ESTIMATION OF PELVIC CAPACITY

TLDR

Cephalopelvic disproportion involves five factors, but only pelvic size can be accurately measured; fetal head size and other factors are difficult to assess and may change during birth, limiting precise prelabor evaluation. The study seeks to estimate pelvic capacity to better evaluate labor progress in women with contracted pelves.

Abstract

There are five components of cephalopelvic disproportion: (1) size and shape of the bony pelvis, (2) size of the fetal head, (3) force exerted by the uterus, (4) moldability of the head and (5) presentation and position. Of these, only the first is susceptible to accurate measurement. Attempts to measure the size of the unborn fetal head have not met with much success. Moreover, such distortion can occur during the birth process that, even if accurate prelabor cephalometry were possible, the problem of cephalopelvic relations could not be reduced to mathematic exactitute. In addition, there remain the three imponderables, force of labor, moldability of the fetal head and method of presentation, about which there is no possibility of acquisition of knowledge before the event of labor. In passing, it may be noted that as our group studies the progress of labor among women with contracted pelves, we are more and