The belly button, or navel, is a scar left on the abdomen from where the umbilical cord once connected a developing fetus to the mother’s placenta. Its shape is determined by the natural healing process after the umbilical cord stump falls off shortly after birth. While the shape is largely set in early life, this article explores the natural and medical changes that can cause a protruding navel to retract.
Defining the “Outie” and “Innie”
The difference between an “innie” and an “outie” is primarily cosmetic, reflecting how the skin and underlying scar tissue healed. An innie is the more common type, where the scar tissue is recessed, creating a concave depression in the abdomen. Approximately 90% of people have this inward-folding shape.
An outie, present in about 10% of the population, occurs when the scar tissue or skin protrudes outward. This convex shape is simply a natural variation in the way the tissue healed. The final appearance is not influenced by how the umbilical cord was cut or clamped at birth.
Common Reasons for Navel Protrusion
Beyond simple scar tissue variation, a protruding navel is often caused by a medical condition that pushes the tissue outward. The most common medical reason is an umbilical hernia, particularly in infants. This occurs when abdominal contents, such as fat or a loop of the intestine, push through a weak spot in the abdominal wall near the navel.
The protrusion becomes more noticeable when the child or adult strains, cries, or coughs, as increased abdominal pressure forces the tissue through the opening. Another cause, typically seen in newborns, is an umbilical granuloma. This is a soft, moist mass of excess scar tissue that forms during the healing process. Granulomas are generally harmless but cause a visible protrusion until they shrink or are treated.
Natural Resolution and Appearance Changes
A protruding navel can change its appearance, often retracting and becoming less prominent or even turning into an innie. The most common mechanism for this natural change is the spontaneous closure of an infant umbilical hernia. In newborns and young children, the opening in the abdominal wall, called the umbilical ring, often closes on its own as the surrounding muscles strengthen.
More than 90% of pediatric umbilical hernias resolve without intervention, typically by age five. When the abdominal wall opening seals, the bulging tissue is no longer pushed through, and the navel retracts. Umbilical granulomas can also shrink and disappear over time, or they may be treated with simple methods like silver nitrate application or common salt, which causes the excess tissue to shrivel.
Body composition changes in adults can dramatically alter the navel’s appearance. Significant weight loss, especially the reduction of fat in the midsection, can cause the stretched skin and tissue to retract. This often results in a deeper, more defined navel that takes on an innie appearance. Conversely, pregnancy or rapid weight gain can stretch the abdominal skin, sometimes forcing an innie to temporarily become an outie that usually reverts after childbirth.
When to Consult a Medical Professional
While many outies are a benign cosmetic variation or a harmless infant hernia, certain signs warrant a medical consultation. If a protruding navel in an adult or child is accompanied by pain, tenderness, or swelling, it should be examined by a doctor. This is especially true if the bulge cannot be gently pushed back into the abdomen, indicating it may be incarcerated.
Immediate medical attention is necessary if the skin over the protrusion becomes discolored, blue or dark red, or if the individual experiences vomiting or severe pain. These symptoms could signal a strangulated hernia, where the blood supply to the trapped tissue is cut off. This is a serious medical emergency requiring prompt surgical repair.