Fibroids are grouped by where they grow in the uterus. The three main types are submucosal (bulging into the inside of the uterus), intramural (within the muscle wall) and subserosal (on the outer surface). Some fibroids hang from a stalk and are called pedunculated. Doctors describe location more precisely with the FIGO system, which numbers fibroids from type 0 to type 8. Location matters because it shapes which symptoms you are likely to have and which treatments can reach the fibroid.
The three main locations
The uterus has three layers: the lining on the inside (endometrium), a thick muscle wall (myometrium), and a thin outer covering (serosa). Fibroids start in the muscle, then may grow inward, stay put, or grow outward. The federal Office on Women's Health (OWH) describes the groups this way:
- Submucosal fibroids grow into the uterine cavity, the space where a pregnancy implants and where menstrual blood comes from.
- Intramural fibroids grow within the wall of the uterus.
- Subserosal fibroids grow on the outside of the uterus and can press on nearby organs such as the bladder or bowel.
Fibroids that grow on a stalk, either from the outer surface or into the cavity, are called pedunculated. OWH notes they can look like mushrooms. Many women have more than one fibroid, often of different types.
The FIGO classification, types 0 to 8
To describe location consistently, gynecologists and radiologists use a system from the International Federation of Gynecology and Obstetrics (FIGO), first published in 2011 and revised in 2018. ACOG's 2021 practice bulletin on fibroids uses the same system. Your ultrasound or MRI report may mention these numbers.
| FIGO type | Where the fibroid sits | Plain-language group |
|---|---|---|
| 0 | Pedunculated, entirely inside the cavity | Submucosal |
| 1 | Submucosal, less than 50% in the wall | Submucosal |
| 2 | Submucosal, 50% or more in the wall | Submucosal |
| 3 | Touches the lining but is 100% in the wall | Intramural |
| 4 | Entirely within the wall | Intramural |
| 5 | Subserosal, 50% or more in the wall | Subserosal |
| 6 | Subserosal, less than 50% in the wall | Subserosal |
| 7 | Subserosal, on a stalk | Pedunculated subserosal |
| 8 | Other locations, such as the cervix, or "parasitic" fibroids | Other |
A fibroid that spans the whole wall, touching both the lining and the outer surface, is written as a hybrid with two numbers, such as "2-5". This means it is partly submucosal and partly subserosal.
Questions about your treatment options? Dr. Fox can help.
Book a ConsultationThis article is part of our Fibroid Treatment Guide.
How fibroid type relates to symptoms
Every type can cause symptoms, and every type can also be silent. Still, some patterns are useful to know.
Fibroids near or inside the cavity (types 0 to 3)
These fibroids sit closest to the lining that bleeds each month and to the space where a pregnancy implants. The UK's National Institute for Health and Care Excellence (NICE) advises that women with heavy periods whose history suggests submucosal fibroids, such as persistent bleeding between periods, be offered a hysteroscopy, a camera look inside the uterus. On fertility, the American Society for Reproductive Medicine (ASRM) found in a 2017 guideline that the evidence was insufficient to say fibroids in general reduce the chance of pregnancy, but that there was fair evidence that removing fibroids that distort the cavity improves pregnancy rates.
Fibroids within the wall (types 3 and 4)
Intramural fibroids enlarge the uterus from within. ACOG lists an enlarged uterus and abdomen among fibroid symptoms, and a type 3 fibroid also touches the lining, which is why it is grouped with the cavity-related types for some treatments.
Fibroids on the outside (types 5 to 7)
Subserosal fibroids grow outward, toward the bladder, bowel and back. OWH notes that fibroids can press on the bladder, causing frequent urination, or on the rectum, causing rectal pressure, and that very large fibroids can make the abdomen look enlarged. ACOG notes that a fibroid on a stalk may twist, which can cause pain, nausea or fever.
For a symptom-by-symptom guide, see our article on fibroid symptoms.
Why location drives treatment
NICE advises doctors to take the size, number and location of fibroids into account when agreeing on treatment. Here is how type affects some common options.
- Hormonal IUD. ACOG describes the progestin IUD as an option for fibroids that do not distort the inside of the uterus. NICE suggests it first for heavy bleeding when fibroids are smaller than 3 cm and are not distorting the cavity.
- Hysteroscopic myomectomy. Removing a fibroid through the cervix, with no incision, works for fibroids that protrude into the cavity. The European Society for Gynaecological Endoscopy (ESGE) lists hysteroscopic approaches for FIGO types 0 to 3. ACOG notes this approach cannot remove fibroids deep in the wall.
- Abdominal myomectomy. Laparoscopic, robotic or open surgery is needed for FIGO types 4 to 7 and for some larger type 2 and 3 fibroids, according to ESGE's 2024 recommendations.
- Uterine fibroid embolization (UFE). UFE blocks the blood supply to fibroids through a catheter rather than cutting them out, so it is not limited to one route. In the US FIBROID Registry, a 2005 study of women treated with UFE, a submucosal location was one of the factors that predicted greater symptom improvement. Submucosal fibroids can sometimes pass out through the vagina after UFE; in one 2010 study, 10 of 20 dominant submucosal fibroids were fully expelled within a year. For fibroids on a thin stalk, the European interventional radiology society (CIRSE) in its 2015 guideline listed treatment as a relative, and debated, contraindication.
- Hysterectomy. Removing the uterus treats fibroids of every type. ACOG's 2021 practice bulletin describes it as the definitive surgical option for women who do not want future pregnancy or to keep the uterus.
We cover two of these situations in depth: hysteroscopic myomectomy vs UFE for submucosal fibroids and embolization for pedunculated fibroids. For how UFE works overall, read our guide to uterine fibroid embolization (UFE).
How doctors find out what type you have
A pelvic ultrasound, usually through both the abdomen and the vagina, is the standard first test. A 2025 review in American Family Physician notes that pelvic MRI with contrast may further characterize fibroids and guide treatment. NICE recommends an ultrasound before UFE or myomectomy and an MRI when more detail on position, size, number and blood supply is needed. A hysteroscopy or a saline ultrasound can show how much a fibroid bulges into the cavity.
When you get a report, it is reasonable to ask:
- How many fibroids do I have, and what FIGO type is each one?
- How large is the largest one, and how big is my uterus overall?
- Is any fibroid distorting the inside of my uterus?
- Is any fibroid on a stalk?
- Which treatments can reach the fibroids that are causing my symptoms?
Our article on fibroid diagnosis with ultrasound and MRI explains the tests themselves.
The bottom line
The type of fibroid you have is one of the most useful facts in your file. It helps explain your symptoms and narrows down which treatments make sense. Bring your imaging report to every appointment, and ask your doctor to walk through where each fibroid sits. Our fibroid treatment guide compares every option once you know your fibroid map.
Frequently Asked Questions
What are the main types of fibroids?
Submucosal fibroids grow into the inside of the uterus, intramural fibroids grow within the muscle wall, and subserosal fibroids grow on the outer surface. Any of them can grow on a stalk, which is called pedunculated.
What does FIGO type 2 mean on my report?
In the FIGO system, type 2 is a submucosal fibroid with half or more of it inside the muscle wall and the rest bulging into the cavity. Types 0 to 2 are the submucosal group.
Which type of fibroid affects fertility?
Fibroids that distort the inside of the uterus are the main concern. A 2017 ASRM guideline found fair evidence that removing cavity-distorting fibroids improves pregnancy rates, but not enough evidence that fibroids in general reduce the chance of pregnancy.
Can every type of fibroid be treated with UFE?
UFE treats fibroids through their blood supply, so it can reach fibroids in different locations. Fibroids on a very thin stalk are a relative, debated contraindication in CIRSE's 2015 guideline, and your imaging decides whether you are a candidate.
How do I find out what type of fibroid I have?
A pelvic ultrasound is the usual first test. An MRI gives more detail about the position, size, number and blood supply of fibroids and is often used before UFE or myomectomy.
Keep Reading
- Uterine Fibroid Embolization (UFE) in New York City
- What Are Uterine Fibroids?
- Fibroid Diagnosis: Ultrasound vs MRI
- Submucosal Fibroid Treatment: Hysteroscopic Myomectomy or UFE?
- Pedunculated Fibroids and UFE: Safety, Stalk Width and Results
- Fibroid Symptoms: 9 Signs to Know
- Fibroid Treatment Guide: every option, compared
Sources
- Munro et al., Int J Gynaecol Obstet, 2018 — The two FIGO systems for abnormal uterine bleeding: 2018 revisions
- Saridogan et al., Facts Views Vis Obgyn, 2024 — ESGE Good Practice Recommendations on fibroid removal, part 1 (includes FIGO table)
- ACOG Practice Bulletin No. 228, Obstet Gynecol, 2021 — Management of Symptomatic Uterine Leiomyomas
- ACOG, Uterine Fibroids patient FAQ (last reviewed December 2025)
- Office on Women's Health, Uterine fibroids (updated February 2025)
- NICE guideline NG88, Heavy menstrual bleeding: assessment and management (updated July 2026)
- ASRM Practice Committee, Fertil Steril, 2017 — Removal of myomas in asymptomatic patients to improve fertility
- Spies et al., Obstet Gynecol, 2005 — FIBROID Registry 1-year outcomes after uterine artery embolization
- Radeleff et al., Eur J Radiol, 2010 — Expulsion of dominant submucosal fibroids after UAE (20 fibroids)
- van Overhagen and Reekers, Cardiovasc Intervent Radiol, 2015 — CIRSE standards of practice for uterine artery embolization
- Keating et al., Am Fam Physician, 2025 — Uterine Fibroids: Rapid Evidence Review
Medically reviewed by David Fox, MD, FACS, RPVI. This article is general information, not a substitute for a medical evaluation.
Living with heavy periods, pelvic pressure or other fibroid symptoms? Schedule a consultation with Dr. David Fox at Fox Vein & Vascular in Manhattan to find out whether uterine fibroid embolization is right for you. Call (212) 362-3470 or request a UFE consultation online.
