THE USE OF THE VACUUM-EXTRACTOR IN NARROW OUTLETS.

Abstract

The problem of cephalo-pelvic disproportioii is always a question of great interest in obstetrics. As has been pointed out many times, the narrow inlets have grown more rare during the last decades. Outlet disproportion, however, is is still not uncommon, the frequency in Sweden being given by Borell and Fernstrom (1960) to between 0.2-2.5 per cent. There seems to have been no change in this number during the last years. According to Borell and Fernstrom (1960), the capacity of the outlet is best defined by stating the sum of 3 diameters determined by X-ray pelvimetry, the posterior intertuberous (i. t. d.), the interspinous (i s. d.) and the sagittal outlet diameter (s. 0. d.). - Using the values obtained by the modified technique of B ore 11 and R B d b er g (I 964), in which a so-called ortho-diagraphic projection is used, the sums of outlet diameters can be divided into 3 groups, one group of normal outlets with a sum exceeding 31.5 em, one group of contracted outlets with a sum below 29.5 cm, where complications are met with to a great extent, and finally a so-called “border-line” group, 29.5-31.5 cm, in which is found a varying rate of complicated deliveries. In the last group obviously many factors play a part, e.g. the size of the fetus, the nature of labour and so on. Each case must be evaluated individually. However, there is in this group a possibility of surmounting a slight degree of disproportion by the use