The obstetric forceps is constantly undergoing modifications of construction, and there is no part of the original instrument that has not been, in some manner, altered to suit the ideas of the designer. Blade, shank, lock and handle have been changed in shape and size. Nevertheless, it may be said, but two distinct alterations of the original Chamberlen forceps have been made. They are the pelvic curve of the blade, and the application of axis traction.
Varied as are the designs, the method of employing the forceps is as little fixed as the instrument itself. The application of the blades to the sides of the pelvis, disregarding entirely the position of the head; the application of the blades to the sides of the head whenever practicable; intermittent manual traction; continuous mechanical traction; the advisability or non-advisability of compressing the fœtal head; the utility or inutility of lever action, express some