The Spiral

Synonyms

Intrauterine device (IUD), Intrauterine system (IUS)

Definition

The intrauterine device, colloquially called a “coil”, is a contraceptive device that is inserted into the woman’s uterus. Modern intrauterine devices are usually T-shaped, 2.5 to 3.5 cm in size and made of tissue-friendly, flexible plastic. The spiral was first described by Gräfenberg in 1928.

He developed a spiral ring which was inserted into the uterus. However, an increased rate of ascending infections and the resulting deaths led to a ban on its use. Only after IUDs were made of plastic in the 1960s, which had no connection to the vagina except for a small thread, the coil was considered a real possibility for contraception.

Today, due to further development, only 3rd and 4th generation IUDs, also known as intrauterine devices (IUS), are still on the market. The following types are known:

  • IUD with copper
  • IUD with hormone supplement (progestin)
  • Plastic IUDs without additives (“inert” IUDs)

The vertical arm of the T-shaped spiral is wrapped with a copper wire and thus stabilizes the position in the uterus. The copper ions are continuously distributed into the surrounding tissue.

The surface area of the copper varies between 195 mm2 and 375 mm2 depending on the product. The mechanism of action is not fully secured. However, the following factors are involved: There is also speculation about a positive effect of copper ions on preventing the development of a malignant tumor of the uterine lining (endometrial carcinoma).

At least it is known that fewer endometrial carcinomas are observed when using copper IUD. This effect seems to be related to the length of time the IUD is in place.

  • The foreign body irritation of the uterine lining (the endometrium) leads to superficial inflammation, which is associated with an immigration of white blood cells (leukocytes) and specialized scavenger cells (macrophages) into the mucosa.

    This leads to an inhibition of the fertilized egg cell’s implantation in the uterus.

  • Copper ions have a harmful (toxic) effect on the fertilization ability of the sperm. The contraceptive effect is directly proportional to the total surface area of the copper used.
  • Copper ions also have a local toxic effect on the fallopian tubes and on the fertilized egg cell itself and thus directly inhibit implantation (direct nidation inhibition). Due to this mechanism, the IUD can also be used as a means of terminating pregnancy (post-coital abortion).

The shape of the spiral is similar to the copper spiral, but in this spiral the vertical arm here contains 52 mg levonorgestrel, a synthetic progestin.

Like the copper spiral, it causes a foreign body reaction of the endometrium. In addition, progestins cause a thickening of the cervical secretion, a reduction in the mobility of the fallopian tubes (tube motility) and a constant remodelling of the endometrium, which leads to a decrease in the intensity of bleeding. This alleviates existing menstrual pain (dysmenorrhea) and increased menstrual bleeding (hypermenorrhea). Inert IUDs are no longer available in Germany due to local irritation of the endometrium.