Levonorgestrel Implant

Levonorgestrel two-rod implants consist of two flexible silicone rods, each containing 75 mg levonorgestrel (150 mg in total), inserted subdermally in a narrow V in the inner upper arm. Two systems are used: one effective for 5 years and one effective for 3 years. They contain no oestrogen and protect against pregnancy for the full lifespan without user action.

Classification. Progestin-only, long-acting reversible, two-rod implant.

Design. Each rod is about 43 to 44 mm long and 2.4 to 2.5 mm in diameter, with levonorgestrel mixed in a silicone (polydimethylsiloxane) matrix within a silicone tube. The rods are not radiopaque in a way that reliably allows plain X-ray location; ultrasound is the first imaging test.

Mechanism. Thickening of cervical mucus is the main action. Ovulation is suppressed in many cycles, more often in the early years, and the endometrium is thinned.

Release profile. Release is about 100 micrograms daily in the first month, falling to about 40 micrograms daily at 1 year and to about 25 to 30 micrograms daily in later years. Levonorgestrel is almost fully bioavailable, binds strongly to sex hormone binding globulin, and is metabolised in the liver by cytochrome P450 3A4.

Effectiveness. About 0.05 pregnancies per 100 women in the first year with typical and with perfect use.

Duration of action. 5 years for the 5-year system; 3 years for the 3-year system.

Return to fertility. Levonorgestrel is cleared within days of removal; most patients ovulate within the first month.

Ideal candidates. Patients wanting long-term contraception without daily action, including adolescents, nulliparous and postpartum patients. The 5-year system suits patients wanting longer protection with fewer replacement procedures.

History and examination. Last menstrual period, intercourse since then, current method, breastfeeding status, medicines, breast cancer, liver disease, current venous thromboembolism and unexplained bleeding. Inspect the insertion arm.

Investigations. None routinely. Pregnancy test only when pregnancy cannot be reasonably excluded.

Eligibility categories.

• Category 1: adolescents, nulliparity, smoking, obesity, hypertension, sickle cell disease, HIV infection, dolutegravir or raltegravir-based antiretroviral therapy, current or past pelvic infection.

• Category 2: breastfeeding under 6 weeks postpartum, past venous thromboembolism, migraine without aura, uncomplicated diabetes, irregular or heavy bleeding, efavirenz, nevirapine, ritonavir-boosted protease inhibitors, rifampicin, rifabutin, enzyme-inducing antiseizure medicines.

• Category 3: current deep vein thrombosis or pulmonary embolism, severe cirrhosis, hepatocellular adenoma or malignant hepatoma, unexplained vaginal bleeding before evaluation, ischaemic heart disease, stroke or worsening migraine with aura during use.

• Category 4: current or past breast cancer.

Interactions. Efavirenz reduces levonorgestrel exposure by about half, and pregnancy rates are higher with efavirenz-based therapy, especially after the first year. Rifampicin, rifabutin and enzyme-inducing antiseizure medicines also lower levels. Advise condoms throughout inducer use and for 28 days after stopping, or switch to DMPA, copper IUD or levonorgestrel IUD.

Body weight. No restriction on use by body weight. Effectiveness of levonorgestrel rods may fall in heavier patients in the final years of use.

Counselling points. Irregular bleeding is common, particularly in the first year, and is not harmful. The rods can be removed at any time on request. Condoms are needed for STI and HIV protection.

Regimen lines.

• Levonorgestrel 5-year implant: two 75 mg rods; subdermal, inner upper arm about 8 cm proximal to the elbow crease, in a narrow V opening towards the shoulder, through one 2 mm incision with a trocar after lidocaine 1%, 2 to 3 mL; protection immediate if inserted within 7 days of the start of bleeding, otherwise backup 7 days; replace at 5 years.

• Levonorgestrel 3-year implant: two 75 mg rods; same site and technique; same start and backup rules; replace at 3 years.

• For both: no grace window after expiry; with enzyme inducers or efavirenz add condoms throughout and for 28 days after stopping, or switch; no adjustment for breastfeeding, adolescence or perimenopause; avoid in severe liver disease.

Start timing.

• Within 7 days of the start of menstrual bleeding: insert, no backup.

• Any other day: insert if reasonably not pregnant; backup 7 days.

• Non-breastfeeding postpartum: up to 21 days, insert without backup; from 21 days without menses, exclude pregnancy and use backup 7 days.

• Breastfeeding: may be inserted immediately postpartum; if amenorrhoeic, at any time, with backup 7 days if 6 months or more postpartum.

• After abortion or miscarriage: insert immediately.

Switching. From another hormonal method used correctly: immediately, no backup. From an injectable: on or before the date of the next injection. From an IUD: insert within 7 days of bleeding and remove the IUD at the same visit; after day 7, insert and remove the IUD at the next period.

Verification. Palpate both rods after insertion and record their position and the system inserted.

Follow up. No routine visit. The card records the system (3-year or 5-year), insertion date and removal date. Return for site problems, an expelled or non-palpable rod, suspected pregnancy or wish to remove.

Discontinuation. Removal of both rods through one incision at the apex of the V. A new set may be inserted through the same incision.

Bleeding changes. Irregular, frequent or prolonged bleeding is common in the first year; amenorrhoea is less frequent than with etonogestrel. Exclude pregnancy, STI and pelvic pathology when bleeding is heavy or new.

Treat bothersome bleeding with no cause using ibuprofen 800 mg three times daily for 5 days, mefenamic acid 500 mg twice daily for 5 days, or, if oestrogen is eligible, ethinylestradiol 30 micrograms with levonorgestrel 150 micrograms daily for 21 days. For heavy bleeding, tranexamic acid 500 mg three times daily for 5 days or ethamsylate 500 mg three times daily for 5 days. Remove if bleeding stays unacceptable or threatens health.

Other effects. Headache, breast tenderness, acne, mood change, weight change and enlarged ovarian follicles.

Complications. Site infection, expulsion of one or both rods, deep placement, difficult removal from fibrous sheathing, and nerve injury from deep insertion or traumatic removal.

Management. Infection without abscess: oral antibiotic and review; remove if no response or abscess. Expulsion of one rod: protection cannot be assumed; replace the full set or provide another method, with backup in the meantime. Pregnancy: exclude ectopic pregnancy and remove the rods; no known foetal risk.

Red flags. Non-palpable rod, hand numbness, symptoms of venous thromboembolism, pelvic pain with missed bleeding, new breast mass, jaundice.

Referral and escalation. Refer non-palpable or deep rods for ultrasound localisation and removal by an experienced provider, suspected ectopic pregnancy and suspected nerve injury.