Intrauterine Insemination (IUI) 2025: indications, process, evidence, risks & comparison

Author photo
Zappelphilipp Marx•
A thin catheter places prepared sperm into the uterus during an IUI procedure

Intrauterine insemination (IUI) is an established technique in assisted reproduction. Prepared sperm are placed into the uterus using a soft catheter; fertilization and implantation occur in the body. This article offers a clear, even-handed overview: indications, realistic success rates, the steps involved, safety considerations, and how IUI compares with ICI, IVF and ICSI.

What is IUI?

Before IUI, the semen sample is washed and concentrated. This removes seminal plasma and enriches progressively motile sperm so the sample is better tolerated. The sample is then introduced into the uterus via a thin catheter. IUI can be done with partner or donor sperm. A concise public introduction is available from NHS Inform.

Who is it for?

IUI is typically considered for unexplained infertility, mild male-factor issues (moderately reduced concentration or motility), cervical factors, dyspareunia/intercourse difficulties, and for treatment using donor sperm. If the fallopian tubes are blocked, semen parameters are markedly impaired, or ovarian reserve is clearly reduced, IVF/ICSI is often more appropriate. A neutral indications overview is provided by the HFEA.

Evidence & success rates

Per-cycle chance depends mainly on age, diagnosis, quality of the prepared sample, stimulation strategy, and precise timing. Guidelines and reviews show, for unexplained infertility, an advantage over expectant management—particularly with mild stimulation and good timing. Absolute rates remain moderate; several structured IUI cycles in series are common before considering a move to IVF/ICSI. Helpful references include NICE fertility guidance and ESHRE guidance.

Prerequisites

  • At least one patent fallopian tube (e.g., confirmed with HSG or HyCoSy).
  • Evidence of ovulation—spontaneous or medication-triggered.
  • Sufficient progressively motile sperm after preparation (centre thresholds vary).
  • No active genital infection; up-to-date STI screening where appropriate.
  • For donor sperm: defined screening, traceability and documented consent processes.

Step-by-step process

  • Preparation: History, cycle monitoring, semen analysis; assess tubal patency if indicated.
  • Stimulation (optional): Letrozole/clomiphene or low-dose gonadotropins; aim for 1–2 mature follicles.
  • Ovulation timing: hCG trigger or monitoring via LH testing and ultrasound.
  • Semen preparation: Swim-up or density-gradient; record concentration and motility after washing.
  • Insemination: Placement with a flexible catheter; usually a brief, well-tolerated procedure.
  • Aftercare: Usual activities can typically resume immediately; luteal progesterone support varies by centre.
  • Testing: Pregnancy test about 10–14 days after IUI.

A succinct overview of steps and success factors is available from the HFEA.

Timing & stimulation

Timing is crucial: IUI is usually performed 24–36 hours after an hCG trigger or near a spontaneous LH surge. Mild stimulation can increase per-cycle chance but requires close monitoring to avoid multiple pregnancy. Guidance recommends conservative dosing, clear cancellation criteria if too many follicles develop, and a limited number of cycles before considering a method change (see NICE).

Risks & safety

IUI is generally safe. The main concern is multiple pregnancy when stimulation leads to excessive follicle numbers. Other uncommon risks include infection, cramping or light bleeding after catheter passage. Good practice includes aseptic technique, conservative stimulation, cancelling cycles with too many follicles, and clear counselling about benefits and limits. A concise risk summary is provided by NHS Inform.

Comparison: ICI · IUI · IVF · ICSI

CriterionICIIUIIVFICSI
SettingLow-threshold; placement near the cervixClinical; washed sample into the uterusClinic + laboratory; fertilization in labClinic + laboratory; micro-injection per oocyte
SampleUnprocessed or simply washedWashed, selectedPrepared; co-incubationSingle sperm injected into each oocyte
Per-cycle successRather low; highly timing-dependentModerate; age/diagnosis dependentHigher than IUI; age dependentSimilar to IVF; advantage with male factor
ComplexityLowLow–mediumMedium–highHigh (micromanipulation)
Key risksSmall; hygiene/testing centralMultiple pregnancy with stimulationOHSS, procedure-related risks, multiplesAs IVF + potential cellular damage
Typical useStarting option without severe factorsUnexplained infertility, mild male factor, donor spermTubal factors, endometriosis, failed IUIPronounced male factor, fertilization failure

Guidelines support a stepwise approach: several well-planned IUI cycles and—if unsuccessful—a structured transition to IVF/ICSI.

Planning & next step

  • Define indication and alternatives; set expectations realistically.
  • Choose a cycle strategy (natural IUI vs mild stimulation); cancel if too many follicles develop.
  • Agree in advance the number of IUI cycles and when to consider switching method.
  • Ask about laboratory quality: preparation report with post-wash concentration and motility.
  • Optimize lifestyle (nicotine, alcohol, BMI, sleep, physical activity) — small gains add up.

RattleStork — IUI well organized

RattleStork is not a clinic and does not replace medical advice. The platform supports your personal organization around IUI: verified profiles and secure messaging, private notes for appointments, medicines and questions for your care team, plus simple checklists for timing and consultations. This keeps information together—from the first visit to the test result.

RattleStork app with verified profiles, secure chat and private notes for IUI planning
RattleStork: find support, structure your information, and make IUI decisions prepared.

Conclusion

IUI is a low-burden option with a moderate per-cycle chance of success. It is particularly relevant for unexplained infertility, mild male-factor issues and treatments with donor sperm. Outcomes depend on precise timing, conservative stimulation, clear cancellation criteria and transparent counselling. If several well-planned cycles are unsuccessful, discuss moving to IVF/ICSI with your centre.

Disclaimer: Content on RattleStork is provided for general informational and educational purposes only. It does not constitute medical, legal, or other professional advice; no specific outcome is guaranteed. Use of this information is at your own risk. See our full Disclaimer.

Frequently Asked Questions (FAQ)

A laboratory-washed, concentrated semen sample is placed via a thin catheter directly into the uterus so progressively motile sperm reach the tube sooner while fertilization still occurs in the body.

Often suitable for unexplained infertility, mild male-factor issues, cervical factors, intercourse pain or difficulties, and use of donor sperm, provided at least one tube is open and ovulation occurs.

No; IUI can be done in a natural cycle but is often combined with mild stimulation to ensure reliable follicle growth and precise timing while keeping the risk of multiples low through close monitoring.

Timing is based on a spontaneous LH surge or an hCG trigger; the procedure is typically 24 to 36 hours after a confirmed ovulation signal and is aligned using ultrasound and hormone checks.

Two to four well-planned cycles are commonly advised before considering a change of method, as moderate per-cycle chances add up while age and findings guide the next step.

It varies with age, diagnosis, sperm quality, stimulation and timing; centres usually quote age- and diagnosis-specific ranges, so an individual prognosis is more helpful than a single percentage.

At least one patent tube, a reliable ovulation pattern, adequate progressive motility after preparation, and no acute infections are considered central prerequisites for a meaningful IUI attempt.

It is usually brief and well tolerated; some people notice mild cramping or pressure, and everyday activities can generally resume right away.

The main risk is multiple pregnancy with excessive stimulation; infections or light bleeding after catheter passage are uncommon; careful monitoring and conservative goals reduce these risks substantially.

Luteal support is used in some protocols; usefulness depends on stimulation, findings and centre practice, so the decision is best made individually.

Yes; around two to three days is often suggested to balance concentration and motility after preparation, but follow the specific instructions given by your laboratory.

Yes; it is common with defined screening, traceability and consent processes, and the sample is prepared to laboratory standards before insemination.

With tubal blockage, markedly impaired semen parameters, no success after several IUIs or complex causes, IVF or ICSI is often recommended to support fertilization and embryo development in the laboratory.

Light to normal daily activity is typically fine immediately; strenuous exercise is often avoided for a few days, while moderate movement is usually acceptable unless your care team advises otherwise.