Overview
Definition:
Functional abdominal pain (FAP) is recurrent abdominal pain in children and adolescents that is not explained by demonstrable structural or biochemical abnormalities
Organic abdominal pain (OAP) is associated with a specific identifiable pathological process or disease
Distinguishing between these two is crucial for appropriate management and avoiding unnecessary investigations or delayed diagnosis.
Epidemiology:
Recurrent abdominal pain affects 10-15% of school-aged children
Approximately 75-90% of these cases are functional in origin
FAP is more common in girls and typically presents between ages 5-15 years
OAP can occur at any age and its prevalence depends on the underlying condition.
Clinical Significance:
Accurate differentiation is vital
Misdiagnosing FAP as OAP leads to extensive, costly, and potentially harmful investigations
Conversely, attributing OAP to FAP can delay diagnosis of serious conditions, leading to poor outcomes and increased morbidity
Identifying alarm features guides the diagnostic pathway, ensuring timely intervention for organic causes.
Clinical Presentation
Symptoms:
Functional Abdominal Pain: Pain often periumbilical or epigastric
Pain can be vague and non-specific
Symptoms may be intermittent with periods of complete well-being
Symptoms often occur during school hours and may lead to school absenteeism
Associated symptoms can include nausea, vomiting, bloating, constipation, or diarrhea, but these are typically mild and do not follow a consistent pattern
Organic Abdominal Pain: Pain may be localized or diffuse, often with characteristics that suggest specific organ involvement
Pain intensity may be severe and progressive
Symptoms are often constant or worsening
Associated symptoms are more specific and may include fever, weight loss, anorexia, vomiting of bile or blood, bloody stools, jaundice, or signs of systemic illness.
Signs:
Functional Abdominal Pain: Generally, normal physical examination findings
No signs of malnutrition or growth failure
Vital signs are stable
Organic Abdominal Pain: Physical examination may reveal tenderness (localized or rebound), guarding, rigidity, masses, hepatosplenomegaly, jaundice, pallor, dehydration, or signs of peritonitis
Vital sign abnormalities like tachycardia, hypotension, or fever may be present depending on the underlying cause.
Diagnostic Criteria:
The Rome IV criteria are commonly used for diagnosing functional gastrointestinal disorders, including functional abdominal pain
These criteria require recurrent abdominal pain for at least 2 months prior to diagnosis, and symptoms must be associated with one or more of the following: defecation, onset of pain related to a change in frequency of stool, onset of pain related to a change in form of stool
Crucially, the pain must not be solely explained by another functional GI disorder or condition.
Diagnostic Approach
History Taking:
A thorough history is paramount
Inquire about the onset, location, character, duration, frequency, and severity of pain
Ask about aggravating and relieving factors
Document associated symptoms like fever, vomiting, diarrhea, constipation, blood in stool, weight loss, anorexia, early satiety, jaundice, urinary symptoms, and menstrual history in adolescent girls
Ascertain psychosocial factors including stress at home or school, bullying, family history of GI disorders, and impact on daily activities and sleep
Crucially, ask about "alarm features".
Physical Examination:
Perform a complete physical examination, including general appearance, nutritional status, and growth parameters (height, weight, BMI)
Assess vital signs
Palpate the abdomen systematically, checking for tenderness (superficial, deep, rebound), masses, organomegaly (liver, spleen), and hernias
Auscultate bowel sounds
Perform a digital rectal examination if indicated, checking for masses, stool consistency, and occult blood
Examine for signs of extra-intestinal pathology.
Investigations:
Initial investigations for suspected FAP are usually minimal or not required if alarm features are absent
If organic pathology is suspected based on alarm features or persistent symptoms, investigations may include: Complete Blood Count (CBC) with ESR and CRP to detect inflammation or infection
Stool occult blood test
Urinalysis and urine culture to rule out urinary tract infection
Abdominal ultrasound to assess for gallstones, appendicitis, intussusception, or masses
Upper GI endoscopy or colonoscopy with biopsies if specific mucosal pathology is suspected
Imaging like CT scan or MRI may be indicated for complex cases or suspected structural abnormalities
Serological tests for celiac disease (anti-TTG, EMA) if suggested by symptoms.
Differential Diagnosis:
When evaluating abdominal pain, consider a broad differential diagnosis, including: Infectious gastroenteritis
Appendicitis
Intussusception
Mesenteric adenitis
Inflammatory bowel disease (Crohn's disease, ulcerative colitis)
Peptic ulcer disease
Celiac disease
Lactose intolerance and other food intolerances
Urinary tract infection
Constipation
Gallstones or cholecystitis
Pancreatitis
Gynecological causes (ovarian cysts, pelvic inflammatory disease) in adolescent girls
Less common conditions like intussusception, Meckel's diverticulum, Henoch-Schönlein purpura, or malignancy.
Alarm Features
Definition:
Alarm features are signs and symptoms that raise suspicion for organic pathology and warrant a more thorough investigation
Their presence suggests that the abdominal pain may not be functional.
Pediatric Alarm Features:
Specific alarm features in children include: Unexplained weight loss or failure to thrive
Growth deceleration
Persistent vomiting, especially bilious vomiting or hematemesis
Rectal bleeding or occult blood in stool
Fever without an obvious source
Severe or progressive abdominal pain
Night awakening due to pain
Localized abdominal tenderness, rebound tenderness, or guarding
Abdominal masses
Jaundice
Persistent diarrhea or constipation
Anorexia
Delayed puberty or abnormal menstrual history in adolescents
Significant psychosocial distress that is not explained by typical FAP symptoms.
Implications Of Alarm Features:
The presence of one or more alarm features mandates a systematic approach to rule out organic disease
This typically involves more extensive laboratory investigations, imaging studies, and potentially endoscopic procedures
A strategy of watchful waiting or conservative management is not appropriate when alarm features are present.
Management
Initial Management:
If alarm features are absent and the diagnosis of functional abdominal pain is suspected, management focuses on reassurance, education, and lifestyle modifications
Explain the functional nature of the pain to the child and parents, emphasizing that it is real but not indicative of serious organic disease
Encourage a return to normal activities, including school attendance
Provide dietary advice if specific intolerances are suspected (e.g., low FODMAP diet under specialist guidance)
Regular meal patterns and adequate fluid intake are recommended.
Medical Management:
Pharmacological interventions are generally reserved for children with significant symptoms or when non-pharmacological measures are insufficient
For pain management, simple analgesics like paracetamol or ibuprofen may be used cautiously
Antispasmodics (e.g., hyoscine butylbromide) can be helpful for colicky pain
For associated constipation, laxatives (e.g., polyethylene glycol) are first-line
For associated diarrhea, consider fiber supplements or antimotility agents
Antidepressants, particularly tricyclic antidepressants (TCAs) or selective serotonin reuptake inhibitors (SSRIs), can be effective in some adolescents with severe FAP by modulating visceral hypersensitivity, but should be prescribed by specialists
Start with low doses and titrate upwards.
Surgical Management:
Surgical management is generally NOT indicated for functional abdominal pain
It is reserved exclusively for confirmed organic causes of abdominal pain that are amenable to surgical intervention, such as appendicitis, intussusception, or complications of inflammatory bowel disease
Exploratory laparotomy for presumed functional pain is generally discouraged due to its low diagnostic yield and potential for complications.
Supportive Care:
Psychological support is an integral part of managing FAP
Referrals to child psychologists or counselors may be beneficial for children experiencing significant anxiety, depression, or stress related to their pain or school
Education for parents regarding the condition and strategies for managing stress is also crucial
Regular follow-up appointments are important to monitor progress, adjust management strategies, and provide ongoing support.
Prognosis
Factors Affecting Prognosis:
Prognosis for FAP is generally good, with a significant proportion of children experiencing resolution of symptoms over time
However, some may have persistent symptoms into adulthood
Factors associated with poorer prognosis include more severe pain, significant psychosocial distress, co-existing functional disorders (e.g., irritable bowel syndrome, headaches), and inadequate management
Prognosis for OAP depends entirely on the underlying organic condition.
Outcomes:
For FAP, outcomes are typically characterized by reduced pain severity, improved quality of life, and return to normal daily activities including school
For OAP, outcomes are determined by the specific disease, its stage at diagnosis, and the effectiveness of treatment.
Follow Up:
Children diagnosed with FAP should have regular follow-up, initially more frequent (e.g., every 3-6 months) and then annually, to assess symptom response, reinforce management strategies, and address any emerging concerns
Follow-up for OAP is disease-specific and guided by the managing specialist
Re-evaluation is necessary if new alarm features emerge or if symptoms do not respond to initial management.
Key Points
Exam Focus:
DNB/NEET SS exams will test your ability to differentiate FAP from OAP using alarm features
Remember the common organic differentials and the appropriate initial investigations based on red flags.
Clinical Pearls:
Always ask about alarm features in any child presenting with abdominal pain
Trust the patient's subjective report of pain
it is real regardless of the cause
Reassurance and a strong physician-patient relationship are powerful therapeutic tools for FAP.
Common Mistakes:
Over-investigating functional abdominal pain without clear indication
Underestimating the significance of alarm features and attributing all abdominal pain to functional causes
Delaying referral or definitive investigation for suspected organic pathology.