Mechanism of action and contraceptive efficacy
Hormone-releasing IUDs work predominantly at the local level. The continuous release of progestogen suppresses the proliferation of the uterine mucosal cells. As a result, endometrial atrophy develops, making the attachment of the fertilized egg impossible. Clinically, this manifests as scanty menstruation or the development of amenorrhea.
The overall reliability of intrauterine contraception reaches 92–98%. To evaluate effectiveness, the Pearl index is used:
- For hormone-releasing systems, it is 0.2–0.5.
- For copper-bearing analogs, it is 1–2.
After device removal, fertility is restored immediately, and oncological risks (cervical, uterine body, and ovarian cancer) do not increase during use.
Rules for insertion and medical follow-up
IUD insertion requires strict asepsis and preliminary preparation: taking a medical history, a gynecological examination, and bacterioscopic smear microscopy of the vagina, urethra, and cervical canal (only grade I–II cleanliness is permitted).
Optimal timing for the procedure:
- 4th–8th day of the menstrual cycle (or any day if there is 100% certainty of the absence of pregnancy).
- Immediately after induced abortion.
- 2–3 months after vaginal delivery.
- No earlier than 5–6 months after cesarean section.
During the first 7–10 days after insertion, the patient is prescribed sexual abstinence. Physical exertion, hot baths, as well as the intake of uterotonics and laxatives must be excluded. Scheduled follow-up examinations are performed after 7–10 days, then after 3 months, after which regular check-ups twice a year with mandatory smear microscopy are indicated.
Indications and therapeutic potential
IUDs are recommended for parous women who do not plan pregnancy for at least a year and have no risk of sexually transmitted infections (STIs). In nulliparous patients, the risk of complications is higher, so the method is used with caution (acceptable in the presence of a single partner and a history of abortions).
The main difference between hormonal IUDs (e.g., the Mirena system) and copper IUDs is their pronounced therapeutic effect. Levonorgestrel is successfully used for:
- Uterine fibroids.
- Menstrual cycle disorders (reduces blood loss and relieves pain).
- Endometrial hyperplastic processes (strictly after histological confirmation of the diagnosis).
Thus, conditions that are contraindications for conventional coils often become direct indications for hormonal ones.
Contraindications to intrauterine contraception
IUD insertion is strictly prohibited during pregnancy, malignant neoplasms of the uterus and cervix, as well as during acute, subacute, and frequent recurrences of chronic pelvic inflammatory disease (PID).
Relative contraindications include:
- Developmental anomalies and uterine hypoplasia, cervical stenosis, and cervical incompetence.
- Submucosal fibroids (however, small nodes that do not deform the cavity do not preclude insertion).
- Blood disorders and severe anemia.
- Algomenorrhea, hyperpolymenorrhea, and metrorrhagia (for non-medicated IUDs).
- Allergy to system components (copper, hormones).
- Severe extragenital diseases of an inflammatory etiology.
Possible complications
Despite high safety, the method is associated with the risk of complications:
- Uterine bleeding (1.5–24%). The most frequent problem leading to iron deficiency anemia. NSAIDs or COCs are prescribed for adaptation. If metrorrhagia occurs, hysteroscopy and diagnostic fractional curettage (DFC) are indicated.
- Pain syndrome and expulsion. Constant intense pain indicates a mismatch between the IUD size and the uterine cavity. Cramping pain with spotting is a sign of spontaneous expulsion (expulsion, frequency 2–9%).
- Inflammatory processes (0.5–4%). They are severe, with pronounced destruction of the uterine and appendiceal tissues. For prevention, a 5-day course of antibiotics is prescribed after insertion.
- Uterine perforation (1 in 5,000). It can be partial (removed by pulling the "strings") and complete (requires surgical intervention—laparoscopy or laparotomy). Important: an asymptomatic IUD located within the thickness of the uterine wall does not need to be removed; an attempt at removal is fraught with serious trauma.
Briefly: answers to topical questions
What doses of levonorgestrel do intrauterine systems release daily?
Levonorgestrel-releasing intrauterine systems (LNG-IUS) release 20 mcg of the hormone daily. The total dose of the active substance in such a system is 52 mg. The mechanism of action of hormone-releasing intrauterine contraceptives is based on the continuous local release of progestogen. This causes suppression of proliferation processes and atrophy of the uterine mucosa (endometrium), which makes the implantation of a fertilized egg impossible. At the same time, levonorgestrel does not exert a noticeable systemic effect, and patients retain ovulation.
Which anatomical structures of the uterine cavity and appendages are affected in severe forms of PID against the background of an IUD?
In severe forms of inflammatory diseases during the use of intrauterine contraceptives, the uterus and appendages are affected. The sources do not detail specific structures of the uterine cavity, but the following pathological processes are described:
- Uterus and appendages — pronounced destructive changes occur in them.
- Uterine appendages — the development of tubo-ovarian inflammatory formations up to abscesses occurs.
The risk of such severe purulent complications is significantly higher in women using intrauterine contraception. These inflammatory processes are severe and often require radical surgical intervention.
The "Five P's" rule for the first 7–10 days after IUD insertion: Pelvic rest (no sexual intercourse), Prevent Pressing/straining (avoid laxatives), Prohibited Pair procedures (hot baths), Pace down Physical exertion.
Class and exam questions
What to do if pregnancy occurs with an IUD in place?
The probability is extremely low, but it exists. If a woman decides to keep the pregnancy, the coil does not need to be removed—the extraamniotic location does not harm the baby, and the IUD will come out in the third stage of labor along with the placenta. Removal in early gestation increases the risk of miscarriage.
How are IUDs removed if the retrieval strings ("threads") are missing?
The procedure is performed strictly in a hospital setting. The localization of the contraceptive is clarified by ultrasound, after which the cervical canal is dilated and the system is removed under hysteroscopic control.
Does an IUD increase the risk of ectopic pregnancy?
The IUD reduces the absolute probability of any pregnancy occurring. However, if conception does happen, the proportion of ectopic pregnancies is statistically higher than in the population without contraception.
What else to study on this topic
- Management tactics for patients with uterine bleeding against the background of an IUD
- Surgical treatment for complete uterine perforation by a contraceptive
- Features of the use of hormonal systems in endometrial hyperplastic processes
- Differential diagnosis of pain syndrome after contraceptive insertion
- Risks and prevention of septic abortion in pregnancy with an IUD in place
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