Postcoital Contraception

Postcoital Contraception

Postcoital contraception is used when condoms break, when combination oral contraceptives have been forgotten, or in cases of rape or misuse of present contraceptive method.

1. Contraceptive pills: The so-called morning after pill is highly effective in preventing pregnancy if it is used within 12 to 24 hours after coitus. The most commonly used regimen is 100 |ig ethinyl estradiol and 1 mg of norgestrel or 0.5 mg levonorgestrel given immediately and then repeated 12 hours later. Antiemetics are sometimes needed with this

regimen. For example, Ovral, 2 double doses are given 12 hours apart totaling 4; Loovral/Nordette/Levelen/Triphasil, 4 tablets are given every 12 hours, totaling 8 pills; or Danazol, 400 mg given every 12 hours, two to three times, totaling 800 to 1200 mg, are effective alternatives for women who are not able to use estrogen. For Plan B (Preven), 2 tablets containing 50 ng per tablet are taken 12 hours apart. Also available is levonorgestrel, 0.75 mg, 1 tablet every 12 hours or 1.5 mg stat.

2. Intrauterine device (IUD): Insertion of a copper IUD within 7 days of coitus is very effective in preventing pregnancy. However, use in women who are at high risk for PID is discouraged. Also it is not to be used in rape situations or nulliparous women. An IUD is an excel- lent option for properly selected patients such as multiparous women who do not desire surgery for birth control. The IUD is indicated in monogamous women.

a. Fewer than 2% of the women in the United States are IUD users. In the 1970s, before many IUDs were taken off the market, about 10% of American women were IUD users. There are presently two IUDs available. The Mirena IUD, approved for 5 years, is produced by Berlex. The copper 380A (Paragard) is a desirable IUD option because it has been recently approved for 10 years of use. It is produced by Gynopharma and is the most commonly used IUD.

b. Composition and mode of action.

(1) The CU T 380A (Paragard) is shaped like a T. The polyethylene T is wrapped with a fine copper wire on all three arms of the T. A single-filament white string projects from the base of the T. The Mirena IUD is a polyethylene T wrapped with levonorgestrel on the vertical arm. Two blue single-filament strings project from the base of the T. The advantage of the Mirena is that it drastically decreases menstrual flow and therefore has a therapeutic indication.

(2) Gyneflex, developed in Belgium, is a new IUD being trialed in Europe. It consists of a monofilament polypropylene thread that dangles six copper bands in the uterus. It is fixed to the fundus by an anchoring loop in the uterus. It is approved for 5 years. Special training for users is required.

(3) The mechanism of action of the IUD includes sperm immobilization and increased speed of ovum transport through the fallopian tubes. It was once thought that IUDs caused abortion of the fertilized egg by preventing implantation. However, it is now known that the device prohibits the sperm from meeting the egg in the fallopian tube.

c. Considerations before insertion of the IUD.

(1) A detailed history must be completed and a thorough physical must be done. Cervical cultures for Chlamydia and gonorrhea must be negative. All abnormal Papanicolaou smears should be diagnosed and treated first.

(2) Discussion of risks and benefits for this form of birth control should be thorough. Patients with the following history should  not be considered candidates for IUD insertion: Known or possible pregnancy, acute PID, or current behavior that suggests the patient is high risk for PID, recent postpartum endometritis, postabortion infection. The IUD should be used with caution in the following patient populations: (a) Those at risk for sexually transmitted diseases and PID. (b) Those with impaired immune response: human immuno-deficiency virus (HIV) positive, diabetics, leukemics, or patients on steroids, (c) Patients with menorrhagia, undiagnosed irregular vaginal bleeding (i.e., known or suspected uterine or cervical

malignancies).

(d) Those who have had previous complications associated with IUDs, such as pregnancies, expulsion, or perforation.

(e) Women with anatomic uterine abnormalities that make insertion difficult (e.g., leiomyoma, cervical stenosis).

(f) Genital actinomycosis.

(g) Mucopurulent cervicitis.

(h) Those with valvular heart disease (women with cardiac lesions are more susceptible to subacute bacterial endocarditis).

(i) History of a previous ectopic pregnancy is no longer a contraindication because IUDs actually decrease the risk of ectopic pregnancies,

(j) Mitral valve prolapse is not a contraindication to IUD use.

 
Table 1 Delivery Systems for Progestin-Only Contraceptives and Combined Pills
Administration Injectable Implant Oral
Depo-Provera Norplant Progestin-Only Pill Combined OC
Frequency Every 3 months 5 years Daily Daily
Progestin dose High Ultra low Ultra low Low
Blood levels Initial peak, then decline Constant Rapidly fluctuating Rapidly fluctuating
First pass through liver No No Yes Yes
Major Mechanisms of Action
Ovary: decreases ovulation* +++ ++ + +++
Cervical mucus: decreases sperm penetrability Yes Yes Yes Yes
Endometrium: decreases receptivity to bastocyst Yes Yes Yes Yes
0.1
First-year failure rate (perfect use) 0.3 0.09 0.5
Menstrual pattern Very irregular Very irregular Often irregular Regular
Amenorrhea during use Very common Common Occasional Rare
Reversibility Yes Yes Yes
Immediate termination possible No
By woman herself at any time No No Yes Yes
Median time to conception from first omitted dose, removal 6 months About 1 month <3 months 3 months

 

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