x-ray pelvimetry, a radiographic examination used to determine the dimensions of the bony pelvis of a pregnant woman and, if possible, the biparietal diameter of her baby’s head. It is performed when doubt exists as to whether the head can pass safely through the pelvis in labor. Because minor degrees of cephalopelvic disproportion are often overcome safely in labor by molding of the fetal skull and because major disproportions may be detected by clinical pelvimetry without x-rays, the value of x-ray pelvimetry is frequently judged to be insufficient to warrant the risk of radiation exposure. Other diagnostic tools, among them ultrasonography, often provide the necessary information with less apparent risk. Compare clinical pelvimetry. See also cephalopelvic disproportion, contraction, dystocia.
