Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Ovulation induction, IUI and IVF concepts
Obstetrics and gynaecology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending
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Ovarian stimulation requires a safety system
Gonadotrophin treatment can cause excessive follicular response, multiple pregnancy and ovarian hyperstimulation syndrome, while post-procedure pain or bleeding may signal torsion, infection or internal bleeding.
Action: Use specialist protocols with ultrasound monitoring and cancellation criteria, provide a 24-hour contact route, and assess severe pain, respiratory symptoms, oliguria, bleeding, collapse or thrombotic symptoms urgently.
Purpose and principles
Match ovulation induction, intrauterine insemination, IVF and ICSI to the diagnosed fertility problem, explain a full treatment cycle, reduce multiple pregnancy and avoid ineffective add-ons.
Assisted-conception treatments solve different bottlenecks. Ovulation induction aims to produce a single ovulation in someone who does not ovulate reliably. Intrauterine insemination prepares and places sperm beyond the cervix near ovulation but still requires tubal transport and fertilisation in vivo. IVF retrieves oocytes and achieves fertilisation in the laboratory, bypassing tubal transport. ICSI injects one sperm into an oocyte to address defined fertilisation problems; it does not improve every IVF cycle.
Treat the cause before choosing a technique. In hypogonadotrophic hypogonadism, improve low weight or excessive exercise and offer gonadotrophins with LH activity or pulsatile GnRH. Hyperprolactinaemic ovulatory dysfunction is treated with cabergoline. For PCOS-related anovulatory infertility without another factor, the 2023 international guideline recommends letrozole first line; in the UK its fertility use is off-label and needs explicit consent and monitored specialist care.
Indications, selection and cautions
Ovulation-induction candidate
A defined anovulatory disorder with patent-tube and semen considerations addressed may benefit from cause-specific induction and monitored intercourse or IUI.
IUI-suitable pathway
At least one usable tube, an adequate prepared sperm sample and an indication such as donor sperm, intercourse difficulty or a selected post-expectant unexplained case support IUI.
IVF indication
Severe tubal disease, failed suitable treatment, qualifying unexplained infertility or failed insemination cycles may warrant IVF after prognosis and access discussion.
ICSI indication
Surgically retrieved sperm, frozen-thawed oocytes, sufficiently abnormal semen or previous failed or very low fertilisation supports ICSI; normal semen in non-male-factor infertility does not.
High-response risk
PCOS, high AMH or AFC, numerous growing follicles or a previous excessive response should prompt an OHSS-prevention strategy and possible freeze-all decision.
Red flags requiring action
Rapid abdominal distension, severe pain, persistent vomiting, dyspnoea, reduced urine output, syncope or leg or chest symptoms after stimulation requires urgent OHSS and thrombosis assessment.
Sudden focal pelvic pain with nausea after ovarian stimulation may represent adnexal torsion and needs urgent gynaecological assessment.
Assessment before treatment
01Complete fertility assessmentFirst step
Why
Confirm ovulatory, tubal, uterine and semen factors before selecting treatment.
Interpretation and limitations
A technique should address the identified bottleneck; ovulation induction cannot overcome bilateral tubal occlusion and IUI cannot correct severe fertilisation failure.
02AMH or antral follicle count
Why
Predict ovarian response and inform stimulation strategy and counselling.
Interpretation and limitations
Low response may limit oocyte yield and high response raises OHSS risk; neither result measures oocyte quality or guarantees outcome.
03Follicle-tracking ultrasound
Why
Measure follicle number and size during gonadotrophin induction or IVF stimulation.
Interpretation and limitations
Excess recruitment may require dose adjustment, trigger change, cycle cancellation or avoidance of fresh transfer to reduce multiple pregnancy and OHSS.
04Virology and infection screening
Why
Meet safety requirements before IVF and reduce infection during procedures.
Interpretation and limitations
Offer HIV, hepatitis B and C testing before IVF and manage positive results with specialist advice; follow licensed-centre screening rules for donation.
05
Treatment approach
01Ovulation inductionAim for safe monofollicular ovulationFirst stepA treatable anovulatory disorder is confirmed.+
1Correct reversible central or endocrine causes and exclude pregnancy, important tubal disease and major semen factors before induction.
2Use diagnosis-specific treatment such as off-label letrozole for anovulatory PCOS, cabergoline for hyperprolactinaemia or gonadotrophin/GnRH therapy for hypogonadotrophic hypogonadism.
3Monitor gonadotrophin cycles with ultrasound, apply cancellation rules and counsel about multiple pregnancy, OHSS and timed intercourse or insemination.
02IUIPlace prepared sperm near ovulationIUI has a defined indication and tubal and semen prerequisites are suitable.+
1
Regimens, contraindications and interactions
Induces ovulation in anovulatory infertility due to PCOS when no other fertility factor requires a different treatment route.
Letrozole
A common specialist regimen is 2.5 mg orally once daily for 5 days early in the cycle, with any escalation determined by the fertility protocol and response.
Fertility use is off-label in the UK. Exclude pregnancy, explain off-label use, and avoid unmonitored repeat cycles or use when tubal or semen factors make induction inappropriate.
Induces ovulation in selected anovulatory disorders or recruits a controlled follicular cohort for IUI and IVF treatment.
Gonadotrophins
Product and starting dose are individualised to diagnosis, AMH or AFC, age and prior response, then adjusted only within a specialist protocol.
Multiple pregnancy and OHSS; do not use without ultrasound access, predefined adjustment and cancellation criteria, and a 24-hour advice pathway.
Lowers pathological prolactin secretion and can restore ovulation when hyperprolactinaemia is the confirmed cause of dysfunction.
Cabergoline
Specialist titration uses the lowest effective regimen according to prolactin, symptoms and product guidance rather than a universal fertility dose.
Review interacting medicines, hypotension and the need for pituitary imaging or valve assessment according to dose and duration; pregnancy planning needs endocrine follow-up.
Complications, monitoring and follow-up
During induction or stimulation, record follicle number and size, response trajectory and the explicit trigger, cancellation or freeze-all decision.
Provide and test understanding of the 24-hour contact route and warning symptoms for OHSS, torsion, bleeding, infection and thrombosis.
Track outcomes by full IVF cycle, keeping all fresh and frozen transfers from one stimulation within that cycle definition.
Review cumulative IUI attempts against the exact indication and total time trying, rather than continuing indefinitely without a decision point.
Audit embryo-transfer number and add-on use against NICE and HFEA guidance, with multiple-pregnancy prevention as a core safety outcome.
Special situations
Induction is not stimulation for its own sake
The therapeutic goal in anovulation is usually one ovulation; excessive follicle recruitment increases harm without being evidence of better care.
A full cycle includes frozen transfers
NICE counts one stimulation and every transfer from its fresh and frozen embryos, which matters when counselling and counting funded cycles.
NG257 changed unexplained options
After two years, current guidance allows consideration of up to four gonadotrophin-stimulated IUI cycles before IVF or proceeding directly to IVF after shared discussion.
ICSI is not premium IVF
It addresses sperm-oocyte fertilisation indications and should not be added routinely when semen is normal and there is no previous fertilisation failure.
Single embryo transfer is treatment
Reducing twins protects maternal and neonatal health while cryopreservation preserves subsequent transfer opportunities from the same full cycle.
Common pitfalls
01
Offering ovarian stimulation alone for unexplained infertility or before completing semen and tubal assessment.
02
Using gonadotrophins without ultrasound monitoring, cancellation rules or counselling about multiple pregnancy and OHSS.
03
Describing one embryo transfer as a full IVF cycle when frozen embryos from the stimulation remain.
04
Using ICSI routinely for normal semen in non-male-factor infertility or adding IMSI or PICSI without evidence.
05
Transferring more embryos to appear to improve success without accounting for the serious risks of multiple pregnancy.
06
Selling scratch, screening hysteroscopy, receptivity testing, immune therapy or PGT-A as proven live-birth improvements contrary to NG257.
Practice
Two practice questions
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Question 1 of 2
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Obstetrics and gynaecologyOriginal SBA
Current options after unexplained infertility
A couple has unexplained infertility after 2 total years of regular unprotected intercourse. Core investigations are complete. Which option reflects NICE NG257?
Sources and review status7 sources · checked 27 Aug 2026 · clinical review pending+
Sources
Sources and review status
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
Oral induction is usually started early in a withdrawal or spontaneous cycle, with local protocols determining dose escalation, ultrasound and biochemical confirmation. The goal is one mature follicle, not the largest possible ovarian response. Gonadotrophins can recruit several follicles, so ultrasound monitoring of number and size is integral. A cycle may need cancellation or advice to avoid unprotected intercourse when the multiple-pregnancy risk is unacceptable.
IUI is performed close to ovulation after laboratory sperm preparation. NICE recommends 12 cycles of unstimulated IUI before IVF for people unable to have vaginal intercourse because of diagnosed disability or psychosexual difficulty and for selected couples using donor sperm after unsuitable or unsuccessful surgical retrieval. For donor insemination without a known cause, after 6 unsuccessful artificial-insemination cycles offer a further 6 cycles of unstimulated donor IUI before IVF.
For unexplained infertility after a total of 2 years of regular unprotected vaginal intercourse, do not offer ovarian stimulation alone. NG257's 2026 options are up to 4 cycles of gonadotrophin-stimulated IUI before IVF, or IVF, after discussing risks, benefits, preference and individual circumstances. The same broad options may arise after expectant or surgical management of endometriosis, with age, reserve, disease and male factors guiding choice.
An IVF treatment episode starts with controlled ovarian stimulation and ultrasound-led monitoring, followed by a trigger for final maturation, transvaginal oocyte retrieval with conscious sedation, fertilisation by conventional IVF or indicated ICSI, embryo culture and transfer. Good-quality surplus embryos are cryopreserved. A 'full cycle' in NICE language means one episode of stimulation plus transfer of every resulting fresh and frozen embryo; it is not synonymous with one embryo transfer.
Current NG257 access recommendations apply when a diagnosed cause has no suitable successful alternative, unexplained infertility has persisted 2 years, or 12 artificial-insemination cycles including at least 6 IUI have not resulted in conception. If the person with ovaries is under 40, offer an initial 3 full cycles and, after unsuccessful completion, discuss prognosis and consider up to 3 more. At age 40 or 41 with no previous IVF, offer 1 full cycle. Actual NHS commissioning may vary locally, which should be explained separately from clinical guidance.
Embryo-number decisions primarily prevent multiple pregnancy. Use single embryo transfer for the first full cycle below age 37, and whenever a top-quality blastocyst is available. Age, cycle number and embryo quality shape later decisions, but no more than two embryos should ever be transferred. With donor oocytes, use donor age. Explain that bed rest beyond 20 minutes after transfer does not improve outcome.
Offer evidence, not marketing. NG257 advises against endometrial scratch, routine pre-treatment hysteroscopy, endometrial receptivity or microbiome testing, intralipids, IVIG, glucocorticoids, PGT-A as a way to improve live birth, assisted hatching, IMSI and PICSI. Conventional ICSI is reserved for its indications. Treatment counselling includes multiple pregnancy, OHSS, procedure risks, ectopic pregnancy, emotional burden, cryostorage, consent and the low but incompletely known long-term risks.
Key points
Ovulation induction treats a defined ovulatory disorder; it is not recommended as stand-alone treatment for unexplained infertility.
Letrozole is the preferred first-line pharmacological ovulation induction for anovulatory infertility in PCOS in the 2023 international guideline, but its UK fertility use is off-label and requires informed specialist prescribing.
Gonadotrophin induction requires ultrasound monitoring of follicle number and size to reduce multiple pregnancy and OHSS.
IUI places prepared sperm in the uterine cavity around ovulation; it does not bypass bilateral tubal occlusion and relies on a suitable total motile sperm population.
After 2 total years of unexplained infertility, NG257 says discuss either up to 4 cycles of gonadotrophin-stimulated IUI before IVF, or IVF directly, according to benefits, risks and preference.
IVF uses ovarian stimulation, oocyte retrieval, laboratory fertilisation, embryo culture and transfer; a full cycle includes one stimulation and transfer of all resulting fresh and frozen embryos.
ICSI is offered with surgically retrieved sperm or frozen-thawed oocytes and considered for sufficiently abnormal semen or previous failed or very low fertilisation, not routinely when semen is normal.
Heavy bleeding, shoulder-tip pain, collapse or peritoneal signs after oocyte retrieval requires urgent review for intra-abdominal bleeding or other procedural complication.
Fever, escalating pelvic pain or offensive discharge after insemination, retrieval or transfer suggests infection.
A positive pregnancy test with pain or bleeding after assisted conception still requires ectopic and heterotopic pregnancy assessment.
Semen assessment and fertilisation history
Why
Choose conventional IVF versus ICSI.
Interpretation and limitations
Use semen severity, surgical retrieval and previous fertilisation outcome; do not substitute ICSI for unexplained or non-male-factor infertility with normal parameters.
06Pregnancy testing after treatment
Why
Determine treatment outcome and trigger early-pregnancy planning.
Interpretation and limitations
A positive result needs appropriate early location assessment according to symptoms and local protocol because ectopic and heterotopic pregnancy remain possible.
Confirm the indication, at least one functional-route expectation, infection safety and whether the cycle will be unstimulated or gonadotrophin stimulated.
2Track or predict ovulation, prepare the semen sample and perform insemination at the planned interval using the licensed pathway where donor sperm is involved.
3Review cumulative outcome after the recommended cycle group and move to IVF, further IUI or another plan based on diagnosis, age, response and preference.
03IVF full cycleFrom stimulation to all embryo transfersIVF criteria are met and informed consent is complete.+
1Individualise stimulation using age, AMH or AFC and previous response, monitor follicles and choose trigger and fresh-versus-freeze strategy for safety.
2Retrieve oocytes, use conventional IVF or indicated ICSI, culture and grade embryos, then transfer an appropriate number with ultrasound guidance.
3Cryopreserve remaining good-quality embryos and count transfers from those embryos as part of the same full cycle before declaring it complete.
04Evidence checkSeparate standard treatment from add-onsAn additional test, procedure or drug is proposed to improve IVF success.+
1Ask what exact outcome the intervention improves, the quality of live-birth evidence, harms, cost and regulatory traffic-light status.
2Decline interventions NG257 says not to offer, including scratch, routine hysteroscopy, receptivity testing, immune therapies, PGT-A to improve live birth, IMSI and PICSI.
3Document shared decisions and preserve access to counselling without implying that declining an add-on reduces commitment to treatment.
Authoring state
Clinical stateAwaiting review
JurisdictionUnited Kingdom
Use single embryo transfer wherever recommended, never transfer more than two embryos, and avoid endometrial scratch, routine pre-IVF hysteroscopy, receptivity tests, PGT-A to improve live birth and immunological add-ons.