Obstetrical Nursing / A Text-Book on the Nursing Care of the Expectant Mother, the Woman in Labor, the Young Mother and Her Baby

by Carolyn Conant Van Blarcom

Fig. 8.—Diagram showing method of estimating the true conjugate by measuring the length of the diagonal conjugate.

A delivery may be, and frequently is, accomplished through a pelvis which is not entirely normal in size or shape. But the obstetrician of to-day is closely observant of the patient whose pelvic measurements depart from the normal by more than the accepted margin of safety, and he plans for labor in accordance with the indications in each case.

Disproportion between the measurements of the mother’s pelvis and the size of the child’s head must be considered in this connection. A small pelvis may permit of the spontaneous delivery of a small child, but be too narrow for the passage of a full-sized baby, while a woman with a normal pelvis may have an extremely difficult labor because of an unusually large child.

The size and shape of the pelvis is found to vary among different races and in different individuals. And the size and contour of the inlet may be so altered by rickets, lack of proper exercise during early life, or by growths upon the pelvic bones, as to seriously interfere with normal labor.

Fig. 9.—Diagram showing method of measuring the inter-tuberous diameter.

The various kinds of malformed pelves may be loosely classified as generally contracted or small; flat; simple funnel; generally contracted funnel; and the rachitic pelves, both flat and generally contracted. There may be a contracted inlet, or a contracted outlet, or both may occur in the same pelvis.[^[1]]

Rachitic pelves are common among negroes and not altogether rare among white women.

The normal male pelvis is deep, narrow, rough and massive as compared with the female structure (see Fig. [1].), and the angle of the pubic arch, formed by the two pubic bones, is deeper and more acute in the male than in the female skeleton.

The normal female pelvis, on the other hand, is light, broad, shallow, smooth and large, giving evidence of the infinite wisdom and skill that entered into constructing it for the high purpose it was designed to serve.