Increased Stromal Vascularity in PCOM: Clinical Significance
Increased stromal vascularity on Doppler ultrasound in women with polycystic ovary morphology (PCOM) indicates heightened ovarian blood flow that is characteristic of PCOS and correlates with metabolic and hormonal dysfunction, though it is NOT currently part of standard diagnostic criteria.
Current Diagnostic Framework
The most recent 2024 systematic review and meta-analysis establishes that follicle number per ovary (FNPO) is the gold standard for ultrasonographic diagnosis of PCOS, with ovarian volume (OV) and follicle number per single section (FNPS) as alternatives 1. Importantly, while stromal features including vascularity have been investigated, their utility to define PCOM remains less defined and they are not included in current diagnostic criteria 1.
What Increased Stromal Vascularity Actually Represents
Pathophysiologic Significance
Increased stromal blood flow in PCOM reflects several underlying mechanisms:
Elevated VEGF levels: Women with PCOS have significantly higher serum vascular endothelial growth factor (VEGF) concentrations (3.4 ± 0.7 ng/ml vs 2.3 ± 0.5 ng/ml in controls, P < 0.001), which directly correlates with increased stromal vascularity 2
Increased IGF-1: Insulin-like growth factor-1 levels are significantly elevated (253.15 ± 70.07 vs 186.65 ± 42.7, P < 0.01) and negatively correlate with resistance indices in ovarian vessels 3
Lower vascular resistance: Pulsatility index (PI) and resistivity index (RI) are significantly lower in PCOS patients compared to controls, indicating reduced vascular resistance and increased blood flow 4
Measurable Doppler Parameters
When stromal vascularity is assessed, specific findings include:
- Peak systolic velocity (PSV): 15-16 cm/s in PCOM vs 9 cm/s in normal ovaries (P < 0.001) 5, 2
- Time-averaged maximum velocity (TAMXV): 9-11 cm/s in PCOM vs 5.8 cm/s in normal ovaries (P < 0.001) 2
- 3D power Doppler indices: Vascularization index (VI), flow index (FI), and vascularization flow index (VFI) are all significantly higher in PCOS 6
Clinical Implications
Association with PCOS Phenotype
Stromal vascularity varies with specific PCOS characteristics:
- Hirsutism: Ovarian vascularity is significantly higher in hirsute women with PCOS (FI: 33.94 vs 29.30, P < 0.05) 7
- Body weight: Normal-weight women with PCOS show higher stromal vascularity than obese women (VI: 4.51% vs 3.25%, P < 0.05) 7
Risk Stratification
Increased stromal vascularity may predict ovarian hyperstimulation syndrome (OHSS) risk during fertility treatment, as the heightened vascular response underlies excessive ovarian response to gonadotropin stimulation 2, 6.
Important Caveats
Not a Diagnostic Criterion
Despite its association with PCOS, stromal vascularity assessment:
- Is not included in Rotterdam, NIH, or 2023 International Evidence-based Guidelines for PCOS diagnosis 8
- Has less defined utility compared to follicle count and ovarian volume 1
- Should not be used alone to diagnose or exclude PCOS
Technical Limitations
- Requires specialized Doppler ultrasound equipment and expertise
- Subjective assessment of color Doppler signals can vary between operators
- 3D power Doppler quantification is more accurate but less widely available 6
Overlap with Normal Variants
PCOM can be transient in adolescents, and increased stroma (S/A ratio >0.3) appears to be a more stable finding than follicle number alone 9. However, this remains an area requiring further research.
Practical Clinical Approach
When you encounter increased stromal vascularity on Doppler in a woman with PCOM:
Confirm PCOS diagnosis using established criteria: hyperandrogenism (clinical or biochemical) and/or ovulatory dysfunction, plus PCOM (≥20 follicles per ovary or ovarian volume ≥10 mL) 8
Screen for metabolic complications as recommended by guidelines: fasting glucose, lipid profile, blood pressure 10
Consider it a marker of disease severity rather than a diagnostic feature, particularly when planning fertility treatment where OHSS risk may be elevated
Document findings but do not rely on vascularity alone for diagnosis or management decisions
The evidence consistently shows that while increased stromal vascularity is a real and measurable phenomenon in PCOS, it remains a research finding rather than a clinical diagnostic tool in 2024.