IUDs are small flexible plastic devices coated with copper, silver or gold. They have different shapes, often they are T-shaped and are inserted into the uterus by a gynecologist. There they act as a spermicide by releasing levels of metal ions. [1] [2]

Modes of action: Due to the foreign object, the uterus becomes inflamed preventing sperm from joining with an egg. Copper ions are toxic and inhibit the sperm's motility. Additionally, the function of the Fallopian tubes is disrupted in order to impede the sperm and eggs. [2] [3]

Advantages: it contains no hormones and has an effective period of up to five years. [2]

Disadvantages: include the possibility of heavier menstrual periods and more painful cramps as well as other complications (less than 3% of users had an inflammation of the genital tract). [2]

Protection: This type of contraception doesn't offer a special protection against sexually transmitted diseases. [1] [2]

Pearl Index*: 0.1-3; it's a very effective type of reversible birth control. [1]

Copper IUDs
Most copper IUDs have a plastic T-shaped frame; the leg of the T is wound around with pure electrolytic copper wire. The sheathing contains 275mg of copper and lasts for three years. IUDs containing 375 mg of copper can be used for five years. [2]
The Pearl index*: between 0.9 and 3. Generally, this method is the most effective type of reversible birth control. [1]
Cots in Austria: between 300 and 500 € for an effective period of three to five years. [4] [5]

Silver and gold IUDs
Visually, silver and gold IUDs are similar to copper IUDs but in contrast, they use a precious metal copper alloy or a copper wire with a silver or gold core. An advantage is their bacteriostatic effect and protection from corrosion. This is why some doctors think that gold IUDs is effective for 10 years or even an entire life. However, these speculations have no scientific basis. [6] [7] [8]
Pearl Index*: similar to copper IUDs
Cots in Austria: between 250 and 450 € for an effective period of five years. [7]

U-shaped IUDs
The so-called U-shaped IUDs, such as the frameless IUD holds several hollow cylindrical minuscule copper beads. It is held in place by a suture (knot) to the fundus of the uterus. This procedure can be painful and might include piercing through the walls of the uterus. [9] They have a similar effect to copper IUDs. According to a study by the "British Journal of Family Planning", the U-shaped IUDs are more secure than all other IUDs. [10]
Pearl Index*: 0.1-0.3 [10]
Cots in Austria: between 200 and 500 € for an effective period of five years. [9]

Intrauterine Ball (IUB)
The uterus friendly frame is coated with white polymer. The 17 IUB copper pearls are strung on this frame. They consist of a special shape memory alloy (special metals which can exist in two different crystal structures). Once the flexible IUB frame is released from the insertion tube in the uterus it remembers its 3-dimensional structure (see further material for the video).
The IUB remains for up to 5 years in the uterus. There are no definite numbers concerning safety or price because it's only on the Austrian market since 2015. Its effectiveness is estimated at that of the pill or a copper IUD. [11] Some gynecologists already offer the IUB.
Cots in Austria: around 400 €, similar to copper IUD and other IUDs. [12]

Further Links:
For varieties of IUDs (Museum of Contraception an Abortion)

* The Pearl Index (PI) is used as a statistical estimation of the number of unintended pregnancies in 100 woman-years of exposure. A PI of 85 or 90 corresponds to no birth control methods used. A lower Pearl index represents a lower chance of getting pregnant. The Pearl Index can change depending on studies and observations. [1]