Some Observations of Cervical Mucus in the Vulva

by Erik Odeblad, Sode Pouyanmehr and Johanna Slettvoll
Department of Medical Biophysics, University of Umeå, Sweden

The Billings Ovulation Method (BOM) relies to a great extent on a woman’s qualitative sensing of the vaginal discharge, present in the vulva. This discharge contains also cervical mucus which contributes to the sensation which is charted. To elucidate the role of the mucus for sensation we have collected vulvar samples and performed microscopic examinations.

Because it is possible that the discharge may have some kind of protective function we have only collected part of it, approximately one fourth. To avoid contamination of mucus lying in the cervix and vagina, the sampling of the cervical mucus was the first moment when the women had come into the lithotomy position on the examination couch.

Number of samples of each mucus type

A total of 71 vulvar samples from 14 apparently healthy women were collected during the different phases of the cycle, see Table 1. In 26 samples it was possible to identify areas containing cervical mucus type G, L, S or P6. The mucus area was of the order of 0.5-6 per cent of the total sample area. The mucus pieces still retained their typical crystal patterns and were easy to identify. The number of samples with observed crystals and the average size of the crystal areas are also shown in Table 1. Representative microphotos of mucus areas are shown in Fig. 1-4.

Because the observed mucus areas were much smaller than mucus obtained from the cervical opening, it is reasonable to assume that the mucus is successively degraded into smaller pieces by some enzymatic cleavage. The zymogen granulae commonly seen in cervical specimens are a possible source of such processes. The probable effects of enzymatic action for the Peak symptom are described in Fig. 5

Mucus classification has been done according to Odeblad.

Fig. 1 L mucus in a sample from vulva 4 days before the Peak day. Pat. TZ. Magn. 45 X	Fig 2 S mucus in a sample from vulva 2 days before the Peak day. Pat. KT. Magn. 180 X
Fig 3 P6 mucus in a sample from vulva one day before the Peak day. Pat. TQ. Magn. 180 X	Fig 4 G mucus in a sample from vulva 5 days before next menstruation. Pat. T1. Magn. 720 X

Fig 5 The effect of enzymatic cleavage of mucus can be illustrated by this intellectual experiment. Suppose a cube of 1 mm² of mucus is divided into 1,000 pieces of 0.1 mm size, then the total area increases 10-fold. This surface enlargement continues until the pieces obtain a size of the order of the mucus molecule, approx. 100 nm. This is 10,000 times smaller than 1 mm and the area should be 10,000 times larger or 60,000 mm² = 600 cm². The volume 1 mm³ weighs 1 mg which is the order of size of slippery P6 mucus reaching the vulva. After enzymatic cleavage this amount reaches to cover several hundreds of cm², which is more than enough to give rise to the slippery sensation on the Peak day. A continued cleavage may give an abrupt end of the water-binding capacity, something which may explain the sudden loss of the Peak sensation reported by many women.