Abdominal Pain in Children — Long Notes

1. Definition and Causes

• Visceral pain — poorly localized, crampy/colicky; arises from hollow organ distension, ischemia, or inflammation
• Parietal (somatic) pain — well-localized, sharp; arises from peritoneal irritation
• Referred pain — perceived away from the source (e.g., diaphragmatic irritation → shoulder tip)

Causes by Age Group

2. Functional vs. Organic Abdominal Pain

Functional Abdominal Pain (FAP)

• Affects ~15% of middle- and high-school students
• Equally affects boys and girls until age 9; female predominance (F:M = 1.5:1) from age 9–12
• Peaks around age 9; rare under age 5 — organic cause must be excluded more vigorously in this group

Differences: Functional vs. Organic Pain

• Pain localised away from umbilicus
• Pain associated with change in bowel habits (diarrhoea, constipation, nocturnal stools)
• Nocturnal awakening with pain
• Recurrent bilious vomiting
• Constitutional symptoms: recurrent fever, weight loss, anorexia, fatigue
• Organomegaly or localised tenderness on exam
• Age <4 years with functional-type symptoms
• Positive stool occult blood

3. Differential Diagnosis of Abdominal Pain in Children

• Appendicitis (most common surgical cause)
• Intussusception
• Malrotation ± volvulus
• Mesenteric lymphadenitis
• Meckel's diverticulitis
• Intestinal obstruction
• Inflammatory bowel disease (Crohn's, UC)
• Peptic ulcer disease / gastritis
• Constipation
• Hirschsprung's disease
• Coeliac disease
• Gastroenteritis
• Necrotizing enterocolitis (neonates)

• Cholecystitis / cholelithiasis
• Pancreatitis
• Hepatitis

• UTI / pyelonephritis
• Urolithiasis
• Hydronephrosis

• Ovarian torsion
• Ovarian cysts
• Ectopic pregnancy
• Dysmenorrhoea / PID

• Testicular torsion
• Incarcerated/strangulated hernia

• Henoch-Schönlein purpura (palpable purpura + colicky pain + arthritis)
• Vaso-occlusive crisis (sickle cell)

• Lower lobe pneumonia (referred pain)
• Diabetic ketoacidosis
• Streptococcal pharyngitis
• ApoC-II deficiency (recurrent abdominal pain + pancreatitis in children)

• Non-accidental trauma (always consider in infants/toddlers)
• Splenic/hepatic laceration

4. General Principles of Management

Supportive

• IV fluids — for dehydration, nil per os in surgical cases
• Analgesia — analgesics do NOT mask surgical conditions; they actually improve the clinician's ability to assess pain and do not worsen outcomes (Tintinalli's EM)
• NPO status if surgical condition suspected
• Reassurance and observation for nonspecific/functional pain
• Planned re-examination for patients discharged without a clear diagnosis

Medical Management

• Gastroenteritis: oral rehydration, antiemetics
• UTI: antibiotics (trimethoprim/nitrofurantoin; pyelonephritis → IV ceftriaxone)
• Constipation: laxatives (PEG), dietary fibre, hydration
• HSP: supportive; corticosteroids for severe GI/renal involvement
• DKA: IV insulin, fluids, electrolyte correction
• Pancreatitis: NPO, IV fluids, analgesia
• IBD: aminosalicylates, corticosteroids, immunomodulators
• FAP: multifactorial — cognitive behavioural therapy (CBT), family education, limited pharmacotherapy
  • CBT has the strongest evidence
  • Tricyclic antidepressants or SSRIs if comorbid anxiety/depression
  • Probiotics may reduce frequency and intensity
  • Laxatives/fibre if constipation is suspected

Surgical Management

• Appendicitis: surgical consultation + antibiotics (cefoxitin, ampicillin-sulbactam, or ceftriaxone + metronidazole for uncomplicated; piperacillin-tazobactam for perforated)
  • Percutaneous drainage for abscess → delayed appendectomy
• Intussusception: air or hydrostatic (barium/water-soluble) enema reduction; surgery if failed/peritonitis
• Volvulus: emergency surgery (Ladd's procedure)
• Incarcerated hernia: emergency repair
• Testicular / ovarian torsion: emergency surgical detorsion
• Meckel's diverticulum: diverticulectomy
• Necrotizing enterocolitis: medical ± surgical resection

5. Laboratory and Imaging Tests

Laboratory Investigations

Imaging Investigations

• Preferred because children have little body fat → excellent acoustic windows
• No radiation exposure; fast, cheap
• Indications: appendicitis, pyloric stenosis, intussusception, testicular torsion, urolithiasis, biliary pathology, gynaecological causes, mesenteric lymphadenitis, renal causes
• Appendicitis criteria on US: tubular blind-ending non-compressible structure, outer diameter >6 mm, wall hyperaemia, surrounding hyperechoic fat, appendicolith

• Radiation dose 1/600th that of abdominal CT
• Selective use only — for suspected bowel obstruction (dilated loops, air-fluid levels) and pneumoperitoneum (free air on upright or left lateral decubitus views)
• NOT indicated for routine constipation work-up

• Most sensitive for appendicitis and intra-abdominal abscesses
• Significant radiation dose — young children more sensitive than adults
• IV contrast risk (anaphylaxis, nephropathy)
• Reserve for: cases where US is inconclusive, complicated periappendiceal abscess, trauma
• Avoid barium if perforation suspected — use water-soluble contrast

• Complementary to US when more detail is needed
• No radiation; may be limited by availability and need for sedation

6. Complications of Abdominal Pain in Children

7. Abdominal Palpation in Children

Preliminary Principles

• Inspect → Auscultate → Palpate (always in this order for the abdomen)
• Begin palpation away from the area of maximal tenderness
• Bring knees up to relax abdominal muscles
• Warm hands; approach gently
• Observe child's facial expression throughout
• Distract with conversation or a toy in young children
• Move hips to test for hip pathology or psoas irritation (appendicitis, psoas abscess)

Light Palpation

• Apply gentle pressure with the flat of the fingers (1–2 cm depth)
• Systematically cover all four quadrants
• Start in the quadrant farthest from pain

1. Tenderness:
   • Note exact location, severity, reproducibility
   • Periumbilical tenderness → FAP, early appendicitis, mesenteric lymphadenitis
   • RLQ tenderness → appendicitis (McBurney's point)
   • RUQ → cholecystitis
   • Generalised tenderness → peritonitis, gastroenteritis
2. Guarding (involuntary muscle rigidity):
   • Reflex contraction of abdominal muscles in response to peritoneal irritation
   • Voluntary guarding: child tenses muscles anticipating pain (can be overcome by distraction)
   • Involuntary guarding: true peritoneal irritation — persists regardless of distraction; indicates surgical condition
3. Superficial masses:
   • Intussusception: "sausage-shaped" mass in RUQ or central abdomen
   • Constipation: faecal masses along the colon (especially sigmoid)
   • Tumour (Wilms', neuroblastoma): firm, fixed flank mass
   • Distended bladder: suprapubic midline mass

Deep Palpation

Organ Palpation:

• Start in RLQ, move upward toward RUQ
• Normal: may be palpable 1–2 cm below right costal margin in infants/young children (normal finding)
• Pathological hepatomegaly: >3.5 cm BCM in infants; record size in cm below costal margin
• Assess: size, surface (smooth vs. nodular), consistency (soft vs. firm/hard), tenderness

• Start in RLQ, palpate toward LUQ with the patient's right side slightly elevated
• Normally not palpable; mild enlargement in infections (EBV, malaria)
• Splenomegaly in: portal hypertension, haemolytic anaemia, storage disorders
• Assess size (Schuffner grades I–VIII), tenderness, consistency

• Palpated in the suprapubic region (midline)
• Distended bladder = dull percussion, visible swelling, child may not void spontaneously
• Urinary retention in: posterior urethral valves, neurogenic bladder

• Bimanual technique: one hand posteriorly (lumbar region), one hand anteriorly
• Ballot the kidney between the two hands
• Normal: right kidney may be just palpable in thin children; left usually not palpable
• Enlarged kidneys: hydronephrosis, Wilms' tumour, polycystic kidney disease
• Assess: size, surface, tenderness (especially costovertebral angle tenderness in pyelonephritis)

Rebound Tenderness (Blumberg's Sign):

• Press deeply and slowly, then release suddenly
• Pain on release > pain on pressure = positive rebound tenderness
• Indicates peritoneal irritation (peritonitis, perforated appendix)
• In children, this can be highly distressing — use judiciously; percussion tenderness is a gentler alternative

Shape, Consistency, and Mobility of GIT Organs:

• Shape: Irregular masses suggest tumour; tubular shapes suggest intussusception or faecal loading
• Consistency: Soft (normal/inflammatory), firm (constipation), hard/stony (calcification, tumour)
• Mobility: Mobile masses are often benign (faecal, mesenteric cyst); fixed masses suggest malignancy or inflammation

8. Pathological Signs on Palpation

Murphy's Sign

• Technique: Place fingers under the right costal margin at the midclavicular line; ask the patient to take a deep breath
• Positive: Patient suddenly stops inspiration because of sharp pain as the inflamed gallbladder descends to meet the examiner's fingers → acute cholecystitis
• Sonographic Murphy's sign: Gallbladder tenderness elicited by the ultrasound probe at the gallbladder site; positive predictive value is high when combined with gallstones and gallbladder wall thickening >3 mm

Phrenicus Sign (Phrenic Nerve Sign / Elekra's Sign)

• Technique: Press on the right shoulder at the junction of the clavicle and the sternocleidomastoid (between the crura of SCM)
• Positive: Pain is elicited → indicates irritation of the right diaphragm and the phrenic nerve
• Significance: Subphrenic abscess, acute cholecystitis, hepatic pathology, right pleuritis

Boas's Sign

• Technique: Apply pressure in the right subcostal region posteriorly (posterior thorax, paravertebral area at right costovertebral angle)
• Positive: Hyperaesthesia or tenderness in the right sub-scapular region / right subscostal area radiating to the back
• Significance: Classically associated with acute cholecystitis (inflammation of the gallbladder causes referred tenderness to the back via the splanchnic nerves)
• Specifically: tenderness at right posterior sub-costal area = Boas's sign for cholecystitis

Openkhovsky's Sign (Oпенховского)

• Technique: Percussion or pressure applied to the spinous processes of the lower thoracic vertebrae (T10–T12)
• Positive: Pain referred to the abdomen / epigastrium on tapping these spinous processes
• Significance: Indicates peptic ulcer disease (gastric or duodenal ulcer), pancreatic disease
• The sign reflects viscerosomatic referral — gastric/duodenal irritation refers pain to the corresponding dermatomes via the splanchnic nerves

9. Percussion in Children

Features and Principles

1. Determine organ borders (liver, spleen, bladder)
2. Detect free fluid (ascites) — shifting dullness, fluid thrill
3. Detect free air (tympany over an area of expected dullness)
4. Assess for tenderness (percussion tenderness is a gentler alternative to rebound testing)

• Use indirect percussion (pleximeter finger of non-dominant hand placed firmly on the child's skin; tap with the middle finger of the dominant hand)
• In neonates and small infants: direct percussion with a single finger may be used
• Apply firm, short, sharp strokes to the pleximeter finger
• Compare symmetrical areas

• Tympany (resonance): over air-filled bowel (most of the abdomen normally)
• Dullness: liver (right upper quadrant), spleen (left upper quadrant), full bladder (suprapubic), gravid uterus

Percussion Notes in Specific Conditions

• Positive costovertebral angle (CVA) tenderness → pyelonephritis, renal pathology
• Diffuse abdominal percussion tenderness → peritoneal irritation (gentler than rebound testing — especially useful in anxious or uncooperative children)

Liver Percussion (Hepatic Span)

• Begin in RLQ with tympany; percuss upward until dullness begins = lower liver border
• Begin at right shoulder; percuss downward until dullness begins = upper liver border
• Normal hepatic span: 4–8 cm in children (increases with age)
• Loss of liver dullness → pneumoperitoneum (perforated viscus — emergency)

Spleen Percussion (Traube's Space)

• Traube's space: left lower anterior chest bounded by the 6th rib, midaxillary line, and left costal margin
• Normally tympanitic (air in stomach/colon)
• Dullness in Traube's space → splenomegaly, left pleural effusion, gastric pathology

Summary of Key Clinical Pearls

• Bilious vomiting = surgical emergency until proven otherwise (27–51% require surgery)
• Stillness suggests peritoneal irritation (appendicitis); writhing suggests obstruction (intussusception, renal colic)
• Analgesia does NOT mask surgical conditions — give it early
• Involuntary guarding is the most reliable sign of peritoneal irritation
• Ultrasound first — always; CT only when US is inconclusive
• In FAP: an organic cause is found in only ~10% of children with recurrent abdominal pain
• Perforation rates are higher in preschool children with appendicitis due to atypical presentation and diagnostic delay
• Always examine the diaper area (hernia, testicular torsion, paraphimosis) and check for extra-abdominal causes (pharyngitis, pneumonia, DKA)