Type 0-2 — Submucosal Leiomyomas
Submucosal fibroids grow beneath the endometrium, distorting the cavity.
- 0%: Type 0 (wall involvement, pedunculated)
- <50%: Type 1 (intramural extension)
- ≥50%: Type 2 (intramural extension)
- High: Cavity distortion (across all three subtypes)
What defines submucosal
Any contact with, or bulge into, the endometrial cavity.
Type 0 fibroids are entirely intracavitary, attached by a stalk.
Why location matters
Cavity distortion drives heavy bleeding and fertility problems.
First-line treatment
Hysteroscopic resection removes types 0-2 without abdominal surgery.
Type 3-4 — Intramural Leiomyomas
Intramural fibroids grow entirely inside the muscular uterine wall.
- 0mm: Type 3 (gap to endometrium, 100% wall)
- 100%: Type 4 (intramural, no surface contact)
- ~40%: Most common type (of diagnosed fibroids)
- Estrogen: Growth driver (and progesterone sensitive)
Wall-confined growth
No contact with endometrium or serosa distinguishes Type 4.
Type 3 nuance
Touches the endometrium but stays fully within the wall.
Type 3 can still distort the cavity despite being intramural.
Symptom profile
Bulk symptoms — pelvic pressure and pain — dominate here.
Type 5-6 — Subserosal Leiomyomas
Subserosal fibroids grow outward, bulging beneath the outer surface.
- ≥50%: Type 5 (intramural, touches serosa)
- <50%: Type 6 (intramural, mostly outward)
- Minimal: Cavity impact (endometrium usually untouched)
- Incidental: Common finding (on routine imaging)
Outward growth pattern
Mass expands toward the peritoneal surface, away from the cavity.
Symptom pattern
Pressure on bladder or bowel rather than bleeding.
Bleeding symptoms are rare since the cavity stays undistorted.
Monitoring approach
Often watched conservatively unless rapidly enlarging.
Type 7 — Pedunculated Subserosal Leiomyoma
Type 7 fibroids hang entirely outside the uterus on a stalk.
- 0%: Wall contact (fully extrauterine mass)
- Pedicle: Attachment (thin vascular stalk)
- Elevated: Torsion risk (stalk can twist)
- Lowest: Symptom load (among all FIGO types)
Stalk anatomy
A narrow pedicle carries the blood supply to the mass.
Torsion danger
A twisted stalk can cut off blood flow, causing acute pain.
Acute pain from stalk torsion is a surgical emergency.
Imaging clue
A visible bridging vessel confirms the pedunculated diagnosis.
Type 8 — Other Locations
Type 8 covers fibroids outside the standard uterine body axis.
- ~8%: Cervical fibroids (of all leiomyomas)
- Rare: Broad ligament (parasitic attachment possible)
- N/A: Classification axis (endometrium-serosa scale unused)
- Highest: Surgical complexity (due to nearby structures)
Beyond the standard axis
These fibroids do not fit the endometrium-to-serosa scale.
Special locations
Cervix, broad ligament, or parasitic sites are typical.
Nearby ureters and vessels raise surgical risk considerably.
Clinical takeaway
Location, not just size, guides the treatment plan.