CERVICAL SMOOTH-MUSCLE CONTRACTILE ACTIVITY AFTER TREATMENT WITH MIFEPRISTONE AND PROGESTERONE

Contractile activity of the uterine cervix in vitro was studied in women pretreated with mifepristone 200 m(chi)2 or progesterone suppositories 200 mg before cervical dilatation and vacuum aspiration in the first trimester. Mifepristone increased the dilatation of the cervix as measured prior to operation whereas progesterone had no effect. Spontaneous muscle activity and contraction frequency were not affected by either drug. Neither the inhibitory response to PGE, nor the excitatory response to noradrenaline were significantly different from that in placebo-treated women. It is concluded that the cervical smooth muscle has no major role in the dilatatory effect of mifepristone in the cervical canal.