Aganglionic Megacolon

Aganglionic Megacolon
Aganglionic Megacolon


Aganglionic megacolon is a condition where part or all of the small or large intestine are missing specific necessary nerve cells within the muscle layers. (This condition is also called Hirschsprung disease.) The missing nerve cells cause severe constipation or possible blockages within the large intestine.

Additional symptoms can include vomiting, fatigue or lack of energy, abdominal swelling, difficulty gaining weight or keeping weight on, bloody diarrhea, and excessive gas.

Aganglionic megacolon is a congenital condition (the person is born with it), but the symptoms don’t always appear immediately, and may present later into the child’s life. This condition has been associated with a higher risk of developing neuroblastoma and thyroid cancer.

A lot of the time, the areas of the intestine that are missing nerve cells are the sigmoid colon and the rectum area. However, some people are missing nerve cells in their entire colon, or even sections of their small intestine. For short-segment aganglionic megacolon, the last section of the large intestine is missing nerve cells. In long-segment aganglionic megacolon, most or all of the large intestine is missing nerve cells, and in some cases the end area of the small intestine as well. In rare occasions, the entire small and large intestine are lacking nerve cells.

Commonly Associated With

Hirschsprung disease, Congenital megacolon   

Cause Of Aganglionic Megacolon

During the early fetal development of those with aganglionic megacolon, their nerve cells cease growing too early, and do not line the entire bowel (small and large intestines, along with the colon and rectum) as they should. When the cells are growing, they typically start at the beginning of the intestines and grow towards the end. For this condition, they just don’t reach the end in their growth pattern. It’s known that certain genetic abnormalities can raise the risk of a person developing aganglionic megacolon. However, no prenatal tests exist for this condition, and it’s not currently known if the mother’s lifestyle factors or medical history have any bearing on the development of the condition.

Symptoms Of Aganglionic Megacolon

The chief symptoms of aganglionic megacolon are constipation and possible intestinal obstruction. These symptoms typically appear shortly after a person is born, as it is congenital in nature. A lot of otherwise healthy newborns and infants will have infrequent bowel movements, or will have obvious difficulty passing stool. However, unlike healthy infants without the disorder, those with it won’t generally respond to oral constipation medications.

Additional symptoms include:

  • Vomiting
  • Abdominal swelling
  • Unexplained fever
  • Failure to thrive, or stunted growth

Symptoms can vary from person to person. However, the variation of symptoms between people isn’t due to the length of intestine missing nerve cells. Wherever the lack of nerve cells begins, that’s where the stool will become stuck, and where blockages can form. The person develops symptoms as a result of missing nerves at that point in the intestines.

Symptoms often seen in newborns

A common first noticed symptom of the disorder is the newborn failing to have their first bowel movement within the first 48 hours after birth. Other symptoms can include:

  • Abdominal swelling
  • Diarrhea, often bloody
  • Vomiting, either green or brown in color
  • Explosive release of stool after a physician examines the rectum with a single finger insertion

Symptoms often seen in toddlers and older children

  • Diarrhea, often with blood
  • Abdominal swelling
  • Slower than normal growth, or failure to thrive
  • Being unable to pass stools without suppository or enema assistance.

Diagnosis Of Aganglionic Megacolon

A health care provider will diagnose this disorder based on:

  • Symptoms
  • A physical exam
  • A family and medical history
  • Test results, if applicable

If a health care provider suspects aganglionic megacolon, they may refer the child/infant to a pediatric gastroenterologist for further tests and evaluation. (These doctors specialize in childhood digestive diseases and disorders.)

Physical Exam

During a physical exam testing for this disorder, a health care provider usually

  • Reviews the child’s weight and height, and then compares it to the average for their age
  • Physically touches/palpates specific areas of the child’s body
  • Performs a rectal exam in some cases. Explosive stool as a result of a rectal exam in infants or toddlers can be a sign of aganglionic megacolon
  • Uses a stethoscope to listen to gut and bowel sounds in the abdomen

Medical and Family History

A health care provider will ask for a family history and a medical history to help diagnose aganglionic megacolon. They will ask about the infant/child’s bowel movements. They will also ask about abdominal swelling, vomiting, and any unexplained fevers the child may have. Children are less often correctly diagnosed if their bowel movement issues begin after one year of age.

Treatment Of Aganglionic Megacolon

Aganglionic megacolon is surgically treatable – surgeons remove the sections of the intestines/colon without nerve cells. After the surgery, sections of the intestines with normal nerve cells can then compensate. A health care provider will need to discuss possible treatment options with the patient or the patient’s parents.

Exams and Tests

In some cases, milder versions of the disorder may not be diagnosed until the infant is older.

When conducting a physical exam, a health care provider may sometimes be able to feel bowel loops within a swollen abdomen. A rectal exam can then reveal unusually tight rectal muscle tone.

Specific tests for diagnosing the disorder can include:

  • An anal manometry (where pressure in the rectum area is measured by inserting and then inflating a balloon)
  • A barium enema
  • A rectal biopsy
  • An abdominal x-ray