Necrotizing enterocolitis (NEC) is a serious bacterial infection in the
intestine, primarily affecting sick or premature newborn infants. It can
cause the death (necrosis) of intestinal tissue and progress to blood
Necrotizing enterocolitis is a serious infection that can produce
complications in the intestine itself such as ulcers, perforations or
holes in the intestinal wall, and tissue necrosis. It can also progress to
life-threatening septicemia. Necrotizing enterocolitis most commonly
affects the ileum, the lower portion of the small intestine. It is less
common in the colon and upper small bowel.
It is estimated that narcotizing enterocolitis affects 2 percent of all
newborns, but it is more frequently seen in very low birth weight infants,
affecting as many as 13.3 percent of these babies. It has a high mortality
rate, especially among very low birth weight babies. Some 20 to 40 percent
of these infants die. It does not appear that male or females are more
susceptible to this condition, and no one race or nationality has a higher
Causes and symptoms
The cause of necrotizing enterocolitis is not clear. It is believed that
the infection usually develops after the bowel wall has already been
weakened or damaged by a lack of oxygen, predisposing it to bacterial
invasion. Bacteria grow rapidly in the bowel, causing a deep infection
that can kill bowel tissue and spread to the bloodstream.
Necrotizing enterocolitis almost always occurs in the first month of life.
Infants who require tube feedings may have an increased risk for the
disorder. A number of other conditions also make newborns susceptible,
respiratory distress syndrome
, congenital heart problems, and episodes of apnea (cessation of
breathing). The primary risk factor, however, is
. Not only is the immature digestive tract less able to protect itself,
but premature infants are subjected to many stresses on the body in their
attempt to survive.
Early symptoms of necrotizing enterocolitis include an intolerance to
formula, distended and tender abdomen,
, and blood (visible or not) in the stool. One of the earliest signs may
also be the need for mechanical support of the infant's breathing.
If the infection spreads to the bloodstream, infants may develop lethargy,
fluctuations in body temperature, and may periodically stop breathing.
The key to reducing the complications of this disease is early detection
by the physician. A series of x rays of the bowel often reveals the
progressive condition, and blood tests confirm infection.
Over two-thirds of infants can be treated without surgery. Aggressive
medical therapy with
is begun as soon as the condition is diagnosed or even suspected. Tube
feedings into the gastrointestinal tract (enteral
) are discontinued, and tube feedings into the veins (parenteral
nutrition) are used instead until the condition has resolved. Intravenous
fluids are given for several weeks while the bowel heals.
Some infants are placed on a ventilator to help them breathe, and some
receive transfusions of platelets, which help the blood clot when there is
internal bleeding. Antibiotics are usually given intravenously for at
least 10 days. These infants require frequent evaluations by the
physician, who may order multiple abdominal x rays and blood tests in
order to monitor their condition during the illness.
Sometimes, necrotizing enterocolitis must be treated with surgery. This is
often the case when an infant's condition does not improve with
medical therapy or there are signs of worsening infection.
The surgical treatment depends on the individual patient's
condition. Patients with infection that has caused serious damage to the
bowel may have portions of the bowel removed. It is sometimes necessary to
create a substitute bowel by making an opening (ostomy) into the abdomen
through the skin, from which waste products are discharged temporarily.
But many physicians avoid this and operate to remove diseased bowel and
repair the defect at the same time.
Postoperative complications are common, including wound infections and
lack of healing, persistent sepsis and bowel necrosis, and a serious
internal bleeding disorder known as disseminated intravascular
Necrotizing enterocolitis is the most common cause of death in newborns
undergoing surgery. The average mortality is 30 to 40 percent, even higher
in severe cases.
Early identification and treatment are critical to improving the outcome
for these infants. Aggressive nonsurgical support and careful timing of
surgical intervention have improved overall survival; however, this
condition can be fatal in about one third of cases. With the resolution of
the infection, the bowel may begin functioning within weeks or months. But
infants need to be carefully monitored by a physician for years because of
possible future complications.
About 10 to 35 percent of all survivors eventually develop a stricture, or
narrowing, of the intestine that occurs with healing. This can create an
intestinal obstruction that requires surgery. Infants may also be more
susceptible to future bacterial infections in the gastrointestinal tract
and to a delay in growth. Infants with severe cases may also suffer
The most serious long-term gastrointestinal complication associated with
necrotizing enterocolitis is short-bowel, or short-gut, syndrome. This
refers to a condition that can develop when a large amount of bowel must
be removed, making the intestines less able to absorb certain nutrients
and enzymes. These infants gradually evolve from tube feedings to oral
feedings, and medications are used to control the malabsorption,
, and other consequences of this condition.
In very small or sick premature infants, the risk for necrotizing
enterocolitis may be diminished by beginning parenteral nutrition and
delaying enteral feedings for several days to weeks.
Breast-fed infants have a lower incidence of necrotizing enterocolitis
than formula-fed infants; however, conclusive data showing that breast
milk may be protective was as of 2004 not available. A large multicenter
trial showed that steroid drugs given to women in preterm labor may
protect their offspring from necrotizing enterocolitis.
Sometimes necrotizing enterocolitis occurs in clusters, or outbreaks, in
hospital newborn (neonatal) units. Because there is an infectious element
to the disorder, infants with necrotizing enterocolitis may be isolated to
avoid infecting other infants. Persons caring for these infants must also
employ strict measures to prevent spreading the infection.
—Liquid nutrition provided through tubes that enter the
gastrointestinal tract, usually through the mouth or nose.
—Localized tissue death due to disease or injury, such as a lack
of oxygen supply to the tissues.
—A surgically-created opening in the abdomen for elimination of
waste products (urine or stool).
—Liquid nutrition usually provided intravenously.
—A severe systemic infection in which bacteria have entered the
bloodstream or body tissues.
Beers Mark H., and Robert Berkow, eds.
The Merck Manual
, 2nd home ed. West Point, PA: Merck & Co., 2004.
Moore, Keith L., et al.
Before We Are Born: Essentials of Embryology and Birth Defects.
Kent, UK: Elsevier—Health Sciences Division, 2002.
Springer, Shelley C., and Annibale, David J. "Necrotizing
, November 25, 2002. Available online at
http://www.emedicine.com/ped/topic2601.htm (accessed November 30,