Intrauterine contraception

Summary

IUDs are long-acting reversible contraceptives. Copper IUDs prevent fertilization but may cause heavier periods, while hormonal IUDs release progestin, reducing bleeding and cramps. They are highly effective, usable postpartum or for emergency contraception, but contraindicated in pregnancy, infection, or unexplained bleeding. Possible complications include pain, expulsion, perforation, and miscarriage if pregnancy occurs.

Overview

Intrauterine contraceptive devices (IUCDs), are small, T-shaped devices inserted into the uterine cavity for long-acting reversible contraception (LARC). They are among the most widely used reversible contraceptive methods globally, particularly suitable for women who cannot use estrogen-containing contraceptives, have a low risk of sexually transmitted infections (STIs), and are in mutually monogamous relationships.

Types

1. Copper IUDs (Nonhormonal)

• Mechanism: Copper ions induce a sterile inflammatory reaction within the endometrium, impairing sperm motility and viability, reducing tubal transport, and inhibiting implantation.

• Duration: FDA-approved for up to 10 years; evidence supports efficacy up to 12 years.

• Effectiveness: Failure rate ~0.6–0.8%.

• Adverse effects: May cause heavier and longer menstrual bleeding, especially during the first 3–6 months.

• Additional considerations: Large devices offer increased protection but are associated with more side effects. Copper IUDs slightly increase the relative risk of ectopic pregnancy in case of method failure, although they reduce the overall incidence of ectopic pregnancy by lowering total pregnancy rates.
  
  

2. Levonorgestrel-Releasing IUDs (Hormonal)

• Examples: Mirena (LNG-20, 52 mg levonorgestrel; 20 μg/day, up to 5–8 years).

• Mechanism: Local progestin effects include thickening of cervical mucus, inhibition of sperm function, reduction of tubal motility, and decidualization/atrophy of the endometrium.

• Effectiveness: Failure rate 0.1–0.4%.

• Benefits: Decreases menstrual blood loss and dysmenorrhea, treats heavy menstrual bleeding, reduces anemia risk, and can be used in postmenopausal women on estrogen therapy.

• Side effects: Amenorrhea in up to 40–50% of users after 2 years; possible irregular bleeding in early months; occasional systemic effects (e.g., mood changes, breast tenderness, headaches). No proven association with weight gain.
  

Mechanisms of Action

• Inhibition of sperm transport through the cervical canal and uterus.

• Increased tubal motility causing premature transport and failure of implantation.

• Sterile inflammatory endometrial reaction impairing sperm and blastocyst survival.

• Thickening of cervical mucus (in hormonal IUDs).

Timing of Insertion

• Can be inserted at least 6 weeks postpartum.

• May also be used as emergency contraception if inserted within 5 days of unprotected intercourse.

Contraindications

Absolute:

• Pregnancy or puerperium (<6 weeks postpartum).

• Unexplained abnormal uterine bleeding.

• Current pelvic infection or recent septic abortion.

• Uterine malignancy (endometrial or cervical), malignant gestational trophoblastic disease.

• Copper allergy (for copper IUD) or Wilson’s disease.

• Hormonal IUD: current breast cancer.

• Severe anemia, coagulopathy, or immunosuppression (e.g., uncontrolled diabetes, chronic steroid use).

• Recent cesarean section (relative for some types).

Relative:

• History of ectopic pregnancy.

• Current menorrhagia or dysmenorrhea.

• Uterine anomalies or fibroids distorting the cavity.

• Recent or recurrent STIs.

Complications

• Pain, bleeding, expulsion, uterine perforation, pelvic infection.

• If pregnancy occurs with IUD in situ: increased spontaneous abortion risk (40–50%); removal is advised if strings are visible.