Prostaglandin Analogue Misoprostol in Obstetrics and Gynecology

The uses of misoprostol, a synthetic prostaglandin, in obstetrics and gynecology have been discussed in an article published in the Reviews in Obstetrics and Gynecology.

Prostaglandins are natural substances found in the body. They mediate several important functions through their effects on different body parts like blood vessels, gastrointestinal system, airways, reproductive system, platelets and kidneys.

Misoprostol is a synthetic prostaglandin that is primarily used to treat stomach ulcers caused by painkiller medications like ibuprofen and diclofenac belonging to the group nonsteroidal anti-inflammatory drugs (NSAIDs).  Prostaglandins protect the inner lining of the stomach, and NSAIDs cause ulcers by reducing prostaglandins. Therefore, replacement of prostaglandins with misoprostol can protect the inner lining of the stomach and prevent ulcers.

Though the use of misoprostol in pregnancy is not advised since it can cause abortion and fetal malformations, it has been used in several obstetric conditions. Misoprostol has two main effects on the female reproductive system.

• It brings about contraction of the uterus
• It causes cervical softening. The cervix is the lower tubular opening of the uterus, which normally remains closed but opens during delivery to allow birth of the fetus. The opening of the cervix is called cervical ripening.

Some of the uses or indications of misoprostol in obstetrics and gynecology are as follows:

• Medical abortion of early pregnancy: Misoprostol is used 48 hours after another medication mifepristone for abortion of very early pregnancy, that is, up to 49 weeks of gestation. An ultrasound is usually done on follow-up to confirm that the products of conception completely expelled. Misoprostol is also sometimes used with another drug called methotrexate to bring about an abortion.
• Before certain cases of surgical abortions in the first or second trimesters to bring about cervical ripening and facilitate the procedure.
• Before procedures like hysteroscopy, biopsy of the inner lining of the uterus, or placement of an intrauterine contraceptive device like Copper-T in women who were not previously pregnant. Hysteroscopy is a procedure that allows inspection of the inner lining of the uterus. The use of misoprostol in these conditions is still being evaluated.
• Incomplete early abortion: Incomplete abortion is a miscarriage where some of the products of conception are still retained in the uterus. Misoprostol can be used to complete the process of abortion that takes place before 12 weeks.
• To induce labor in second trimester: Misoprostol may be used to induce labor in the second trimester following death of the fetus within the uterus or to terminate the pregnancy.
• To ripen cervix and induce labor at term: Misoprostol may be used along with oxytocin for cervical ripening and induction of labor at term.  Women with prior cesarean section are at a risk of uterine rupture with this use of misoprostol.

Misoprostol has several advantages over other prostaglandins used in obstetrics. It is cheap, is widely available and can be stored without refrigeration. It can be given orally, or placed in contact with the vagina, mouth or rectum to be absorbed into the blood. Side effects of misoprostol when used in obstetrics include excessive bleeding, cramping, nausea, vomiting, diarrhea and fever.

References: 

1. Allen R, O’Brien BM. Uses of Misoprostol in Obstetrics and Gynecology. Rev Obstet Gynecol. 2009 Summer; 2(3): 159–168.

Source-Medindia