Pelvic incidence: A study of a spinopelvic parameter in MRI evaluation of pelvic organ prolapse

Tianhang Liu; Xiaoman Hou; Bing Xie; Jing Wu; Xin Yang; Xiuli Sun; Jianliu Wang

doi:10.1016/j.ejrad.2020.109286

Pelvic incidence: A study of a spinopelvic parameter in MRI evaluation of pelvic organ prolapse

Eur J Radiol. 2020 Nov:132:109286. doi: 10.1016/j.ejrad.2020.109286. Epub 2020 Sep 15.

Authors

Tianhang Liu¹, Xiaoman Hou², Bing Xie¹, Jing Wu³, Xin Yang¹, Xiuli Sun⁴, Jianliu Wang¹

Affiliations

¹ Peking University People's Hospital, No.11 Xizhimen South Street, Beijing, 100044, China; Beijing Key Laboratory of Female Pelvic Floor Disorders, Beijing, China.
² The Obstetrics & Gynecology Hospital of Fudan University, Shanghai, China.
³ Peking University People's Hospital, No.11 Xizhimen South Street, Beijing, 100044, China.
⁴ Peking University People's Hospital, No.11 Xizhimen South Street, Beijing, 100044, China; Beijing Key Laboratory of Female Pelvic Floor Disorders, Beijing, China. Electronic address: sunxiulirmyy@hotmail.com.

PMID: 33007519
DOI: 10.1016/j.ejrad.2020.109286

Abstract

Purpose: This study aims to compare pelvic incidence (PI), a skeletal angle formed by the first sacral vertebrae and femoral heads, in women with and without pelvic organ prolapse (POP) and to explore the correlation of PI with the progression of POP, through 3D reconstruction of MRI scans.

Method: The case-control study enrolled 48 prolapse patients and 48 paired subjects by collecting and screening clinical information including age, BMI, vaginal deliveries, and levator ani defect scores. PI values were measured in 3D reconstruction models based on MRI scans, and the mean and standard deviation values of PI in both groups were calculated. Receiver operating characteristic (ROC) analysis and logistic regression were used to quantify relationships between PI and prolapse. Additionally, by performing a cross-section study of 69 patients with POP, correlations between PI values and descending vaginal locations were assessed by multivariate linear regression models.

Results: Compared with the control group, the patient group has a significantly larger average PI (48.68 ± 10.77˚ vs 42.20 ± 8.55˚, P=0.002). ROC analysis for the classification of prolapse based on PI has an area under the curve of 70.1 % (P < 0.001). Logistic regression identified a larger PI value as a risk factor of prolapse with an odds ratio of 2.90 (95 %CI: 1.46-5.74, P = 0.002) for PI per increasing 10˚. Point Ba and Bp represent the most distal positions of any part of the upper anterior and posterior vaginal walls, respectively. In the patient group, internally, Ba and Bp would descend 0.62 (95 %CI: 0.24-1.00, P=0.002) cm and 0.74 (95 %CI 0.22-1.26, P=0.006) cm for every 10° increase in PI, respectively. The coefficients of the partial correlation of PI for Ba and Bp are 0.381 (P = 0.002) and 0.336 (P = 0.006).

Conclusions: PI is significantly related to morbidity and progression of POP, especially for the anterior and posterior pelvic compartments. As an individual constant value of the spinopelvic skeletal shape, a larger PI value is a risk factor and should be evaluated carefully in medical imaging of POP.

Keywords: 3D Reconstruction; Pelvic incidence; Pelvic organ prolapse; Spinopelvic parameter; Urinary incontinence.

MeSH terms

Case-Control Studies
Female
Humans
Magnetic Resonance Imaging
Pelvic Floor
Pelvic Organ Prolapse* / diagnostic imaging
Pelvic Organ Prolapse* / epidemiology
Vagina