Uterine activity and prostaglandin production following intraamniotic hyperosmolar urea

The relationship between endogenous prostaglandin (PG) production and uterine activity was studied in hyperosmolar urea induced abortion patients. Polygraphic recordings of intraamniotic pressure were obtained at periodic intervals following intraamniotic injection of 80 gm urea. At 0, 0.25, 1, 4 and 8 hours amniotic fluid and blood samples were obtained for PGE, PGF and 13,14-dihydro-15-keto-prostaglandin F_2α (PGFM) analysis by radioimmunoassay. Blood was also sampled at time of absorption. In eight patients studies, uterine tone was elevated by 0.25 hour although no rhythmic contractions were observed by 1 hour. At 4 hours, amniotic fluid PGF concentration increased significantly (P < .01) over the pre-injection value and continued to increase at 8 hours. Amniotic fluid PGE, PGFM and all plasma PG's showed no change during the 8 hour period following urea administration. At time of abortion the plasma PGFM concentration was significantly greater than at the time of injection (238 ± 54.4 vs. 86.7 ± 7.3 pg/ml). There was no significant differences between pre-injection and absorption plasma PGF or PGE concentrations. In the present study, there is no evidence that increased prostaglandin production precedes urea induced contractions. The possible role of PG's in uterine contractions is discussed.