Objective: To predict the interspinous distance (ISD) using the relationship between female height and pelvimetric measures on magnetic resonance (MR) images.
Methods: We obtained measurements of the pubic arch angle (PAA), inlet-anteroposterior (AP) distance, mid-pelvis AP distance, outlet-AP distance, ISD, and ischial tuberosity distance using 710 pelvic MR images from nonpregnant reproductive-aged (21-50 years) women from January 2014 to June 2020. Patient height was also assessed from medical records. We determined the formula for predicting ISD using multiple regression analysis.
Results: The mean ± standard deviation of the height, PAA, inlet-AP distance, mid-pelvis AP distance, outlet-AP distance, ISD, and ischial tuberosity distance were 160.0 ± 5.5 cm, 87.31 ± 6.6°, 129.7 ± 9.0 mm, 119.7 ± 8.5 mm, 111.71 ± 8.90 mm, 108.88 ± 8.0 mm, and 121.97 ± 11.8 mm, respectively. Two significant regression formulas for predicting ISD were identified as follows: ISD = 0.24973 × height - 0.06724 × inlet-AP distance + 0.12166 × outlet-AP distance + 0.29233 × ischial tuberosity distance + 0.32524 × PAA (P < 0.001, R2 = 0.9973 [adjusted R2 = 0.9973]) and ISD = 0.40935 × height + 0.49761 × PAA (P < 0.001, R2 = 0.9965 [adjusted R2 = 0.9965]).
Conclusion: ISD is the best predictor of obstructed labor. This study predicted ISD with 99% explanatory power using only the height and PAA. The PAA can be measured by transperineal ultrasound. This formula may successfully predict vaginal delivery or cephalopelvic disproportion.
Copyright: © 2023 Na et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.