# Decoding uterine (dys)function in fibroids through multimodal assessment of functional determinants: a systematic review and meta-analysis

## TL;DR

Women with uterine fibroids show changes in uterine function compared to those without fibroids, including increased blood flow and stiffness, which could help understand and treat related conditions.

## Contribution

This study is the first to systematically review and meta-analyze multiple functional determinants of the non-pregnant uterus in fibroid patients using multimodal imaging techniques.

## Key findings

- Women with fibroids have significantly lower pulsatility and resistance indices in uterine arteries compared to controls.
- Elastography reveals increased myometrial stiffness in fibroid patients, with higher elastic modulus and shear wave velocity.
- Limited evidence suggests reduced peristaltic activity and altered contraction patterns in symptomatic fibroid cases.

## Abstract

Is there a difference in uterine functional determinants between women with fibroids and women without myometrial pathology?

Women with uterine fibroids consistently exhibit altered uterine functional determinants compared to controls, characterized by increased perfusion, elevated stiffness, and impaired contractility.

The functional determinants of the non-pregnant uterus remain largely unexplored and underreported. Uterine fibroids, as a well-defined morphological myometrial pathology, offer a unique model for understanding uterine functionality.

This systematic review and meta-analysis included original articles published in English and indexed in PubMed, Embase, and Scopus databases up to 20 December 2024. The search strategy combined terms related to uterine fibroids with those describing uterine functional parameters (e.g. uterine vascularity, stiffness, and contractility), together with diagnostic methods (including Doppler ultrasound, elastography, and magnetic resonance imaging).

Observational studies evaluating quantitative uterine functional determinants in non-pregnant women with fibroids and controls without myometrial pathology were selected using predefined Population, Intervention (Investigated measure), Comparator, Outcome(s), Study type (PICOS) criteria. Outcomes included quantitative measures of uterine functionality such as vascularization (uterine artery Doppler indices), stiffness (elastography parameters), and contractility (peristalsis parameters). Study quality was evaluated using the Newcastle–Ottawa Scale. Pooled estimates for continuous outcomes were calculated using random-effects models, expressed as mean difference (MD) with 95% CIs. Subgroup analyses addressed potential confounders, including menopausal status, hormonal therapy use, and symptom severity.

Fourteen studies met the inclusion criteria: seven on vascularization (n = 961), five on stiffness (n = 342), and two on contractility (n = 62). The uterine artery pulsatility index was significantly lower in women with fibroids compared to controls (MD −0.63, 95% CI −0.91 to −0.36; I2 = 91.98%), with greater reductions observed in premenopausal, non-hormonally treated, and symptomatic women. The resistance index also decreased (−0.09, 95% CI −0.15 to −0.03; I2 = 95.86%), showing similar patterns across subgroups. Time-averaged maximum velocity was higher in the fibroid group (+18.46, 95% CI +5.54 to +31.37; I2 = 93.64%), particularly in premenopausal and symptomatic cases. Elastography showed increased myometrial stiffness in uterine fibroids compared to controls, with a higher elastic modulus (+35.58 kPa, 95% CI +24.94 to +46.22; I2 = 0%) and shear wave velocity (+1.14 m/s, 95% CI +0.62 to +1.65; I2 = 0%). Limited evidence pointed to reduced peristaltic activity and altered contraction patterns in symptomatic fibroids.

The relatively small study population and high heterogeneity of estimates warrant cautious interpretation, although findings were consistent across multiple uterine functional determinants.

Women with uterine fibroids consistently exhibit altered uterine functional determinants compared to controls without myometrial pathology, highlighting how structural abnormalities parallel functional changes. Leveraging fibroids as a model, integrating structural imaging with functional assessment through advanced multimodal approaches may deepen our understanding of uterine diseases, ultimately enhancing treatment and patient care.

This study was partially funded by the Italian Ministry of Health—Current research IRCCS. The funding source had no role in the study design; in the collection, analysis, or interpretation of data; in the writing of the report; or in the decision to submit the article for publication. E.S. reports payments from Ferring, Theramex, and IBSA for research grants and honoraria from IBSA, Gedeon-Richter, and Sandoz for lectures. He serves as Editor-in-Chief of Human Reproduction Open. P.V. has received honoraria as Co-Editor in Chief of Journal of Endometriosis and Uterine Disorders. The remaining authors have no conflicts of interest to disclose.

PROSPERO ID: CRD42024619633—registered on 10 December 2024.