Colonic atresia is a birth defect in which part of the colon is completely blocked or missing. Colonic stenosis, which may be a birth defect or may develop later in life, is a condition in which part of the colon is more narrow than normal.

About 1 in every 10,000 to 66,000 babies is born with colonic atresia.

Experts don’t know how common colonic stenosis is. At birth, colonic stenosis is rarer than colonic atresia. Most cases of colonic stenosis develop later in life and are caused by injury or inflammation.

Experts don’t know who is more likely to have colonic atresia and stenosis at birth.

People are more likely to develop colonic stenosis later in life if they have an injury or inflammation of the colon that may cause stenosis.

Premature babies might develop colonic stenosis after having necrotizing enterocolitis, a condition in which the wall of the intestine suffers serious damage.

Babies born with colonic atresia may have other birth defects, including

• atresia in the small intestine
• defects of the wall of the abdomen
• Hirschsprung disease
• malrotation

Colonic atresia causes intestinal obstruction, in which the colon is completely blocked. If colonic atresia is not diagnosed and treated shortly after a baby is born, intestinal obstruction can lead to serious complications such as

• dehydration
• a perforation, or hole, in the wall of the intestine
• infection and sepsis, a serious illness that occurs when the body has an overwhelming immune system response to an infection

Colonic stenosis can also cause intestinal obstruction and its complications.

Colonic atresia and stenosis may cause signs and symptoms due to intestinal obstruction. Anyone with signs or symptoms of intestinal obstruction needs medical help right away.

Signs of intestinal obstruction due to colonic atresia include

• bloating or visible swelling of the abdomen
• passing no stool
• vomiting, often with bile in the vomit, which makes it green in color

These signs typically appear in babies soon after birth.

Colonic stenosis can also cause intestinal obstruction, and signs and symptoms may be similar to those of colonic atresia. Signs and symptoms may be milder or may come and go if the colon is not completely blocked.

Experts aren’t sure what causes colonic atresia and stenosis to occur as birth defects. One theory is that before birth, something happens to reduce the flow of blood to part of the colon.

Injury or inflammation of the colon may cause colonic stenosis at any time during a person’s life. For example, necrotizing enterocolitis is a common cause of colonic stenosis in babies. Later in life, inflammatory bowel disease (IBD), such as Crohn’s disease, is a cause of colonic stenosis, also called a stricture.

To diagnose colonic atresia and stenosis, doctors ask about symptoms and medical history and perform a physical exam and imaging tests.

Physical exam

During a physical exam, the doctor may

• check for bloating of the abdomen
• check for a lump or mass in the abdomen
• press or tap on the abdomen to check for tenderness or pain
• use a stethoscope to listen to sounds in the abdomen
• check for signs of complications, such as dehydration or infection

Imaging tests

Doctors may use the following tests to diagnose colonic atresia and stenosis

• x-rays, which use a small amount of radiation to create pictures of the inside of the body
• ultrasound, which uses sound waves to create an image of organs
• lower GI series, which uses x-rays and a chalky liquid called barium to view the large intestine

Doctors treat colonic atresia and stenosis with surgery to remove the blocked or narrowed part of the colon and attach the healthy ends of the colon to each other.

In some cases, doctors treat colonic atresia or stenosis with one operation. In other cases, doctors first perform a colostomy to attach the colon to a stoma, an opening in the abdomen that allows stool to exit the body. Later, doctors perform a second operation to attach the healthy ends of the colon to each other.