spermiogram) must not show very serious alterations in the sperm, because only minor sperm issues can be solved through the use of an IUI treatment.

The higher the female partner’s age, the lower the chance of success of this technique, due to the oocyte quality that we know worsens over the years.


Usually, in case of a high female age, the woman is advised to start her fertility journey directly with an IVF treatment in order not to “waste precious time” doing IUIs.

In fact, performing one or more IUI would lead to postponing the in vitro fertilization later in time when the quality of the oocytes will be further poorer.

Especially if you are 40 years old or older, even if you have never tried to get pregnant, postponing an IVF treatment to try IUI first, risks making you “waste” your last fertile months / years behind an ineffective treatment leading also to a lesser success of any future in vitro fertilization treatments.


IUI, Phase 2: Monitoring of the natural menstrual cycle or Controlled Ovarian Stimulation and Monitoring of the ovarian response

After a careful review of your case and the evaluation of your ovarian reserve through an ultrasound of your ovaries and the measurement of your AMH level, your fertility specialist will decide if an IUI is the right treatment for you and in which cycle to perform the insemination.

IUIs can be performed either in a natural menstrual cycle, if you have regular ovulatory cycles, or can be performed in a mild controlled ovarian stimulation cycle.

During a normal menstrual cycle, the ovaries develop a single dominant follicle which leads to the ovulation of a single egg cell.

In case of a mild hormonal stimulation, your fertility specialist will prescribe you with an oral therapy (of Clomiphene Citrate or Letrozole) or with subcutaneous injections (of Gonadotropins) at a very low dosage to ensure that a minimum of one follicle up to a maximum of three follicles develop in your ovaries at the same time.

iui natural stimulated

In both cases, the growth of the ovarian follicles is monitored with repeated transvaginal ultrasound scans over time, which are scheduled by your gynecologist depending on the response that your ovaries produce.

IUI, Phase 3: natural ovulation Detection or Pharmacological induction of ovulation

In regular menstrual cycles, in which the day of ovulation can be predicted, in order to detect the spontaneous ovulation, urinary luteinizing hormone (LH) monitoring is begun approximately 3 days before the expected day of ovulation.

By doing so the LH surge will be identified and the IUI procedure will be scheduled for the day following the detection of the LH surge.


On the other hand, in stimulated cycles, or in natural cycles in which we want to program the IUI procedure more precisely, ovulation is induced pharmacologically.

In these cases, once the follicles are big enough for the gynecologist to think that there is a mature egg inside them, ovulation can be triggered with the administration of a subcutaneous injection of human chorionic gonadotropin (hCG) also known as the “pregnancy hormone”.

The IUI procedure will be then performed approximately 36 hours after the injection administration (or between 34 and 40 hours later).

Intrauterine Insemination, Step 4: Sperm sample preparation

Intrauterine inseminations can be performed using the sperm of your male partner (homologous IUI) or using donor sperm (heterologous IUI).

Heterologous IUI is the technique of choice for lesbian couples or single women.


It is also used in heterosexual couples when the woman has no fertility problems and the partner’s sperm is inadequate to perform any assisted reproduction technique.

iui heterologous

In case of homologous insemination using partner’s sperm, a period of abstinence between 2 and 5 days is recommended.

To make things as simple as possible, I recommend ejaculating 3 days before the IUI and avoiding intercourse or masturbating until the day of insemination when masturbation for the production of the sperm sample will be performed directly at the fertility clinic.


Your partner’s semen sample is then washed and processed in the laboratory, or, in case of heterologous IUI, your donor’s frozen sperm vial is thawed.

In the end, a sperm sample equal to about 0.5 ml will be ready for the insemination.

Intrauterine Insemination, Stage 5: Insemination

The IUI procedure takes place with you lying on the gynecological bed with your legs up high in women’s most loved yoga position.

lettino ginecologico

The gynecologist will insert the speculum in your vagina, just like when you go for your PAP smear test appointment, and will then gently remove any excess mucus from your cervix to prevent it from obstructing the tip of the catheter with which the sperm sample will be placed into your uterus.

At this point the insemination catheter (i.e. a thin cannula) is inserted into the cervical canal through the external orifice of the cervix and is then slowly pushed in until it reaches your uterine cavity.

A syringe containing the pretreated sperm sample will be attached to the end of the catheter and once in the uterine cavity the sperm will be slowly pushed out (in approximately 10–30 seconds) and released into your uterus.


This part, the actual insemination, can also be carried out by your partner (male or female) once your doctor will have ensured that the catheter is inserted correctly.

Immediately after insemination, the catheter is gently removed and the speculum is also removed.

Although there is no scientific data supporting this practice, the patient is often left lying down for a few minutes after the procedure, after which she can get dressed and can go back to her normal life.

IUI, Phase 6: luteal phase Support

Starting on the evening of the day of the IUI procedure, it is advisable to start vaginal progesterone administration.

This therapy is prescribed to “support the luteal phase”, so to help the corpus luteum (the scar on the ovary produced by ovulation) keep the endometrium well prepared to welcome a possible pregnancy.

The vaginal progesterone will be administered until the day of pregnancy test and in case of a positive result it will be continued.
iui progesterone

IUI, Step 7: Pregnancy Test

Approximately 14 days after the IUI procedure a pregnancy test is performed on a blood sample, so the beta-hCG value is measured.

Even if it is frustrating, the waiting time before taking the pregnancy test must be respected and not anticipated.
This will ensure that the test result is a reliable answer and not a false positive or false negative result.
In fact, an early pregnancy test could be falsely negative but also falsely positive, because if you remember the hormone hCG is used to induce ovulation!

Intrauterine Insemination: success rates

The success rate for each IUI attempt highly depends on the age of the woman, on the type of infertility and its degree of severity and on the quality of the sperm that will be used.

In general, the best results are obtained in young women (under 35 years of age) without fertility problems who use donor sperm.

In these patients, the success rate with each IUI cycle is about 25%, so about 5% higher than the probability of getting pregnant with regular sexual intercourse.

iui 25

Most women who perform donor sperm inseminations are single or lesbian with no fertility issue and are able to conceive within 4-6 cycles of IUI.

As can be guessed, the success rates of IUIs using sperm from a male partner with fertility problems are significantly lower, but can reach 20% if the male infertility is low grade and the age of the female partner is less than 35 years.

Intrauterine Insemination: risks

IUIs are a safe procedure with a low risk of complications.

Among the potential complications is a low risk of developing an infection.
This is because a catheter is inserted into the uterine cavity, but the risk is low because all the instruments used are sterile.
In case a stimulated cycle were used, a risk of ovarian hyperstimulation exists, but by monitoring the ovarian response with ultrasounds, any excessive follicular development will be suppressed and the cycle canceled.

If the stimulated cycle leads to the development of more than one follicle, a multiple pregnancy will be possible.

For this reason, cycles in which more than 3 follicles develop are canceled.

Twin pregnancies are pregnancies with a higher risk of complications than single pregnancies and for this reason a good fertility doctor will always try to minimize this risk.

The insertion and removal of the speculum to perform the IUI procedure can cause a light bleeding, but as scary as it may be to see blood on your panties, this will have no impact on your chances of getting pregnant and on the future course of the pregnancy.

Intrauterine Insemination: key points

Intrauterine insemination, or artificial insemination, reduces the distance that the sperm cells have to travel in order to find and fertilize the oocyte.

Pregnancy is not guaranteed and only occurs if a sperm cell is able to find and fertilize the egg cell in one of the two Fallopian tubes.

Once fertilization has taken place, the embryo produced must develop and reach the uterine cavity to then implant itself in the endometrium (the inner lining of your uterus).

iui endometrium

IUI is a simple and cheaper procedure than other types of fertility treatments, but in order to really increase your chances of pregnancy, it should only be used if recommended by a fertility specialist.

Sometimes performing a more complex and a bit more expensive treatment right from the start can guarantee you better results and even allow you to spend less money in the long run.

Now that you know all about the IUI procedure, you will have fully understood why I call it “power sex”!



The information contained in this website is presented for informational purposes only. In no case can the information presented constitute the formulation of a diagnosis or the prescription of a treatment. All content presented in this website is not intended to, and must not in any way, replace the direct doctor-patient relationship or the medical specialist evaluation. It is recommended to always seek the advice of your doctor and / or specialists regarding any indication reported. In case of any doubts or questions about the use of a drug, you should contact your doctor. Read the Disclaimer »

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Hi, I’m Rebecca, I’m the Medical Director of an LGBTQ+ friendly fertility clinic and in my free time I create simple content to make obstetrics and gynecology no longer a mystery.
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