IUI (Intrauterine Insemination) — How It Works, Benefits & Recovery — Procedure Guide, Recovery & Risks | MyMedicPlus

Intrauterine insemination (IUI) is a minimally invasive fertility procedure in which a specially prepared (washed and concentrated) sperm sample is deposited directly into the uterine cavity through a thin, flexible catheter inserted through the cervix, timed to coincide with ovulation. By bypassing the cervical mucus and placing the sperm directly within the uterus, IUI increases the number of motile sperm reaching the fallopian tubes where fertilisation occurs, improving the probability of conception compared with timed intercourse. The procedure can be performed in a natural menstrual cycle (natural or 'unstimulated' IUI) or combined with ovarian stimulation medications to increase the number of developing follicles and mature eggs available for fertilisation ('stimulated' IUI), which significantly increases per-cycle success rates. The sperm used may be from the woman's partner or from an anonymous or known donor (therapeutic donor insemination, TDI) — donor insemination is used by single women, same-sex female couples, or couples where the male partner has an untreatable absence of sperm. IUI is typically offered as a first-line assisted conception treatment before proceeding to the more complex and expensive IVF (in vitro fertilisation).

IUI is indicated as a first-line assisted reproductive treatment in several clinical scenarios. Unexplained infertility in women under 38 years: IUI with mild ovarian stimulation (clomiphene citrate or low-dose gonadotrophins) is recommended for up to 3–6 cycles before IVF, with cumulative success rates of 30–40% in optimally selected patients. Mild-to-moderate male factor infertility: post-wash total motile sperm count (TMSC) of 5–10 million or above is the minimum threshold for IUI candidacy; severe oligospermia (TMSC below 5 million) has poor IUI outcomes and IVF/ICSI is preferred. Cervical factor infertility: hostile cervical mucus or post-surgical cervical stenosis preventing natural sperm penetration. Donor sperm insemination: for couples with severe male factor, same-sex female couples, or single women. Ovulatory dysfunction: women with irregular cycles can be stimulated to achieve predictable ovulation for IUI. Key prerequisites are confirmed bilateral tubal patency (by hysterosalpingography or laparoscopy — at least one open fallopian tube is required for IUI, unlike IVF which bypasses the tubes), adequate endometrial thickness (minimum 7 mm), and female age under 38 (IUI success rates decline sharply above 38 and IVF is preferred sooner in older women).

In stimulated IUI cycles, the woman takes oral clomiphene citrate (50–100 mg for 5 days from day 2–5 of the cycle) or low-dose injectable gonadotrophins (FSH 37.5–75 IU/day). Follicle development is monitored by transvaginal ultrasound starting on day 10–12 of the cycle. When one or two dominant follicles reach 18–20 mm in mean diameter, an hCG trigger injection (5,000–10,000 IU) is given to induce the final oocyte maturation and predictable ovulation approximately 36–40 hours later. In natural cycles, a urinary LH surge is monitored using home ovulation predictor kits. The male partner provides a semen sample by masturbation 30–60 minutes before the procedure. The sample is processed in the andrology laboratory by density gradient centrifugation or swim-up technique — sperm are separated from seminal plasma (which contains prostaglandins that cause uterine cramping if injected directly), white blood cells, and non-motile sperm. The processed, concentrated motile sperm suspension (0.3–0.5 mL) is loaded into a soft flexible IUI catheter. The woman lies supine; a speculum exposes the cervix. The catheter is gently inserted through the cervical os into the uterine cavity without instrumentation, and the sperm are slowly injected. The procedure takes 5–10 minutes and is usually painless.

The procedure is performed in an appropriately equipped facility by experienced specialist clinicians. Prior to commencement, the patient undergoes pre-procedural assessment including vital signs measurement, review of relevant investigations, and confirmation of informed consent. Intravenous access is established and monitoring equipment including ECG, pulse oximetry, and blood pressure monitoring is applied.

The procedural site is prepared according to aseptic technique standards. Anaesthesia or analgesia is administered as appropriate for the specific procedure and patient needs, ranging from local anaesthesia for minor procedures to regional or general anaesthesia for more complex interventions.

The procedure is performed under direct visualisation or image guidance as appropriate. Key technical steps are executed with attention to anatomical landmarks and patient safety parameters. Haemostasis is achieved and confirmed before completion. Post-procedural assessment includes clinical evaluation of the immediate result, complication surveillance, and documentation of the procedure.

Recovery room monitoring continues until the patient meets defined discharge criteria. Written post-procedural instructions covering activity restrictions, wound care, medication management, and symptoms requiring urgent review are provided before discharge.

IUI offers several practical advantages as a first-line assisted conception treatment. It is significantly less invasive, less expensive (typically 5–10 times less per cycle than IVF), and requires no sedation, egg collection surgery, or embryo culture compared with IVF. Per-cycle clinical pregnancy rates are: natural (unstimulated) IUI 5–8%; stimulated IUI 10–20% depending on the woman's age and indication. Cumulative pregnancy rates over 3–6 IUI cycles in optimally selected patients under 38 years with unexplained infertility are 30–40%, comparable to what most couples achieve by natural conception over 6–12 months of trying. For donor sperm insemination with stimulated cycles in women under 38, cumulative pregnancy rates of 50–60% at 6 cycles are achievable. IUI allows couples to attempt fertility treatment while avoiding the physical and emotional burden of IVF, preserving IVF as a subsequent escalation option. For single women and same-sex couples using donor sperm, IUI offers an accessible and effective pathway to parenthood at significantly lower cost and complexity than IVF. Treatment can be performed in outpatient fertility clinic settings without day-case facilities.

IUI has a very favourable safety profile compared with IVF. Multiple pregnancy is the most clinically significant risk with stimulated IUI — when more than two follicles develop, there is a 5–15% risk of twin pregnancy and 1–3% risk of higher-order multiples (triplets or more). Multiple pregnancy carries substantially higher risks of pre-term birth, low birth weight, NICU admission, gestational diabetes, and maternal complications. To minimise this risk, cycles with more than two leading follicles above 14 mm are typically cancelled or converted to timed intercourse. Ovarian hyperstimulation syndrome (OHSS) is a rare complication of IUI stimulation compared with IVF, occurring in fewer than 1% with the low gonadotrophin doses used; severe OHSS requiring hospitalisation is extremely rare. Mild uterine cramping and spotting commonly occur for several hours after insemination — these are normal and do not affect the outcome. Ascending uterine infection (pelvic inflammatory disease) is rare (less than 0.5%) and is prevented by standard aseptic technique. Ectopic pregnancy risk (implantation outside the uterus) is similar to background population rates of approximately 1–2%; patients with previous tubal disease are at higher risk and require early pregnancy ultrasound to confirm intrauterine location.

No recovery is required after IUI. Patients may resume all normal activities — including work, exercise, and driving — immediately after the procedure. Mild uterine cramping similar to period pain may occur for a few hours and is managed with paracetamol; vaginal spotting may be visible for 24–48 hours. Progesterone supplementation (vaginal pessaries 400 mg twice daily or oral dydrogesterone 10 mg twice daily) is prescribed from the day of insemination to support the luteal phase of the cycle, as ovarian stimulation may shorten the luteal phase. A urine pregnancy test is performed 14 days after the procedure; a blood hCG level is sometimes checked by the clinic at the same time for quantitative confirmation. If the cycle is unsuccessful, a follow-up appointment is arranged to discuss results and plan the next cycle. A maximum of 3–6 stimulated IUI cycles are recommended before escalating to IVF — the marginal improvement from additional IUI cycles after 3 failures is small, and IVF offers substantially higher per-cycle success rates (35–50% per cycle under 35 years). Detailed documentation of all stimulated cycles — follicle sizes, endometrial thickness, sperm parameters, and cycle outcome — informs subsequent cycle adjustments and the timing of escalation to IVF.