M–N

malabsorption Inadequate absorption of NUTRI-
ENTS into the BLOODcirculation from the SMALL
INTESTINEduring digestion, also called malabsorp-
tion syndrome. Malabsorption may result from
damage to the small intestine that restricts the
surface area of the intestinal mucosa (lining) or
may develop as a consequence of digestive
enzyme deficiencies. CELIAC DISEASE, LACTOSE INTOL-
ERANCE, CYSTIC FIBROSIS, GASTROENTERITIS, and
INFLAMMATORY BOWEL DISEASE(IBD) are among the
more common causes of malabsorption. Condi-
tions affecting the PANCREAS, LIVER, and GALLBLAD-
DER can result in secondary malabsorption.
Untreated malabsorption characteristically causes
NUTRITIONAL DEFICIENCIESand MALNUTRITION.
The diagnostic path may include stool analysis,
blood tests, and URINALYSIS. The gastroenterologist
may perform an ENDOSCOPYwith biopsy when pre-
liminary test findings are inconclusive. Treatment,
which often includes a combination of dietary and
medical management methods, targets any under-
lying condition. Secondary malabsorption gener-
ally goes away when the underlying condition
improves. Severe malabsorption with malnutrition
requires PARENTERAL NUTRITION(intravenous solu-
tions) to replenish the body’s nutrients. Malab-
sorption related to enzyme deficiencies often
resolves with dietary changes alone.
See also BORBORYGMUS; DIET AND HEALTH; DIGESTIVE
ENZYMES; NUTRITIONAL NEEDS; PANCREATITIS; SHORT
BOWEL SYNDROME; SMALL BOWEL TRANSPLANTATION;
STEATORRHEA; WHIPPLE’S DISEASE.

meconium The first stool a newborn passes,
made up of AMNIOTIC FLUID,BILE, and mucus. Meco-
nium resembles tar in consistency and color. Its
passing is a key indictor of the infant’s health and
gastrointestinal patency (clear passage). Infants

with healthy gastrointestinal systems pass their

first meconium stools within 24 hours of birth and

may continue to pass meconium for two or three

days. An infant that fails to pass meconium within

24 hours may have a congenital malformation of

the gastrointestinal tract such as BOWEL ATRESIA. A

complication common in infants who have CYSTIC

FIBROSIS, a genetic disorder that affects multiple

body systems, is meconium ILEUS in which

impacted meconium obstructs the bowel. Enemas

often relieve the impaction; when they do not,

surgery is necessary.

See also CHILDBIRTH; CONGENITAL ANOMALY; ENEMA.

nasogastric aspiration and lavage The clinical

term for the procedure commonly called “pump-

ing the STOMACH.” In nasogastric aspiration and

lavage, the health-care provider inserts a narrow

tube (catheter) through the NOSE, down the back

of the THROAT and the ESOPHAGUS, and into the

stomach. The stomach’s contents are then sucked

through the tube. The health-care provider may

also use the tube to instill a rinsing solution, often

a mixture of liquid and activated charcoal, into the

stomach to absorb and neutralize remaining gas-

tric content. Nasogastric aspiration and lavage is

most commonly an emergency treatment for

ingested toxins, including DRUG OVERDOSE, though

also can help diagnose gastric bleeding.

See also GASTROINTESTINAL BLEEDING; INGESTED

TOXINS.

nausea A sensation of queasiness and the feeling

of being about to vomit. Though nausea feels as

though it arises from the gastrointestinal tract, the

signals that initiate its sensations originate in two

areas of the BRAIN, the chemoreceptor trigger zone

and the emetic (VOMITING) center. These areas are

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