Endometrial polyp vs submucosal fibroid: differentiation by feeding vessel sign on ultrasound
Key difference: origin of the lesion
The differential approach is based on the original layer from which the lesion originates. Endometrial polyp represents a localized echogenic or mixed-echogenicity lesion within the uterine cavity, sometimes with a feeding vessel. Submucosal leiomyoma deforms the uterine cavity from the myometrium inward and may demonstrate a more 'whorled' character or acoustic shadowing, which distinguishes it from truly endometrial lesions.
Feeding vessel sign
According to sources, endometrial polyps frequently demonstrate a feeding vessel—a single vascular 'pedicle' pattern directed toward the lesion. This sign helps attribute the focal lesion to endometrial origin. Submucosal fibroid more characteristically shows connection with the myometrium and a 'whorled' pattern or shadowing feature rather than a solitary feeding vessel.
Role of SIS (sonohysterography)
On contrast-enhanced imaging (SIS), both endometrial polyps and submucosal fibroids may appear as single or multiple rounded filling defects with well-defined borders within the uterine cavity. SIS provides clearer visualization of localization, size, number, and extent of the lesion, as well as the relationship of its base to the endometrium or myometrium, facilitating the definitive diagnosis.
Comparative table of ultrasound signs
| Sign | Endometrial polyp | Submucosal fibroid |
|---|---|---|
| Echostructure | Echogenic or mixed-echogenicity lesion | 'Whorled' character, possible acoustic shadowing |
| Feeding vessel | Sometimes present (feeding vessel) | Not characteristic as a key sign |
| Relationship to cavity | Localized within the cavity, originates from endometrium | Deforms the cavity from myometrium inward |
| SIS appearance | Rounded filling defect with well-defined borders | Rounded filling defect; base connected to myometrium |
Clinical significance of differentiation
Differentiation is critical because a focal lesion within the cavity does not equate with malignancy, and management differs: in one case office biopsy is indicated, in another targeted hysteroscopic removal. Diffuse endometrial thickening implies a different differential than a pedunculated focal lesion. For standardization of sonographic descriptors of myometrial and uterine lesions, the MUSA consensus terminology is used (Van den Bosch T. et al.).
Classification of submucosal node localization
The FIGO classification (2011), types 0–8, is considered standard for describing the localization of myomatous nodes; its use in protocols is preferable. In ultrasound protocols, significant parameters include localization (subserosal / intramural / submucosal), structure, and blood flow (peripheral, mixed, avascular).
Frequently asked questions
Which ultrasound sign indicates endometrial polyp when differentiating from submucosal fibroid?
Endometrial polyp often appears as a localized echogenic or mixed-echogenicity lesion, sometimes with a feeding vessel, originating from the endometrium.
How does submucosal fibroid behave relative to the uterine cavity?
Submucosal leiomyoma deforms the uterine cavity from the myometrium inward and may demonstrate a more 'whorled' structure or acoustic shadowing, unlike true endometrial lesions.
How does SIS help differentiate these lesions?
SIS provides clearer visualization of localization, size, number, and extent of the lesion, as well as the relationship of its base to the endometrium or myometrium, facilitating definitive diagnosis.
How do polyp and fibroid appear on contrast-enhanced imaging?
Both may appear as single or multiple rounded filling defects with well-defined borders within the uterine cavity.
Which classification is used to describe submucosal nodes?
The FIGO classification (2011), types 0–8, is considered standard for describing node localization; its application in protocols is preferable.