Severe pain at interval IUD insertion: a case-control analysis of patient risk factors.

ABSTRACT

PIP: This investigation, using a case-control analysis approach on an intrauterine device (IUD) data set from a less-developed country center, delineated 4 risk factors in patient characteristics that are associated with severe pain at interval IUD insertion. They are: higher education ( or = 7 years) low parity (1-2 live births), longer open interval ( or = 13 months) between the end of the last pregnancy and insertion, and non-breast feeding at the time of insertion. Adjusted relative risks estimated by odds ratios are 2.1, 2.7, 2.7, and 5.0 respectively. For women with a combination of the above risk factors, they have a further increased (additive in nature) risk of suffering severe insertion pain. Similar analysis was also performed on a developed country center data set for which only the effect of education and parity could be studied; an odds ratio of 5.0 for nulliparity was obtained. Better educated women are probably less inhibited to complain of pain than less-educated women. A tighter uterine cervix and a smaller uterine cavity in women of low parity may account for IUD insertion pain. Postpartum involution of the uterus could explain pain upon insertion for women with a long open interval. These findings support the hypothesis that cervical stretching and direct endometrial pressure are probably the most important factors for IUD insertion pain.