Study on possible breakage of IUDs in the uterus.

A pilot study was conducted on 30 Lippes loop IUDs which had been in use for up to 7 years to test the validity of the belief that IUDs should be replaced every few years. Most IUDs in use are made of plastic which occasionally breaks in utero causing discomfort bleeding and difficult removal. It is this breaking which leads many family planning physicians to recommend routine replacement every few years. It was found that a sediment composed of 80% calcium carbonate 1% sodium and trace amounts of magnesium zinc and organic materials froms with time. Over the years the thickness of the sediment increases but the composition does not change. Microscopic examination showed some corrosion of the body of the loop the amount increasing with time in use. This corrosion decreased thickness of the IUD; those which broke had identical segments thinner by up to 15%. Length of time in use also increased rigidity and decreased flexibility. Fracture tests showed older IUDs were more likely to break. Tests carried out on a modified tensometer showed that after 1 year in use a pressure of 80 kg would cause only a depression in a device whereas after 5 1/2 years in use a pressure of 25 kg would break it. These breaks occurred mainly at the curved porions. The belief that IUDs should be replaced every few years appears to have some validity.