Definition
Intestinal obstructions are a partial or complete blockage of the small or large intestine, resulting in failure of the contents of the intestine to pass through the bowel normally.
Description
Intestinal obstructions can occur in children as a result of congenital defects, with symptoms appearing any time between birth and adulthood. Abdominal pain and vomiting are the most frequent symptoms and a common cause of admission to emergency rooms. It is difficult for doctors to predict at birth which infants will suffer intestinal obstructions.
Intestinal obstructions can be mechanical or nonmechanical. Mechanical obstruction is the physical blockage of the intestine by a tumor, scar tissue, or another type of blockage that prevents intestinal contents from getting past the point of obstruction. One type of mechanical obstruction is caused by the bowel twisting on itself (volvulus) or telescoping into itself (intussusception). Mechanical obstruction can also result from hernias, fecal impaction, abnormal tissue growth, the presence of foreign bodies in the intestines, or inflammatory bowel disease (Crohn's disease). Non-mechanical obstruction occurs when the normal wavelike muscular contractions of the intestinal walls (peristalsis), which ordinarily move the waste products of digestion through the digestive tract, are disrupted (as in spastic ileus, dysmotility syndrome, or psuedo-obstruction) or stopped altogether as in paralysis of the bowel walls (paralytic ileus).
Mechanical obstruction in infants under one year of age can be caused by meconium ileus, volvulus, intussusception, and hernias. Meconium ileus is a disorder that occurs in newborns in which the meconium, the neonate's first fecal excretion after birth, is abnormally thick and stringy, rather than the collection of mucus and bile that is normally passed. The abnormal meconium blocks the intestines and must be removed with an enema or through surgery. This condition is due to a deficiency of the enzyme trypsin and other digestive enzymes produced in the pancreas. It can be an early clue that the infant may have cystic fibrosis. Intussusception commonly follows an infection that causes increased lymph node size in the gut, which acts as the point of folding for the intussusception.
Hirschsprung's disease (congenital megacolon), which may involve meconium ileus, is a motility disorder that is responsible for 25 percent of newborn non-mechanical intestinal obstructions, though symptoms may not develop until late in infancy or in childhood, delaying diagnosis. Children diagnosed with Hirschsprung's disease lack nerve cells (ganglia) in the large intestine, severely affecting the wavelike movements that propel material through the colon. In most affected infants, the first sign is failure to pass a stool (meconium) within 24 to 48 hours after birth. Between birth and age two, these children will likely develop other symptoms, such as chronic constipation, small watery stools, a distended abdomen, vomiting, poor appetite, slow weight gain, and failure to thrive. Most children will require surgery to remove the affected part of the colon. Surgery can be performed at age six months or as soon as diagnosed in an older infant or child. Symptoms can be removed in at least 90 percent of children born with Hirschsprung's disease. The disease is sometimes associated with other congenital conditions, such as Down syndrome.
Volvulus is the twisting of the small or large bowel around itself (malrotation). Volvulus of the large bowel is rare in infants and children; when it does occur it is usually in the sigmoid (sigmoid volvulus) in the lower colon. Duodenal volvulus occurs when the duodenum, the portion of small intestine that connects the stomach and jejunum, is twisted. Twisting of any portion of the intestines may cut off the supply of blood to a loop of bowel (strangulation), reducing the flow of oxygen to bowel tissue (ischemia) and leading to tissue death (gangrene). Strangulation occurs in about 25 percent of bowel obstruction cases and is a serious condition that can progress to gangrene within six to 12 hours.
Intussusception is a condition in which the bowel telescopes into itself like a radio antenna folding up. Intussusception is the most common cause of intestinal obstruction in children between the ages of three months and six years. Boys are twice as likely as girls to suffer intussusception.
Hernias are weaknesses in the abdominal wall that can trap a portion of intestine (incarceration) and cut off the passage of food and waste through the digestive tract. In 1–5 percent of children, a hernia results when a feature of fetal anatomy in the inguinal area of the groin (processus vaginalis, the space through which the testis or ovaries descend) fails to close normally after birth. These inguinal hernias easily become incarcerated, trapping the bowel and causing obstruction. They are sometimes found on both sides (bilateral hernia) and they occur nine times more often in boys than girls. Parents may see a bulge in the groin area when an inguinal hernia is present. Incarceration occurs only rarely after eight years of age. In most cases, the incarcerated hernias are corrected manually rather than surgically by pushing the incarcerated bowel back up into the abdominal cavity.
Congenital adhesions or post-surgical adhesions can also cause intestinal obstruction in children. Adhesions are bands of fibrous tissue that can bind the loops of intestine to each other or to abdominal organs, narrowing the space between the intestinal walls or pulling sections of the intestines out of place, blocking the passage of food and waste. In adults, adhesions are most often caused by repeat surgery; children who have a history of abdominal surgery can also develop adhesions that can obstruct the intestines. It is not known precisely what causes the abnormal growth of fibrous tissue in congenital adhesions.
Demographics
Each year, one in 1,000 individuals of all ages are diagnosed with intestinal obstruction. Adhesions are responsible for 50–70 percent of cases. In children, 2.4 cases of intussusception are reported among 1,000 live births annually in the United States. Inguinal hernias occur in 1–5 percent of infants, with a male to female ratio of nine to one. Volvulus occurs in older children (mean age seven years) with a male to female ratio of 3.5 to one.
Causes and Symptoms
The causes of small bowel obstruction in children are most often volvulus, intussusception, adhesions, or abdominal hernia, a weakness in the abdominal wall that traps a portion of intestine. The most frequent causes of large-bowel obstruction are tumors, volvulus, or small pouches that form on the intestinal wall (diverticula) that can fill with waste and expand to block the intestines. Motility disorders such as Hirschsprung's disease and psuedo-obstruction may cause blockages by retarding peristalsis, the intestinal muscle contractions that move food and waste.
Meconium ileus in newborns is caused by increased viscosity of waste products in the intestinal tract, and is sometimes secondary to cystic fibrosis. Its primary symptom will be failure of the infant to eliminate the meconium within the first two days of life.
One of the earliest signs of mechanical intestinal obstruction is abdominal pain or cramps that come and go in waves. Infants typically pull up their legs and cry in pain, then stop crying suddenly. They may behave normally for as long as 15–30 minutes between episodes, only to start crying again when the next cramp begins. The cramping results from the inability of the muscular contractions of the bowel to push the digested food past the obstruction. A classic symptom is passage of "current jelly stool" (i.e. blood) by infants after a crying fit during intussusception. Some children with intussusception may appear lethargic or have altered mental status, believed by physicians to be related to ischemia of the bowel and a decreased level of consciousness.
Vomiting is another typical symptom of intestinal obstruction. The speed of its onset is a clue to the location of the obstruction. Vomiting follows shortly after the pain if the obstruction is in the small intestine, but is delayed if it is in the large intestine. The vomited material may be green from bile or fecal in character. If the blockage is complete, the individual will not pass any gas or feces. If the blockage is only partial, however, diarrhea can occur. Initially there is little or no fever.
When the material in the bowel cannot move past the obstruction, the body reabsorbs large amounts of fluid and the abdomen becomes sore to the touch and swollen (distended). Persistent vomiting can result in dehydration. Fluid imbalances upset the balance of certain important chemicals (electrolytes) in the blood, which can cause complications such as irregular heartbeat and, without correction of the electrolyte imbalance, shock. Kidney failure is a serious complication that can occur as a result of severe dehydration and/or systemic infection from perforation of the bowel.
When to Call the Doctor
Medical attention is needed early in intestinal obstruction and should be sought as soon as symptoms suggest abdominal distress. Symptoms may begin with abdominal pain or cramping that may cause a toddler or older child to double over in pain. Infants will periodically cry in pain and pull their legs up to their chest. Fever may or may not be present. Vomiting may occur along with pain. If pain and crying occur every 15 or 30 minutes, it is critical to see the pediatrician or go to the emergency room so that early diagnosis can be made and treatment begun.
Diagnosis
If the doctor suspects intestinal obstruction based on the child's symptoms and the physical examination, imaging studies will be ordered that may include abdominal x rays, computed tomography (CT scan), or an ultrasound evaluation of the abdomen. Abdominal ultrasound is able to effectively visualize and diagnose most obstructions. The x ray images may be enhanced by giving the child a barium enema, a form of contrast or opaque media that allows more detail to be seen in x rays and MRI or CT scans. In a barium enema, barium sulfate is infused through the rectum and the intestinal area is scanned. With contrast enhancement, the exact location of the obstruction can be pinpointed in the scans or x ray film. Sometimes a lighted, flexible fiber optic instrument (sigmoidoscope) may be inserted rectally in conjunction with a barium enema to visualize the bowel. It may not possible to determine if an obstruction is simple or strangulated on scanning, and this will only be determined by performing abdominal surgery.
Diagnostic testing will include a complete blood count (CBC), electrolytes (sodium, potassium, chloride) and other blood chemistries, blood urea nitrogen (BUN), and urinalysis. Coagulation tests may be performed if the child requires surgery.
Treatment
Children with suspected intestinal obstruction will be hospitalized after the initial diagnostic evaluation. Treatment will likely begin immediately and proceed rapidly to avoid strangulation, which can be fatal. The first step in treatment is inserting a nasogastric tube to suction out the contents of the stomach and intestines. Intravenous fluids will be infused to prevent dehydration and to correct electrolyte imbalances that may have already occurred. Surgery can be avoided in some cases. With volvulus, for example, it may be possible to guide a rectal tube into the intestines to straighten the twisted bowels. In infants, a barium enema may reverse intussusception in 50–90 percent of cases. Another newer contrast agent, gastrografin, may be used; it is believed to have therapeutic properties as well as its ability to enhance scans. An air enema is sometimes used instead of a barium or gastrografin enema. This treatment successfully relieves partial obstruction in many infants. Children usually remain hospitalized for observation for two to three days after these procedures.
Surgical treatment will be necessary if other efforts are unsuccessful in correcting or removing the blockage. Generally, complete obstructions require surgery while partial obstructions do not. Strangulated obstructions require emergency surgery. The obstructed area is removed and part of the bowel is cut away (bowel resection). If the obstruction is caused by tumors, polyps, or scar tissue, they will be surgically removed. Hernias, if present, are repaired to correct the obstruction. Antibiotics may be given pre- or post-operatively to avoid the threat of infection at the site of the obstruction. Fluid replacement is given intravenously as needed.
Alternative Treatment
Immediate surgery is often the only means of correcting intestinal obstruction. Alternative practitioners may recommend a high fiber diet to encourage proper stool formation; however, simple constipation is not the cause of intestinal obstruction.
Prognosis
Most intestinal obstructions can be corrected with prompt treatment and the affected child will recover without complications. Untreated intestinal obstructions can be fatal, however. The bowel either strangulates or perforates, causing massive infection. Recurrence is likely in as many as 80 percent of those in whom volvulus is treated medically rather than surgically. Recurrences in infants with intussusception are most likely to happen during the first 36 hours after the blockage has been cleared. The mortality rate for unsuccessfully treated infants is 1–2 percent.
Prevention
Most cases of intestinal obstruction are not preventable. Surgery to remove tumors or polyps in the intestines helps prevent recurrences, although adhesions can form after surgery, which can be another cause of obstruction.
Nutritional Concerns
Preventing certain types of intestinal problems that may lead to intestinal obstruction may include making sure that the diet includes sufficient fiber to help encourage proper stool formation and regular elimination. High-fiber foods include whole grain breads and cereals; apples and other fresh fruits; dried fruits such as prunes; pumpkin and squash; fresh raw vegetables; beans and lentils; and nuts and seeds.
Parental Concerns
Diagnosis of intestinal obstruction in a child is dependent on recognizing related symptoms. Parents may be concerned about preventing intestinal problems in their children and about missing the symptoms of possible intestinal obstruction. It is important to remember that a healthy diet with plenty of whole fruits, vegetables, and grains, and drinking a sufficient amount of water each day, will help keep the intestines healthy and elimination regular. Parents should be aware of the child's bowel habits and report constipation, diarrhea, abdominal pain, and vomiting to the pediatrician when it occurs. Diagnosed early, intestinal obstruction can be corrected without complications.
Resources
Books
Allan, W., M.D., et al. Pediatric Gastrointestinal Disease: Pathophysiology, Diagnosis, Management, 3rd ed. Boston: BC Decker, 2000.
"Intestinal Obstruction." The Merck Manual of Medical Information, Second Home Edition Eds. 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. (800) 274-2237. Web site: .
Web Sites
Intestinal Obstruction. National Library of Medicine, Medical Encyclopedia, 2004. [cited October 11, 2004]. Available online at: .
Intestinal Obstruction (Pediatric). A.D.A.M., 2002. [cited October 11, 2004]. Web site: www.medformation.com/ac/adamsurg.nsf/page/100165.
[Article by: L. Lee Culvert Tish Davidson, A.M.]
