Fibroid Nodule: What It Is, Types, and Sizes on Ultrasound

An ultrasound report containing the phrase "fibroid nodule" often raises more questions than it answers. Let us look together at what this formation is, what types of nodules exist, and what the numbers in the report mean.

What a fibroid nodule in the uterus is

Uterine fibroids, or leiomyoma, are a benign tumor arising in the muscular layer of the uterus, the myometrium. A nodule is a rounded tangle of chaotically interwoven smooth muscle fibers. Each nodule arises from a single cell, so all of its cells are identical. Fibroids are a hormone-dependent tumor: they contain receptors for sex hormones, appear during the reproductive years, and regress after menopause. This is one of the most common tumors in women: according to various estimates, it occurs in every second to fourth woman during the reproductive period, predominantly after age 30. In half of cases, fibroids are asymptomatic.

Types of nodules: intramural, subserosal, and others

Several variants are distinguished by the location of the nodules. Submucosal nodules are located closer to the uterine cavity and are relatively rare — in no more than 13% of cases; sometimes a nodule on a thin stalk descends into the cervix or vagina. Intramural (interstitial) nodules are located in the uterine wall, in the muscular layer — this is the most common variant, from 50 to 61% and more. Subserosal nodules are located on the outer side of the uterus, closer to the abdominal cavity, and occur in 26–35% of cases; a nodule may have a base of smaller diameter than the nodule itself — then it is called a pedunculated nodule. Intraligamentary and cervical nodules are less common. By number, single and multiple fibroids are distinguished.

How uterine fibroids appear on ultrasound

The most informative diagnostic method is ultrasound, transvaginal or transabdominal. On ultrasound, fibroids appear as rounded foci of reduced echogenicity: their structure is less dense than that of the myometrium. The examination shows whether nodules are present, how many there are, where they are located, and what size they are. Sometimes fibroids are found incidentally, during other examinations, for example, on an ultrasound for pregnancy. For differential diagnosis with an ovarian tumor, MRI is used in some cases.

Which fibroid sizes are considered significant

Most nodules have a diameter of a few millimeters to a few centimeters, but sometimes they reach large sizes and a weight of several kilograms. There is no single universal norm for acceptable sizes: not only the size but also the location, number of nodules, and symptoms matter. Small single or multiple fibroids with an intramural and subserosal location are more often asymptomatic. Large nodules can cause a feeling of heaviness or pressure in the lower abdomen, as well as compress neighboring organs.

Uterine fibroids during pregnancy and when a doctor is needed

Many women with fibroids can become pregnant without problems. At the same time, some nodules can cause infertility, pregnancy loss, problems with the development or course of labor, so when planning a pregnancy the issue is discussed with a doctor. You should consult a specialist if heavy or painful periods appear, bleeding between them, pain in the lower abdomen or lower back, frequent urination, bowel problems, discomfort during intercourse, or difficulty conceiving. A reason for a visit is also a situation where symptoms interfere with daily life, work, and relationships.

• Heavy or painful periods, bloody discharge between them
• A feeling of heaviness, pressure, or pain in the lower abdomen and lower back
• Frequent urination or bowel problems
• Discomfort or pain during intercourse
• Difficulty conceiving, recurrent miscarriages

Fibroids by themselves are not a reason to call an ambulance. The numbers 103 or 112 are needed if sudden sharp cutting pain appears in the lower abdomen — this may be how a rare complication, torsion of the stalk of a subserosal nodule, manifests.

This material is for reference: it helps to understand the terms in an ultrasound report, but does not replace a consultation with a doctor, who will assess your situation together with your partner and, if necessary, prescribe an examination.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer