#143 Medical Management of First-Trimester Abortion Flashcards
What percentage of abortions are performed before 63 days of gestation?
64%
What percentage of all abortions are medical abortions in the US? What percentage at or before 9 weeks?
16.5%. 25.2%
What is the most common medical abortion regimen used in the US and Western Europe?
Mifepristone and misoprostol
What is the mechanism of action of mifepristone?
Antiprogestin - binds to progesterone receptor with greater affinity than progesterone, but does not activate it
What are the effects of mifepristone on a uterus/cervix in a pregnant woman?
Decidual necrosis, cervical softening, and increased uterine contractility and prostaglandin sensitivity
How long after mifepristone administration does uterine contractility increase?
24-36 hours after administration
By how much does mifepristone increase the sensitivity of the myometrium to prostaglandins by 24-36 hours?
Five fold increase
What type of prostaglandin is misoprostol?
Prostaglandin E1 analogue
Which route(s) of misoprostol administration have the longer duration of action?
Buccal and vaginal
Which route(s) of administration of misoprostol are more efficacious than oral administration?
Buccal, vaginal, sublingual
Which route(s) of misoprostol administration have the most rapid onset and significant absorption?
Sublingual. More adverse effects
Is misoprostol only or combined misoprostol-mifepristone regimen more efficacious for first trimester abortion?
Combined
What is the mechanism of action of methotrexate?
Dihydrofolate reductase inhibitor. Enzyme involved in producing thymidine during DNA synthesis
What does dihydrofolate reductase do?
Enzyme involved in producing thymidine during DNA synthesis
Where does methotrexate mostly exert its abortifacient effect?
Primarily on the cytotrophoblast rather than the developing embryo, which inhibits syncytialization of the cytotrophoblast. Stops implantation
Does mifepristone have a direct effect on the trophoblast?
No
What is the mifepristone-misoprostol regimen for first trimester abortion? FDA vs evidence based regimens
FDA: 600mg mifepristone orally, followed about 48 hours later by 400mcg misoprostol orally
Evidence-based: 200mg mifepristone, followed by miso (vaginal at same time as mife or 6-8hr after, buccal and sublingual 24 hrs after)
What are the benefits of medical abortion over surgical first trimester abortion?
Usually avoids invasive procedure, usually avoids anesthesia
What are the cons of medical abortion over surgical first trimester abortion?
Days to weeks to complete, bleeding commonly not perceived as light, requires follow-up to ensure completion, patient participation through multi-step process
Benefits of surgical first-trimester abortion compared to medical abortion?
Allows use of sedation if desired, predictable time period, bleeding commonly perceived as light, does not require follow up in most cases
What is the success rate of first trimester medical abortion
~95%