Prevention of intrauterine contraceptive device expulsion and intolerance: Determination of the anchor mechanism

Objective: The intrauterine device (IUD) is an important long-acting reversible contraceptive method (LARC) which plays a major role in contraception. Expulsion and intolerance because of pain and/or bleeding are two factors which limit more widespread use. IUDs have to form some type of ‘anchor’, which must be well tolerated in order not to be expelled and not cause problems as might any other intrauterine object. We considered how an IUD might behave in comparison to a physiological or pathological intra-uterine body. Methods: We reviewed historical and present day IUDs on a three point rating scale of i) flexibility ii) horizontal to vertical ratio and iii) percentage increase in size of the IUD over mean cavity measurements to determine an Anchor Index(AI) to separate the types of anchor methods the various devices employ. Results: The AI generally varied from 3-7 in multiparous women signifying a marginally ‘physiological’ fit. The AI was mainly above 5 for most IUDs in nulliparous women indicating a largely nonphysiological (‘pathological’ type) fit. Conclusions: The structure, composition and design of most IUDs are still not optimal for the nulliparous and occasionally the multiparous endometrial cavity. IUD design should be such that they appear to the endometrial cavity to be a physiological rather than a pathological incumbent. Correspondence to: Dr. N Goldstuck, Department of Obstetrics and Gynaecology, Faculty of Medicine and Health Sciences, Stellenbosch University and Tygerberg Hospital, Western Cape, South Africa, Tel: +27-21-555-1756, +27823418200; E-mail: [email protected]