The belly button, or “umbilicus,” is the scar left over after the remains of the umbilical cord fall off after birth. Typically oval or round, it takes many forms. Most people have an “innie” with an inward scar, but about one in 10 people have an “outie,” or button-like umbilicus, with the belly button bulging out.
Outie belly buttons aren’t preventable. They often occur by chance, though certain medical conditions can cause them. They can also develop temporarily due to pregnancy or excess weight.
There are no health risks associated with having an outie belly button. It’s mainly a cosmetic concern that can be treated with elective surgery. However, bulging umbilicus can also be a sign of umbilical hernia, a condition that, in rare cases, causes complications in infants. As such, it’s critical to understand what can cause outie belly buttons and when to seek treatment.
Belly buttons are usually located in the center of the abdomen, at the level of the iliac crests, found at the tips of the hip bone. The size varies, but they’re generally about 2.3 centimeters (0.9 inches) in diameter for people assigned male at birth and about 2.1 centimeters (0.83 inches) in diameter for people assigned female at birth.
Outie belly buttons have what is clinically known as a” mamelon” (a central protruding area). Round in shape, it pokes out from the abdomen. Depending on the case, there may be a fold of flesh along a margin of the umbilicus (belly button), known as a “cushion.”
There’s also a cicatrix, a scar that arises at the spot where the umbilical cord detached. In an outie belly button, this looks like criss-crosses on the mamelon, giving it a knot-like appearance.
If you push on an outie belly button, it should feel denser than the surrounding skin. With aging, the skin around an outie belly button can loosen, causing sagging.
When you’re born, you’re connected to the person who birthed you via the umbilical cord. After delivery, the healthcare provider cuts this cord, leaving a stump that shrivels and shrinks. This stump generally falls off within two weeks of birth.
Outie belly buttons are the scars that form as this site heals. Underlying conditions can also cause this scarring to occur in infants and adults.
Natural Development
Scars are unpredictable, and outies often develop randomly. They aren’t caused by how healthcare providers cut or clamp the umbilical cord. They also aren’t related to how parents care for the umbilical stump before it detaches.
Most of the time, the type of belly button you have depends on natural variations in how the umbilical scar heals. Differences in the thickness of the surrounding tissues at this stage may also play a role, allowing the belly button to push out as it forms.
Umbilical Hernia
An umbilical hernia is a birth defect seen in 10-15% of newborns. It can also be acquired in adulthood. In infants, it arises when the muscles and tissues around the belly button don’t form fully. Due to internal pressure, the small intestines poke out around this area, creating a bulge. Typical signs of umbilical hernia include:
- Bulging in the belly button that comes and goes
- Bulging that worsens when crying or straining the abdomen
- Bulging that reduces with relaxation
- The hernia stretching or changing shape with growth
In infants, most cases of umbilical hernia are often asymptomatic (have no symptoms). They typically don’t require treatment and resolve on their own by age 5. Surgery is needed if there are symptoms or if the protruding intestine becomes cut off from the blood supply (known as strangulation).
Umbilical Granuloma
An umbilical granuloma is a common growth that infants develop after the umbilical stump falls off. A granuloma is an area of chronic (long-term) inflammation that can harden, forming tough, hardened tissue. A pink or red lump forms at the site, often accompanied by yellow or clear fluid discharge.
An umbilical granuloma generally resolves on its own if kept clean. An infection can cause fever and skin irritation, warranting treatment.
Umbilical Polyp
An umbilical polyp (growth) is a rare birth defect that can cause a protruding belly button after the umbilical stump detaches. Researchers believe they are caused by remains of the omphalomesenteric duct (OMD)—a structure that nourishes the developing embryo. Polyps can form if this doesn’t close properly during gestation or if parts of the umbilical cord remain in the tissue.
Umbilical polyps look like outie belly buttons that are red, swollen, and may bleed. Unlike umbilical granulomas, only surgery can remove them.
Acquired Outie Bellybuttons
Some can develop outie belly buttons later in life. They’re often temporary and resolve as the underlying condition resolves. Possible causes include:
- Pregnancy: As the fetus develops and grows, the pressure on the mother’s abdominal walls increases. This can cause the belly button to protrude.
- Umbilical hernia: An umbilical hernia can develop in adults due to weaknesses in the abdominal walls.
- Ascites: Ascites is a fluid buildup in the abdominal cavity that causes swelling, difficulty breathing when lying down, and digestive symptoms. An outie belly button can develop as a result of ascites, which is often caused by liver or kidney damage.
- Granuloma: A granuloma can form as tissue heals after a navel piercing, which can lead to infection.
In most cases, outie belly buttons don’t pose health risks or cause symptoms. However, because an umbilical hernia or other health condition may be at play, it’s important to know when to reach out to a healthcare provider. The following are signs you should call your or your infant’s healthcare provider:
- Infection symptoms: Foul-smelling discharges, redness, and skin irritation in the belly button, especially after the umbilical stump falls off a baby
- Bleeding: If bleeding doesn’t stop after your child’s umbilical stump detaches
- Severe umbilical hernia: Severe pain, vomiting, fever, refusal to feed (in infants), and a large and persistent bulge—which may be signs of strangulation (when the hernia cuts off blood supply to the affected tissue) and become a severe complication
- Infected granuloma: In infants, a granuloma that grows, turns red, or persists
Pediatricians or primary care providers (PCPs) typically diagnose and will refer you to pediatric or general surgeons if they deem surgery necessary. In most cases, diagnosis is based on an assessment of symptom history and physical examination of the belly button.
Unless there’s an underlying condition, there’s no medical need to treat an outie belly button. Some choose to have elective treatment, and it may be necessary in cases of hernia and granuloma that don’t resolve or become symptomatic.
Surgeries and other medical treatments can treat conditions that cause outie belly buttons or, when elective, directly change their appearance. These include:
- Umbilicoplasty: An elective surgery in which plastic surgeons cut away tissue and reshape the belly button to improve its appearance.
- Hernia repair: In cases of umbilical hernia that don’t resolve, the surgeon uses sutures (stitches) or other methods to fix weakened areas of the abdominal wall around the belly button.
- Double ligature: The healthcare provider ties surgical thread around the base of a granuloma, cutting off its blood supply. The granuloma shrinks and withers away.
- Resection: Using minimally-invasive techniques, surgeons remove polyps or granuloma, which can correct outie belly button.
- Cryotherapy: This involves applying extreme cold to freeze the umbilical granuloma in order to remove it.
- Electrocautery: Extreme heat is directed to a granuloma or other abnormal growth to destroy the abnormal skin.
- Silver nitrate: With this treatment for granuloma, the healthcare provider applies silver nitrate to affected areas to destroy abnormal tissue.
Belly button shape is determined by the healing after the umbilical stump falls off. There’s no way to prevent one from forming. That said, it’s important for newborn caretakers to understand how to care for the umbilical stump and prevent complications. Here are some recommendations:
- Don’t force it: During the first 15 days, the umbilical stump should shrivel and dry, eventually falling off. Let this happen naturally, and don’t try to pull it off.
- Clean minimally: Only use wet gauze to clean the umbilical stump if dirt or debris is present. Avoid any moisture in this area if at all possible.
- Bathing: Don’t bathe your baby in a tub until the stump falls off. Instead, use a sponge to keep the newborn clean.
About 10% of people have an outie belly button that is round and sticks out. This is mostly a cosmetic issue, and it happens randomly. That said, an outie belly button can also be a sign of umbilical hernia, certain congenital (from birth) conditions, pregnancy, or ascites (abdominal swelling).
An outie belly button is typically a cosmetic issue with no symptoms that doesn’t require treatment. People may elect to have surgery to improve its appearance. Surgeries and medical procedures can help treat underlying causes, especially when they start causing complications.
