Ectopic pregnancy among early abortion patients: does prostaglandin reduce the incidence?

Prostaglandins in the ovary and fallopian tube

More than 20 years following the recognition of a possible role for eicosanoids in ovarian function a physiological role for prostaglandins and/or leukotrienes in human ovulation, corpus luteum function and tubal motility remains to be demonstrated. With respect to ovarian function, the well-characterized preovulatory rise in eicosanoid production in animal species and humans, in conjunction with the large body of experimental evidence employing inhibitors of prostaglandin synthesis and replacement of individual prostaglandins, has provided strong evidence for a role in follicular rupture independent of other LH-mediated ovulatory events. The possible mechanism of prostaglandin-induced follicle rupture may involve stimulation of proteolytic activity via substances such as plasmin and PA; however, this is controversial. A role for prostaglandins in ovarian luteal function is well established in laboratory animals and large ruminant species, where PGF2 alpha derived from the uterus has been demonstrated to be the luteolytic factor. In humans, luteal function may be influenced by local intraovarian eicosanoid production, which has been suggested to involve the paracrine interaction of local ovarian hormones such as oxytocin, noradrenaline, insulin and IGFs, to name but a few. Several lines of evidence have also implicated prostaglandins as an aetiological factor in ovarian pathological states such as seen in the OHSS. However, the bulk of clinical experimental evidence to date has failed to support this contention. Prostaglandin production has likewise been well characterized in the fallopian tube in both humans and animal species. Whereas a role for prostaglandins in tubal transport has been demonstrated with animal species such as the rabbit, several studies have failed to define a similar function in humans. More recently, direct injections of prostaglandin analogues into the fallopian tube and the corpus luteum have been shown to be efficacious as a treatment for ectopic pregnancy. Whether the primary mechanism of action involves effects on tubal musculature or corpus luteum function, or is simply a local vascular effect, remains to be demonstrated. Therefore, although the physiological role for eicosanoids in ovarian and tubal function remains unclear, particularly in the human, an increasing body of recent evidence has suggested an important paracrine function for this class of cellular mediators whose interaction with other more recently characterized local ovarian factors has only begun to be recognized.

Treatment of tubal pregnancy by laparoscope-guided injection of prostaglandin F2 alpha

Twenty-six cases of unruptured tubal pregnancy were treated by laparoscope-guided injection of prostaglandin (PG) F2 alpha into the affected tube and the ovary containing the corpus luteum. Preoperative serum human chorionic gonadotropin (hCG) levels were 22 to 2,050 IU/L (mean 328 IU/L). The procedure was successful in 24 patients (92%), as indicated by reduction of hCG values to less than 20 IU/L. The remaining 2 cases showed an initial fall in hCG after injection and thereafter a plateau phase indicating the persistence of trophoblast. In both cases, a second surgical intervention was necessary. The total subsequent conception rate among 19 women desiring pregnancy was 90% (17/19). The intrauterine conception rate was 58% (11/19), and the repeat rate of ectopic pregnancy was 32% (6/19). Two-thirds (12/19) of the subsequent pregnancies occurred within 6 months "at risk" for conception. It is concluded that local injection of PGF2 alpha represents an attractive method for termination of selected cases of tubal pregnancy, preferentially in subjects with low trophoblastic activity.

Local prostaglandin F2 alpha injection for termination of ectopic pregnancy

In nine women with unruptured ectopic pregnancy, prostaglandin F2 alpha was injected under laparoscopic control into the affected oviduct and in eight patients also into the ovary containing the corpus luteum. Termination of the pregnancy was achieved in all cases (in one at the second attempt), without complications. Fertility after this procedure needs to be compared with that after conventional surgery.