Reactive oxygen intermediates and reactive nitrogen intermediates in copper intrauterine device users

The mechanism of action of copper in copper intrauterine devices (Cu IUD) as an antimicrobial agent is not well understood. Copper and iron are supposed to be responsible for release of reactive oxygen intermediates (ROI) and reactive nitrogen intermediates (RNI), which are very active in the presence of infection. The copper in a copper IUD could be responsible for limiting pelvic inflammatory disease. The present study was composed of 20 IUD seekers in whom ROI and RNI were studied before insertion of Cu IUD and then at 1, 4, and 12 weeks afterward. ROI showed a rise after insertion, whereas RNI showed a steady decline. Hence, it is presumed that the rise in ROI could be responsible for both the bactericidal effect of Cu IUD and also for the fall in RNI.

Mechanisms of action of intrauterine devices

The major effect of all intrauterine devices (IUD) is to induce a local inflammatory reaction in the endometrium whose cellular and humoral components are released into the uterine cavity. This inflammatory reaction has a variable effect on the reproductive strategy of the species studied. For example, this foreign body reaction can be localized within the uterus of rodents; and in farm animals it can have striking extrauterine effects. Thus, the action of IUDs in humans cannot be discerned from animals. In humans, copper ions released from Cu-IUDs enhance the inflammatory response and reach concentrations in the luminal fluids of the genital tract that are toxic for spermatozoa and embryos. In women using the IUD, the entire genital tract seems affected, at least in part, because of luminal transmission of the fluids that accumulates in the uterine lumen. This affects the function or viability of gametes, decreasing the rate of fertilization and lowering the chances of survival of any embryo that may be formed, even before it reaches the uterus. Studies on the recovery of eggs from women using IUDs and from women not using contraception show that embryos are formed in the tubes of IUD users at a much lower rate compared with nonusers. This is believed to be the major action of IUDs. Therefore, the common belief that the major mechanism of action of IUDs in women is through destruction of embryos in the uterus (i.e., abortion) is not supported by the available evidence. In Cu-IUD users, it is likely that few spermatozoa reach the distal segment of the fallopian tube, those that encounter an egg may be in poor condition. Thus, the few eggs that are fertilized have little chance for development and their possibility for survival in the altered tubal milieu become worse as they approach the uterine cavity.

Effects of various IUDs on the composition of cervical mucus

The influence of three different intrauterine devices on the composition of cervical mucus was studied. The amount of mucin, albumin and immunoglobulin G was estimated. After the insertion of an inert IUD, a decrease in mucin was observed. During copper-IUD use the content of mucin, albumin and IgG was increased in cervical mucus, while weight was not affected. In the levonorgestrel-IUD users, ovulation was inhibited in 2 out of 8 women. Mucus weight was increased. The amounts of mucin, albumin and IgG were not changed. In an in vitro experiment the effect of copper-IUDs on autooxidation of cholesterol was studied. There was an extensive conversion of cholesterol but addition of albumin quenched the oxidation of cholesterol. It is suggested that the increased secretion of albumin induced by copper-IUD users may offer protection against copper-induced cell damage.

Modern trends in contraception

Substantial improvements have been made in oral contraceptives, a new injectable contraceptive (Norplant), and the intrauterine device (IUD). Major risks with oral contraceptives have declined substantially, and a number of noncontraceptive health benefits have been discovered. Norplant is probably the first new contraceptive in recent years, and offers long-term contraception with high efficacy and modest risks. The IUD, by carefully selecting users, is a safe and efficacious contraceptive method. The major risk, pelvic inflammatory disease (PID), is far less common if one avoids use in the presence of risk factors for PID.

Endometrial reaction to intrauterine device in pregnancy

It is generally assumed that the intrauterine device (IUD) exerts its action by altering endometrial receptivity for the implanting embryo. The most frequently encountered endometrial reaction reported in the presence of an IUD is a chronic inflammatory reaction which may be responsible for the alterations in the normal physiology of the human endometrium. In order to evaluate the endometrial response to the IUD when pregnancy occurs with the device in situ, we have examined the morphology of decidual tissue obtained during interruptions of pregnancy of 32 patients who had conceived in the presence of IUDs. Twenty-three decidual specimens, obtained during interruption of pregnancies without an IUD, served as controls. The incidence of chronic inflammatory reaction was 6.25% in the presence of an IUD and 4.34% in the control group. The incidence of chronic endometritis reported in nonpregnant IUD users is higher (14-100%) than the incidence of chronic endometritis observed in both groups. This observation may be the result of the generally observed alterations in the immune system during a normal pregnancy, but may also be interpreted as a primary reduced endometrial reaction to the IUD, consequently leading to the contraceptive failure in this group.

Intrauterine steroid contraceptives

Progestagen releasing IUDs were specially developed to diminish the problems of bleeding and pain with inert and copper containing IUDs. The intrauterine release of the progestagen causes endometrial atrophy, resulting in impairment of nidation, and interferes with transport of the ovum and the spermatozoa. Two available types, Progestasert, Biograviplan (Alza Corporation, California; Grünenthal) and Levonorgestrel Nova-T (Leiras Pharmaceuticals, Finland), have been sufficiently tested in multinational trials. Compared with Progestasert, LNG Nova-T showed lower pregnancy rates (Pearl Index 0.30), less risk for ectopic pregnancy and a longer effective lifetime (7 years). With both IUDs the amount and duration of menstrual blood loss is decreased. Amenorrhea is a frequent occurring side effect of LNG Nova-T, caused by endometrial atrophy. Intermenstrual blood loss and spotting incidences are not uniformly reduced and are still a frequent reason for removal. Preinsertion counselling may improve the acceptance of these non-health-threatening side effects. With both IUDs a decrease of menstrual cramps during periods is percepted and a low incidence of PID is found. Basically, the progestagen releasing IUD can be recommended to all women who wish an IUD for contraception and to women with contraindications for oral contraceptives, especially to those with menorrhagia, anaemia or risk for anaemia.

Mechanism of action of intrauterine devices: biochemical changes

The mechanism of action of intrauterine devices varies from one type of device to another, although the principle of action is the same, namely, to interfere with the physiology of reproduction at the endometrial level. The biochemical changes of the endometrial tissue and the composition of the uterine fluid have been reviewed in relation to the use of inert, copper-medicated and steroid-releasing IUDs. All IUDs, whether inert or medicated, provoke a significant increase in the number of neutrophils, mononuclear cells and plasma cells, the presence of which is unrelated to the tissue infiltration of inflammatory cells occurring pre-menstrually of the normal menstrual cycle. The increase of leucocytes in IUD-users is compatible with a foreign body reaction which may be related to the antifertility effect. The addition of copper to an inert IUD has been shown to significantly alter the metabolism of the endometrial cells, e.g. the enzymatic activity and the DOVA-synthesis. The steroid-medicated IUDs represent a new approach to intrauterine contraception where the morphology of the endometrium is considerably altered, showing massive decidual changes, atrophic glands and sometimes atrophy of the whole functional layer. In addition, there is an important foreign body reaction, similar to that of the inert IUDs. The enzymatic activity, as well as the proliferative activity was significantly altered in the endometrium of these IUD-users. Changes in the endometrial fibrinolytic activity in IUD-users have been demonstrated to be related to the presence of irregular bleeding. Micro-traumata of the endometrium and the increased fibrinolytic activity may also interfere with the protective processes present in the physiologically normal endometrium. Further studies on the factors influencing the fertilizing ability of the spermatozoa in the female genital tract, as well as on the conditions of the human endometrium required for the implantation of a blastocyst, may yield important information for the improvement of intrauterine contraception.

Mineral deposits formation in bioactive IUD's

Mineral organic deposits have been observed in inert IUDs. The authors studied the presence of these deposits in bioactive IUDs. Inert, progesterone, and copper-releasing IUDs were removed at 12,24, and 36 months postinsertion. When the devices were cut between their vertical (body) and horizontal (arms) branches, both parts were processed independently. After laxly bound organic material was eliminated, the devices were extracted at 60 degrees Celsius for 90 minutes with 3N HC1, and finally all undissolved material was dissolved in 1N NaOH. In each fraction, protein and inorganic ions were measured. Mineral organic deposits were formed in all types of IUDs. The deposits increased with time in utero in a characteristic device-dependent pattern. The deposits were essentially made of proteins, sodium, and calcium ions and were higher on the inert Lippes Loop D (7.0 +or- 2.4 mg proteins; 2.8 +or- 0.85 mg calcium, and 0.138 +or- 0.048 mg sodium/device); less in the copper IUD (5.7 +or- 1.36 mg proteins, 0.89 +or- 0.12 mg calcium, and 0.180 +or- 0.046 mg sodium/device at 24 months); and even less in the progesterone-releasing IUDs (1.6 +or- 1.3 mg protein, 0.235 +or- 0.028 mg calcium, and 0.262 +or- 0.063 mg sodium/device).