It’s not unusual for a parent or teacher to hear a child say, “My tummy hurts.” Most of the time, abdominal pain in children represents a brief problem that resolves on its own without any treatment. However, many children suffer from recurrent abdominal pain. It is the most common reason children are referred by their primary care provider to a pediatric gastroenterologist. In the past, the dominant view was that chronic or recurrent abdominal pain in children was a separate and distinct clinical entity from the irritable bowel syndrome found in teenagers and adults. It was believed that children were simply too young to develop IBS. However, as our understanding of the disorder has expanded, our views about IBS and children have also changed. In this chapter, I explain available data about abdominal pain in children and try to answer the question of whether recurrent abdominal pain in children is the forerunner of IBS in adulthood. In addition, I discuss the current diagnostic criteria for IBS in adolescents.
In the late 1950s Dr. Apley, a British pediatrician, observed that a large number of school-age children suffered from recurrent episodes of abdominal pain. He defined recurrent abdominal pain as repeated episodes of pain during a period of three months or more, each of which went away without treatment. He noted that in children who had recurrent abdominal pain, symptoms were likely to first occur at approximately age 5, and in girls there appeared to be a rise in occurrences during puberty. He found that the region around the umbilicus (belly button) was the most common site of pain, although it could develop anywhere in the abdomen. As in adults, the pain could be sharp or dull or aching and could be either continuous during an episode or intermittent. He carefully evaluated these children, but in only 10 percent was he able to identify a specific disease or disorder as the cause of the pain. In this small group (10 percent of all children studied), the most common causes of the pain were inflammatory bowel disease, celiac disease, and lactose intolerance.
For the vast majority of children Dr. Apley examined, however, a distinct cause of the pain could not be identified, so the abdominal pain was assumed to be functional in nature (meaning that no organic cause for it could be identified). He did note that abdominal pain seemed to be more frequent in children who were anxious or high-strung, and that overall, children who had chronic abdominal pain were more likely to have psychological problems than children who did not have abdominal pain.
For many of the children in this informal study, their abdominal pain went away as they grew older; however, a significant proportion had persistent symptoms that lasted into adulthood. Dr. Apley labeled this condition “recurrent abdominal pain of childhood,” or RAP, and this description is still used. The current most commonly accepted definition of RAP is at least three distinct episodes of abdominal pain during the course of three months, and the child’s activities must be affected by these episodes. For many years health care practitioners debated whether or not RAP was exactly the same as IBS. Recurrent abdominal pain of childhood does represent IBS in some cases; however, RAP is a broader category than IBS and includes three major subcategories: organic diseases (such as inflammatory bowel disease), functional disorders (like IBS and dyspepsia), and idiopathic disorders (conditions of unknown origin).
Another research study that addressed the issue of recurrent abdominal pain in children was conducted in the 1990s, nearly 40 years after Apley made his preliminary observations. This study was performed in part to take advantage of technology that was not available earlier. These technological advances make it easier to recognize medical conditions that were present decades ago but could not be easily or accurately diagnosed. Two such conditions are Helicobacter pylori infection (a cause of ulcers) and acid reflux disease. This study, which was done in Europe, evaluated 103 children with recurrent abdominal pain (all of whom were older than 3 years, with an average age of 10 years). The children underwent extensive testing, including blood work to look for celiac disease, blood tests to evaluate liver and pancreatic function, a complete blood count, tests to measure kidney function, sedimentation rate, urinalysis, stool studies (cultures, ova and parasites, fecal leukocytes, occult blood), tests for sickle cell disease (if appropriate), and an ultrasound of the abdomen. In addition, many children underwent invasive testing, including upper endoscopy, colonoscopy, and pH testing (to look for acid reflux disease); these tests were performed on an individualized basis and depended on the presence of certain symptoms and warning signs.
After this extensive battery of tests, an organic problem could be identified in less than a third of the children. In many cases, this organic problem was considered fairly minor (for instance, mild gastritis) or uncommon in children (inflammatory bowel disease, celiac disease). Sometimes the organic problem was one that is also present in approximately the same percentage of all children in the general population, which means that it was unlikely to be the cause of the child’s pain. One interesting observation was that pain at night and pain localized to a specific area usually had an organic cause, like inflammation, as opposed to a functional one.
Of the majority of patients whose pain was due to nonorganic causes, over half fulfilled the criteria for IBS. Health care workers determined that 36 percent of the children who entered the study had IBS. These results have been confirmed by two published American studies, which found that 26 to 51 percent of children who meet the criteria for RAP also fit the criteria for IBS. It appears that IBS in children is not uncommon. A 1996 study by the Connecticut Children’s Medical Center found that 17 percent of high school students and 8 percent of middle school students reported symptoms consistent with IBS. Other studies have confirmed these data. Overall, it is estimated that 10 to 20 percent of school-age children in the United States have symptoms of IBS.
Irritable bowel syndrome in children is a significant medical condition that warrants thoughtful evaluation and treatment because it can dramatically affect how children behave socially, adversely influence learning and school grades, and increase school absenteeism. In fact, IBS is one of the leading causes of school absenteeism across the country. In addition, IBS in children may necessitate frequent and costly physician visits and can disrupt family and social life.
Many children who have RAP do develop IBS later in life. In fact, one large research study found that approximately one-third of children who had RAP as a child had symptoms of IBS as an adult. This highlights the fact that better treatment options are needed for children in an attempt to minimize or even prevent this progression.
Irritable bowel syndrome in children is currently defined in much the same way as it is in adults (see Chapter 2), although no studies have verified or validated the Rome criteria for children. One major difference is that children need to have symptoms only once per week for at least two months before diagnosis (in adults, symptoms should be present for at least six months and active for the last three months before diagnosis). In children, IBS generally falls into one of three main types: pain predominant, constipation predominant, and diarrhea predominant. The pattern of alternating constipation and diarrhea found in nearly one-third of adults who have IBS is much less common in children. However, the bowel habits of young children differ from those of adults. The average baby has four to six stools per day during the first year of life. This decreases to an average of one to three stools per day after the age of one, and by age five, most children settle into nearly an adult pattern of bowel habits, meaning that they range from three bowel movements per day to three per week.
Symptoms of IBS are generally the same in children as they are in adults, with the following exceptions: bloating and distention appear to be less common in children than in adults; a pattern of alternating constipation and diarrhea is uncommon in children; and children are more likely to complain of nausea, especially after eating. Nausea after eating is most consistent with the diagnosis of dyspepsia (upper GI complaints), which occurs in 40 percent of adults who have IBS. While the passage of mucus with a bowel movement, occasionally noted in children who have symptoms of IBS, occurs in adults as well, it often generates more concern in children. Adults become aware that passing a small amount of mucus with a bowel movement is not unusual or uncommon; the mucus represents normal secretion from the cells that line the colon, and it coats the stool and facilitates evacuation.
The pathophysiology of IBS in children is thought to be similar to that in adults, although far fewer studies have been performed with children to verify the presence of the abnormalities in gastrointestinal motility and visceral sensitivity seen in adults. One of the reasons that few studies of children who have IBS exist is that researchers are reluctant to employ in children the invasive tests used in many of these diagnostic studies. These tests often require sedation, and they usually require the placement of a tube or catheter into the colon or small intestine. Most parents and pediatricians feel that the risks of these tests, although quite small, outweigh any possible benefits for the individual children. Thus, there is much less information available on children than on adults. However, some information is available that is worth discussing.
Like adults, children who have symptoms of IBS and diarrhea experience rapid transit of food through the GI tract, while those children who have symptoms of constipation have slower transit than normal. Children may have disordered motility in both the small intestine and the colon, including either more frequent contractions than normal or the presence of very strong contractions in the small intestine and colon. Strong contractions may cause abdominal cramps, spasms, and pain. The central nervous system is likely to play a major role in the manifestation of IBS symptoms in children as well, and certainly, as in adults, environmental influences that produce feelings of fear, anxiety, or stress can influence both gut motility and gut sensation. Two separate studies showed that feelings of fear and depression can delay the normal emptying of the stomach in children, while another study demonstrated that feelings of aggression can stimulate gut motility. Finally, studies have confirmed that visceral hypersensitivity probably plays a critical role in the manifestation of IBS symptoms in children, as it does in adults. In summary, the pathophysiology (abnormal physiology) of IBS symptoms in children appears to be quite similar to that in adults.
The etiology of IBS for children is probably the same as it is for adults. The fact that young children can develop IBS strongly suggests that there is at least a partial genetic basis for the development of IBS. A second important reason for the development of IBS in children is a preceding infectious illness. One study showed that children who have IBS were more likely than their healthy counterparts to have received antibiotics. The antibiotic use probably indicates treatment of an infection. External stressors and internal emotions like anxiety, fear, and depression seem to influence the frequency and severity of IBS symptoms, although, just as in adults, these factors are not the cause of IBS in children.
What external factors might precipitate the onset of symptoms? Very few studies have prospectively evaluated risk factors for IBS in children. A recently published Australian study reported on a group of people who were followed from age 3 to age 26 with routine examinations and questionnaires. Study participants in the highest socioeconomic group were much more likely to develop IBS than those in lower socioeconomic groups. Unfortunately, the study did not isolate which factors about a more privileged upbringing were associated with the development of IBS. More important, it seems that children who have not developed adequate coping skills are more likely to experience symptoms of IBS.
Several good research studies performed in the United States have focused on the relationships between parents who have IBS and their children. These studies were trying to determine whether a child who has a parent with IBS is at increased risk for developing IBS later in life. The answer seems to be an unqualified yes. Although having a parent who has IBS is not a guarantee that a child will develop IBS, it definitely makes it much more likely. There are several reasons why this may be so, beyond an inherited predisposition to the disorder. Children carefully observe their parents and notice their IBS symptoms and the way the parents handle the symptoms. The children may later mimic those same symptoms and responses. Sometimes children are in effect rewarded for being sick, by being given a special toy or treat. During a time when parents are busy, the extra attention a parent gives an ill child may unintentionally encourage the child to feel sick more often. For many children, school can be quite stressful. For some, stress develops at school because of learning difficulties; for others, stress occurs because they are being bullied. In an effort to avoid this stress, some children, consciously or unconsciously, take on illness behaviors. If they are then rewarded as well, the strategy is reinforced.
The initial steps in diagnosing IBS in children are the same as in adults (see Chapter 7). The health care provider needs to take a thorough history of the child’s symptoms and perform a complete physical examination. Most pediatricians believe that a careful evaluation of social and psychological factors is important as well. Children obviously have a shorter medical history to record than adults do, but there are as many, or more, topics to address. They include
• nature of the child’s birth (any complications)
• history of the child’s growth (normal, slow, periods of weight gain or loss)
• history of infections and how treated
• dates and place of any travel outside the United States
• usual source of drinking water; any episodes of contamination
• history of medication use, especially antibiotics
• history of diet and any dietary changes
• health of other family members (especially a history of parents who have IBS symptoms)
• history of IBS symptoms (first occurrence, frequency, severity, type)
• other physical problems (rashes, joint pain, fevers, vomiting, mouth ulcers)
• nature of nighttime behavior (sleep, GI problems)
Warning signs, or “red flags,” that might alert a pediatrician to an organic cause of a child’s symptoms, include the following (finding an organic cause means that symptoms are a result of a structural change in an organ):
• dysphagia (difficulty swallowing)
• persistent vomiting
• anemia (low blood count)
• pain that awakens the child from sleep
• nocturnal (nighttime) diarrhea
• ulcers in the mouth
• inflamed or swollen joints
• new rashes
• involuntary weight loss
• a slowing down of the normal growth curve
• unexplained fevers
• delay in attaining puberty
These symptoms, either alone or in combination, may prompt specialized tests and/or a referral to a specialist.
With regard to psychosocial factors, the health care provider will try to determine if symptoms are correlated with times of stress. Have symptoms occurred around the time of stressful events, such as tests at school, problems with friends, being bullied by another child, and/or difficulties at home (financial problems, parents fighting, parents going through a divorce, hospitalization or death of a parent, parent changing jobs, moving of the household)?
Currently, no guidelines specify the tests to be ordered for an evaluation of a child suspected of having IBS. In general, pediatricians take a more conservative approach than do health care providers who treat only adults. This is in part because in children, symptoms often represent a benign or transitory process that resolves on its own without any medical intervention. This approach, which is appropriate for children, is called “watchful waiting.” In contrast, physicians who treat adults often work on the assumption that there is an organic problem at the root of the patient’s symptoms and that this problem needs to be diagnosed. Thus, diagnostic testing is much more prevalent in adults. This approach is called “test and treat.”
For children who have recurrent or chronic abdominal pain and disordered bowel habits, many health care providers initiate the evaluation by performing blood tests, including a complete blood count (CBC) and a sedimentation rate (ESR). In addition, many pediatricians routinely order a urinalysis. For children who have persistent diarrhea, stool samples may be collected to look for evidence of an infection, and additional blood work may be requested to determine whether the child has celiac disease (a wheat allergy).
If abdominal pain persists, an abdominal x-ray may be taken. This can show whether a kidney stone is present, whether the child is severely constipated (e.g., stool is present throughout the entire colon), and whether there is evidence of a mechanical obstruction of the intestinal tract, among other findings. If the persistent symptoms are in the upper abdomen, the pediatrician may order an x-ray study of the upper GI tract (an upper gastrointestinal series). During this procedure, children are asked to swallow approximately a cup of barium solution, and then x-rays are taken as the barium coats the esophagus, stomach, and upper small intestine. This test can be used to look for evidence of an ulcer or other problem that could cause recurrent abdominal pain.
If all of the testing described above has yielded normal results and symptoms persist or if new symptoms develop, the child will usually be referred to a pediatric gastroenterologist, a physician who specializes in treating gastrointestinal disorders in children. At this point, the child may be scheduled for an upper endoscopy (EGD) if upper abdominal symptoms predominate or a colonoscopy if symptoms of lower abdominal discomfort, persistent diarrhea, or constipation predominate. In children, these tests are usually performed under general anesthesia rather than with conscious sedation. During general anesthesia, the patient is completely unconscious, and his or her breathing is assisted with the use of a ventilator. The patient is carefully monitored by an anesthesiologist, a nurse, and the physician performing the test. Colonoscopy would be especially important in evaluation of patients who have persistent diarrhea, because of the concern that the child could have inflammatory bowel disease (IBD).
Organic abnormalities are rarely found in children. In one study, only 4 percent of children who had recurrent abdominal pain and underwent colonoscopy and upper endoscopy were found to have an abnormality. Thus, if a careful history and physical examination are performed and warning signs of other disease are absent, and if a child meets the Rome criteria for IBS, then IBS is the likely diagnosis. This diagnostic approach has proven to be reliable for children as well as adults. The results of an Italian study support this approach. The study followed children who had been diagnosed with functional GI disorders and found that only rarely did an organic problem turn out to be the cause of their symptoms instead of IBS. A study from the Mayo Clinic reported similar findings. These data further support the practice of watchful waiting employed by most pediatricians.
Children who have severe constipation (significant straining at stool, very infrequent bowel movements) of long standing should be evaluated for Hirschsprung’s disease. This is an uncommon but well recognized condition that results from a lack of normal nerve supply in the anal and rectal area. Hirschsprung’s disease develops before birth, when nerve cells fail to migrate into the anorectal area. The missing cells are those that normally help the internal anal sphincter to relax, thus assisting evacuation. After birth, the smooth muscles in the anorectum cannot relax properly, and children become severely constipated. Hirschsprung’s disease can be diagnosed with anorectal manometry (see Chapter 8). In many cases, flexible sigmoidoscopy is performed as well, to make sure there is no evidence of obstruction. In the case of Hirschsprung’s disease, taking biopsies requires a surgeon, because the biopsies have to go through the entire thickness of the rectum. Definitive treatment for Hirschsprung’s disease involves surgery.
Encopresis is an uncommon problem in which there is repetitive passage of stool at inappropriate times. This evacuation of stool can be either voluntary or involuntary. The condition affects 1 to 3 percent of children over the age of 4. Encopresis is very different from fecal incontinence, which typically occurs in adults due to injury or trauma to the nerves or muscles in the anorectal area. People who have fecal incontinence usually leak small amounts of liquid stool. With encopresis, young children either repeatedly soil their underwear (which parents usually assume are recurrent episodes of diarrhea) or pass a formed bowel movement during the night.
Encopresis is unrelated to IBS and does not indicate any known neuromuscular disorder of the pelvic floor or anorectal area. It usually results from the withholding of stool in the rectum. The retained stool is then released while the child is asleep or at some other inappropriate time. Stool withholding may be voluntary (for any of a variety of reasons) or may represent an inability of the child to sense that there is stool in the rectum, which may represent a nerve disorder. In many cases, children who have encopresis have an underlying psychological problem, such as anxiety, depression, or severe stress or tension. Treatment of encopresis is generally directed at the underlying psychological problem (if present) and combined with bowel training.
The treatment for children who have IBS is similar in many ways to that for adults. Both the similarities and differences relate to the use of medications. It is not widely known that most medications used to treat disorders in children have never been tested on children. In fact, less than 25 percent of the medications currently available to the public have been tested directly in children, and even those have not been studied in the trials involving thousands of patients that are now required for approval of a medication for adults. At best, hundreds of children were included in the studies.
Why aren’t all medications tested in children before being released? There are four main reasons. One, health care workers are concerned with the safety of testing unproven medications on children. Two, most parents will not give consent for their children to participate in drug trials. Three, the cost of safety trials in children specifically, added to the already high cost of testing in adults, could further increase the cost of the medication. Four, pharmaceutical companies are worried that an even greater danger exists of their being sued when children are involved in drug studies than when the participants are adults. For example, let’s say that a company includes children in a medication study that determines that the medication is both safe and effective. However, 15 years later, after tens of millions of doses have been prescribed, new data comes to light showing that the medication can have serious long-term side effects. In the current legal climate, it is virtually guaranteed that a host of lawyers will sue the pharmaceutical company, saying that the medication caused harm to these children during the drug studies (whether it did or not). For all of these reasons, drug trials in children are few and far between. Because of that, most pediatricians are forced to rely on information from adult studies, which they then try to translate into useful information that they can apply to the pediatric population.
Faced with this shortage of information, most pediatricians try other treatment approaches before prescribing medications. After they identify the predominant symptom, whether it is pain, constipation, or diarrhea, the first step is typically some form of dietary intervention focused on eliminating foods thought to be triggering the symptoms. Depending on symptoms, dietary interventions may include a lactose-free diet, a fructose-free diet, a wheat-free diet, a diet free of eggs, or a diet without any caffeine (this includes avoiding soft drinks, cocoa, coffee, and tea). Many physicians also emphasize decreasing the amount of junk food and snack foods. For children who have constipation, bowel training and use of fiber supplements is recommended (and see Chapter 15).
Although no medication is approved by the FDA for the treatment of IBS with constipation in children, many health care providers recommend using a polyethylene glycol product (i.e., Miralax or glycolax) to help with the symptoms of constipation. However, as discussed in Chapter 16, the polyethylene glycol product won’t relieve the child’s abdominal pain. Other pediatricians recommend the use of lubiprostone, which is FDA approved for the treatment of women who have IBS and constipation and has been shown to be safe and effective. Trials are currently being performed with children, and data should be available in the near future.
Children who have problems with recurrent diarrhea are usually treated with small doses of Pepto-Bismol or Imodium (see Chapter 17) and helped to change their diet. Two recent studies reported that a lowdose tricyclic antidepressant (amitriptyline) improved quality of life and symptoms of anxiety for children who had IBS. However, amitriptyline did not significantly improve symptoms of abdominal pain in either study. A small clinical trial involving children who had IBS found that peppermint oil improved symptoms of abdominal pain, although the study results are weakened by the fact that the study lasted only two weeks.
Most pediatricians want to minimize medication use. They are concerned about overmedication and possible adverse events, such as fatigue, drowsiness, mood changes, and inability to function normally at school and during social activities. However, if initial treatment efforts fail, most will resort to the medications reviewed in the previous chapters, according to the predominant symptom. Because few of these medications have been subjected to rigorous testing in children, specific dosing guidelines for children are not provided in most standard pharmacology texts; the dosing guidelines are based on studies performed in adults. Generally, pediatricians calculate a quarter, third, or half of the lowest recommended adult dose, depending on the age and size of the patient. This is used as the starting dose, and when the patient is seen in follow-up, adjustments up or down can be made, if necessary. Safe, careful medication of children, like that of adults, focuses on starting with a low dose, increasing it slowly if necessary, maintaining regular follow-up with the patient, and watching for side effects and drug interactions. Fortunately, many children who have IBS respond well to simple dietary interventions and reassurance and do not require the use of any medications.
• Abdominal pain is a frequent but very nonspecific symptom in children. In the vast majority of cases, the pain goes away on its own without any treatment.
• Recurrent abdominal pain (RAP) of childhood represents a broad collection of disorders, including IBS.
• Ten to twenty percent of school-age children are estimated to have symptoms consistent with the diagnosis of IBS.
• Symptoms of IBS in children are similar to those in adults, with a few exceptions. Bloating and abdominal distention and IBS with alternating constipation and diarrhea are less common in children, and nausea is more common in children.
• Children who have IBS are often evaluated and treated more conservatively than adults who have IBS symptoms. A “watch and wait” approach prevents unnecessary diagnostic testing of children.