Chapter 56. Abdominal and Pelvic Pain in Children and Adolescents

Recurrent abdominal pain (RAP) refers to a condition described by Apley1 of paroxysmal abdominal pain in children between the ages of 4 and 16 years. These children are otherwise healthy, but the abdominal pain persists for more than 3 months and affects normal activity.2 RAP is very common, occurring in approximately 10% to 20 % of school-aged children.3

RAP has certain characteristic features that help to distinguish it from other sources of chronic abdominal pain in children and adolescents. Typically, patients experience episodes of pain interspersed with pain-free periods. Fewer than 10% of patients report continuous pain. Males and females are equally affected in early childhood; however RAP is more common in females in early adolescence at a ratio of 5:3.4 Children frequently describe periumbilical pain that is diffuse in location, and many children will have difficulty describing their pain. Rarely does the pain of RAP radiate to the back or chest. Children often report that their pain worsens at night and that they have difficulty falling asleep. Pain that wakes a child from sleep is not characteristic of RAP and should warrant further investigation. Approximately 50% to 70% of children will experience headaches, nausea, or dizziness during the episodes, which can be of variable severity.5 There is often a family history of migraines, irritable bowel disease, or ulcer disease.

Most cases of RAP are described as functional, which refers to a lack of readily identifiable specific biochemical, structural, infectious, or other organic abnormality. This lack of ability to diagnose a specific physiologic disorder may be a result of limitations in our understanding of RAP or of limitations in ways to test for a physiologic abnormality. Functional RAP does not imply psychogenic causes. Most children with RAP are, in general, medically and psychologically well. A subgroup of patients will have lactose intolerance, ureteropelvic junction obstruction, inflammatory bowel disease, endometriosis, or gastroesophageal reflux. In most cases of functional RAP, an underlying organic cause is rarely eventually diagnosed.6 A 5-year follow-up study by Walker et al7 reported that only 1 in 31 patients with RAP eventually received a diagnosis of a specific organic disorder. Other longitudinal studies show that only 30% of children with RAP have resolution of their pain within 5 years, and 25% to 50% continue to have symptoms as adults.4,8,9

There can be varying degrees of disability associated with RAP; however, most children with RAP are able to function well despite their symptoms. Children seen at pediatric pain clinics represent a subpopulation with more severe disability. At least 28% of children with RAP miss more than 1 out of 10 days of school. School absenteeism in children and adolescents is a sign of significant functional disability and is analogous to workman disability in adults. Patients with RAP can develop altered peer and family relationships, which may further reinforce a patient’s maladaptive behavior. In a study by Gaber et al,10 mothers of children with RAP reported more child somatic and depressive symptoms than did their children.

A number of studies in the past 6 years have investigated the possibility of a specific underlying organic disorder in RAP. Roma et al11 performed 396 upper endoscopies in children with RAP and found a remarkably high incidence of gastric inflammation (85%) and Helicobacter pylori infection (28%). A limitation of this study was that not all patients had classic symptoms of RAP as described by Apley. A systematic review of six prospective, controlled studies by MacArthur12 found that current evidence suggests no association between H. pylori infection and RAP in children with symptoms based on Apley’s criteria. On the basis of these findings, MacArthur concluded that routine endoscopies are not indicated in children with RAP without symptoms of esophageal or gastric pathology.

Webster and colleagues13 evaluated 137 children with RAP by screening history and physical examination, blood chemistry tests, and breath hydrogen testing. They found lactose intolerance in 24% of patients. The study reported that symptoms of lactose intolerance such as abdominal pain, bloating, diarrhea, and constipation were similar in children with and without lactose maldigestion, and that clinical evaluation alone could not reliably predict which children were lactose intolerant. Children with positive breath testing had improvement in clinical symptoms with a lactose-restricted diet, suggesting that a trial of a lactose-restricted diet may be appropriate in children with RAP.

Gastrointestinal motility studies in children using manometry and measurements of intestinal transit have suggested increased intestinal muscle contraction and delayed transit time in children with RAP. There is controversy in the interpretation of motility tests in children. Olafsdottir et al14 used ultrasonography to measure proximal and distal gastric volumes following test meals in children with and without RAP. Children with RAP had smaller cross-sectional areas in the proximal stomach with more pain and sensation of bloating. They concluded that differences in gastric volumes following a test meal were related to impaired relaxation of the proximal stomach, which may support the view of altered motility in these patients.

Some studies have suggested that RAP in children and adolescents may be a precursor to irritable bowel syndrome (IBS) in adults. Hyams et al15 studied 171 patients with RAP and found that 117 patients had IBS that met the standardized criteria for IBS in adults. Walker and coworkers16 reported on a 5-year follow-up study of children and adolescents with RAP to determine the likelihood of progression to adult-type IBS symptoms. They found that female patients with RAP were more likely than a control group to meet criteria for IBS in adults, and that patients with RAP who had IBS symptoms experienced greater functional disability, higher levels of depression, and more clinic visits. A potential relationship between RAP and IBS may have therapeutic implications as new 5HT3 inhibitors, such as alosetron, are used for treatment in adult patients with IBS.17,18

The diagnosis of RAP should be based on a careful history and thorough physical examination that will point the clinician to a presumed diagnosis or to focused diagnostic tests. A physical examination should include a rectal examination and stool guaiac and an evaluation for undescended testes, hernias, abdominal fullness, or masses. Findings on history and physical examination that suggest the possibility of an underlying organic disorder should serve as guide to laboratory and other diagnostic tests. In general, extensive routine screening tests are of low yield, especially in patients with an otherwise normal history and physical examination. Screening radiographic studies and endoscopies have particularly low yield without specific clinical suspicions.19 A study by Wever et al20 examined children with RAP by ultrasonography and found an abnormality in 7% of patients. However, other studies examining the use of ultrasound in children with RAP have shown that abnormalities found on ultrasound could have been predicted by history and physical examination and focused laboratory testing. Extensive testing may increase patient and parental anxiety and even reinforce a patient’s sick role. In addition to a history and physical examination, baseline complete blood count and urinalysis help rule out occult organic disease such as inflammatory bowel disease and ureteropelvic junction obstruction. In making the diagnosis of RAP, patients should have the characteristic features with respect to age, chronicity, location of pain, and absence of concerning findings on history and physical examination. Any evidence of systemic illness on either history or physical examination such as fever, rash, weight loss, joint pain, or failure to follow growth curve should prompt further investigation of organic causes.21 Occurrence of persistent or recurrent abdominal pain in a child younger than 4 years should also prompt further workup. A family history of inflammatory bowel disease in a child with chronic abdominal pain warrants further laboratory testing, such as sedimentation rate, and possibly further diagnostic testing, such endoscopy and/or colonoscopy.21

Once an organic disorder has been excluded, a significant component of treatment is education and reassurance of patient and parents that a serious illness is not the cause of symptoms. It should be emphasized that the pain is genuine; patients are not “faking it” or malingering. A functional approach with emphasis on cognitive-behavioral treatment is used in our clinic.22,23 Treatment is directed at reducing maladaptive and pain-reinforcing behaviors in patients and their families and improving coping skills. Underlying anxiety or depression is addressed. Return to school and participation in normal activities is essential. Often a plan to return to school is coordinated with the school and the psychologist, particularly in patients who have developed signs of school avoidance. Extensive diagnostic tests, referrals to subspecialists, and multiple medication trials may heighten anxiety in patients and parents and may reinforce pain behaviors. A trial period of a lactose-restricted diet and lactose supplementation may be helpful. Fiber supplementation was successful in reducing pain episodes in one study of children with RAP; however, excessive fiber supplementation may be associated with increased symptoms. Tricyclic antidepressants are often used in conjunction with biofeedback, self-hypnosis, and other behavioral-cognitive therapy. There are limited data on the efficacy of drug therapy, such as tricyclic antidepressants, antispasmodics, and anticonvulsants, in the treatment of RAP. Tricyclic antidepressants may be helpful in patients with sleep disorders; however, higher doses may worsen symptoms in patients who have constipation.

Pelvic pain is one of the most frequent presenting symptoms of adolescent women. Typically, chronic pelvic pain (CPP) affects women during their reproductive years but can occur in young adolescents prior to menstruation. Usually, patients have experienced at least 3 months of constant or intermittent pelvic pain and have seen a variety of physicians without significant relief in their symptoms. Patients often experience moderate to severe pain, significant school absenteesim, and have tried a number of analgesics.

In most cases, there is a gynecologic cause for CPP in adolescent women. The more common gynecologic diagnoses among adolescents with CPP are endometriosis and pelvic adhesions.24 However, a subgroup of patients will have gastrointestinal, urologic, and musculoskeletal disorders that present as pelvic pain. In a review of 282 patients undergoing diagnostic laparoscopy for chronic pelvic pain, Emans et al found that 45% of patients had endometriosis, 13% had postoperative adhesions, and 25% had no identifiable pathology.24 The authors reported that patients 16 years of age and older were 2 to 3 more times likely to have endometriosis on diagnostic laparoscopy than patients between 11 and 15 years of age; however, the incidence of no identifiable pathology was similar for all age groups. Laufer et al found that on laparoscopy in patients with CPP who did not respond to conservative management with oral contraceptives and nonsteroidal anti-inflammatory drugs (NSAIDs), 70% of patients had endometriosis and almost 24% of patients had adhesions.25 In addition to pelvic pain, 34% of patients with endometriosis also experienced gastrointestinal symptoms and 12.5% experienced urologic symptoms.

Endometriosis is the growth of endometrial tissue outside the uterus associated with inflammatory reactions, scarring, and fibrosis. Most endometrial implants contain estrogen, progesterone, and androgen receptors and are regulated by steroid hormones. In general, estrogen stimulates the growth of endometrial implants, and androgens induce their atrophy. The cause of pain associated with endometriosis is unclear but is probably related to the release of prostaglandins, peritoneal inflammation, and scar formation. It occurs in approximately 15% of all menstruating women ranging in age range from 10.5 to 76 years.26 Endometriosis accounts for 45% of CPP in adolescents, compared with 30% in adult women, and 70% of adolescents with CPP who fail conventional therapy.24,25 Unlike adult women who primarily experience cyclic pain, adolescent women with endometriosis report both cyclic and acyclic pain.25

Over 90% of female adolescents with CPP referred to our clinic have endometriosis. This represents a subpopulation of patients who, despite aggressive surgical and medical therapy, continue to have significant pain and disability. Resistance to medical therapy may be explained in part by insufficient estrogen and progesterone receptors in endometrial implants. Treatment of endometriosis and CPP consists of a combination of medical and surgical management. Once a presumed diagnosis of endometriosis is made, patients begin a trial of NSAIDs and oral contraceptives. Hormonal therapy attempts to create a hypoestrogenic state and atrophy of endometrial tissue, and has been reported to be 90% effective in either reducing or resolving pain in patients with endometriosis. For continued or severe pain, pelviscopy can confirm the diagnosis of endometriosis through biopsy and tissue diagnosis and permits laser ablation of the endometriosis. There is no obvious correlation between the severity of pain and dysfunction and the extent of disease found on laparoscopy. A trial of GnRH agonists such as Lupron usually follows surgical therapy.

Our clinic uses a multimodality treatment plan consisting of biobehavioral therapy, physical therapy, and selected medication trials. Patients should be evaluated for other conditions in addition to endometriosis that might be contributing to their CPP, such as constipation, irritable bowel symptoms, urolithiasis, or psychosocial stresses. The pain associated with CPP may be multifactorial. A prospective, randomized trial by Peters et al compared the outcome of patients with pelvic pain who were evaluated for organic and psychosocial causes of pain at the initial visit with patients with pelvic pain who were evaluated for psychosocial causes of pain only after organic causes were ruled out.27 The patients in the group that had organic and psychosocial causes of pelvic pain had better response to therapy and had improved long-term outcome. As in the treatment of RAP, a functional approach is emphasized with return to school, participation in social and family activities, and recognition of reinforcers of maladaptive behaviors. Pelvic pain support groups, TENS unit, and acupuncture have been helpful in many of our patients. COX-2 inhibitors may be effective for patients who experience gastrointestinal distress with other NSAIDs. Medication trials of tricyclic antidepressants and anticonvulsants may be indicated, although there are little data on efficacy. Opioids are rarely used for long-term treatment.