Indications for Intrauterine Insemination (IUI)

1. Cervical Factor Infertility

• Hostile cervical mucus - poor sperm penetration (e.g., due to anti-sperm antibodies in mucus, or after cervical surgery/cone biopsy)
• Cervical stenosis preventing natural sperm transit
• Inadequate cervical mucus (e.g., following prolonged clomiphene use, which thickens cervical mucus)

2. Male Factor Infertility

• Low sperm count (oligospermia) - at least 5 million total motile sperm in the ejaculate is generally required
• Reduced motility (asthenospermia)
• Mechanical/anatomical problems of sperm delivery, such as hypospadias, retrograde ejaculation, or erectile dysfunction preventing normal deposition
• Immunologic infertility - anti-sperm antibodies in the male (sperm washing partially removes antibody-bound sperm)

3. Unexplained (Idiopathic) Infertility

4. Ovulatory Dysfunction

• Induce and time ovulation precisely
• Synchronize sperm delivery with follicle rupture

5. Donor Sperm Insemination (Therapeutic Donor Insemination - TDI)

• Azoospermia (absence of sperm in ejaculate) where surgical sperm retrieval is not desired
• Severe male factor infertility where the couple does not wish to proceed to ART
• Same-sex female couples seeking pregnancy
• Single women seeking pregnancy
• Berek & Novak's Gynecology; Campbell-Walsh-Wein Urology

6. Endometriosis (Minimal to Mild)

7. Sexual Dysfunction / Coital Disorders

• Vaginismus preventing intercourse
• Severe dyspareunia making intercourse impossible
• Neurological conditions affecting coital function

Summary Table

Pre-requisites for IUI

1. At least one patent fallopian tube (confirmed by HSG or laparoscopy)
2. Adequate uterine cavity (no significant fibroids/polyps distorting it)
3. Minimum post-wash total motile sperm count of ~1 million (ideally 5-10 million)
4. No active pelvic infection

• Berek & Novak's Gynecology (Artificial Insemination/IUI section, p. 2036-2037)
• Smith and Tanagho's General Urology, 19th Ed. (IUI section, p. 744)
• Campbell-Walsh-Wein Urology (IUI section, p. 2037)

When Should IUI Treatment Be Initiated?

1. Pre-requisite: Complete Infertility Evaluation First

• Female assessment: At least one patent fallopian tube (confirmed by HSG or laparoscopy), adequate ovarian reserve, normal uterine cavity (baseline ultrasound or saline infusion sonography), and hormonal profile (FSH, LH, AMH, TSH)
• Male assessment: Semen analysis showing at least 5 million total motile sperm (some sources allow a minimum of 1 million post-wash motile sperm)
• No active pelvic infection in either partner

2. When to Initiate Based on Clinical Scenario

A. Unexplained Infertility

• The classic teaching is a stepwise escalation approach: timed intercourse (expectant management) → CC/IUI → FSH/IUI → IVF
• However, contemporary evidence from the FASTT trial (Fast Track and Standard Treatment trial) showed that CC/IUI and FSH/IUI had significantly lower ongoing pregnancy rates (7.6% and 9.8% per cycle respectively) vs. IVF (30.7%), with IVF also being more cost-effective overall
• The FASTT trial concluded that couples with unexplained infertility who have not achieved pregnancy after 3 cycles of clomiphene/IUI should proceed directly to IVF, skipping the FSH/IUI step
• Meta-analysis of over 1,159 participants found CC alone or CC/IUI showed no improvement over no treatment/expectant management, questioning the traditional stepwise approach
• Current evidence supports early IVF, but IUI + COS continues to be used widely because it is far less expensive and more accessible - Berek & Novak's Gynecology

B. Mild-to-Moderate Male Factor Infertility

• IUI is initiated once semen analysis shows parameters within the acceptable range (post-wash total motile sperm >1 million, ideally 5-10 million)
• For patients who fall below this threshold, IVF/ICSI is preferred from the outset

C. Cervical Factor

• IUI can be initiated early in the treatment course, often as a first-line intervention, since the rationale is straightforward (bypassing the cervix)

D. Ovulatory Dysfunction (e.g., PCOS)

• IUI is initiated after ovulation induction agents are started (clomiphene 100 mg days 3-7, or letrozole, or gonadotropins). The IUI procedure itself is timed to ovulation trigger within that stimulated cycle

E. Advanced Female Age (≥38 years)

• The FORT-T trial showed patients aged 38-42 had higher live birth rates from IVF directly compared to CC/IUI or FSH/IUI
• For women ≥38, the window of IUI attempts should be very limited (1-3 cycles at most) before escalating to IVF, given the time-sensitive nature of ovarian reserve
• For women aged ≥40, many guidelines recommend proceeding directly to IVF without a prolonged IUI trial

F. Donor Insemination (azoospermia, same-sex couples)

• IUI with donor sperm can be initiated as a first-line treatment once the female partner's workup is complete and normal

3. How Many Cycles of IUI Before Moving On?

• 90% of successful IUI pregnancies occur within the first 6 treatment cycles. If pregnancy does not occur within 6 cycles, the chance of success with further IUI attempts is very low. - Dikshit Textbook of Forensic Medicine
• Most clinicians recommend 3-6 cycles before re-evaluation or escalation to IVF
• For unexplained infertility, evidence supports stopping at 3 cycles of CC/IUI and proceeding to IVF rather than continuing with gonadotropin/IUI - Berek & Novak's Gynecology
• For donor IUI, up to 6-12 cycles may be attempted in younger women with no identified female factor

4. Timing Within the Menstrual Cycle

• Baseline ultrasound on day 2-3 of the menstrual cycle to check for cysts, measure antral follicle count, and confirm endometrial thinness
• Ovarian stimulation begins on day 3 (clomiphene: days 3-7; gonadotropins: daily injections from day 3)
• Serial transvaginal ultrasound to monitor follicle growth; trigger with hCG when the lead follicle reaches ≥18-20 mm
• IUI is performed 34-36 hours after the hCG trigger (or 24-36 hours after the spontaneous LH surge)
• No significant difference in pregnancy rates between performing IUI at 24 vs. 36 hours post-trigger - Berek & Novak's Gynecology

• Berek & Novak's Gynecology (Treatment of Unexplained Infertility; Superovulation with IUI; Cost-Effectiveness sections)
• Smith and Tanagho's General Urology, 19th Ed. (IUI section)
• Dikshit Textbook of Forensic Medicine (Artificial Insemination: IUI procedure and success rates)

When is Ovarian Stimulation (OS) Required in an IUI Cycle?

Unstimulated (Natural Cycle) IUI - When OS is NOT Required

1. Cervical factor infertility in a woman with regular, confirmed ovulation - bypassing the cervix is all that is needed; there is no benefit to recruiting extra eggs
2. Mild male factor infertility in a regularly ovulating woman - the purpose is sperm delivery, not increasing egg numbers
3. Donor IUI in regularly cycling women (single women, same-sex female couples) with no identified female-factor infertility - natural cycle IUI gives ongoing pregnancy rates of ~10% per cycle and ~40% cumulative over 6 cycles; the addition of clomiphene or hMG has not been shown to improve fecundity in these patients
4. Immunological infertility (anti-sperm antibodies) in an ovulatory woman

• Berek & Novak's Gynecology

When OS IS Required in an IUI Cycle

1. Ovulatory Dysfunction / Anovulation (Primary Indication)

• PCOS - first-line agents are letrozole (preferred) or clomiphene citrate to induce monofollicular or bifollicular growth before IUI
• Hypothalamic amenorrhea - low-dose gonadotropins are used if oral agents fail
• Hyperprolactinemia or hypothyroidism - the underlying endocrine disorder is treated first; if ovulation still doesn't occur spontaneously, OS is added
• Without OS in these patients, there is no oocyte available for fertilization, making IUI futile
• Harrison's Principles of Internal Medicine, 22nd Ed.

2. Unexplained Infertility

• Achieve superovulation (deliberately developing 2-3 follicles) rather than single-egg ovulation induction
• The goal is to maximize the number of eggs available, increasing the probability that at least one is fertilized
• Options in order of effectiveness: CC/IUI → letrozole/IUI → FSH/IUI

• The FASTT trial showed CC/IUI (7.6%) and FSH/IUI (9.8%) had much lower ongoing pregnancy rates vs. IVF (30.7%)
• Meta-analysis of >1,159 patients found CC alone or CC/IUI showed no improvement over expectant management
• Despite this, OS/IUI remains widely used due to lower cost and greater accessibility than IVF
• Berek & Novak's Gynecology

3. Mild Male Factor Infertility - When Female Has Borderline Fertility

• Increases available oocytes so that even if sperm quality is marginal, fertilization can occur
• Harrison's Principles of Internal Medicine, 22nd Ed.: "First-line treatment for mild to moderate male factor infertility includes IUI alone or IUI combined with ovulation induction, depending on the female partner's parameters"

4. Diminished Ovarian Reserve

• Oral agents (letrozole/CC) + IUI is the initial approach
• If no pregnancy, escalate to IVF given lower overall live birth rates in this group
• Harrison's Principles of Internal Medicine, 22nd Ed.

OS in IUI: Natural Cycle vs. Stimulated - Key Distinctions

Superovulation Protocol Specifics (When OS Is Used)

• Baseline ultrasound on day 2-3 to exclude cysts and assess AFC
• Clomiphene 100 mg × 5 days (days 3-7) - higher dose than ovulation induction
• Gonadotropins (FSH): 150-300 IU daily starting day 2-3; max 450 IU/day
• Monitoring: Serial US from day 6-7; trigger hCG when ≥2 follicles reach ≥17-18 mm AND endometrial thickness ≥8 mm
• Cancellation criteria to prevent high-order multiples: E2 >1,000-2,500 pg/mL, or ≥3 follicles ≥16 mm, or ≥2 follicles ≥16 mm + ≥2 follicles ≥14 mm
• IUI is performed 34-36 hours after trigger
• Berek & Novak's Gynecology

Key Takeaway

• Berek & Novak's Gynecology (Superovulation with IUI; Donor IUI; Treatment of Unexplained Infertility)
• Harrison's Principles of Internal Medicine, 22nd Ed. (Infertility: Counseling and Treatment)

Influence of Sperm Quality on IUI Outcomes

1. Total Motile Sperm Count (TMSC) - The Single Most Important Parameter

• Minimum threshold for IUI to be worthwhile: ≥5 million total motile sperm in the pre-wash ejaculate (volume × concentration × % motility)
• Post-wash inseminate thresholds:
  • ≥5 million motile sperm (most widely cited) - Berek & Novak's Gynecology; Smith and Tanagho's Urology
  • ≥10 million motile sperm (some studies prefer this) - Campbell-Walsh-Wein Urology
  • A French study found similar pregnancy rates across all values ≥1 million post-wash
• Reported pregnancy rates when thresholds are met: 10.5% per cycle; 38% cumulative after 4-6 cycles
• Below threshold (<1 million post-wash motile sperm): IUI effectiveness drops substantially; IVF/ICSI should be considered
• Severe male factor (sperm count <5 million/mL OR motility <20%): IVF with ICSI is preferred over IUI - Harrison's Principles of Internal Medicine, 22nd Ed.

2. Sperm Motility (Asthenozoospermia)

• Progressive motility is essential for sperm to traverse the fallopian tubes and reach the oocyte
• Reduced progressive motility (<32% per WHO 2010 criteria) directly reduces IUI success
• Sperm washing and density gradient centrifugation select the most motile fraction, partially compensating for poor overall motility
• However, with very severe asthenozoospermia, even the post-wash yield of motile sperm may be insufficient for IUI

3. Sperm Morphology (Teratozoospermia)

• Older evidence (strict/Kruger criteria): Teratozoospermia was historically associated with IUI failure
• More recent retrospective studies: Low strict normal morphology of 2%-4% has NOT been found to be predictive of IUI failure compared to morphology >4%
• Severe teratozoospermia (<2% strict normal forms): The effect on IUI outcomes "remains nebulous" - the evidence is insufficient to make firm conclusions
• Practical implication: Morphology alone should not be the sole reason to withhold IUI, particularly for borderline values, but very severe teratozoospermia shifts the preference toward ICSI
• Berek & Novak's Gynecology

4. Sperm DNA Fragmentation (SDF)

• High SDF did NOT significantly reduce clinical pregnancy rate after IUI (RR 0.82, 95% CI 0.52-1.29, P=0.38)
• Miscarriage rate tended to be higher in high-SDF group vs. low-SDF group, but this was not statistically significant (RR 2.11, 95% CI 0.93-4.8, P=0.07)
• Conclusion: SDF appears to have limited impact on IUI pregnancy rates, though a trend toward higher miscarriage exists. Evidence is limited and should be interpreted cautiously
• [Liu X et al., Urology 2025, PMID 40412538]

5. Sperm Concentration (Oligozoospermia)

• Mild-to-moderate oligozoospermia (5-20 million/mL) is an indication for IUI
• Severe oligozoospermia (<5 million/mL) significantly reduces the post-wash yield, often falling below the viable TMSC threshold
• At this level, IVF/ICSI is preferred

6. Abstinence Duration - A Modifiable Sperm Quality Factor

• Optimal abstinence before IUI specimen collection: ≤2 days
• Prolonged abstinence (>5 days) leads to:
  • Elevated sperm DNA fragmentation (oxidative stress during epididymal storage)
  • Reduced total motile sperm count in oligozoospermic men
  • Reduced progressive motility, viability, and tail morphology
• A 2024 dose-response meta-analysis (85 studies) confirmed that IUI clinical pregnancy rates significantly decrease around the 3rd day of abstinence - supporting the recommendation to collect the sample after ≤2 days of abstinence for IUI cycles
• Shortening abstinence to ≤2 days improves IUI pregnancy rates - Berek & Novak's Gynecology; [Du C et al., Andrology 2024, PMID 38197853]

7. Leukocytospermia

• Elevated WBCs in semen (>1 million/mL) generate reactive oxygen species that damage sperm DNA and reduce motility
• Associated with reduced IUI success; sperm washing partially removes leukocytes and their oxidative by-products

Summary: Sperm Parameter Thresholds for IUI Decision-Making

• Berek & Novak's Gynecology (IUI section, p. 2036-2037; Abstinence section, p. 2028)
• Campbell-Walsh-Wein Urology (IUI section)
• Smith and Tanagho's General Urology, 19th Ed.
• Harrison's Principles of Internal Medicine, 22nd Ed.
• Liu X et al. - Sperm DNA fragmentation and IUI, Urology 2025, PMID 40412538
• Du C et al. - Abstinence time and semen quality, Andrology 2024, PMID 38197853