Anthropometric measurements in the diagnosis of pelvic size: an analysis of maternal height and shoe size and computed tomography pelvimetric data

Background To determine whether measurements of maternal height and shoe size are predictors of pelvic size, using erect lateral computerized tomography (CT) pelvimetry as gold standard. Materials and methods Three hundred and fifty three obstetric patients out of a sequential population of 6112 (5.8%) had CT pelvimetry performed between January 1990 and December 1991 at the Department of Obstetrics and Gynecology, York District Hospital, United Kingdom. Multivariable logistic regression models were built using maternal height (n = 322), shoe size (314) and weight at last clinic visit (n = 318). The reference standard for pelvic size was CT Pelvimetry. Pelvic adequacy was defined as an anterior-posterior diameter of the inlet of ≥11 cm and an anterior-posterior diameter of the outlet ≥10 cm on erect lateral CT pelvimetry. Women with values lower than these were regarded as having an inadequate pelvis. The diagnostic accuracy of the models was determined by the area under the receiver operating characteristic curve (AUC). Results The area under the curve (AUC) for maternal height (0.768) was not significantly greater than that for shoe size (0.686, p = 0.163 for the difference in AUC’s) and weight at the last clinic visit (0.655, p = 0.057 for the difference in the AUCs). The change in the AUC for each of the models (the full model with height, shoe size and weight 0.769]; model for height and shoe size 0.767] model for just height 0.768]) was also not significantly different. Conclusions Measurements of maternal height, shoe size and weight at the last clinic visit are not useful for the identification of women with inadequate pelvis.