Residency · Residency · Obstetrics Gynecology
Long-Acting Reversible Contraception: IUDs and Implants
Introduction
Long-acting reversible contraceptives (LARCs) represent the most effective reversible methods of birth control, with failure rates comparable to permanent sterilization. LARCs include intrauterine devices (IUDs) and the subdermal contraceptive implant. Their effectiveness is largely independent of user adherence, making them the first-line recommendation for most women seeking contraception per ACOG guidelines.
Intrauterine Devices
Types of IUDs
The copper IUD (Paragard) is a T-shaped polyethylene frame wrapped with copper wire that provides up to 10 years of contraception and is the only non-hormonal LARC option. The levonorgestrel 52 mg IUD (Mirena, Liletta) releases approximately 20 mcg per day of levonorgestrel initially, declining over time, and is approved for up to 8 years. The levonorgestrel 19.5 mg IUD (Kyleena) delivers a lower hormone dose, is approved for up to 5 years, and has a smaller frame that may be preferred for nulliparous patients. The levonorgestrel 13.5 mg IUD (Skyla) provides the lowest dose, is approved for up to 3 years, and has the smallest T-frame available.
| Device | Hormone/Agent | Duration | Mechanism | Failure Rate |
|---|---|---|---|---|
| Paragard (Copper T380A) | Copper ions | 10 years | Spermicidal inflammatory reaction | 0.8% |
| Mirena / Liletta (52 mg LNG) | Levonorgestrel 20 mcg/day | 8 years | Cervical mucus + endometrial atrophy ± ovulation suppression | 0.1-0.4% |
| Kyleena (19.5 mg LNG) | Levonorgestrel (lower dose) | 5 years | Cervical mucus + endometrial atrophy | 0.2% |
| Skyla (13.5 mg LNG) | Levonorgestrel (lowest dose) | 3 years | Cervical mucus + endometrial atrophy | 0.4% |
| Nexplanon (Implant) | Etonogestrel 68 mg | 5 years | Ovulation suppression + cervical mucus | 0.01% |
Mechanism of Action
The copper IUD works by creating a sterile inflammatory reaction in the endometrium through copper ions that are toxic to sperm and ova. It inhibits sperm motility, capacitation, and fertilization and does not act as an abortifacient. The levonorgestrel IUDs primarily thicken cervical mucus, suppress endometrial proliferation, and variably inhibit ovulation, particularly with the 52 mg devices. The typical-use failure rate for all IUDs ranges from 0.1 to 0.4% in the first year.
Eligibility and Contraindications
US MEC Category 4 (absolute contraindications) includes current pregnancy, active pelvic infection (PID, cervicitis, endometritis), unexplained vaginal bleeding not yet evaluated, cervical or endometrial cancer, and uterine cavity distortion incompatible with IUD placement. US MEC Category 3 (relative contraindications) includes the copper IUD in Wilson disease and the LNG-IUD in current breast cancer. Nulliparity is not a contraindication; IUDs are safe and recommended for adolescents and nulliparous women. STI screening follows routine guidelines, and same-day insertion is acceptable even before screening results are available.
<image>Comparative illustration of available IUD types showing the copper T380A (Paragard) and levonorgestrel-releasing IUDs (Mirena, Kyleena, Skyla) with labeled dimensions, hormone content, and approved duration of use</image>
Insertion Technique
An IUD can be inserted at any point in the menstrual cycle as long as pregnancy can be reasonably excluded. Immediate postpartum and post-abortion insertion are both safe and effective. The pre-procedure assessment includes a bimanual exam to determine uterine size and position and sounding of the uterus, with a normal cavity depth of 6 to 9 cm. For pain management, NSAIDs are given 30 to 60 minutes prior, and a paracervical block with 1% lidocaine is offered for patients with anticipated difficulty. Misoprostol is not routinely recommended. The procedure involves tenaculum placement on the anterior cervical lip, sounding, and IUD deployment per manufacturer instructions, with strings trimmed to 3 to 4 cm from the external os. Post-insertion ultrasound is obtained only if there is concern about placement; routine imaging is not required.
Complications and Management
Expulsion occurs in 2 to 10% of insertions, with the highest risk in the first 3 months and with postpartum placement. Risk is also higher in patients with heavy menses or uterine anomalies. Perforation is rare, occurring in 1 to 2 per 1,000 insertions, with higher risk during lactation. If perforation is suspected, ultrasound and abdominal X-ray are obtained, and laparoscopic retrieval is performed for intra-abdominal IUDs. The risk of PID is transiently elevated in the first 20 days post-insertion. PID is treated with antibiotics without removing the IUD unless there is no clinical improvement after 48 to 72 hours. If pregnancy occurs with an IUD in situ, the IUD is removed if the strings are visible, which reduces the risk of miscarriage, preterm birth, and infection. If the strings are not visible, the IUD is left in place.
Contraceptive Implant
Device Characteristics
The etonogestrel implant (Nexplanon) is a single rod measuring 4 cm by 2 mm that contains 68 mg of etonogestrel. It is radiopaque and comes preloaded in a disposable applicator. It is FDA-approved for up to 5 years, with evidence supporting efficacy for up to 5 years. The primary mechanism is ovulation suppression via inhibition of the LH surge, and it also thickens cervical mucus. With a failure rate of 0.01%, it is the most effective reversible contraceptive available.
Insertion and Removal
The insertion site is subdermal in the medial aspect of the non-dominant upper arm, 8 to 10 cm from the medial epicondyle in the sulcus between the biceps and triceps. Local anesthesia with 1% lidocaine is administered. The preloaded applicator is inserted at a 30-degree angle, then reduced to horizontal for deployment. The rod must be palpated immediately after insertion. If the implant cannot be palpated, a second device should not be inserted, and imaging with ultrasound or MRI should be obtained. For removal, the distal tip is palpated, local anesthesia is injected beneath the tip, a 2 mm incision is made, and the rod is grasped with mosquito forceps and extracted. Deep implants may require ultrasound-guided removal.
<image>Step-by-step illustration of subdermal contraceptive implant insertion technique showing proper arm positioning, insertion site landmarks relative to the medial epicondyle, applicator angle, and correct subdermal placement depth</image>
Side Effects
Irregular bleeding is the most common reason for discontinuation, occurring in up to 30% of users. It can be managed with short courses of combined oral contraceptives, NSAIDs, or reassurance. Other effects include headache, weight change, acne, and mood changes, which are generally mild. There is no clinically significant effect on bone mineral density.
Counseling and Shared Decision-Making
LARC-first counseling should present all options without coercion, emphasizing patient autonomy and avoiding implicit bias. LARCs must be removed whenever the patient requests, regardless of the reason or duration of use. Barriers to removal are unethical. The quick start method allows LARCs to be initiated at any time in the cycle with reasonable exclusion of pregnancy. Backup contraception is used for 7 days with hormonal IUDs and implants if not placed during menses. Return to fertility is immediate after removal for both IUDs and the implant.
<image>Infographic comparing LARC methods (copper IUD, hormonal IUD, implant) side by side with efficacy rates, duration of use, bleeding profile changes, non-contraceptive benefits, and return to fertility timeline</image>
Clinical Pearls
LARCs are first-line contraception for most women, including adolescents and nulliparous patients. No age or parity restrictions exist.
The copper IUD doubles as emergency contraception when inserted within 5 days of unprotected intercourse, with a failure rate less than 0.1%.
Same-day insertion improves uptake and should be offered whenever possible. Waiting for STI results or menses is unnecessary.
IUD-related PID is treated with antibiotics while leaving the IUD in situ. Removal is only indicated for clinical failure after 48 to 72 hours of appropriate therapy.
The etonogestrel implant is the single most effective reversible contraceptive and should be prominently discussed in counseling.
References
- ACOG Practice Bulletin No. 186. Long-Acting Reversible Contraception: Implants and Intrauterine Devices. Obstet Gynecol. 2017;130(5):e251-e269.
- Curtis KM, Jatlaoui TC, Tepper NK, et al. U.S. Medical Eligibility Criteria for Contraceptive Use, 2016. MMWR Recomm Rep. 2016;65(3):1-103.
- McNicholas C, Maddipati R, Zhao Q, et al. Use of the etonogestrel implant and levonorgestrel intrauterine device beyond the U.S. Food and Drug Administration-approved duration. Obstet Gynecol. 2015;125(3):599-604.
- Diedrich JT, Desai S, Zhao Q, et al. Association of short-term bleeding and cramping patterns with long-acting reversible contraceptive method satisfaction. Am J Obstet Gynecol. 2015;212(1):50.e1-8.
