Vaginal Ring

The combined vaginal contraceptive ring is a flexible ring placed in the vagina that releases an oestrogen and a progestin continuously. It stays in place for 3 weeks, then is removed for a ring-free week in which withdrawal bleeding occurs. It prevents pregnancy mainly by suppressing ovulation and gives no protection against HIV or other sexually transmitted infections.

Composition. Etonogestrel 11.7 mg with ethinylestradiol 2.7 mg in a ring of 54 mm outer diameter, releasing about 120 micrograms of etonogestrel and 15 micrograms of ethinylestradiol daily. A year-long ring containing segesterone acetate 103 mg with ethinylestradiol 17.4 mg, releasing about 150 and 13 micrograms daily, is used for 13 cycles of 21 days in and 7 days out; its availability and efficacy at higher body mass index need confirmation.

Pharmacokinetics. Vaginal absorption avoids first-pass metabolism, gives steady hormone levels and is not reduced by vomiting or diarrhoea. Systemic ethinylestradiol exposure is lower than with pills containing 30 micrograms.

Effectiveness. First-year pregnancies: 8 in 100 women with typical use and 0.3 in 100 with perfect use. Risk is greatest when a new ring is inserted late.

Onset of protection. Immediate when inserted within 5 days of the start of menses; otherwise 7 days of backup.

Return to fertility. Without delay after removal.

Suitable candidates. Patients who want no daily or weekly action, who vomit or have diarrhoea, or who have malabsorption including after malabsorptive bariatric surgery, and who are comfortable with vaginal insertion and removal.

Less suitable. Severe pelvic organ prolapse or vaginal anatomy that prevents retention, cultural or personal reluctance to handle the genitalia, and repeated expulsion.

Eligibility. Categories are those of every combined method.

• Category 4:
  • breastfeeding under 6 weeks; blood pressure 160/100 or more; ischaemic heart disease, stroke or complicated valvular disease; migraine with aura; current or past breast cancer.
  • current or past deep vein thrombosis or pulmonary embolism, or thrombogenic mutation; diabetes with vascular disease; smoker 35 years or more with 15 or more cigarettes daily.
  • lupus with positive or unknown antiphospholipid antibodies; decompensated cirrhosis; liver adenoma or malignancy.
• Category 3: breastfeeding 6 weeks to under 6 months; not breastfeeding under 21 days postpartum; blood pressure 140/90 to 159/99; rifampicin; rifabutin; enzyme-inducing antiseizure medicines.

Investigations. Blood pressure and body mass index. No pelvic examination is required to start.

Interactions. Rifampicin, rifabutin, phenytoin, carbamazepine, barbiturates, primidone, topiramate, oxcarbazepine, griseofulvin and St John’s wort reduce effectiveness. Efavirenz, nevirapine and ritonavir-boosted regimens are category 2 and need added condoms. Lamotrigine levels fall.

Counselling points for the clinician. Demonstrate insertion and removal. The ring is not felt when placed deeply and does not interfere with intercourse for most patients. Consent, no coercion, assent from under 18 years.

Regimen line. Etonogestrel 11.7 mg with ethinylestradiol 2.7 mg ring, vaginal. Fold the ring, insert it deeply in any comfortable position, leave it in continuously for 3 weeks, remove it by hooking a finger through it, then leave a ring-free week and insert a new ring. The ring may be left out for sex or cleaning, but this is not advised because it is often forgotten; it must be back within 48 hours.

If it slips out, rinse it in clean water and reinsert it at once. Start within 5 days of the start of menses with no backup; later starts need 7 days of backup. Grace: insertion up to 48 hours late needs no backup. Dispose of the used ring in a waste bin, not the toilet. Enzyme inducers: do not use. Postpartum: not before 21 days if not breastfeeding; breastfeeding from 6 months.

Late and expelled ring rules.

Switching. From another hormonal method used correctly, start at once. From an injectable, start when the next dose is due. From an intrauterine device, start within 5 days of menses and remove the device then; if later, remove it at the next menses.

Follow up. Review at about 3 months and then yearly: blood pressure, weight, smoking, medicines, vaginal symptoms, bleeding. Reassess from 40 years; at about 50 years a change to a progestin-only or non-hormonal method is usual practice.

Expected effects. Bleeding changes, headache, vaginal irritation, redness or inflammation, white vaginal discharge, foreign body sensation and occasional expulsion.

Management. Vaginitis: identify and treat the infection; the ring may stay in place. Expulsion: rinse and reinsert; if repeated, change method. Coital discomfort: reposition deeper or change method. Unscheduled bleeding: exclude pregnancy, infection, ring lapses and interactions; give ibuprofen 800 mg orally three times daily for 5 days with food (maximum 2.4 g daily; avoid in renal impairment, active peptic ulcer or significant liver disease; not used in pregnancy); if bleeding persists after 3 months, change formulation or method.

Serious complications. Venous thromboembolism, stroke, myocardial infarction and hypertension.

Red flags. Severe abdominal pain, chest pain or breathlessness, severe or new headache, eye problems and severe calf pain. Remove the ring and arrange urgent evaluation.

When to change method. Category 4 condition, migraine with aura, enzyme-inducing medicines, repeated expulsion or unacceptable vaginal symptoms.

Referral and escalation. Suspected thrombosis, stroke or myocardial infarction needs emergency transfer. A ring that cannot be removed or is lost in the vagina needs examination by a clinician.