How Does Intrauterine Insemination Work?

Quick Answer

Intrauterine insemination (IUI) works by placing washed, concentrated sperm directly into the uterus through a thin catheter at the time of ovulation. This shortens the distance sperm must travel to reach the egg, increasing the chance of fertilization. The procedure takes only a few minutes and requires no sedation.

Markham Fertility Centre performs IUI at its main location in Markham and can monitor patients across 5 Ontario locations.  Cycles last approximately three weeks from start to pregnancy test.

The Science Behind IUI

In natural conception, sperm must travel from the vagina through the cervix and uterus to reach the fallopian tubes, where fertilization occurs. Most sperm do not survive this journey. Out of the millions released during ejaculation, only a few hundred typically reach the egg.

IUI improves these odds in two ways:

• Sperm washing removes seminal fluid, dead sperm, and debris, isolating the healthiest, most motile sperm into a concentrated sample
• Direct placement deposits that concentrated sample past the cervix, directly into the uterus, significantly reducing the distance to the fallopian tubes

Fertilization still happens inside the body, in the fallopian tube, just like natural conception. IUI simply gives the sperm a head start.

Step-by-Step IUI Process

A complete IUI cycle follows the length of a menstrual cycle, approximately three weeks, with three to four clinic visits.

Step 1: Pre-Cycle Testing and Consultation

Before your first IUI cycle, your fertility specialist will confirm you are a good candidate through:

• Sonohysterogram : A diagnostic ultrasound exam to evaluate the shape of the uterus and determine whether the fallopian tubes are open or closed.
• Ovarian reserve testing: AMH blood test and/or antral follicle count via ultrasound
• Semen analysis: Evaluates sperm count, motility, and morphology
• Hormone blood work: FSH, estradiol, TSH, and other markers as needed

These tests are typically completed in one or two visits. In Ontario, most diagnostic testing is covered by OHIP, except AMH (typically between $95 and $125)

Step 2: Ovarian Stimulation (Days 1 to 12)

Once you report day 1 of your menstrual cycle, your physician will start you on a medication protocol to stimulate egg development:

• Oral medications (letrozole or clomiphene citrate): Taken for 5 days, typically starting on cycle day 2 or 3
• Injectable gonadotropins: Used in some cases for 8 to 12 days when a stronger ovarian response is needed

During stimulation, you will visit the clinic two to four times for morning monitoring appointments. Each visit includes a blood draw and transvaginal ultrasound to measure:

• Follicle size and number (each follicle contains one egg)
• Uterine lining thickness
• Hormone levels (estradiol and progesterone)

Your physician adjusts medication dosages based on these results.

Step 3: Triggering Ovulation

When one or more follicles reach the target size your physician may prescribe a trigger injection (hCG, such as Ovidrel). This injection causes the mature egg(s) to release from the follicle within 36 hours.

The IUI procedure is then scheduled to coincide with this ovulation window. Timing is critical because an egg remains fertilizable for only 12 to 24 hours after release.

Step 4: Sperm Collection and Washing

On the morning of the insemination:

• Partner sperm: Collected by ejaculation into a sterile container at the clinic or at home (if delivered within the 2 hours of production). Abstinence of 2 to 5 days beforehand is recommended.
• Donor sperm: A frozen vial is thawed and prepared by the andrology team.  The clinic must have received your frozen sperm before your cycle can proceed.

The sample then undergoes sperm washing, a laboratory process that takes approximately two hours. Washing removes seminal fluid (which can cause uterine cramping), white blood cells, and non-motile sperm. The result is a small volume of highly concentrated, active sperm ready for insemination.

Step 5: The Insemination Procedure

The insemination itself is quick and minimally invasive:

1. You lie on an exam table, similar to a Pap test
2. The physician inserts a speculum to visualize the cervix
3. A thin, flexible catheter is threaded through the cervix into the uterus
4. The washed sperm sample is slowly injected through the catheter
5. The catheter and speculum are removed

The entire procedure takes 3 to 5 minutes. Most patients feel only mild discomfort from the speculum. The insemination itself is typically painless. You can resume normal activities immediately afterward.

Step 6: Post-IUI Support and Pregnancy Test

After insemination, your physician may prescribe progesterone (oral, vaginal, or injectable) to support the uterine lining and improve the chances of implantation.

Approximately 14 days later, you return to the clinic for a blood test measuring beta-hCG, the pregnancy hormone. Testing before this point is not recommended as it can produce inaccurate results.

Natural Cycle vs. Medicated IUI

IUI can be performed with or without fertility medications:

Type	How it works	Best suited for	Success rate per cycle
Natural cycle IUI	No medications; timed to your natural ovulation	Donor sperm patients without infertility diagnosis	5 to 10%
Oral medication IUI	Letrozole or Clomid stimulate 1 to 3 follicles	Unexplained infertility, PCOS, mild male factor	10 to 15%
Injectable medication IUI	Gonadotropins stimulate multiple follicles	Patients who did not respond to oral medications	15 to 20%

Medicated cycles are more commonly used because they improve success rates by increasing the number of mature eggs available at ovulation.

What Makes IUI at Markham Fertility Centre Different

• Physician-performed inseminations: Every IUI is performed by one of five reproductive endocrinologists, not a nurse or technician
• On-site andrology lab: Sperm washing and preparation happen at the clinic, ensuring fresh samples are processed without delays
• Five monitoring locations across Markham, Barrie-Innisfil, Oshawa, Orillia, and Sudbury, reducing travel for early-morning monitoring visits
• Donor and Surrogacy program: Full support for donor sperm selection, ordering, and transport through a Health Canada-approved program
• On-site dispensary: Pick up your fertility medications at the clinic on the same day as your monitoring appointment

Start your IUI journey at Markham Fertility Centre →

FAQ

How long does an IUI procedure take?

The insemination itself takes 3 to 5 minutes. Plan for 1 to 2 hours at the clinic on insemination day to allow time for sperm collection and washing.

Can I exercise or have intercourse after IUI?

Most physicians advise resuming normal activities immediately. Light exercise is fine. Some clinics recommend timed intercourse on the same day or the day after insemination to further improve chances.

How many follicles is ideal for IUI?

One to three mature follicles is the typical target. If too many follicles develop (usually more than three), your physician may cancel the cycle to reduce the risk of a high-order multiple pregnancy.

What happens if IUI does not work?

If pregnancy does not occur, you can begin a new IUI cycle with your next menstrual period. Most physicians recommend 3 to 5 IUI attempts before considering a transition to IVF.