Reduction of the stretch modulus of human cervical tissue by prostaglandin E2

Samples of cervical tissue were obtained from women immediately following term delivery from spontaneous labor or oral PGE2-induced labor and from a small number of nonpregnant women in the reproductive years undergoing hysterectomy for benign gynecologic disease. The measured strips were placed in a well-oxygenated bath at 37°C. containing Ringer's solution and stretched at a constant rate while continuously recording length and tension. The data were converted to stress-strain diagrams. Each curve contained a long linear portion which allowed one to compute a stretch modulus for each sample. A total of 71 strips from 23 patients was used. The average stretch modulus from the oral PGE2-induced patients was significantly lower than the spontaneous labor group (p < 0.005), which, in turn, was significantly lower than the stretch modulus of the nonpregnant cervical tissue. It was also noted that the yield point was lower in the PGE2 series when compared to the spontaneous labor series (p < 0.05). The effect of the PGE2 at a bath concentration of 10−5 to 10−6 Gm. per cubic centimeter was to materially reduce the stretch modulus within 5 to 15 minutes of the drug addition in both the PGE2-induced and spontaneous labor series. The results of these experiments indicate that PGE2 has the effect of reducing cervical stiffness.