Functional Abdominal Pain

Introduction

Chronic abdominal pain is a commonly encountered clinical problem in pediatrics that can be devastating for patients and their families, and difficult and costly to manage as a provider.

• It is defined as intermittent or constant abdominal pain that is present for at least two months, and can be divided into organic etiologies:
  • anatomic, physiologic, or biochemical dysfunction,
  • functional etiologies that occur without an identifiable cause within those domains.
• Functional etiologies are more common than organic causes, making functional abdominal pain the most common cause of chronic abdominal pain in children and adolescents.
• The four criteria that classically define functional abdominal pain disease process are:

1. Greater than or equal to three episodes of abdominal pain.
2. Pain severity great enough to affect daily activities.
3. Pain episodes occuring over greater than or equal to three months.
4. No identifiable organic cause of pain.

Pathophysiology

The pathophysiology of functional abdominal pain is poorly understood, but may be related to the interplay between neuro-regulatory factors shared by the enteric and central nervous systems.

Epidemiology

• Population-based studies of children aged 2 to 6 years found the prevalence of chronic abdominal pain to be 11.8% in six-year-old children.
  • Community based studies found that 17% of high school students suffered from chronic abdominal pain.
  • A pooled meta-analysis of 58 prevalence studies conducted all around the world with a patient population ranging from 4-18 years showed an overall prevalence of functional abdominal pain disorders of 13.5%.
  • There is a higher prevalence of disease burden among female patients and those who suffer from comorbid psychiatric illness, especially anxiety and depression.

Presentation

• The distinction between functional and organic causes for patients with chronic abdominal pain is often blurry
  • There can be significant overlap between the two etiologies.
    • Psychosocial stressors can trigger or exacerbate organic sources of chronic abdominal pain.
  • The largest distinction between the two major divisions of chronic abdominal pain are the presence of alarm findings on history or physical examination. These include:
    • Involuntary weight loss
    • Growth retardation (height gain <5 cm/year in a pre-pubertal child and/or delayed puberty)
    • Dysphagia, odynophagia
    • Significant emesis (bilious, protracted, projectile)
    • Diarrhea (3 or more loose or watery stools per day for more than two weeks)
    • Unexplained fever
    • Urinary symptoms (change in bladder function, dysuria, hematuria, flank pain)
    • Gastrointestinal blood loss
    • Hepatosplenomegaly,
    • Localized tenderness (RUQ, RLQ, LLQ, suprapubic)
    • Guaiac-positive stool
    • Extra-intestinal symptoms (skin changes, oral aphthous ulcers, costovertebral angle tenderness). See Figure 2 in “Work-Up” section.

Certain characteristic patterns of pain symptoms should increase suspicion for a functional etiology of chronic abdominal pain. These include pain that is:

• Poorly defined or localized, or is localized to the periumbilical region
• Episodic, lasting < 1 hour
• Associated with autonomic features (e.g. pallor, nausea, dizziness, headache, or fatigue)
• Triggered or exacerbated by stress
• Not associated with alarm symptoms
• Experienced by an individual with comorbid depression or anxiety (e.g. separation anxiety disorder, social phobia, specific phobia, generalized anxiety disorder)
• Associated with a family history of gastrointestinal complaints

Differential Diagnosis

The differential diagnosis for chronic abdominal pain is extensive and varies based upon the location of the pain and associated symptoms.

Data Gathering and Clinical Decision Making

Figure 2 describes a targeted approach to the evaluation of a pediatric patient presenting with chronic abdominal pain

• A comprehensive history and physical examination should be performed on any pediatric patient complaining of chronic abdominal pain.
  • The purpose of these examinations is to:
    • Rule out the presence of alarm findings necessitating emergent evaluation
    • Distinguish organic from functional causes of pain
    • Direct additional work-up for the patient’s complaint if necessary

History

• A standard assessment of the history of present illness including onset, location, radiation, duration, pain character, associated symptoms, aggravating/alleviating factors, timing, and severity of the pain should be conducted.
• A focused history should be performed to assess for organic etiologies of pain and the presence of alarm findings.
• Regardless of pain etiology, biological and psychosocial factors contributing to pain should also be determined.
• A detailed menstrual history for adolescent female patients is important to assess the likelihood of a genitourinary etiology of the pain (Figure 1).
• All adolescent patients should be screened with a comprehensive HEADDSSS examination.

Physical Exam

Physical examination of a pediatric patient complaining of chronic abdominal pain should include:

• An assessment of the patient’s growth curve, with particular emphasis on height, weight, and growth velocity parameters.
• Vital signs, especially temperature and blood pressure.
  • These can be elevated in patients with organic causes of abdominal pain.
• Full abdominal examination, including inspection, auscultation and percussion of all four abdominal quadrants, assessment for hepatosplenomegaly, and special testing for Carnett and psoas signs.
  • Carnett sign: test to distinguish visceral pain from abdominal wall pain.
    • Have the patient assume the supine position, cross his or her arms and sit halfway forward.
    • Focal tenderness that increases or remains the same during abdominal muscle contracture constitutes a positive Carnett sign and indicates pain originating in the abdominal wall, e.g. from a hernia.
  • Psoas sign: hyperextension at the hip causing pain suggests inflammation of the psoas muscle.
• Rectal examination with a test for stool occult blood.
• External genital and perianal inspection.
  • If there is high suspicion for a gynecologic etiology of abdominal pain, referral for pelvic ultrasound is warranted.

Laboratory Studies

• As described in Figure 2, lab work should include screening CBC, CMP, ESR/CRP and stool hemoccult testing unless there is a compelling diagnostic clue or alarm finding requiring further evaluation through specific diagnostic testing.

Application of the Rome Criteria

• After excluding the presence of alarm findings and other diagnostic clues suggestive of an organic cause of the patient’s abdominal pain in the history, physical, and lab results, the Rome III Criteria can be applied to categorize the specific type of functional abdominal pain experienced by the patient.

• A link to the Rome III criteria can be found here: Rome III Criteria

Management

The management of functional abdominal pain is challenging and requires a multidisciplinary approach individualized to the patient, with consistent follow-up and education for patients and families. 

• The primary goal of management of functional abdominal pain in children and adolescents is a return to normal functional status rather than a complete elimination of pain.
  • Following initial diagnosis, critical steps to management taken by the provider include:
    • Establishing a therapeutic relationship:
      • Acknowledge the existence of the patient’s pain and the functional difficulties it has created for the patient
      • Incorporate patient perspectives and preferences into therapeutic decision-making, and frequent follow-up.
    • Patient and family education
    • Determining a plan for return to school
  • Education about identification and avoidance of pain triggers as well as adjustments in nutritional behavior such as small frequent meals and avoidance of foods, beverages, and medications that aggravate symptoms should be provided at this time.
    • Completion of a pain diary including the following information is another mainstay of initial treatment:
      • Time of day when pain symptoms occur
      • Location/severity/functional limitation of the pain
      • Pain triggers
      • Duration of the pain
      • Interventions attempted and any successes in controlling the pain
  • Subsequent follow-up determines the effectiveness of this initial intervention and guides further therapeutic approaches.
  • Alternative therapies include:
    • Non-pharmacological measures
      • Cognitive-behavioral therapy aimed at the reinforcement of non-pain (healthy or adaptive) behaviors
      • Avoiding reinforcement of pain or pain (sick, illness, maladaptive) behaviors
      • Stress reduction techniques (e.g., relaxation, distraction, and guided imagery) to improve coping and decrease stress and anxiety caused by the pain
      • Hypnotherapy
    • Other interventions that may be combined with psychological interventions include:
      • Probiotics
      • Supplementation with water-soluble fiber or peppermint oil.
      • Pharmacologic approaches include trials of:
        • antispasmodics
        • anti-reflux medications
        • antihistamines
        • antidepressants
      • Pharmacologic approaches should be dictated by patient and parent preference whenever possible.
  • Overall, the prognosis is excellent, with a persistence of pain in only 29.1% of cases at median 5-year follow-up.

Resources

Resources for Parents and Children

• Culbert T, Kajander R. Be the Boss of your Pain: Self-care for Kids. Minneapolis, MN: Free Spirit Publishing; 2007.
• Culbert T, Kajander R. Be the Boss of your Stress: Self-care for kids. Minneapolis MN: Free Spirit Publishing; 2007.
• Huebner D. What to do When You worry Too Much: A Kid’s Guide to Overcoming Anxiety. Washington, DC: Magination Press; 2006.
• Krane EJ. Relieve your Child’s Chronic Pain: A Doctor’s Program for Easing Headaches, Abdominal Pain, Fibromyalgia, Juvenile Rheumatoid Arthritis, and more. New York, NY: Simon & Schuster; 2005.
• Miles BS. Imagine a Rainbow: A Child’s Guide for Soothing Pain. Washington, DC: Magination Press; 2006.
• Rapee RM, Spence SH, Cobham V, Wignall A. Helping Your Anxious Child: A Step-by-step Guide for Parents. Oakland, CA: New Harbinger Publications; 2000.
• Zeltzer LK. Conquering your Child’s Chronic Pain: a Pediatrician’s Guide for Reclaiming a Normal Childhood. New York, NY: HarperCollins; 2005.

References

1. Korterink J, Devanarayana NM, Rajindrajith S, Vlieger A, Benninga MA. Childhood functional abdominal pain: mechanisms and management. Nat Rev Gastroenterol Hepatol. 2015 Mar;12(3):159–71.
2. Chitkara DK, Rawat DJ, Talley NJ. American Journal of Gastroenterology - The Epidemiology of Childhood Recurrent Abdominal Pain in Western Countries: A Systematic Review. Am J Gastroenterol. 2005 Aug;100(8):1868–75.
3. Crushell E, Rowland M, Doherty M, Gormally S, Harty S, Bourke B, et al. Importance of Parental Conceptual Model of Illness in Severe Recurrent Abdominal Pain. Pediatrics. 2003 Dec 1;112(6):1368–72.
4. Noe JD, Li BUK. Navigating recurrent abdominal pain through clinical clues, red flags, and initial testing. Pediatr Ann. 2009 May;38(5):259–66.
5. Ramchandani PG, Hotopf M, Sandhu B, Stein A, ALSPAC Study Team. The epidemiology of recurrent abdominal pain from 2 to 6 years of age: results of a large, population-based study. Pediatrics. 2005 Jul;116(1):46–50.
6. Korterink JJ, Diederen K, Benninga MA, Tabbers MM. Epidemiology of Pediatric Functional Abdominal Pain Disorders: A Meta-Analysis. PLoS ONE [Internet]. 2015 May 20 [cited 2015 Nov 9];10(5). Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4439136/
7. Walker LS, Beck J, Anderson J. Functional Abdominal Pain and Separation Anxiety: Helping the Child Return to School. Pediatr Ann. 2009 May;38(5):267–71.
8. Saps M. Functional Abdominal Pain in Children [Internet]. Lurie Children's Hospital of   Chicago; 2009 [cited 2015Aug]. Retrieved from: http://www2.luriechildrens.org/ce/online/article.aspx?articleid=229
9. Friedlander J. Ch 7: Chronic Abdominal Pain. AccessPediatrics.

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