hCG Injection: Uses, Testing, Tracking and What to Expect

If your doctor has prescribed an hCG injection as part of fertility treatment, you may have questions about what the hormone does, how the dose is determined and what to expect after the injection. Human chorionic gonadotropin is a hormone that occurs naturally during pregnancy. As a medicine, hCG can be used in selected fertility treatments and certain hormonal conditions in men and boys. It is also used as a trigger to induce final follicular maturation and ovulation in appropriately monitored fertility cycles.

Human chorionic gonadotropin (hCG) is a glycoprotein hormone with biological activity similar to luteinising hormone (LH). hCG binds to the LH/hCG receptor and can produce effects similar to an LH surge. In fertility treatment, this action can stimulate final maturation of the egg and trigger ovulation or final oocyte maturation before egg retrieval.

hCG is administered by injection because it is a protein hormone that would be broken down if taken orally. Depending on the specific formulation, it may be administered subcutaneously or intramuscularly. Recombinant hCG products such as choriogonadotropin alfa are administered subcutaneously, while some urinary-derived hCG products are administered intramuscularly. The route therefore depends on the prescribed product.

An hCG injection is prescribed for specific fertility and hormonal conditions. Its use and dosing depend on the indication and the formulation.

In Women

hCG injections are used in women mainly as part of fertility treatment, depending on the treatment protocol and ovarian response.

• Ovulation induction: hCG may be used after ovarian stimulation when follicular development is considered adequate. It acts on the LH/hCG receptor to trigger final follicular maturation and ovulation.
• IVF treatment: hCG can be used as a trigger for final oocyte maturation before egg retrieval. The trigger is given at a carefully selected time based on the ovarian response and the planned retrieval.
• Luteal-phase support: hCG has been used in some fertility protocols to support the corpus luteum. However, it is not appropriate for every patient or every fertility cycle because additional hCG can increase the risk of ovarian hyperstimulation syndrome. The decision should therefore be made by the fertility specialist.

In Men and Boys

In men and boys, hCG may be prescribed for specific hormonal conditions where stimulation of the testes is appropriate.

• Hypogonadotropic hypogonadism: hCG can stimulate the testes to produce testosterone and may be used as part of treatment intended to support fertility in men with an appropriate hormonal cause of hypogonadism.
• Cryptorchidism: Certain hCG products have historically been indicated for selected boys with undescended testes when the condition is not caused by anatomical obstruction. Treatment depends on the child's individual circumstances and specialist assessment.

The appropriate indication, formulation, dose and schedule should always be determined by the prescribing clinician.

Monitoring is an important part of fertility treatment because hCG is generally administered according to the response to ovarian stimulation and the timing of the fertility procedure.

Beta-hCG Blood Tests

A quantitative beta-hCG blood test measures the concentration of hCG in the blood. After an hCG injection, however, the test cannot automatically distinguish injected hCG from hCG produced by a pregnancy.

This is particularly important after an hCG trigger:

• Testing very soon after the injection may detect the medicine rather than pregnancy-related hCG.
• The amount of time required for the injected hCG to decline varies with the formulation, dose and individual factors.
• A positive pregnancy test after an hCG trigger therefore needs to be interpreted according to the timing of the injection and the fertility treatment cycle.

For recombinant hCG such as choriogonadotropin alfa, the reported terminal elimination half-life after subcutaneous administration is approximately 29 hours. This does not mean that every person's pregnancy test will become negative at a fixed time, so a universal 10-to-14-day clearance rule should be avoided.

If pregnancy occurs, your fertility team may use serial beta-hCG measurements and ultrasound findings to assess the pregnancy. A single rule that hCG should always double every 48 hours is not appropriate because the expected rate of increase varies with the starting concentration and stage of pregnancy.

Ultrasound Monitoring

In stimulated fertility cycles, transvaginal ultrasound is used to monitor follicular development. The decision to administer an hCG trigger is based on the overall ovarian response, including follicle development and other clinical findings, rather than one universal follicle-size threshold.

Many fertility protocols use leading follicles around the high teens in millimetres as part of the trigger decision, but 17–20 mm should not be presented as a mandatory range for every patient or protocol. The number of follicles, hormone levels, treatment type and risk of OHSS also influence the decision.

In IVF, the timing of the trigger is particularly important because egg retrieval is planned around the expected final maturation of the oocytes. ASRM describes the trigger as activating the LH receptor over a roughly 24-to-36-hour window before oocyte retrieval.

An hCG trigger can interfere with pregnancy tests because the injected hormone is the same hormone that pregnancy tests detect.

For this reason:

• Do not interpret a very early positive home pregnancy test as confirmation of pregnancy without considering when the hCG injection was administered.
• Follow the testing date provided by your fertility clinic rather than using a fixed 10- or 14-day rule for every formulation and treatment cycle.
• If your clinic requests a serum beta-hCG test, have it performed on the date advised by the clinic.

The pharmacokinetics of hCG vary between products. For example, recombinant hCG has a mean terminal half-life of about 29 hours, while other hCG formulations and doses may differ.

The dose of hCG depends on the specific product, indication, route of administration and treatment protocol. It should never be adjusted independently.

Examples from approved prescribing information include:

For example, prescribing information for urinary-derived chorionic gonadotropin lists 5,000–10,000 IU for ovulation induction following appropriate gonadotropin or menotropin treatment. It also gives different regimens for male hypogonadotropic hypogonadism, demonstrating why one universal male dose range is not appropriate.

Some recombinant hCG products use microgram dosing rather than IU. For example, Ovidrel contains 250 micrograms of choriogonadotropin alfa for a single subcutaneous dose in its labelled indication.

The timing of the injection can be just as important as the dose in fertility treatment. Follow your fertility clinic's instructions exactly and do not change the scheduled injection time without contacting the clinic.

Whether hCG is appropriate depends on the specific product and the reason it is being prescribed. Tell your doctor about any existing medical conditions before starting treatment.

Important considerations include:

• Hormone-sensitive cancers: hCG should not be used in certain hormone-dependent malignancies where stimulation of reproductive hormone pathways could be harmful.
• Primary ovarian failure: hCG cannot induce ovulation when the ovaries are unable to respond appropriately.
• Uncontrolled thyroid or adrenal disorders: These conditions should be appropriately evaluated and managed before fertility treatment.
• Pregnancy: hCG used as a fertility treatment is not indicated once pregnancy has been established.
• Previous or current OHSS: Patients at increased risk of ovarian hyperstimulation require careful assessment before an hCG trigger is given. ASRM identifies factors including PCOS, elevated AMH and an anticipated high oocyte yield as important OHSS risk factors.
• Allergy or hypersensitivity: Do not use a product if you have a known hypersensitivity to hCG or any component of the formulation.

In men, hCG is most useful when the underlying hormonal problem is one in which the testes can respond to gonadotrophin stimulation. It is not a treatment for every cause of male infertility.

Some side effects can occur with hCG treatment, while others may indicate a significant complication.

Common Side Effects

Depending on the product and indication, possible side effects include:

• Pain, redness or swelling at the injection site
• Headache or tiredness
• Irritability or mood changes
• Breast tenderness or enlargement
• Bloating or pelvic discomfort during fertility treatment

Serious Symptoms Requiring Prompt Assessment

Women receiving hCG as part of ovarian stimulation should be alert for symptoms that may indicate ovarian hyperstimulation syndrome.

Seek prompt medical advice if you develop:

• Significant abdominal swelling or severe abdominal pain
• Persistent nausea or vomiting
• Reduced urine output
• Shortness of breath
• Rapid weight gain
• Dizziness, fainting or symptoms of a blood clot

ASRM classifies rapid weight gain of more than 1 kg in 24 hours among the clinical features associated with critical OHSS. Therefore, the original 1–2 kg threshold has been replaced with the more specific ASRM criterion.

OHSS can become more severe if pregnancy occurs and may develop after the hCG trigger. The prescribing information for recombinant hCG recommends monitoring patients for at least two weeks after administration because OHSS can occur after treatment and may peak several days later.

hCG is a prescription medicine and should be used only under appropriate medical supervision. Indian drug regulations classify Schedule H medicines as prescription drugs, and the CDSCO rules specify that such medicines are not to be sold by retail without a prescription from a registered medical practitioner.

Current Apollo Pharmacy listings identify several hCG injections as prescription medicines, including Sifasi 5000 IU Injection, Sifasi Aqua 5000 Injection, Sifasi HP 5000 IU Injection and Hucog-5000 HP Injection. Product availability and stock can change, so these should not be treated as an exhaustive list.

A few practical safety points:

• Storage: Follow the storage instructions for the exact product. Storage requirements can differ between formulations, so do not assume that every hCG injection must be refrigerated.
• Reconstitution: If your medicine comes as a powder and diluent, use it exactly as instructed for that formulation. Some products require reconstitution before use.
• Injection technique: If you have been taught to self-administer the medicine, follow the prescribed route and technique. Do not share needles or syringes.
• Sharps disposal: Dispose of used needles and syringes safely according to your clinic's instructions.
• Treatment timing: Fertility treatment schedules can depend on the exact time of hCG administration. Contact your clinic promptly if you miss or delay a scheduled dose rather than taking an additional dose yourself.
• Pregnancy testing: Tell your healthcare professional that you recently received hCG if you have a positive pregnancy test, because residual injected hCG can affect interpretation.
• OHSS monitoring: Follow your fertility clinic's instructions for monitoring after the trigger, particularly if you have risk factors for OHSS.

hCG injections are used in specific fertility and hormonal treatment protocols to mimic the action of luteinising hormone. In fertility treatment, the timing and dose are carefully determined based on the treatment plan, ovarian response and the specific hCG formulation being used. Because injected hCG can affect pregnancy-test results and fertility treatment can carry risks such as ovarian hyperstimulation syndrome, follow your clinic's instructions for testing and monitoring. Do not change the dose, timing or route of administration without medical advice.