IUI Protocol
For couples with unexplained infertility and TMSC >10 million with <30% chance of spontaneous pregnancy within a year, perform IUI with ovarian stimulation using low-dose gonadotropins (≤75 IU) or clomiphene citrate, trigger with hCG when dominant follicle reaches ~18mm, perform single IUI 24-40 hours post-trigger, and complete at least 3 consecutive cycles. 1
Patient Selection and Timing of Treatment
When to Start IUI:
- If spontaneous pregnancy probability >30% within 12 months (using Hunault score): delay IUI for at least 6 months of expectant management 1
- If spontaneous pregnancy probability <30% within 12 months: proceed directly to IUI with ovarian stimulation 1
Sperm Parameters:
- Post-wash TMSC >10 million is optimal for IUI-OS 1
- Consider withholding IUI if TMSC <1 million or morphology <4%, though evidence is weak 1
- No definitive lower cutoff exists; clinical judgment required for borderline cases 1
Ovarian Stimulation Protocol
Medication Selection (in order of preference):
Low-dose gonadotropins (≤75 IU) - First choice
Clomiphene citrate (100mg daily for 5 days) or Letrozole - Acceptable alternative
Do NOT use:
- GnRH agonist added to gonadotropins (increases multiple pregnancy and costs without improving pregnancy rates) 1
Cycle Monitoring and Triggering
Monitoring:
- Ultrasound follicle tracking combined with hCG trigger for stimulated cycles 1
- LH testing for natural cycles 1
Trigger Timing:
- Administer hCG when dominant follicle(s) reach mean diameter ~18mm 1
Critical Safety Threshold - CANCEL CYCLE if:
2 dominant follicles ≥15mm, OR
5 follicles ≥10mm at time of hCG/LH surge 1
- This prevents dangerous multiple pregnancy rates
Insemination Timing and Technique
Timing:
- Stimulated cycles with hCG trigger: Perform single IUI anytime between 24-40 hours post-hCG 1
- Natural cycles: Perform IUI 1 day after LH rise 1
- Provider can choose specific timing method within these windows (no evidence favoring one over another) 1
Number of Inseminations:
- Single IUI per cycle only 1
- Despite some older studies suggesting benefit of double IUI, evidence is dominated by one unclear-quality study 1
- For unexplained infertility specifically, double IUI shows no benefit 1
Post-Procedure:
- 10-15 minutes bed rest after insemination 1
Semen Preparation:
- Any standard technique acceptable (swim-up, gradient, wash-and-centrifugation) - no superior method proven 1
Number of Cycles
- Perform at least 3 consecutive IUI-OS cycles before considering IVF 1
- Most pregnancies occur within first 3-4 cycles 3
- No maximum number definitively established, but diminishing returns after 3-4 cycles 1
Infection Prevention
- Screen couples for infectious agents per local/regional/national standards before starting IUI 1
- Follow WHO laboratory safety protocols for semen handling 1
Key Clinical Pitfalls
Multiple Pregnancy Prevention: The most serious complication of IUI-OS is multiple pregnancy with associated maternal and neonatal morbidity. The strict cancellation criteria (>2 follicles ≥15mm or >5 follicles ≥10mm) are non-negotiable 1. While follicle aspiration is mentioned as an alternative to cancellation, this remains low-quality evidence 1.
Overstimulation Risk: Using gonadotropin doses >75 IU increases multiple pregnancy rates without improving pregnancy rates - this is wasteful and dangerous 1. Start low and individualize based on response.
Cost-Effectiveness: For couples meeting criteria (unexplained infertility, TMSC >10 million, poor spontaneous prognosis), 3 cycles of IUI-OS is more cost-effective than proceeding directly to IVF 1. However, don't persist beyond 3-4 unsuccessful cycles.
Natural Cycle IUI: Evidence for IUI in completely unstimulated natural cycles is weak, with only one trial showing marginal benefit 1. Ovarian stimulation combined with IUI provides significantly better outcomes 1.