A 35-year-old G2P2 presents for a contraceptive counseling visit. She and her husband desire a long-term contraceptive method, and are uncertain if they want more children. She has been happily married for 10 years. Her only medical problem is mild hypertension, for which she takes a diuretic, and she has never had a sexually transmitted disease. She is considering the copper IUD and wants to know how it works.
Which of the following mechanisms does not potentially contribute to the mechanism of the action of the copper IUD?A. Decreased tubal motility inhibits ovum transport
Several mechanisms of action have been proposed for a copper IUD. These include inhibition of sperm migration and viability, change in transport speed of the ovum, and damage to or destruction of the ovum. The data demonstrates that these prefertilization mechanisms constitute the primary mechanism of action for prevention of pregnancy with the copper IUD; however, postfertilization effects, including damage or destruction of the fertilized ovum, may also occur. All of these effects occur before implantation. IUDs have few contraindications, and almost all women are eligible. Paragard should not be used in the following situations: pregnancy or suspected pregnancy, uterine abnormalities resulting in distortion of the uterine cavity, acute pelvic inflammatory disease, postpartum endometritis in the last 3 months, genital bleeding of unknown etiology, known or suspected uterine or cervical malignancy, mucopurulent cervicitis, or Wilson disease. The reported failure rate of a copper IUD at 1 year is very low, at 0.8 per 100 women. Although there is an increased risk of spontaneous abortion, and a small risk of infection, an intrauterine pregnancy can occur and continue successfully to term with an IUD in place. However, if the patient wishes to keep the pregnancy and if the string is visible, the IUD should be removed in an attempt to reduce the risk of infection, abortion, or both. Although the incidence of ectopic pregnancies with an IUD was at one time thought to be increased, it is now recognized that in fact the overall incidence is unchanged. The apparent increase is the result of the dramatic decrease in intrauterine implantation without affecting ectopic implantation. Thus, while the overall probability of pregnancy is dramatically decreased, when a pregnancy does occur with an IUD in place, there is a higher probability that it will be ectopic. With this in mind, in the absence of signs and symptoms suggestive of an ectopic pregnancy, especially after ultrasound documentation of an intrauterine pregnancy, laparoscopy is not indicated. The incidence of heterotopic pregnancy, in which intrauterine and extrauterine implantation occur simultaneously, is not increased.