While IUI may seem less intensive than treatments like IVF, it is more intensive than alternatives like oral medications on their own or timed intercourse. The steps involved in an IUI cycle, and the timeline of that cycle, are largely determined by two decisions: which (if any) drugs to use, and whether or not monitoring is done.
A natural IUI cycle is when the woman takes no drugs -- she will grow a follicle and ovulate naturally. Here, the goal of IUI is simply to get sperm to the right place at the right time.
In this case, if no monitoring is done, a woman will simply call her doctor when she sees an LH surge on her home ovulation predictor kit (OPK), and she’ll likely come in the next day for insemination.
If she is doing monitoring, a patient might come in to her clinic on day 3 of her cycle (the third day of bleeding) to ensure that she is at her “baseline”. This means that no follicles (the fluid filled sacs that contain an egg) are growing, and she has a “thin uterine lining” (the part of the womb that grows each month in preparation for a possible pregnancy). This ultrasound sets the schedule for the cycle.
If a patient is confirmed to be at her “baseline,” she is typically instructed to come back about 3 - 4 days before ovulation is expected (to account for the rare cycle in which ovulation occurs early). From that point, the goal is to wait for the “dominant” (largest) follicle to be ready for ovulation.
The IUI is scheduled according to one of two scenarios:
Using A Trigger Shot: When the follicle is at least 20mm and the uterine lining is at least 7mm, a medication (known as a “trigger shot”) can be given to trigger ovulation. This medication is an injection with a small needle in the abdomen. The IUI is scheduled 36 hours after the trigger medication is injected.
Awaiting Natural Ovulation: Blood work or urine-based ovulation predictor kits (OPKs) can predict when a woman will naturally ovulate. In this case, the IUI occurs either later that day or the next morning.
Anovulatory Patients: Can start medication at any time. The only exception to this rule is if a patient’s uterine lining is noted to be abnormally thick at baseline (>10mm), because this might indicate a problem with the uterus. In this case, a 7 to 10 day course of progesterone (like provera or aygestin) can be given to cause the onset of a period and clomid or letrozole would be started thereafter.
Unexplained Patients: Can start medication on day 3 or 5 of the cycle. If the patient is having her treatment cycle monitored, she will come in on day 3 for bloodwork and an ultrasound. On ultrasound, the doctor will be checking to make sure that no follicles have already started the process of growing (because once one follicle is already growing, it is unlikely that others will also start growing in response to clomid or letrozole). The doctor will also look at estrogen levels through blood work to confirm this.
Once the patient has started taking clomid or letrozole, they continue for 5 days, and 4 days thereafter the woman may return to the office for monitoring and blood work. During this time the doctor will observe if any follicles are growing and record how big they are (reflecting the egg’s maturity).
Thereafter the doctor will either:
Increase dosing if no follicles are growing or switch to gonadotropins if no follicles are growing and the patient has reached the maximum dose for clomid (200 mg) or letrozole (7.5 mg)
Continue waiting if the cycle looks promising. Patients may return the next day for insemination if the follicles are large (18mm) or in 2 - 3 days if follicle growth is slower
Cancel the cycle, if too many (4 or more) follicles are growing quickly
If letrozole or clomid haven’t worked in causing ovulation, patients are considered “resistant” to these medications -- some strategies for helping ovulation along in these patients include adding medications such as dexamethasone or metformin to the treatment regimen.