DES (diethylstilbestrol) is a hormone that was prescribed for pregnant womenin the 1950s and early 1960s. Many years later, doctors discovered that the daughters of the women who received DES were at high risk for a variety of problems, including infertility, premature labor, and cancer of the vagina and cervix.
In the 1950s and early 1960s, several drug companies claimed that DES could prevent miscarriages. DES is a synthetic hormone, related to estrogen. Since up to 20% of all pregnancies end in miscarriage, this seemed an important breakthrough and DES was prescribed for many women who had bleeding in early pregnancy. Ultimately, it was found to have no effect on miscarriages and the practice of prescribing DES was stopped in the 1960s. Almost 10 years later, thedaughters of women who had taken DES during pregnancy began to develop unusual symptoms.
Doctors discovered that when these young women reached their teens, they wereat higher risk for a variety of problems, including a rare cancer known as clear cell adenocarcinoma of the vagina and cervix, infertility, premature labor, and other problems in pregnancy.
DES has affected a very specific group of women who were exposed to DES in the womb before 18 weeks of pregnancy. In other words, their mothers must havetaken DES within the first 4-5 months of pregnancy, when the female reproductive organs are formed. DES appears to interfere with proper growth and development of the uterus, cervix, vagina, and fallopian tubes.
In the early 1970s, there was an increase in clear cell adenocarcinoma of thevagina and cervix. Up until that time, doctors had seen these cancers only in elderly women. Suddenly, the disease began to appear in young women.
This was so unusual that researchers studied these women to see if they had anything in common. After a great deal of questioning and examination, it wasfound that all had been exposed to DES in the womb during the early weeks ofpregnancy.
Today, it is difficult to imagine how shocking this discovery was. Doctors had only recently recognized that medications and exposure to chemicals duringpregnancy could cause birth defects. This defect had gone undetected for almost two decades.
Since then, doctors have studied DES daughters very carefully. Fortunately, the risk of clear cell adenocarcinoma is actually quite low. In fact, it appears that if a DES daughter has not developed this cancer by age 30, she will not develop it. Since all DES daughters are now over age 30, there should be no further cases related to DES exposure. However, there are a number of othersymptoms and problems associated with DES exposure:
- DES daughters often have distinctive changes of the cervix and vagina that can be seen duringa pelvic exam. These changes include a cervical hood (a vaginal fold draped over the cervix), cockscomb cervix (an abnormally shaped cervix), and adenosis(glandular cells normally located within the cervix that appear on the outside of the cervix and in the vagina).
- Some DES daughters have fallopian tube abnormalities that lead to infertility.
- Many DES daughters have a uterus that is abnormal in size and shape. The classic sign is the T-shaped uterus. In the normal uterus, the cavity (hollow space inside) is rounded. The abnormal T shape makes it harder for a woman to get pregnant and leadsto a higher risk of premature labor and birth.
Women who have been exposed to DES should have a pelvic exam at least once ayear. In addition to the usual pelvic exam and Pap smear, DES daughters should also have Pap smears of the vagina and, if possible, colposcopy, in which the cervix and vagina are examined through a special magnifying scope. In thisway, tiny areas of abnormal cells can be seen. This procedure is easily performed in the doctor's office.
When DES daughters get pregnant, they may be at high risk for premature laborand birth and should be monitored very carefully.
Not all women who were exposed to DES develop problems in pregnancy. However,if problems like infertility or miscarriage do occur, the doctor may recommend a special xray to check the woman's fallopian tubes and uterus. This special test is called a hysterosalpingogram.
There is no treatment for the abnormalities of the fallopian tubes and uteruscaused by DES exposure. Fortunately, there are treatments that can help withinfertility or premature labor. Clear cell adenocarcinoma of the vagina or cervix must be treated with surgery and, possibly, chemotherapy.