A New Technique for Introducing Iuds Into Rat Uteri

Abstract

Summary. Intra-uterine contraceptive devices (IUDs) were made from monofilament nylon and inserted by a non-surgical technique through the cervical os of rats so as to be wholly within the uterine lumen. Most of these devices were retained and exhibited local contraceptive action in the uterine horn in which they were placed. This new method of insertion in rats offers advantages over other ways of studying the physiological and biochemical factors important to IUD function.Increasing acceptance of the intra-uterine contraceptive device (IUD) as a method of population control makes necessary a better understanding of the mechanism(s) of action of such devices. More familiarity with the precise contraceptive nature of IUDs will probably lead to increased use and improved effectiveness of these methods.The small size and low cost of the albino rat affords an opportunity for extensive laboratory investigations on the mechanism of IUD action. Further, the bicornate uterus of rats has proved to be especially advantageous since it offers the possibility of using the horn contralateral to the one containing the IUD as a control. Thus, although the control horn is independent and implanta¬ tion and pregnancy can occur normally, it is under the same general hormonal, genetic, nutritional and metabolic influences as the IUD horn in which blasto¬ cysts do not implant. Differences of any kind that can be demonstrated to exist between the horns are possible causes of the infertility induced by IUDs.A review of the literature on IUDs in rats and mice did not indicate that any investigators had inserted the devices through the cervix. All have been put in after laparotomy by sewing through the uterus, usually in two places (Doyle & Margolis, 1963, 1966Kar, Kamboj & Datta, 1964;Kar, Goswami, Kamboj & Chowdhury, 1964;Marston & Chang, 1964;Schuchner & Davidson, 1964;Chaudhury & Tarak, 1965;Greenwald, 1965;Parr, 1966;Speilberger & Olewine, 1966;Havránek, Dyková & Tichy, 1967;Laumas & Farooq, 1967).Since insertion through the cervix seemed to offer advantages over the trau¬ matic method being used, and further, since the cervical approach was more closely analogous to the practice in man, we investigated the efficacy of produc¬ ing unilateral sterility by insertion of a device wholly within the uterine lumen. G 515

A study of the possible role of prostaglandins in decidualization using a nonsurgical method for the instillation of fluids into the rat uterine lumen

“…The vaginal route has been used to insert an IUD (Wrenn, Wood & Bitman, 1968), for egg transfer (Bennett & Vickery, 1970), or to apply drugs to the endometrium (Barker, 1967) but, as far as I know, none of the numerous studies on the DCR in the rat has used this approach. The transcervical route used in the present study avoids the trauma and expenditure of time associated with laparotomy.…”

Alterations in the Uterine Environment Produced by Iuds

“…The incidence of uterine exúdate in this experiment was low, only 4-3% of the IUD horns showing visible amounts. In a previous study (Wrenn et al, 1968), 54% of the IUD horns contained exúdate in 10to 21-day pregnant rats. This suggests that the rat may be more susceptible to infection and/or inflammatory reaction during later pregnancy than at earlier times, and seems to merit further investigation.…”

“…The recent development in our laboratory of a method for the cervical introduction of an IUD lying wholly within the lumen of one uterine horn of the albino rat has provided an experimental preparation that facilitates studies of chemical differences between the infertile IUD horn and the contralateral horn possessing normal fertility (Wrenn, Wood & Bitman, 1968). This method avoids the trauma of surgery and the associated inflammatory alterations involved in placing a suture through the walls of the uterus.…”

Effects of polyethylene IUDs and unilateral ovariectomy in golden hamsters

“…In mice, however, there is a decrease in the number of implantations in the contralateral horn (Marston & Kelly, 1969), and in rats the IUD-containing uterus can support implantations . Previous investigators have not described the formation of exúdate in hamsters as a response to an IUD, but in rats a visible accumulation of fluid was noted in 54% of the IUD-containing uteri (Wrenn, Wood & Bitman, 1968). El Sahwi & Moyer (1971) noted that the antifertility action of a silicone-plastic IUD was in proportion to the number of leucocytes observed in the uterine lumen.…”