(a) Rapid dilatation by means of graduated metal bougies.
(b) Gradual dilatation by means of tents.
(c) Combined gradual and rapid dilatation.
In a large majority of cases rapid dilatation is the operation selected. Its one disadvantage is that when a great degree of dilatation is necessary, or when the operation is performed too rapidly, the cervix is liable to be torn, an event which is especially liable to occur when the tissues of the cervix are rigid. These lacerations are longitudinal in direction and in the neighbourhood of the internal os uteri. They sometimes result in hæmorrhage, which can easily be controlled by plugging the cervical canal. Unless strict asepsis be maintained, these lacerations of course form a channel for infection of the pelvic cellular tissue.
It is obvious that dilatation will be easier to perform, and laceration less liable to occur, if the cervix is in a softened condition—a physiological state which is always present during pregnancy and labour. Efforts should therefore be directed, when possible, to ensure a soft state of the cervix before performing rapid dilatation.
Immediately after the cessation of a period, the cervix is soft and somewhat patent, and advantage may be taken of this fact. The introduction of a glycerine tampon two hours beforehand produces a certain amount of softening. But nothing ensures so much softening as the introduction of a tent into the cervix about twelve hours previous to the rapid dilatation.
It is therefore recommended in all cases, where possible, to perform dilatation by this latter means, viz. a combination of the gradual and rapid methods.
Rapid dilatation by means of graduated metal bougies. Hegar’s original dilators ([Fig. 56]) were solid vulcanite bougies, graduated from 1 to 26, the numbers corresponding to the diameter of the bougie in millimetres. Each was 5¼ inches in length, the handle measuring 1½ inches and the bougie the remainder. The bougie formed a slight curve and tapered off to a blunt point.
These bougies were rather short and too sharply pointed, and they could not be sterilized by boiling. To overcome these disadvantages, uterine dilators are now made about the same length as a male catheter, with a sharper curve than Hegar’s original one, and a blunter point; the larger sizes are of hollow metal for the sake of lightness. There are many varieties of dilator, each with minor differences as to length, curve, handle, and shape of the point.
The author uses metal bougies. These have somewhat the shape of the ordinary uterine sound, are thirty-five in number, and graduated in size. Like the sound, the upper portion is bent at an angle of about 160° with the solid handle, a circular shallow depression indicating the 2½ inch mark in the smaller numbers; in the larger this is not considered necessary.