Mirena: Long Answer for MS Obstetrics and Gynaecology Final Examination

Definition

1. Device and composition

• T-shaped polyethylene intrauterine system.
• Contains a steroid reservoir around the vertical stem.
• Total levonorgestrel content: 52 mg.
• Initially releases approximately 20 micrograms of levonorgestrel daily; release declines progressively with time.
• Has a radiopaque component, enabling localization on X-ray.
• Two retrieval threads project through the cervix into the vagina.

2. Mechanism of action

A. Cervical effects

• Thickens cervical mucus.
• Prevents sperm penetration into the upper genital tract.
• Reduces sperm transport and survival.

B. Endometrial effects

• Produces profound endometrial suppression.
• Causes glandular atrophy and decidualization of endometrial stroma.
• Makes the endometrium unsuitable for implantation.
• Reduces endometrial proliferation and menstrual blood loss.

C. Tubal and sperm effects

• Impairs sperm motility and function within the female genital tract.
• May alter tubal transport.

D. Ovulation

• Ovulation is inhibited in some women, particularly initially, but ovulation commonly continues during longer-term use.
• Therefore, it should not be described as a primarily ovulation-suppressing method.

Key exam point

3. Efficacy

• One of the most effective reversible contraceptive methods.
• Typical-use and perfect-use failure rates are below 1%.
• Failure rate is roughly 0.1-0.2 pregnancies per 100 woman-years.
• If pregnancy occurs with an IUS in situ, the proportion of pregnancies that are ectopic is increased, although the absolute risk of ectopic pregnancy is lower than in women using no contraception.

4. Indications

A. Contraceptive indication

1. Long-term reversible contraception.
2. Women desiring highly effective, user-independent contraception.
3. Suitable for nulliparous and parous women, including adolescents after appropriate counselling.
4. Useful where estrogen-containing contraception is unsuitable.

B. Therapeutic indications in gynaecology

1. Heavy menstrual bleeding (HMB)
   • A highly effective medical treatment for idiopathic HMB.
   • Reduces menstrual blood loss substantially.
   • May prevent or correct iron-deficiency anemia.
   • FDA indication for HMB is for 5 years in women also choosing intrauterine contraception.
2. Endometrial protection during estrogen replacement therapy
   • Prevents estrogen-induced endometrial hyperplasia in women with a uterus receiving menopausal hormone therapy.
   • Licensing may vary by country.
3. Endometriosis
   • Reduces dysmenorrhea, pelvic pain, and recurrence of symptoms after conservative surgery.
   • Levonorgestrel causes endometrial glandular atrophy and decidual transformation and may reduce endometriosis-associated pain. Berek & Novak’s Gynecology, section “Intrauterine Progesterone”.
4. Adenomyosis
   • Reduces heavy bleeding, dysmenorrhea, and uterine pain.
   • A 2024 systematic review and meta-analysis compared LNG-IUS with dienogest for adenomyosis, supporting its role as a medical option, although individual treatment selection remains important. Adenomyosis review
5. Endometrial hyperplasia without atypia
   • Can be used as progestin therapy in appropriate patients, with surveillance by endometrial sampling.
   • Not a substitute for evaluation of abnormal uterine bleeding or exclusion of malignancy.
6. Menstrual suppression
   • Useful in women with anemia, bleeding disorders, disability, or preference for amenorrhea.

5. Contraindications

Absolute contraindications

1. Confirmed or suspected pregnancy.
2. Current pelvic inflammatory disease.
3. Current purulent cervicitis or untreated gonorrhea/chlamydial infection.
4. Postpartum endometritis or infected abortion within the preceding 3 months.
5. Known or suspected cervical or uterine malignancy.
6. Undiagnosed abnormal genital bleeding suspicious for significant pathology.
7. Congenital or acquired uterine anomaly that distorts the uterine cavity, including cavity-distorting fibroids.
8. Acute liver disease or liver tumor, depending on product guidance.
9. Current breast cancer or other progestogen-sensitive malignancy.
10. Hypersensitivity to levonorgestrel or device components.

Relative contraindications or situations requiring caution

• Previous ectopic pregnancy.
• Severe immunosuppression or high risk of pelvic infection.
• Valvular heart disease requiring individual assessment.
• Significant cervical stenosis.
• Large fibroids without definite cavity distortion.
• Unexplained pelvic pain.
• Previous pelvic actinomycosis.
• Current breast cancer is generally considered a contraindication to hormonal IUS use.

6. Pre-insertion assessment and counselling

History

• Menstrual history and nature of abnormal bleeding.
• Obstetric and gynaecological history.
• Previous PID, sexually transmitted infections, ectopic pregnancy, uterine surgery, or uterine anomaly.
• Medical history, particularly breast cancer and liver disease.
• Current contraceptive method and possibility of pregnancy.
• Sexual history and STI risk assessment.

Examination

• General examination as indicated.
• Bimanual pelvic examination:
  • Uterine size.
  • Position: anteverted, retroverted, axial.
  • Uterine tenderness.
  • Adnexal mass or tenderness.
• Speculum examination:
  • Cervical lesions.
  • Discharge or cervicitis.
  • Ability to visualize cervix.

Investigations when indicated

• Pregnancy test if pregnancy cannot be excluded.
• NAAT for chlamydia/gonorrhea in women at risk. Insertion need not necessarily be delayed while testing is pending if there is no clinical cervicitis or PID.
• Cervical cytology only according to the routine screening schedule, not as a mandatory pre-insertion test.
• Ultrasound if fibroids, congenital anomaly, enlarged uterus, suspected cavity distortion, or difficult insertion is anticipated.
• Investigate abnormal uterine bleeding before insertion, especially in women at risk of endometrial pathology.

Counselling points

• High contraceptive efficacy and duration of use.
• Expected irregular spotting or bleeding in the first 3-6 months.
• Gradual reduction in menstrual blood loss.
• Amenorrhea may occur and is safe.
• No protection against HIV or other STIs. Condoms are needed for STI prevention.
• Possibility of pain, vasovagal episode, expulsion, perforation, infection, and rare contraceptive failure.
• When to seek medical attention: lower abdominal pain, fever, offensive discharge, missed period with pain, pregnancy symptoms, inability to feel threads, or unusually heavy bleeding.

7. Timing of insertion

1. During menstruation or within the first 7 days of cycle
   • Pregnancy is readily excluded.
   • Immediate contraceptive protection if inserted within the appropriate early-cycle window.
2. At any time in the cycle
   • If reasonably certain the woman is not pregnant.
   • Advise additional contraception for 7 days if required by timing and local guidance.
3. Post-abortal
   • Immediately after first-trimester surgical abortion if no infection is present.
   • Following medical abortion, insert after completion is confirmed.
   • Delay after septic abortion until infection has resolved.
4. Postpartum
   • Immediate postplacental insertion is possible in trained hands.
   • Alternatively, insert after uterine involution, commonly at or after 4-6 weeks postpartum.
   • Counsel that expulsion is more likely after immediate postpartum insertion.
5. After removal of another IUD
   • Can be inserted immediately if pregnancy is excluded.

8. Procedure of insertion

Preparation

• Obtain informed consent.
• Ensure aseptic technique.
• Explain each step and offer analgesia, such as NSAID before procedure where appropriate.
• Keep resuscitation facilities available for rare vasovagal syncope.

Steps

1. Place patient in lithotomy position.
2. Perform bimanual pelvic examination to assess uterine position and size.
3. Insert speculum and visualize cervix.
4. Clean cervix with an antiseptic solution.
5. Apply tenaculum to anterior lip of cervix to stabilize and align uterus.
6. Sound the uterus gently to assess:
   • Direction of uterine cavity.
   • Uterine depth.
   • Obstruction or false passage.
7. Adjust flange on inserter to measured uterine depth.
8. Introduce the loaded Mirena through the cervical canal into the uterine cavity without force.
9. Release the arms in the uterine cavity as per manufacturer technique.
10. Advance or withdraw as instructed to achieve correct fundal placement.
11. Release the device completely.
12. Withdraw inserter.
13. Trim threads to about 2-3 cm beyond external os.
14. Document date, lot number, uterine sounding length, insertion difficulty, and planned date for replacement/removal.

Important technical principles

• Never force the inserter against resistance.
• If severe pain, bleeding, or unexpected resistance occurs, stop and assess for perforation or incorrect route.
• Ultrasound can confirm location after difficult insertion or if threads are not seen.

9. Follow-up

• Routine review is not essential for every asymptomatic woman, but many practices offer review after 4-6 weeks.
• Advise patient to return earlier for pain, fever, discharge, pregnancy symptoms, heavy bleeding, or missing threads.
• Confirm thread visibility at follow-up if indicated.
• Device duration:
  • Contraception: 8 years.
  • Heavy menstrual bleeding: 5 years.
• Replace or remove at expiry if ongoing treatment or contraception is needed.

10. Adverse effects

Common and expected

1. Irregular bleeding and spotting, especially during the first 3-6 months.
2. Reduced menstrual blood loss.
3. Amenorrhea.
4. Dysmenorrhea or pelvic cramps initially.
5. Headache.
6. Acne.
7. Breast tenderness.
8. Mood changes.
9. Nausea.
10. Vaginal discharge or vaginitis.

Ovarian cysts

• Functional ovarian cysts or enlarged follicles can occur.
• They are usually asymptomatic and resolve spontaneously.
• One textbook source reports enlarged follicles in about 12% of LNG-IUS users. Pfenninger and Fowler’s Procedures for Primary Care, section “Ovarian Cysts”.

11. Complications and management

A. Expulsion

• More common in the first few months, in young women, immediately postpartum, and in women with heavy bleeding or uterine cavity distortion.
• May be partial or complete.
• Symptoms: increased bleeding, cramping, longer threads, or inability to feel threads.
• Management:
  • Exclude pregnancy.
  • Examine and perform ultrasound if required.
  • Remove partially expelled device.
  • Insert a new device if appropriate.

B. Uterine perforation

• Rare, usually occurs at insertion.
• Risk is increased with inexperienced insertion, postpartum state, and breastfeeding.
• Suspect with severe pain, unexpected bleeding, loss of resistance, or missing threads.
• Management:
  • Stop procedure.
  • Pregnancy test and ultrasound.
  • If not seen intrauterine, obtain abdominal/pelvic X-ray.
  • Extrauterine device generally requires laparoscopic removal.

C. Pelvic infection

• Risk is related largely to pre-existing cervical infection and is greatest soon after insertion.
• Symptoms: pelvic pain, fever, cervical motion tenderness, adnexal tenderness, offensive discharge.
• Treat according to PID protocol.
• The IUS need not always be removed immediately. Reassess after antibiotics; consider removal if no clinical improvement within 48-72 hours or if the woman wishes.

D. Missing threads

• Thread retraction into cervical canal or uterine cavity.
• Expulsion.
• Pregnancy.
• Uterine perforation and migration.

1. Exclude pregnancy.
2. Speculum examination and gentle cervical exploration if appropriate.
3. Ultrasound to confirm intrauterine location.
4. If uterus is empty, abdominal/pelvic X-ray to identify extrauterine device.
5. If intrauterine and woman wants continuation, it can remain in place.
6. If removal is desired, remove under ultrasound guidance or hysteroscopy.

E. Pregnancy with Mirena in situ

• Urgently exclude ectopic pregnancy.
• If intrauterine pregnancy is confirmed and threads are visible, remove the device gently as early as possible.
• Removal reduces, but does not eliminate, risks of miscarriage, septic abortion, chorioamnionitis, and preterm birth.
• If threads are not visible, individualized counselling is required.

F. Actinomyces-like organisms on cervical smear

• Asymptomatic colonization does not necessarily require removal.
• Treat and remove IUS if there is clinical pelvic actinomycosis or pelvic infection.

12. Advantages

1. Very high contraceptive efficacy.
2. Long-acting and reversible.
3. Fertility returns rapidly after removal.
4. No daily adherence required.
5. Reduction in heavy menstrual bleeding and dysmenorrhea.
6. May produce amenorrhea, which is useful in anemia and menstrual suppression.
7. Minimal systemic hormonal exposure compared with oral progestins.
8. No estrogen-related risk of venous thromboembolism.
9. Useful when combined oral contraception is contraindicated.
10. Can be used during lactation.
11. Provides endometrial protection with estrogen therapy in selected women.
12. Cost-effective over long-term use.

13. Disadvantages

1. Requires trained provider for insertion and removal.
2. Initial irregular bleeding and spotting.
3. Does not protect against STIs.
4. Requires pelvic examination and uterine instrumentation.
5. May cause hormonal adverse effects, though systemic effects are usually mild.
6. Risk of expulsion, perforation, infection, and ovarian cysts.
7. Not appropriate in uterine cavity distortion or active pelvic infection.
8. Amenorrhea may be unacceptable to some women.

14. Comparison: Mirena versus Copper IUD

Viva Questions and Model Answers

1. What is Mirena?

2. How long is Mirena effective?

3. What is the main mechanism of action?

4. Does Mirena consistently inhibit ovulation?

5. What hormone does Mirena contain?

6. What is the total dose of levonorgestrel in Mirena?

7. Name therapeutic non-contraceptive uses.

8. What is the most common bleeding pattern in the first months?

9. Is amenorrhea with Mirena harmful?

10. What is the commonest reason for early discontinuation?

11. What are absolute contraindications?

12. Does Mirena protect against STIs?

13. When can it be inserted postpartum?

14. Can Mirena be used in lactation?

15. What is the risk of uterine perforation?

16. What should you do when strings are not visible?

17. What are the causes of missing threads?

18. What should be done if pregnancy occurs with Mirena in situ?

19. Why is ectopic pregnancy important in a Mirena failure?

20. Is PID more common in all IUD users?

21. How do you manage PID in a Mirena user?

22. Can Mirena be inserted in a woman with fibroids?

23. What is the role of Mirena in HRT?

24. How does Mirena help heavy menstrual bleeding?

25. What is the difference between LNG-IUS and LNG-IUD?

26. Is routine antibiotic prophylaxis required before insertion?

27. Is a routine follow-up visit mandatory?

28. What advice should be given after insertion?

29. What is the role of ultrasound after insertion?

30. Give a one-line conclusion for the examiner.