A hernia occurs when an organ or tissue pushes through a weak spot in the surrounding muscle or tissue wall, creating a noticeable bulge under the skin. The umbilical region, or the area around the belly button, is a common site for this condition, known specifically as an umbilical hernia. This article explains the anatomy of this condition and clarifies the meaning of a “fat containing” umbilical hernia.
The Anatomy of an Umbilical Hernia
An umbilical hernia develops at the navel (umbilicus), a naturally weak point in the anterior abdominal wall. This site is where the umbilical cord passed through the muscle layers during fetal development. Normally, this opening closes completely shortly after birth, fusing the rectus abdominis muscles in the midline.
When this closure is incomplete or fails to hold, it leaves a defect, a small ring or hole in the muscle fascia. This defect allows the inner lining of the abdominal cavity, the peritoneum, to push outward, forming a sac. The size of this muscular defect, often referred to as the hernia ring, can vary significantly.
Why is it “Fat Containing”?
The term “fat containing” refers to the specific contents that have pushed into the hernia sac through the defect in the abdominal wall. When a weakness exists, the most mobile tissue often protrudes first, which is frequently pre-peritoneal fat lying just beneath the abdominal wall muscles, or a portion of the omentum.
The omentum is a large, apron-like sheet of fatty tissue that covers the front of the intestines. When this fat-rich tissue enters the hernia sac, the condition is categorized as a fat-containing umbilical hernia. This distinction is important because the sac can also contain a loop of the small intestine.
Hernias containing only fat are generally considered less urgent than those containing bowel. This is because fat is less prone to strangulation, a dangerous complication where the blood supply is cut off.
Symptoms and Risk Factors
The most common symptom is a soft, noticeable bulge directly at or near the belly button. This swelling often becomes more prominent when a person increases intra-abdominal pressure, such as when coughing, crying, laughing, or straining. The bulge may also temporarily disappear or reduce in size when the person lies down or if gentle pressure is applied.
While many umbilical hernias cause no discomfort, some people experience a mild aching sensation or a feeling of pressure in the area. Risk factors differ between age groups. In infants, the primary risk is the congenital failure of the umbilical ring to close completely after birth; premature babies have a higher incidence.
For adults, the condition is generally acquired due to factors that chronically increase pressure within the abdomen. These risk factors include obesity, multiple pregnancies, and chronic conditions involving persistent straining, such as a long-term cough or chronic constipation. Another factor is the accumulation of abdominal fluid, known as ascites.
Diagnosis and Treatment
Diagnosis typically occurs through a physical examination. The doctor will feel the bulge to determine its size, tenderness, and whether it is “reducible,” meaning the contents can be gently pushed back into the abdominal cavity. The patient may be asked to cough or stand up to make the protrusion more visible for confirmation.
Imaging studies, such as an ultrasound or a CT scan, are usually not required for a straightforward diagnosis. They may be used if the physical exam is inconclusive or if there is concern about complications. For small, asymptomatic hernias, especially those that are fat-containing and easily reducible, watchful waiting may be recommended.
Watchful waiting is especially true for children, where the defect often closes on its own by the age of five. Surgical repair, known as a herniorrhaphy or hernioplasty, is generally recommended for adults since the defect is unlikely to close and carries a risk of worsening.
Surgery is also indicated if the hernia is causing pain, is large, or becomes incarcerated, meaning the contents are trapped and cannot be pushed back. The goal of the procedure is to push the protruding fat back into the abdomen and then close the muscular defect, often using stitches or a synthetic mesh.