From the Guidelines
IUI should be performed 24-40 hours after HCG injection, which can be administered immediately since the follicle has already reached 19×18 mm in size. The timing of IUI is crucial, and according to the study by 1, if a HCG injection is used, single IUI can be performed any time between 24 and 40 h after HCG injection without compromising pregnancy rates. Given that the follicle has already reached the desired size, the trigger shot can be administered, and the IUI procedure can be scheduled accordingly.
- Key factors to consider:
- The follicle size is already optimal for triggering ovulation
- The timing of IUI after HCG injection is critical for maximizing the chance of fertilization
- The mature egg remains viable for about 24 hours after ovulation
- The study by 1 provides the most recent and highest quality evidence for determining the optimal timing of IUI, and its recommendations should be followed to maximize the chances of conception while minimizing the risks of multiple pregnancies and other complications.
- It is essential to note that the use of gonadotrophins in IUI, as discussed in the study by 1, should be carefully managed to prevent multiple pregnancies, and regimens with 75 IU or lower should be used to minimize this risk. However, this does not directly impact the timing of IUI in this specific scenario.
From the Research
Follicular Studies and IUI Timing
- The given follicular study shows an egg size of 19×18 mm on the 12th day, which is a crucial factor in determining the optimal time for intrauterine insemination (IUI) 2.
- According to a study published in the International Journal of Gynaecology and Obstetrics, the optimal follicular diameter associated with increased pregnancy rates in gonadotropin-stimulated IUI cycles is between 19 and 20 mm 2.
- Another study published in Fertility and Sterility suggests that IUI should be performed 36 hours after triggering ovulation if at least one follicle measuring >16 mm and an endometrial thickness of >7 mm are obtained 3.
Predictive Factors for Pregnancy after IUI
- The predictive factors for pregnancy after IUI include the woman's age, type of infertility, spermogram characteristics, total motile spermatozoa count, E2 level before hCG injection, and the number of mature follicles 3.
- A study published in Reproductive Biomedicine Online found that spontaneous triggering of ovulation by detecting LH rise results in higher pregnancy rates compared to administration of human chorionic gonadotrophin (HCG) in patients undergoing IUI 4.
- The number of mature follicles on the day of hCG administration is also an important prognostic indicator of success with IUI, with higher numbers of follicles associated with increased pregnancy rates 5.