What Is Heterotopic Pregnancy And Who's At Risk?
Once considered rare, heterotopic pregnancy is on the rise with the risk for women undergoing IVF a startling one in 100. Heterotopic pregnancy is a condition in which uterine and extrauterine (outside the uterus) gestations occur at the same time. Since multiple embryos are transferred to the uterus at the same time during IVF, the risk is increased. When more than five embryos are implanted, the risk for heterotopic pregnancy increases to one in 45.
It is suggested that the rise in cases of heterotopic pregnancy may be due in part to the increased incidence of pelvic inflammatory disease. There may be other contributors to the condition as well, such as previous pelvic surgery and congenital or acquired abnormalities of the uterus. The numbers alone have convinced the medical profession that there is a need to be on the alert for this often-elusive condition.
A Condition That Often Goes Undiagnosed
Heterotopic pregnancies are very difficult to diagnose. More than 50 percent go undiagnosed until the eccyesis (extrauterine pregnancy) ruptures. They are not visible on ultrasound often until two or more weeks after the intrauterine pregnancy is seen. In order to confirm a heterotopic pregnancy, serial serum quantitative beta human chorionic gonadotropin (hCG) tests are done in conjunction with transvaginal ultrasound. However, even these methods have been found to be lacking in the ability to determine an extrauterine pregnancy along with an intrauterine pregnancy.
About 4 percent of heterotopic pregnancies occur in the fallopian tubes and they fail to raise any suspicions of an extrauterine pregnancy because the gestational sac mimics that of a single intrauterine pregnancy. However, failure to recognize the condition increases a woman's risk of hemorrhage at a stage as late as 16 weeks.
The condition and viability of the intrauterine pregnancy must be taken into consideration when a course of treatment is being determined. The choice between medical and surgical treatment depends upon the circulatory condition of the woman and the skill of the doctor. When surgery is the chosen method of treatment, a laparoscopy is used for removing an unruptured eccyesis without disturbing the intrauterine pregnancy. If the extrauterine pregnancy ruptures, the intrauterine gestation is still able to survive, however it is at greater risk for miscarriage. There are many precautions to be taken during a laparoscopic surgery, and when done with consideration for blood loss to the surviving pregnancy, there is hope for a viable pregnancy after the surgery.
Medical Treatment Options
Medical or therapeutic treatments for heterotopic pregnancy include an injection of potassium chloride, potassium chloride with methotrexate, or hyperosmolar glucose, into the unruptured eccyesis. This is done transvaginally and it has been found that an injection with methotrexate can potentially harm the surviving pregnancy. In addition, potassium chloride has been shown to cause long-term impairment of tubal function.
In general, surgery is the preferred method of treating a heterotopic pregnancy because it can be done quickly and it eliminates the potential for an ectopic rupture. Early diagnosis is key to successful treatment and delivery of the intrauterine pregnancy.