How are fibroids classified?
Fibroids are grouped by their position in the uterine wall: submucosal fibroids grow toward the uterine cavity, intramural fibroids sit within the muscle wall, and subserosal fibroids grow toward the outer surface. The international FIGO classification refines these positions into detailed subtypes used in treatment planning.
Several types can coexist in the same patient; assessment then focuses on the fibroids contributing most to symptoms.
The three main locations
Submucosal fibroids
Sitting just beneath the uterine lining and growing into the cavity — the least common type, yet the one most strongly linked to bleeding and fertility problems.
Intramural fibroids
Located within the muscle wall — the most common type, with symptoms that vary by size and exact position.
Subserosal fibroids
Growing toward the outer surface — presenting with pressure rather than bleeding. Some hang from a stalk (pedunculated), a subtype assessed separately in treatment planning.
What is the FIGO classification for?
The FIGO system describes a fibroid’s relationship to the cavity and the outer surface using types 0–8. This shared language helps predict bleeding risk, plan for pregnancy and judge which treatments are technically suitable. The "FIGO type" on your report tells your care team exactly where your fibroid sits.