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. 2022 Apr 24;11(9):2395.
doi: 10.3390/jcm11092395.

Effects of Sex, Age and Height on Symphysis-Ischial Spine Distance Measured on a Pelvic CT

Daniel Sánchez García  1   2   3 , Alejandra Aguado Del Hoyo  1   2   3 , María Sánchez Pérez  1   2   3 , Santiago García-Tizón Larroca  2   3   4   5 , Yolanda Ruiz Martín  1   2   3 , Isabel Gordillo Gutiérrez  1   2   3 , Coral Bravo Arribas  2   3   4   5 , Melchor Alvarez-Mon  6   7   8 , Miguel A Ortega  6   7 , Juan De Leon-Luis  2   3   4   5
Affiliations

Effects of Sex, Age and Height on Symphysis-Ischial Spine Distance Measured on a Pelvic CT

Daniel Sánchez García et al. J Clin Med. .

Abstract

Objective: To examine the influence of age, sex and height on the symphysis-ischial spine distance (SID) measured on pelvic Computed tomography (CT)images in subjects of reproductive age, and to determine the interobserver reproducibility. This measurement (SID) is of great importance because the use of intrapartum ultrasound is based on the assumption of a specific value (30 mm) of such a measurement.

Methods: This was a cross-sectional descriptive study in which SID was measured in subjects aged 20 to 44 years who had been scheduled for pelvic CT at our centre from January 2018 to May 2021 for different reasons. Radiographic measurements of the pelvis were obtained through the multiplanar reconstruction of the CT image. The images obtained from all of the participants were independently assessed by three senior radiologists, and the SID measurements made by each one were blinded from those of the remaining observers. Correlations between the SID and patient age, height and sex were analyzed by univariate and multivariate linear regression.

Results: The mean SID for 87 of the enrolled participants (45 women, 42 men) was 28.2 ± 6.25 mm. Among the observers, the mean difference in this distance was 1 to 2 mm, and was scarcely related to measurement size, with agreement being greater than 70%. The mean SID was significantly related to sex and height (SID = -24.9 - 6.51 × sex (0 or 1) + 0.34 × height (cm); p = 0.01; sex equals 1 for a man and 0 for a woman), such that it was a mean of 2.5 mm greater in women than men (29.50 mm vs. 26.99 mm).

Conclusion: Measurements of SID on CT images show good interobserver reproducibility, and are related to sex and height.

Keywords: pelvic CT images; reproducibility; symphysis–ischial spine distance.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Lines A and B are drawn on the sagittal plane that crosses the pubic symphysis (left). Lines A, B and C are drawn on the plane that crosses the top of the left ischial spine. Line C is the SID distance (right). symphysis–ischial spine distance (SID).
Figure 2
Figure 2
Three-dimensional reconstructions of a male and female pelvis in the coronal (top) and sagittal (bottom) planes through the pubic symphysis. Note the different morphologies of the male and female pelvis. Especially noticeable in the coronal reconstruction is the difference in the pelvic bone. The sagittal reconstruction shows the mean symphysis–ischial spine distance (SID), as measured between the planes of the pubic symphysis and the ischial spine in men and women. Note its higher value in women (29.50 mm vs. 26.99). The dotted line in the left image marks on the male pelvis the mean SID obtained in the women.
Figure 3
Figure 3
Bland–Altman plot of the mean differences in the mean symphysis–ischial spine distance (SID) values obtained by the observers (A–B, A–C and B–C). The regression lines indicate the trends shown by these differences.
See this image and copyright information in PMC

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