What medicine can be used to initiate menses in a female who has missed her period by 5-6 days?

Medications to Initiate Menses in a Female with 5-6 Day Delayed Period

Medroxyprogesterone acetate or other progestins are the most appropriate medications to initiate menses in a female who has missed her period by 5-6 days. 1

First-Line Options

Oral Progestins

• Medroxyprogesterone acetate (MPA): 5-10mg daily for 5-10 days
• Micronized progesterone: 200mg daily for 5-10 days

When administered, these progestins will typically induce withdrawal bleeding within 2-7 days after completing the course of medication.

Mechanism of Action

Progestins work by:

1. Stabilizing the endometrial lining that has been built up by estrogen
2. Upon withdrawal of the progestin, the sudden drop in hormone levels triggers endometrial shedding
3. This results in withdrawal bleeding similar to a menstrual period

Patient Selection Considerations

• Before administering any medication to initiate menses, it's essential to rule out pregnancy
• For women with a 5-6 day delay in menses, a pregnancy test should be performed before starting progestin therapy
• Progestins should not be given if pregnancy is confirmed or suspected, as they may affect the developing embryo

Contraindications

• Known or suspected pregnancy
• Undiagnosed abnormal vaginal bleeding
• Active thromboembolic disease
• History of breast cancer
• Severe liver disease

Monitoring and Follow-up

• If withdrawal bleeding does not occur within 7 days after completing the progestin course, a pregnancy test should be performed
• In cases of persistent abnormal vaginal bleeding, appropriate diagnostic measures should be undertaken to rule out malignancy 1
• Patients with a history of depression should be monitored carefully as progestins may worsen depressive symptoms 1

Alternative Options

Combined Hormonal Contraceptives

• Can be started at any time if it is reasonably certain the woman is not pregnant 2
• Will regulate menstrual cycles and can be used to induce withdrawal bleeding
• Requires 7 days of additional contraceptive protection if started >5 days since menstrual bleeding began 2

Emergency Contraception (if appropriate)

• If there is concern about unprotected intercourse, emergency contraception options include:
  • Ulipristal acetate (30mg single dose)
  • Levonorgestrel (1.5mg single dose)
  • Combined estrogen-progestin regimen 2

Special Considerations

• For women with chronic anovulation or irregular cycles, a more comprehensive evaluation may be needed
• Tranexamic acid can reduce menstrual blood loss by approximately 50% but is not specifically used to initiate menses 3
• NSAIDs can reduce menstrual blood flow but are not indicated for initiating menses 3

Common Pitfalls to Avoid

1. Failing to rule out pregnancy before administering progestins
2. Not considering underlying causes of menstrual irregularity (PCOS, thyroid disorders, hyperprolactinemia)
3. Inappropriate use in cases of abnormal uterine bleeding without proper diagnostic evaluation
4. Overlooking contraindications such as history of thromboembolic disease or breast cancer

Progestins remain the most effective and appropriate medication for initiating menses in women with delayed periods when pregnancy has been ruled out. The treatment is generally well-tolerated and effective for most women.