Necrotizing Enterocolitis in Infants

By Meg Marinis, Director of Medical Research Feb 23, 2012
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Baby Tommy is TINY. Not only was he born extremely premature at twenty-four weeks gestation, but also he only weighs fourteen ounces – less than one pound! Let's put that into perspective: According to the Centers for Disease Control and Prevention, preterm infants are those born before thirty-seven weeks gestation, and low birth weight describes any baby born less than five pounds and eight ounces. 

So like I said, Baby Tommy is TINY.

And to make matters worse, he has now developed necrotizing enterocolitis.

Mostly affecting premature infants, necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency seen in the Neonatal Intensive Care Unit (NICU). "Necrotizing" means death of tissue; "entero" means small intestine; "colo" means large intestine; and, "itis" means inflammation. Therefore, NEC can be defined as inflammation in the intestines that can be life-threatening if not treated promptly. It can affect only the intestinal lining or its entire thickness, but regardless, the damage may cause bacteria to leak out of the intestine and into the abdomen, causing an infection which can spread very quickly.

Here are a few important NEC stats:

- NEC affects only 1 in 2,000-4,000 births or between 1% and 5% of NICU admissions.

- 10% of babies weighing less than 3lb, 5 oz (1500 g) develop NEC.

- NEC typically occurs within the first two weeks of life, usually after milk feedings have begun.

There is no exact cause for NEC, but prematurity is the most common factor.

Preterm infants experience difficulty with blood and oxygen circulation, and therefore they are born with immature bowel. When food begins to move through these weakened intestines, the stress allows bacteria (normally present in the intestines) to invade and damage the intestinal walls. Subsequently, the infant will not tolerate feedings, become ill, and the infection may spread to the bloodstream.

Some researchers have also proposed additional risk factors such as the makeup of infant formula and the rate of the delivery of formula. Also, some babies undergo deliveries where they might be deprived of adequate oxygen levels. In those instances, the available oxygen and blood will circulate to the vital organs first, leaving the intestines with a shortage. And finally, babies born with increased red blood cells will have thickened blood, which will impede the transport of oxygen to the rest of the body, including the gastrointestinal tract.

NEC's symptoms include:

- Bloating or swelling in the belly.
- Poor tolerance to feeding.
- Decreased bowel sounds.
- Blood in the stool.
- Redness or abnormal coloring of the abdomen.
- Lethargy.
- Vomiting.
- Fever.
- Apnea (pauses in breathing).
- Slowed heart rate.

More severe symptoms have shown to be fluid in the abdominal cavity, peritonitis (infection of the membrane lining of the abdomen), and shock.

After noticing these symptoms, an abdominal X-ray will be taken.

If the imaging shows a "bubbly" appearance of gas in the intestinal walls, large veins of the liver, or air in the abdominal cavity, then doctors will seriously suspect that the baby suffers from NEC. They can confirm their diagnosis by inserting a needle into the abdomen to withdraw fluid – this finding indicates a possible hole in the intestines.

Before scheduling surgery, doctors will try and treat the infant's NEC medically. Feedings will be stopped and replaced with intravenous fluids for fluid replacement and nutrition. Doctors may place a nasogastric tube down the baby's nose into the stomach to safely remove air and fluid. Antibiotics will also be given to fight the infection, and frequent examinations and follow-up X-rays will ensue. However, if the baby worsens, or if the intestines perforate, surgery most likely will occur to remove the diseased portions.

Most infants with NEC do recover fully and may continue regular feeding after their tests have shown stable results. Unfortunately, a few infants will have residual problems if scarring and narrowing of the bowel occurs. And if the babies do in fact need surgery, they could suffer from malabsorption in the future – the inability of the bowel to absorb nutrients normally.

For more information on necrotizing enterocolitis, please visit:

http://www.nlm.nih.gov/medlineplus/ency/article/001148.htm