The navel, or umbilicus, marks the site where the umbilical cord once connected a developing fetus to the placenta, supplying nutrients and oxygen. Once the cord is severed after birth, the remnant dries and falls off, leaving behind a scar. This scar, the belly button, takes on a variety of shapes and appearances depending on how the tissue heals.
The question of whether a protruding navel, commonly called an “outie,” is a harmless variation or a medical concern like a hernia is a frequent concern. While many outies are simply a normal cosmetic feature, a protrusion in this area can sometimes signify an underlying condition requiring attention.
The Anatomy of a Non-Hernia Outie
A non-pathological outie is a natural variation in the healing process of the umbilical cicatrix, the scar tissue left after the umbilical cord detaches. In the majority of people, this healing results in an inverted navel, or an “innie.” However, in approximately 10% of the population, the scar tissue protrudes outward instead of folding inward, forming the characteristic outie shape.
This outward protrusion is sometimes referred to as a mamelon, a central bump composed of dense skin and scar tissue that sticks out from the abdominal surface. The appearance is determined purely by the way the final tissue layers fuse and contract, and it has no bearing on the underlying abdominal wall structure. This type of outie is a benign, static feature that presents no health risks and represents only a difference in surface anatomy.
Understanding Umbilical Hernias
An umbilical hernia is a medical condition where an organ or tissue pushes through a defect in the abdominal wall near the navel. This occurs because the fascia, the strong connective tissue layer of the abdominal wall, has a weakness or gap that allows internal contents to bulge outward. The protruding contents are typically a small portion of fat or, less commonly, a loop of the small intestine.
In infants, an umbilical hernia develops when the umbilical ring, the opening in the abdominal muscles, fails to close completely after birth. While common in newborns, many of these hernias resolve spontaneously as the child’s abdominal muscles strengthen, usually by age five.
Umbilical hernias in adults are typically acquired and result from conditions that increase intra-abdominal pressure. Causes include multiple pregnancies, significant weight gain, chronic coughing, or fluid buildup in the abdomen (ascites).
Telling the Difference Between an Outie and a Hernia
Distinguishing a benign outie from an umbilical hernia involves observing several key physical characteristics. A true umbilical hernia is defined by the underlying defect in the abdominal wall, which gives the protrusion distinct properties. The feel and texture of the protrusion are often the clearest indicators, as a non-hernia outie is generally firm, dense scar tissue. Conversely, a simple, non-complicated hernia usually feels softer because it contains pliable internal tissue like fat or intestine.
Another distinguishing factor is reducibility, which refers to whether the bulge can be gently pushed back into the abdominal cavity. A non-hernia outie is a fixed piece of scar tissue that cannot be reduced or pushed inward. In contrast, an uncomplicated umbilical hernia is often reducible, meaning the protruding tissue can be temporarily massaged back through the fascial opening.
The changeability of the protrusion is another important sign to watch for. A normal outie remains static in size regardless of activity. However, a hernia will frequently increase in size or become more prominent when the pressure inside the abdomen rises, such as when an adult strains, lifts heavy objects, or coughs. In infants, a hernia is often most noticeable when the baby is crying. Finally, a benign outie is generally painless, whereas an adult umbilical hernia may cause dull discomfort, a pulling sensation, or pressure that worsens with activity.
When to Consult a Doctor
While many umbilical hernias in children close on their own, and most small adult hernias are not immediately dangerous, a medical evaluation is warranted for any new or concerning bulge near the navel. It is particularly important to seek professional advice if the protrusion is increasing in size or if an adult experiences persistent pain or discomfort. Pediatricians typically monitor infant hernias over time to ensure they are resolving as expected.
Certain symptoms signal a complication that requires immediate medical attention, indicating the hernia may have become incarcerated or strangulated. Signs of this medical emergency include:
- The sudden onset of severe, escalating pain in the area.
- A color change in the skin over the bulge, such as a shift to red, purple, or dark discoloration, suggests the blood supply to the trapped tissue has been cut off.
- The inability to gently push the bulge back in.
- Persistent vomiting.
- Signs of an infection like a fever.