Subdermal contraceptive implant — what is it, how does it work, how effective is it?

The contraceptive implant is a small rod, 4cm long and 2mm thick, which is placed in the arm at the subdermal level. This implant progressively releases a hormone similar to progesterone, preventing ovulation and therefore pregnancy.

It is a reliable and reversible contraceptive method with years of experience.

What is the subdermal contraceptive implant?

• Types of implants: there’re two types of contraceptive implants available in Spain:
  • Implanon: this consists of a rod and lasts for 3 years. The progestin released is etonogestrel.
  • Jadelle: consists of two rods and lasts for 5 years. It releases levonorgestrel, another form of progestin.

• Indications: Women who want an effective, reversible, non-estrogen hormonal method of contraception. Women who are contraindicated for an IUD or who frequently forget to take oral contraceptives.

• Contraindications: The contraceptive implant is not indicated for women with prothrombotic pathology. Nor in women with systemic diseases that increase the risk of thrombi (lupus, arterial hypertension, diabetes, migraine), or in hormone-dependent diseases (breast cancer, ovarian cancer, etc.). The use of the implant is also not recommended in women with undiagnosed vaginal bleeding or allergy to the active ingredient of the implant. It should always be assessed by a doctor beforehand.

How does the subcutaneous implant work?

The implant releases the hormone (etonogestrel or levonorgestrel) continuously. This hormone, which is similar to progesterone, prevents ovulation. It also changes the consistency of the cervical mucus, making it difficult for sperm to enter the cervix. It also causes a decrease in endometrial growth.

What are the advantages and disadvantages of the subdermal implant?

• Advantages:
  • Its high efficacy of 99%.
  • It avoids the possibility of forgetfulness, as sometimes happens with the pill, patches and rings. It is also not altered in case of vomiting.
  • It is a reversible method. It can be withdrawn at any time, and the activity of the ovaries returns to normal in a short time.
  • It is a long-lasting method. Depending on the model, it lasts between 3 and 5 years, and can be removed and a new one implanted at the same time. 
  • It can be used during breastfeeding.

• Disadvantages:
  • Does not prevent sexually transmitted diseases (STDs), so must be combined with a condom if having risky relationships.
  • Adverse effects associated with hormones: Can sometimes also cause acne, headache, abdominal pain, change in digestive pattern, etc.
  • Change in menstrual bleeding pattern, both due to cessation of menstrual periods (amenorrhoea) and irregular bleeding (spotting).

How is the subcutaneous contraceptive implant inserted and removed?

The implant is inserted by the gynaecologist in the consultation room, usually in the non-dominant arm.

It is recommended that it be inserted during the first few days of the cycle. If it’s inserted at another moment, it’s recommended an additional method of contraception be used for the first fortnight.

The implant can usually be felt through the skin, and if necessary, an X-ray can be taken to locate it.

To remove it, a small incision is made in the skin and the implant is removed using tweezers.

Dr Cristina Gavilán, a gynaecologist at Instituto Bernabeu.