A study was carried out in order to determine the impact of Nomegestrol acetate on the human cervix and to evaluate the ability of changes induced in cervical mucus to render the cervical canal hostile to spermatozoa at midcycle. Under the influence of Nom Ac, loss of spinability, absence of ferning pattern and drastic tightening of the glycoprotein meshwork rendered midcycle mucus very similar to that elaborated during physiological states under total progesterone dominance. The results obtained in this study gave clear evidence that Nomegestrol acetate may provide cervical blocking thereby preventing sperm transport to the uterine cavity.
PIP: The effect of the oral progestin nomegestrol acetate on spinnbarkeit, ferning and mesh size of midcycle cervical mucus was examined. This 19-norprogestin inhibits ovulation and LH surges, and binds to uterine cytosol progesterone receptors. It is 17-alpha-acetoxy-6-methyl-19-nor-4,6-pregnadiene-3,20-dione, or Lutenyl (Laboratories Theramex, Monaco). Nomegestrol was given to 16 normally cycling volunteers at 2.5 or 5 mg/day for 3 consecutive cycles. Spinnbarkeit was determined automatically with 10 mcl mucus with a spinability-meter (Filancemetre SEFAM), or manually between tweezers if too thick to measure. Cervical mucus was scant, to dry, and related to dose. Spinnbarkeit ranged from absent to 3 mm at 5 mg, and from 11-28 on the meter, compared to 90mm in controls at midcycle. Ferning by standard methods was nonexistent with amorphous structure at 2.5 and 5 mg doses, compared to the usual dendrites and arborization at midcycle in controls. When the mucus was observed by scanning electron microscopy, it resembled that seen at the end of pregnancy or menopause. Mesh size averaged 0.5 mcm at both doses, smaller than the diameter of sperm heads. Nomegestrol acetate is currently used to treat luteal deficiency.