Duodenal obstruction is a partial or complete obstruction of the duodenum, the first part of the small intestine. Obstruction prevents food from passing through the digestive tract, interfering with digestion and nutrition.
Description
The duodenum is the first part of the small intestine, extending from the valve at the bottom of the stomach that regulates stomach emptying (pylorus valve) to the second part of the small intestine (jejunum). It is a short but often troublesome section of the digestive tract. The stomach, gallbladder, and pancreas each empty their contents into the duodenum in anticipation of digestion. Obstruction prevents the normal passage of stomach contents into the duodenum and keeps the gallbladder and pancreas from draining their secretions. This problem can lead to a number of conditions and complications involving digestion, nutrition, and fluid balance. In infants and children, congenital defects (anomalies)
usually cause duodenal obstruction, and symptoms are present at birth or shortly after when the infant attempts to feed.
When obstruction occurs, regardless of cause, food, gas, and secretions from within the intestine will accumulate above the point of obstruction, bloating (distending) the affected portion of intestine. Infection of peritoneal tissue lining the intestines and the abdomen (peritonitis) may result from bacteria growing in the accumulation of undigested material. As the distention increases, fluids continue to increase, and the intestine absorbs less. The fluid accumulation and reduced absorption lead to bilious vomiting, which is the vomitus will appear greenish, the classic sign of upper intestinal obstruction. Persistent vomiting or diarrhea (which can occur in a partial blockage) can result in dehydration. Fluid imbalances upset the balance of specific essential chemicals (electrolytes) in the blood, which can cause complications such as irregular heartbeat and, without correction of the electrolyte imbalance, shock.
In newborns, congenital duodenal obstruction can occur when the duodenal channel (duodenal lumen) is not correctly formed (recanalized) during fetal development. The duodenum may have a membrane reducing the channel size (lumen), or two blind pouches instead of one duodenal channel, or a gap or flap of tissue may be present. In each case, the channel is not be sufficiently developed at birth or sufficiently open to allow the passage of food and liquid, resulting in poor digestion and poor nutrition. This condition is known as duodenal atresia, and it results in duodenal obstruction. About 30 to 50 percent of infants born with duodenal atresia also have Down syndrome, and some have cardiac abnormalities as well. Duodenal atresia can occur with other conditions such as a narrowing of the duodenal lumen (duodenal stenosis) or twisting of the duodenum around itself (duodenal volvulus). It may also occur in combination with volvulus in another part of the bowel below the duodenum. Inflammation of the pancreas (pancreatitis) may also accompany duodenal atresia.
Malrotation of the duodenum is a more common cause of duodenal obstruction, typically appearing in the first few weeks of life. In malrotation, the duodenum is usually coiled to the right, causing obstruction of the duodenum and failure of the stomach contents to pass through to the next portion of small intestine. Malrotation may also involve the presence of Ladd's bands, abnormal folds or bands of tissue under tension across the lumen of the duodenum. Malrotation can also occur with duodenal volvulus or volvulus lower in the bowel. With volvulus, it can result in serious consequences by cutting off the supply of blood to a portion of bowel (strangulation), reducing the flow of oxygen to bowel tissue (ischemia), and leading to tissue death (gangrene) and shock or to rupture (perforation) of the intestine. Surgery is required immediately to correct this type of duodenal obstruction.
Demographics
Duodenal atresia, one of the causes of duodenal obstruction, affects one in 10,000 live births in the United States and is found equally among boys and girls and more often among premature births. Intestinal malrotation is a more common cause, occurring in one in 500 live births, although only a small percentage of these have duodenal malrotation. The male to female ratio is two to one in the first year of life and then becomes equal.
Causes and symptoms
Obstruction of the duodenum occurs in infants as a result of congenital causes. The duodenal channel may be underdeveloped (duodenal hypoplasia), narrowed (duodenal stenosis), or the duodenum channel may not be properly formed (duodenal atresia). Malrotation or coiling of the duodenum can also obstruct the duodenum, sometimes accompanied by volvulus, a twisting of the duodenum around itself. As of 2004 the specific cause of these congenital defects was not known.
Vomiting is the prevailing symptom of duodenal obstruction and may occur in the first day of life. The vomitus will be greenish (bilious) because it contains bile from the gallbladder. An infant will vomit feedings, lose weight, and be restless and irritable. Other symptoms may include difficulty breathing, excessive salivation and drooling, the presence of a palpable mass in the abdomen, yellow-tinted skin (jaundice), and failure to respond (lethargy). If the duodenum is twisted as in volvulus, the newborn may have a distended abdomen and bloody diarrhea.
When to call the doctor
Frequent or constant vomiting, unsuccessful feeding, and poor weight gain should be reported to the pediatrician as soon as noted. If an infant in the first few weeks of life pulls the knees up and intermittently cries in pain along with frequent vomiting, the pediatrician should be consulted immediately, and examination in the emergency department of the hospital may be necessary.
Diagnosis
Abdominal x-rays will be performed and will typically show what is called the characteristic "double bubble," a combination of air bubbles in the stomach and a dilated duodenum. An echocardiogram and chest x rays may be done to evaluate the infant for any other possible abnormalities, including cardiac defects and abnormal development of the pancreas, which is often associated with duodenal obstruction. If malrotation is suspected, contrast-enhanced x rays of the upper intestinal region are usually able to visualize the twisted duodenum. Ultrasound imaging may also be used to evaluate these conditions.
Diagnostic tests performed in the clinical laboratory will include a complete blood count (CBC), electrolytes (sodium, potassium, chloride), blood urea nitrogen (BUN), and other blood chemistries, especially to evaluate kidney and pancreas function. A urinalysis will be performed. Coagulation tests may be performed if the child is going to have surgery.
Treatment
Duodenal obstruction requires surgery, but it is not always urgent. Treatment may be delayed to evaluate or treat other life-threatening congenital anomalies. A nasogastric tube will first be placed through the infant's nose down into the stomach to decompress both the stomach and duodenum. Intravenous fluids may be given to maintain fluid levels and urine output or to correct dehydration that already has occurred. Electrolyte solutions may be given intravenously to restore electrolyte balance. Surgery to correct duodenal atresia is usually duodenoduodenostomy. It involves opening the duodenum channel along its length from the stomach to the next portion of intestine, correcting the duodenal lumen end to end (gastrojejunal anastomosis) so that it is a fully open channel.
KEY TERMS
Anastomosis—Surgical reconnection of two ducts, blood vessels, or bowel segments to allow flow between the two.
Anomaly—Something that is different from what is normal or expected. Also an unusual or irregular structure.
Atresia—The congenital absence of a normal body opening or duct.
Bowel—The intestine; a tube-like structure that extends from the stomach to the anus. Some digestive processes are carried out in the bowel before food passes out of the body as waste.
Contrast agent—Also called a contrast medium, this is usually a barium or iodine dye that is injected into the area under investigation. The dye makes the interior body parts more visible on an x-ray film.
Electrolytes—Salts and minerals that produce electrically charged particles (ions) in body fluids. Common human electrolytes are sodium chloride, potassium, calcium, and sodium bicarbonate. Electrolytes control the fluid balance of the body and are important in muscle contraction, energy generation, and almost all major biochemical reactions in the body.
Gangrene—Decay or death of body tissue because the blood supply is cut off. Tissues that have died in this way must be surgically removed.
Hypoplasia—An underdeveloped or incomplete tissue or organ usually due to a decrease in the number of cells.
Ischemia—A decrease in the blood supply to an area of the body caused by obstruction or constriction of blood vessels.
Lumen—The inner cavity or canal of a tube-shaped organ, such as the bowel.
Peritonitis—Inflammation of the peritoneum. It is most often due to bacterial infection, but can also be caused by a chemical irritant (such as spillage of acid from the stomach or bile from the gall bladder).
Shock—A medical emergency in which the organs and tissues of the body are not receiving an adequate flow of blood. This deprives the organs and tissues of oxygen and allows the build-up of waste products. Shock can be caused by certain diseases, serious injury, or blood loss.
Ladd's procedure is used to surgically correct malrotation. The abdomen is opened and the large intestine is placed to the left side in order for the doctor to perform the surgery. The appendix is usually removed to avoid a later diagnosis of appendicitis. The malrotation, stenosis, or membranous bands are corrected surgically so that
the duodenum has a normal opening and connects properly to the stomach and jejunum. Broad-spectrum antibiotics may be given to help avoid infection.
Prognosis
Prognosis will depend on the type and extent of the obstruction, the infant's age at diagnosis, the infant's overall condition, and the presence and severity of any other congenital anomalies. Survival rates for surgical repair of the duodenum is greater than 90 percent, regardless of the cause. Most children do not have continuing digestive problems. Complications occur in 12 to 15 percent of those undergoing surgery. Complications can include other digestive disorders such as intestinal motility, duodenogastric reflux, gastritis, peptic ulcers, and megaduodenum. If malrotation or duodenal volvulus has caused the blood supply to be cut off in a portion of the intestine before surgery, death of intestinal tissue can result and life-threatening gangrene can develop. Widespread infection (peritonitis) may also develop from bacteria growing in the accumulation of undigested material above the obstruction. Mortality in infants who have gangrene or peritonitis is particularly high in those with other defects.
Prevention
No specific measures are recommended to prevent congenital anomalies that result in duodenal obstruction.
Parental concerns
In most cases, parents do not know before the birth of the child that an intestinal obstruction is present, although sometimes examination of the amniotic fluid during pregnancy (amniocentesis) alerts the obstetrician of possible abnormalities and prepares parents for the diagnosis. If obstruction is suspected or diagnosed in the first few days of the child's life, parents may be concerned about the risks associated with surgery and possible complications in infancy or early childhood. Parents can be reassured that newer surgical techniques have constantly improved the outcome of surgeries for intestinal obstruction, including duodenal obstruction. Diagnosed early, intestinal obstruction can be corrected with few complications, and a child who does not have other congenital problems usually is able to resume normal development.
Resources
Allan, W., et al. Pediatric Gastrointestinal Disease: Pathophysiology, Diagnosis, Management, 3rd ed. Boston, MA: B. C. Decker, 2000.
"Intestinal Obstruction." The Merck Manual of Medical Information, 2nd ed. Edited by Mark H. Beers et al. White House Station, NJ: Merck & Co., 2003.
ORGANIZATIONS
American Association of Family Physicians. 11400 Tomahawk Creek Parkway, Leawood, KS 66211-2672. Web site: <www.aafp.org>.
WEB SITES
"Intestinal Obstruction." MedlinePlus, 2004. Available online at <www.nlm.gov./medlineplus/ency/article/000260.htm> (accessed December 21, 2004).
