Pediatrics (System-Integrated)

Pediatric abdominal pain: red flags

Clinical Overview and When to Suspect Surgical Abdomen in Children

— <2 years: intussusception, malrotation with midgut volvulus, incarcerated hernia, Hirschsprung enterocolitis, necrotizing enterocolitis (neonate), pyloric stenosis (3–6 wk)

— 2–5 years: intussusception (tail end), HSP, UTI, constipation, foreign body, testicular torsion

— >5 years/adolescent: appendicitis (peak 10–12 yr), ovarian/testicular torsion, ectopic pregnancy, DKA, PID, IBD, nephrolithiasis

— Bilious emesis at any age → malrotation/volvulus until proven otherwise

— Pain preceding vomiting (vs. vomiting first in gastroenteritis)

— Localized RLQ pain, pain with movement, or focal peritoneal signs

— Hematochezia, currant-jelly stool, melena

— Abdominal distension with absent bowel sounds

— Hemodynamic instability, toxic appearance, or pain >24 h with worsening trajectory

— Scrotal/inguinal pain or swelling in a boy with abdominal complaints

— Pregnancy possibility in any post-menarchal female

Scope of problem: Abdominal pain accounts for ~5–10% of pediatric ED visits. The majority is benign (constipation, viral gastroenteritis, mesenteric adenitis, functional pain), but the Step 3 task is to rapidly separate benign from surgical/life-threatening etiologies using red flags rather than relying on imaging alone.

Age-stratified differential drives suspicion:

Universal red flags ("never-miss" list):

Step 3 management: When a child presents with abdominal pain, first screen for surgical emergencies and hemodynamic compromise before pursuing the broader differential — this triage step is what board stems test. Order vitals, glucose, pregnancy test (post-menarchal), and a focused exam before committing to imaging pathways.

Board pearl: Bilious vomiting in an infant <1 month is a surgical emergency — get upper GI series urgently, not an abdominal ultrasound first. Delay = bowel necrosis within hours.

Presentation Patterns and Key History

— Sudden, severe onset → volvulus, torsion, perforation, intussusception

— Progressive, migratory (periumbilical → RLQ over 12–24 h) → classic appendicitis

— Colicky, episodic with pain-free intervals and drawing up legs → intussusception (peak 6 mo–2 yr)

— Constant, worse with movement → peritonitis

— Bilious (green) emesis → malrotation/volvulus, SBO, ileus from any cause

— Projectile, non-bilious, post-prandial in 3–6 wk infant → pyloric stenosis

— Vomiting AFTER pain onset → surgical (appendicitis pattern)

— Vomiting BEFORE pain → medical (gastroenteritis pattern)

— Currant-jelly stool (late finding) → intussusception

— Bloody diarrhea → HUS (post-EHEC), IBD, Meckel, intussusception, HSP

— No stool/flatus → obstruction

— Delayed meconium >48 h (now presenting later) → Hirschsprung

— Fever timing: fever after pain favors appendicitis; fever before pain favors gastroenteritis or mesenteric adenitis

— Dysuria, urinary frequency → UTI/pyelonephritis

— Sore throat preceding pain → strep with mesenteric adenitis; also consider HSP (palpable purpura on buttocks/legs)

— Joint pain, rash → HSP, IBD, SLE

— Last menstrual period and sexual activity (pregnancy, ectopic, PID)

— Trauma, including non-accidental (duodenal hematoma, pancreatic injury)

— Sickle cell status (vaso-occlusive crisis, splenic sequestration)

— Diabetes (DKA can present as acute abdomen)

Pain characteristics that flag surgical disease:

Vomiting pattern (critical history element):

Stool history:

Associated symptoms to elicit:

Don't-forget questions:

Key distinction: Functional abdominal pain (Rome IV) is periumbilical, recurrent, no nocturnal awakening, normal growth, normal exam. Any deviation — weight loss, night pain, hematochezia, fever, joint symptoms — mandates organic workup. Boards exploit the periumbilical pattern as a distractor for early appendicitis; migration to RLQ is the discriminating feature.

Physical Exam Findings and Hemodynamic Assessment

— Tachycardia out of proportion to fever → dehydration, sepsis, hemorrhage (ruptured ectopic, splenic injury)

— Hypotension is a late finding in children — pediatric shock is compensated until ~30% volume loss, then crashes abruptly

— Capillary refill >3 sec, cool extremities, narrow pulse pressure = compensated shock — start isotonic fluid bolus 20 mL/kg immediately

— Distension with visible peristalsis → obstruction (pyloric "olive" in epigastrium)

— Absent bowel sounds → ileus/peritonitis; high-pitched/tinkling → obstruction

— Rebound, guarding, rigidity → peritonitis (perforated appendix, perforated viscus)

— Rovsing, psoas, obturator signs → appendicitis (less reliable in young children)

— Sausage-shaped RUQ mass + empty RLQ (Dance sign) → intussusception

— Genital exam in boys — testicular torsion presents as abdominal pain in ~20%

— Hernia orifices — incarcerated inguinal hernia

— Back/flank — CVA tenderness, HSP purpura on buttocks and lower extremities

— Rectal exam selectively — empty rectum in Hirschsprung, hematochezia, mass

General appearance first: A child who is playing, walking, or jumping in the exam room has a very low likelihood of surgical abdomen. A still, guarded, knees-flexed child is concerning. Ask the child to hop or cough — pain with these maneuvers suggests peritoneal irritation.

Vital signs and hemodynamics:

Abdominal exam sequence (inspect → auscultate → palpate):

Mandatory components often missed on boards:

CCS pearl: On a pediatric CCS case with abdominal pain, order "Vital signs," "Examine abdomen," "Examine genitalia," and "Examine skin" as discrete actions early. Missing the genital exam in a boy with "abdominal pain" is a classic trap for missed testicular torsion — the 6-hour window for testicular salvage starts at symptom onset, not arrival.

Board pearl: Serial abdominal exams every 2–4 hours by the same examiner outperform any single imaging study for evolving appendicitis in equivocal cases.

Diagnostic Workup — Initial Labs and Imaging

— CBC with differential (leukocytosis with left shift in appendicitis; anemia in IBD, HUS, intussusception)

— BMP (electrolytes, glucose, BUN/Cr) — hypochloremic hypokalemic metabolic alkalosis = pyloric stenosis; anion gap acidosis = DKA presenting as abdominal pain

— CRP (adjunct to WBC; rises later but more specific)

— Urinalysis — pyuria, hematuria, ketones; also detects pregnancy precursor signs

— Urine or serum β-hCG in every post-menarchal female — non-negotiable

— Lipase if epigastric/back pain (pancreatitis: trauma, gallstones, drugs, viral)

— LFTs if RUQ pain or jaundice

— Appendicitis: graded-compression ultrasound first in children (no radiation); CT or MRI if US non-diagnostic

— Intussusception: ultrasound — "target/bull's-eye" or "pseudokidney" sign (sensitivity ~98%)

— Pyloric stenosis: ultrasound — pyloric muscle thickness >3 mm, channel length >14 mm

— Malrotation/volvulus: upper GI series is gold standard — abnormal duodenal C-loop, ligament of Treitz right of midline, "corkscrew" duodenum

— Obstruction/perforation: upright + supine abdominal X-ray (free air, dilated loops, air-fluid levels)

— Testicular torsion: Doppler ultrasound — but do not delay urology consult for imaging if exam is classic

— Pediatric Appendicitis Score (PAS) or Alvarado: low (0–3) discharge with return precautions; intermediate (4–6) US/observation; high (≥7) surgical consult

Universal initial labs when red flags present:

Stool studies: if bloody diarrhea — culture, Shiga toxin (EHEC → HUS risk), C. difficile if antibiotic exposure

Imaging — first-line by suspected diagnosis:

Scoring tools:

Step 3 management: In a stable child with possible appendicitis and equivocal US, observation with serial exams and repeat US in 6–12 hours beats jumping to CT — minimizes radiation while preserving diagnostic accuracy. Reserve CT for non-diagnostic US in higher-risk presentations.

Board pearl: Plain films are insensitive for appendicitis (~50%) and should not be used to rule it out, but they remain first-line for suspected obstruction or perforation.

Diagnostic Workup — Advanced and Confirmatory Studies

— MRI (where available, especially in pregnant adolescents) — no radiation, high sensitivity

— CT with IV contrast if MRI unavailable or clinical urgency — use pediatric-weight–based dose protocols ("image gently")

— Diagnostic laparoscopy for high clinical suspicion with non-diagnostic imaging

— Air (pneumatic) or contrast enema is both diagnostic and therapeutic — reduces ~80–90% of ileocolic intussusceptions

— Contraindicated if peritonitis, perforation, or shock — go to OR

— Surgical consult should be in-house before enema in case of perforation

— Upper GI confirms; ultrasound can show reversed SMA/SMV relationship (vein normally to the right of artery; reversed = malrotation)

— Any bilious emesis in a neonate → simultaneous NPO, NG decompression, IV fluids, surgical consult, and upper GI — do not wait

— Technetium-99m pertechnetate scan ("Meckel scan") identifies ectopic gastric mucosa

— Suspect in painless lower GI bleeding in child <5 yr ("rule of 2s": 2% population, 2 ft from ileocecal valve, 2 inches long, age <2)

— CBC, ESR/CRP, albumin, fecal calprotectin, then endoscopy/colonoscopy with biopsy

— MR enterography for small bowel Crohn evaluation

— Clinical diagnosis — palpable purpura, arthralgia, abdominal pain, renal involvement

— Urinalysis essential to detect nephritis; monitor weekly for 1–2 months, then monthly to 6 months

— Abdominal pain may precede rash by days — high index of suspicion

When ultrasound is non-diagnostic for appendicitis:

Intussusception confirmation and treatment combined:

Malrotation/volvulus workup pearls:

Meckel diverticulum:

IBD workup (older children, chronic/recurrent pain, weight loss, bloody stools):

HSP (IgA vasculitis):

Key distinction: Functional vs. organic recurrent pain — alarm features (weight loss, growth failure, nocturnal pain/diarrhea, GI bleeding, fever, family history of IBD, abnormal labs) mandate workup. Without alarm features, avoid extensive testing; positive diagnosis of functional pain reduces parental anxiety and unnecessary imaging.

Board pearl: Pneumatosis intestinalis on plain film in a premature neonate = NEC — NPO, IV antibiotics (ampicillin/gentamicin/metronidazole), NG decompression, surgical consult.

Risk Stratification and First-Line Management Logic

— Bucket 1: Immediate surgical/life-threatening → OR or procedure within hours

Bilious emesis in infant, peritonitis, hemodynamic instability, testicular torsion, incarcerated hernia, intussusception with perforation signs, suspected volvulus, ruptured ectopic

— Bucket 2: Urgent evaluation, likely intervention → admit, consult, image

Appendicitis, intussusception (stable), pyloric stenosis, HSP with severe abdominal pain, DKA, pyelonephritis in young child, severe pancreatitis

— Bucket 3: Outpatient or observation → reassurance, return precautions

Constipation, viral gastroenteritis, mesenteric adenitis, functional pain, mild UTI in older child, uncomplicated HSP

— IV access × 2, NPO, NG decompression if obstruction/vomiting

— Isotonic crystalloid bolus 20 mL/kg for any signs of dehydration or shock; reassess and repeat up to 60 mL/kg before pressors

— Correct hypoglycemia (D10 2–5 mL/kg in neonates, D25 2–4 mL/kg in older)

— Empiric broad-spectrum antibiotics if peritonitis or sepsis (e.g., piperacillin-tazobactam, or ceftriaxone + metronidazole)

— Analgesia: giving analgesia does NOT mask the surgical abdomen — morphine 0.05–0.1 mg/kg or fentanyl 1 mcg/kg IV is appropriate and humane

— Discharge requires: tolerating PO, normal vitals, reliable follow-up, caregiver understands return precautions, definitive diagnosis or low-risk score

— Observation unit for equivocal appendicitis is increasingly standard

Triage framework — three buckets:

Initial resuscitation priorities (Bucket 1 or 2):

Disposition decisions:

Step 3 management: For a pediatric outpatient with vague recurrent abdominal pain and no alarm features, the correct answer is usually reassurance, dietary counseling, scheduled follow-up in 2–4 weeks, and a symptom diary — NOT immediate CT or specialist referral. Boards reward judicious resource use.

CCS pearl: Order "NPO," "IV fluids," "surgical consult," and "serial abdominal exams" as separate actions in any high-suspicion case.

Pharmacotherapy — First-Line Drug Regimens

— Mild–moderate: acetaminophen 15 mg/kg PO/IV q4–6h (max 75 mg/kg/day); ibuprofen 10 mg/kg PO q6h (avoid if dehydrated, GI bleeding, suspected surgical abdomen with renal concerns)

— Moderate–severe: morphine 0.05–0.1 mg/kg IV q2–4h or fentanyl 1 mcg/kg IV

— Antiemetic: ondansetron 0.15 mg/kg IV/PO (max 4–8 mg) — also reduces ED revisits in gastroenteritis

— Perforated appendicitis or peritonitis: piperacillin-tazobactam 100 mg/kg IV q8h, OR ceftriaxone 50 mg/kg/day + metronidazole 30 mg/kg/day

— Uncomplicated appendicitis (preoperative): cefoxitin or ceftriaxone + metronidazole single dose

— Pyelonephritis: ceftriaxone 50–75 mg/kg IV daily, transition to oral per culture

— NEC: ampicillin + gentamicin + metronidazole (or pip-tazo)

— C. difficile: oral vancomycin or fidaxomicin (metronidazole no longer preferred in pediatrics for moderate–severe)

— HSP: supportive care; prednisone 1–2 mg/kg/day for severe abdominal pain or orchitis (does not prevent nephritis)

— IBD induction: corticosteroids (prednisone 1–2 mg/kg/day) or exclusive enteral nutrition (preferred in pediatric Crohn for growth)

— Constipation: PEG 3350 1–1.5 g/kg/day for disimpaction × 3 days, then 0.4–0.8 g/kg/day maintenance; combine with behavioral toilet training

— Functional abdominal pain: SSRIs, peppermint oil, CBT have modest evidence; avoid chronic opioids

— H. pylori (if confirmed in dyspepsia): triple therapy — amoxicillin + clarithromycin + PPI × 14 days

— Aspirin in children (Reye syndrome) — exception: Kawasaki disease

— Loperamide in young children or bloody diarrhea (toxic megacolon, worsens EHEC/HUS risk)

— Promethazine in <2 yr (respiratory depression — black box)

Analgesia (do not withhold):

Empiric antibiotics by scenario:

Disease-specific pharmacotherapy:

Medications to avoid or use cautiously:

Board pearl: In suspected EHEC (bloody diarrhea + young child), avoid antibiotics and antimotility agents — both increase HUS risk by promoting Shiga toxin release.

Procedures and Invasive Management

— Laparoscopic appendectomy is standard for uncomplicated and most complicated appendicitis

— Non-operative management with antibiotics is an option in select uncomplicated cases (no appendicolith, no perforation) — ~70% success at 1 year; family must accept ~25–30% recurrence

— Perforated appendicitis with abscess: percutaneous drainage + IV antibiotics, interval appendectomy in 6–8 weeks (controversial; increasingly omitted)

— Pneumatic (air) enema under fluoroscopy is first-line — success ~85–90%

— Contraindications: peritonitis, free air, shock → straight to OR

— Post-reduction: admit for observation 12–24 h (10% recurrence, mostly within 24 h)

— Failed reduction or pathologic lead point (Meckel, lymphoma, polyp — more common >3 yr) → surgery

— Correct electrolytes (hypochloremic, hypokalemic metabolic alkalosis) before anesthesia — surgery is not emergent, but metabolic correction is mandatory

— Ramstedt pyloromyotomy — laparoscopic preferred; refeed within hours postop

— Ladd procedure — counterclockwise detorsion, division of Ladd bands, appendectomy, broadening of mesenteric base

— True surgical emergency — bowel necrosis within 6 hours

— Manual detorsion ("open the book" — lateral rotation) as temporizing measure

— Surgical exploration with bilateral orchiopexy within 6 h for ~90% salvage; <50% at 12 h; near 0% at 24 h

— Attempt manual reduction with sedation if no peritonitis

— If reduced: elective repair within 24–72 h (high re-incarceration risk)

— If not reducible or peritonitis: emergent repair

Appendectomy:

Intussusception reduction:

Pyloric stenosis:

Malrotation with midgut volvulus:

Testicular torsion:

Incarcerated inguinal hernia:

CCS pearl: For volvulus on a CCS case, the correct order sequence is: NPO → NG tube → IV fluids → labs/type & cross → surgical consult → upper GI (only if stable) → OR. Do not delay surgery for imaging in an unstable infant with bilious vomiting.

Special Populations — Renal, Hepatic, and Metabolic Considerations

— HUS after EHEC gastroenteritis: triad of microangiopathic hemolytic anemia, thrombocytopenia, AKI — peak 5–10 days after bloody diarrhea, mostly children <5 yr

Management: supportive — fluid/electrolyte management, transfusion thresholds, dialysis if needed; avoid antibiotics and antimotility agents; eculizumab for atypical HUS

— HSP nephritis: check urinalysis at diagnosis and monitor — proteinuria/hematuria can develop weeks later; nephrology referral if persistent proteinuria, hypertension, or renal dysfunction

— Dose-adjust renally cleared drugs (aminoglycosides, vancomycin, acyclovir)

— Acetaminophen dosing capped in chronic liver disease; avoid if active hepatitis

— RUQ pain + jaundice in adolescent: consider gallstones (sickle cell, obesity, hemolysis, ceftriaxone-associated biliary sludge in infants), autoimmune hepatitis, acute viral hepatitis

— Reye syndrome (rare) — encephalopathy + hepatic dysfunction after aspirin in viral illness → avoid aspirin

— Up to 40–75% of pediatric DKA presents with abdominal pain; pain resolves with treatment

— Workup for new-onset DM in any child with acidosis + abdominal pain + polyuria/polydipsia

— Avoid bicarbonate (increases cerebral edema risk)

— Fluid resuscitation cautious in pediatric DKA: typically 10 mL/kg bolus, then 1.5× maintenance; monitor mental status closely for cerebral edema (leading cause of DKA mortality in children)

— Vaso-occlusive crisis can mimic acute abdomen

— Also at risk for: splenic sequestration, acute chest, cholelithiasis, splenic infarct, functional asplenia → encapsulated organism sepsis

— Fever in SCD = immediate ceftriaxone + admission until cultures negative

Renal impairment / AKI in pediatric abdominal pain:

Hepatic considerations:

Diabetes — DKA presenting as abdominal pain:

Sickle cell disease:

Key distinction: Abdominal pain + acidosis + hyperglycemia in a previously well child = new-onset DKA, not gastroenteritis. Always check glucose and urine ketones in any child with abdominal pain and tachypnea — Kussmaul respirations are easily missed and labeled "fast breathing from pain."

Special Populations — Neonates, Adolescents, and Non-Accidental Trauma

— Bilious vomiting = malrotation/volvulus until proven otherwise — emergent upper GI

— NEC in preemies and stressed term neonates: feeding intolerance, bloody stools, abdominal distension, pneumatosis on X-ray → NPO, NG, broad-spectrum antibiotics, surgical consult

— Hirschsprung enterocolitis: failure to pass meconium >48 h, explosive diarrhea, distension, sepsis — life-threatening; rectal irrigation + antibiotics, then surgery

— Incarcerated inguinal hernia more common in premature male infants

— Pyloric stenosis 3–6 weeks: firstborn males, projectile non-bilious vomiting, palpable "olive," visible gastric peristalsis

— Intussusception 6 months–2 years: viral prodrome (Peyer patch hypertrophy as lead point), colicky pain, currant-jelly stool (late), lethargy can dominate presentation ("the lethargic infant with no other findings — get an abdominal US")

— Always pregnancy test in post-menarchal females — ectopic, threatened abortion, ovarian torsion of corpus luteum cyst

— PID: lower abdominal pain + cervical motion tenderness + sexually active — outpatient ceftriaxone 500 mg IM + doxycycline 100 mg BID × 14 d + metronidazole 500 mg BID × 14 d

— Ovarian torsion: sudden unilateral pain, nausea, palpable adnexal mass; Doppler may show preserved flow (don't rule out) — laparoscopic detorsion preserves ovary

— Testicular torsion: any boy with abdominal pain needs genital exam; bell-clapper deformity, sudden onset, high-riding testis, absent cremasteric reflex

— Eating disorders, IBD, dysmenorrhea as causes of chronic pain

— Duodenal hematoma, pancreatic transection, mesenteric tear from blunt abdominal trauma — leading cause of trauma death in abused children after head injury

— Red flags: inconsistent history, delayed presentation, bruising in non-ambulatory child, multiple bruise stages

Neonates (<1 month):

Infants (1–24 months):

Adolescents:

Non-accidental trauma (NAT):

Step 3 management: Suspected NAT requires mandatory reporting to child protective services, skeletal survey if <2 yr, ophthalmology for retinal hemorrhages if head trauma suspected, social work, and child protection team consult — reporting is based on reasonable suspicion, not proof.

Complications and Adverse Outcomes

— Incidence ~30–40% in children, higher in <5 yr due to delayed/atypical presentation

— Complications: intra-abdominal abscess, sepsis, postoperative ileus, small bowel obstruction (adhesions), wound infection

— Length of stay 5–7 days vs. 1–2 days for uncomplicated

— Bowel ischemia → perforation → peritonitis → shock

— Recurrence ~10% (mostly within 24 h of reduction — admit for observation)

— Pathologic lead point in older children: Meckel, polyp, lymphoma (think Burkitt in ileocecal mass in older child)

— Short bowel syndrome if extensive necrosis → lifelong TPN dependence, intestinal transplant candidacy

— Mortality 3–15% even with prompt surgery

— Severe hypochloremic, hypokalemic metabolic alkalosis with paradoxical aciduria

— Dehydration, weight loss, failure to thrive

— Aspiration pneumonia from emesis

— Nephritis (20–60%) — can progress to ESRD in 1–3% of all HSP cases

— Intussusception (ileoileal more than ileocolic — harder to detect on US, may need contrast study)

— GI bleeding, intestinal perforation

— Orchitis, scrotal swelling

— AKI requiring dialysis (50%)

— Hypertension, chronic kidney disease (20–40% long-term)

— CNS involvement (seizures, stroke)

— Pancreatitis, diabetes

— Cerebral edema — 0.5–1% of episodes, 20–25% mortality — risk factors: young age, new-onset DM, severe acidosis, elevated BUN, bicarbonate use, rapid fluid resuscitation

— Hypokalemia, hypoglycemia during treatment

— Lifetime risk after any abdominal surgery ~5–10%; presents as colicky pain, distension, vomiting, obstipation — KUB, NG decompression, surgical consult

Perforated appendicitis:

Intussusception complications:

Malrotation with volvulus:

Pyloric stenosis (if delayed):

HSP complications:

HUS complications:

DKA complications:

Post-surgical adhesive small bowel obstruction:

Board pearl: The leading cause of mortality in pediatric DKA is cerebral edema, not the acidosis itself. Watch for headache, altered mental status, bradycardia, hypertension during treatment — give 3% saline 2.5–5 mL/kg or mannitol 0.5–1 g/kg immediately.

When to Escalate Care — ICU, Consult, Inpatient Triage

— Hemodynamic instability requiring vasopressors or repeat fluid boluses

— Severe DKA (pH <7.1, altered mental status, very young)

— Sepsis with end-organ dysfunction

— Post-op complications (volvulus with bowel resection, perforation with peritonitis)

— HUS with severe AKI, hyperkalemia, fluid overload, or neurologic involvement

— Respiratory compromise from any cause

— Bilious vomiting in infant (immediate)

— Suspected appendicitis, intussusception, volvulus, pyloric stenosis

— Incarcerated hernia, testicular torsion (urology)

— Peritonitis from any source

— GI bleeding requiring intervention

— Pediatric GI: suspected IBD, chronic recurrent pain with alarm features, severe pancreatitis, persistent vomiting, hepatobiliary disease

— Nephrology: HUS, HSP nephritis, AKI, severe hypertension

— Hematology/Oncology: abdominal mass (Wilms, neuroblastoma, lymphoma, hepatoblastoma)

— Endocrinology: new-onset diabetes

— Adolescent medicine / gynecology: PID, ectopic, ovarian torsion

— Child protection team: suspected NAT

— Lack of pediatric surgery, pediatric anesthesia, or PICU

— Complex cases: short bowel, transplant evaluation, complex congenital anomalies

— Use pediatric transport teams when available — higher safety than adult transport

— Uncomplicated appendicitis pre-op

— Intussusception post-reduction (observation 12–24 h)

— Moderate dehydration not tolerating PO

— HSP with severe abdominal pain or GI bleeding

— Pyelonephritis in young child or with bacteremia

PICU admission criteria:

Pediatric surgery consult (urgent):

Subspecialty consults:

Transfer to children's hospital:

Inpatient general admission appropriate for:

CCS pearl: On CCS, call the consult as soon as the diagnosis is suspected — don't wait for confirmatory imaging. Surgical consult should be placed in parallel with US for suspected appendicitis or volvulus. Delaying consultation while awaiting tests loses points and mirrors real-world preventable harm.

Step 3 management: Discharge criteria must include tolerating PO, normal vitals, adequate pain control on oral analgesics, reliable caregiver, follow-up within 24–48 h, and clear return precautions — written instructions in caregiver's preferred language.

Key Differentials — GI/Surgical Same-Category Causes

Appendicitis — periumbilical → RLQ migration, anorexia, low-grade fever, leukocytosis; US or MRI in children

Intussusception — 6 mo–2 yr, colicky pain, currant-jelly stool, palpable sausage mass, target sign on US; air enema reduces

Malrotation with midgut volvulus — bilious emesis in infant, sudden severe distress, upper GI series shows abnormal C-loop, corkscrew duodenum; Ladd procedure

Pyloric stenosis — 3–6 wk firstborn male, projectile non-bilious emesis, olive sign, hypochloremic hypokalemic metabolic alkalosis; pyloromyotomy

Meckel diverticulum — painless hematochezia in child <5 yr; Meckel scan; surgical resection

Incarcerated inguinal hernia — tender groin mass, vomiting; reduce manually if no peritonitis, then elective repair

Constipation — most common cause of recurrent abdominal pain; palpable stool, hard stools, withholding behavior; PEG 3350 + behavioral plan

Mesenteric adenitis — viral or strep URI prodrome, mild RLQ pain, often diagnosed when appendectomy reveals normal appendix; supportive

Gastroenteritis — vomiting before pain, diarrhea, sick contacts; oral rehydration, ondansetron

Hirschsprung disease — delayed meconium, chronic constipation, episodic enterocolitis; rectal biopsy (absent ganglion cells); pull-through procedure

IBD (Crohn, UC) — older child/adolescent, weight loss, bloody diarrhea, growth failure, perianal disease (Crohn); elevated CRP/calprotectin; colonoscopy

Necrotizing enterocolitis — premature neonate, feeding intolerance, bloody stools, pneumatosis on KUB

Cholelithiasis/cholecystitis — RUQ pain, fatty food trigger; risk factors: sickle cell, obesity, hemolytic anemia, TPN, ceftriaxone

Pancreatitis — epigastric pain radiating to back, vomiting, elevated lipase; causes: trauma, gallstones, valproate, viral, hypertriglyceridemia

Peptic ulcer disease / gastritis / H. pylori — epigastric pain, dyspepsia; endoscopy with biopsy

Adhesive small bowel obstruction — prior abdominal surgery, colicky pain, distension, obstipation

Key distinction: Currant-jelly stool is a late finding in intussusception — do not wait for it. Lethargy alone in a 1-year-old can be the only sign — get an abdominal ultrasound liberally in unexplained altered mental status in infants. Boards exploit the classic triad expectation; the modern teaching is that fewer than 25% of cases show all three features (pain, vomiting, bloody stool).

Key Differentials — Non-GI and Systemic Causes

— UTI/pyelonephritis — fever, dysuria, flank/abdominal pain; UA + culture; ceftriaxone or oral cephalexin

— Nephrolithiasis — colicky flank-to-groin pain, hematuria; US first in children (avoid CT radiation)

— Testicular torsion — boy with abdominal pain; check genitals every time

— Ovarian torsion — sudden unilateral pelvic pain, nausea; Doppler US; laparoscopic detorsion

— Ectopic pregnancy — post-menarchal female, β-hCG positive, unilateral pain ± bleeding

— PID — sexually active adolescent, cervical motion tenderness

— Hydronephrosis / UPJ obstruction — episodic flank pain

— HSP (IgA vasculitis) — palpable purpura on buttocks/legs, arthralgia, abdominal pain (can precede rash), renal involvement

— Sickle cell vaso-occlusive crisis — known SCD, pain crisis, may have splenic sequestration or acute chest

— HUS — bloody diarrhea → MAHA + thrombocytopenia + AKI

— DKA — new-onset or known T1DM, Kussmaul respirations, fruity breath, polyuria, hyperglycemia, ketosis

— Adrenal crisis — known CAH or adrenal insufficiency, hypotension, hyponatremia, hyperkalemia

— Porphyria (rare) — recurrent severe abdominal pain, neurologic symptoms

— Lower lobe pneumonia — fever, cough (may be subtle), abdominal pain referred from diaphragmatic irritation; CXR

— Streptococcal pharyngitis can cause abdominal pain via mesenteric adenitis

— Myocarditis can present with abdominal pain in young children

— Iron, lead, mushroom, caustic ingestions

— Lead poisoning — recurrent abdominal pain, anemia, developmental concerns; screen blood lead level

— Wilms tumor — painless abdominal mass, hematuria, hypertension, age 2–5 yr

— Neuroblastoma — abdominal mass crossing midline, may have opsoclonus-myoclonus, elevated catecholamines

— Burkitt lymphoma — rapidly growing ileocecal or abdominal mass; tumor lysis risk

— Hepatoblastoma — RUQ mass, elevated AFP, age <3 yr

Genitourinary:

Vascular/hematologic:

Metabolic/endocrine:

Respiratory referred pain:

Cardiac:

Toxic:

Oncologic:

Board pearl: Any child with abdominal pain + palpable purpura on lower extremities and buttocks = HSP; check urinalysis for nephritis and consider steroids for severe abdominal pain. HSP intussusception is ileoileal — may need contrast study to detect.

Secondary Prevention, Discharge Planning, and Long-Term Care

— Uncomplicated: discharge POD 1, oral antibiotics not routinely needed

— Complicated/perforated: complete IV antibiotics → oral course (total 4–7 days based on clinical course), follow-up in 2–4 weeks

— Activity restriction: no heavy lifting/contact sports × 2–4 weeks

— Return precautions: fever, increasing pain, wound drainage, vomiting

— Observe 12–24 h post-reduction for recurrence (10%)

— Educate caregivers on recurrence signs

— Consider lead point evaluation if recurrent or >3 yr at first episode

— Refeeding within hours; expect some emesis first 24–48 h

— Discharge usually POD 1–2; follow-up 2 weeks

— Weekly urinalysis × 1–2 months, then monthly to 6 months — renal involvement can develop late

— Blood pressure monitoring at each visit

— Nephrology referral for persistent proteinuria or hypertension

— Recurrence in ~30%

— Long-term nephrology follow-up — annual BP, urinalysis, renal function for at least 5 years

— 20–40% develop CKD, hypertension, or proteinuria long-term

— Diabetes education, insulin regimen, CGM, hypoglycemia recognition, sick-day rules, glucagon prescription

— Endocrinology follow-up within 1–2 weeks

— Annual screening: HbA1c every 3 months, lipid panel, thyroid, celiac, retinal/foot exam per ISPAD

— Positive diagnosis (not diagnosis of exclusion) using Rome IV criteria

— Lifestyle: regular meals, fiber, hydration, sleep, school attendance

— CBT, mindfulness, biofeedback

— Pharmacologic adjuncts only if persistent: SSRI, peppermint oil, antispasmodics

— Avoid escalating imaging and procedures (iatrogenic harm)

— Maintenance PEG 3350 for 3–6 months minimum after regular soft stools achieved — premature discontinuation = relapse

— Behavioral toileting after meals (gastrocolic reflex), reward systems for young children, foot stool for proper posture

Post-appendectomy:

Post-intussusception:

Post-pyloromyotomy:

HSP:

HUS:

DKA / new-onset T1DM:

Functional abdominal pain:

Constipation:

Step 3 management: Successful chronic constipation management requires prolonged maintenance therapy, behavioral plan, and follow-up at 4–6 weeks then every 3 months — boards reward continuity, not just disimpaction. Document growth parameters at each visit.

Follow-Up, Monitoring, and Counseling

— Post-appendectomy: 2–4 weeks with surgery; pediatrician at 1–2 weeks for any acute illness

— Post-intussusception: 1–2 weeks; return immediately for symptom recurrence

— HSP: weekly UA × 4–8 weeks, monthly × 6 months

— IBD: GI follow-up 2–4 weeks after diagnosis, then every 3 months; labs (CBC, CRP, albumin, LFTs) every 3 months

— DKA: endocrine 1–2 weeks, then every 3 months for HbA1c

— Functional pain: every 4–6 weeks initially, then every 3 months

— Plot height, weight, BMI at every visit

— Crossing percentiles downward is a red flag for organic disease (IBD, celiac, malabsorption)

— Pubertal staging in adolescents with chronic disease (delayed puberty in IBD)

— Return precautions: persistent or worsening pain >24 h, bilious vomiting, blood in stool, fever, lethargy, refusal to eat/drink, signs of dehydration

— Constipation prevention: fiber, fluids, regular toileting, avoid withholding behavior

— Recognize alarm features in recurrent pain

— Confidential sexual health history; contraception and STI screening per CDC

— Substance use screening (SBIRT, CRAFFT)

— Mental health screening — chronic pain has high comorbidity with anxiety/depression

— School absences: minimize through pain management plan and 504 accommodations if needed

— Rotavirus vaccine: small increased intussusception risk (1–5 per 100,000) — counsel but recommend; benefit outweighs risk

— Pre-splenectomy or asplenia (sickle cell, trauma): pneumococcal, meningococcal, Hib vaccines per CDC

— Hand hygiene, food safety to prevent gastroenteritis, EHEC

— Avoid unpasteurized dairy, undercooked meat (HUS risk)

Standard post-discharge follow-up timing:

Growth and development monitoring:

Counseling — caregivers:

Counseling — adolescents:

Vaccination considerations:

Anticipatory guidance:

CCS pearl: Schedule "office visit in 2 weeks" explicitly on CCS for any patient with an acute abdominal process — points are awarded for follow-up planning, not just acute care. Order patient education and written discharge instructions in counseling actions.

Ethical, Legal, and Patient Safety Considerations

— All physicians are mandated reporters for suspected child abuse — based on reasonable suspicion, not proof

— Failure to report is a misdemeanor and grounds for license action in all states

— Red flags in abdominal pain: duodenal hematoma, pancreatic injury, mesenteric tear with no clear trauma history, multiple stages of bruising, history inconsistent with injury, delayed presentation

— Report to state child protective services AND involve hospital child protection team

— Minor consent laws vary by state but generally allow adolescents to consent independently for: contraception, STI testing/treatment, mental health, substance use treatment, pregnancy care

— Emancipated minor, mature minor doctrine — varies by state

— For a sexually active adolescent with abdominal pain, confidential pregnancy testing and STI workup can proceed without parental consent in most states

— For life-threatening conditions (e.g., parents refuse surgery for volvulus, transfusion in Jehovah's Witness child with hemorrhagic shock), seek emergency court order — child's best interest supersedes parental autonomy

— For non-emergent care, engage ethics consult, attempt shared decision-making

— Children are more radiation-sensitive than adults; lifetime cancer risk from CT is 1 in 500–1000 in young children

— Use ultrasound and MRI first when feasible; pediatric weight–based CT dose protocols

— Document the indication for any CT

— ED-to-home transition: clear discharge instructions, return precautions in caregiver's preferred language, scheduled follow-up

— Inpatient-to-outpatient: medication reconciliation, pending labs/cultures communicated to PCP, "warm handoff" for complex cases

— Adolescent-to-adult care transition for chronic disease (IBD, T1DM) — formal transition program starting at age 14–16

— Missed pediatric appendicitis is a leading cause of pediatric malpractice claims

— Mitigation: serial exams, structured discharge criteria, explicit return precautions, follow-up call/visit at 24 h for equivocal cases

Mandatory reporting of child abuse:

Informed consent and adolescent autonomy:

Parental refusal of treatment:

Radiation stewardship — "Image Gently":

Transition-of-care risks:

Diagnostic error and missed appendicitis:

Step 3 management: When discharging a child with undifferentiated abdominal pain, document: (1) reassessment after observation, (2) tolerating PO, (3) normal vitals, (4) specific written return precautions, (5) scheduled follow-up within 24 hours, and (6) caregiver verbal teach-back. This is both clinically sound and medico-legally protective.

High-Yield Associations and Rapid-Fire Clinical Facts

Bilious vomiting in neonate → malrotation/volvulus → upper GI series → Ladd procedure

Olive mass + non-bilious projectile vomiting + alkalosis → pyloric stenosis → pyloromyotomy (correct lytes first)

Currant-jelly stool + colicky pain + sausage mass → intussusception → air enema

Pneumatosis intestinalis in preemie → NEC → NPO + antibiotics + surgery consult

Painless hematochezia in toddler → Meckel diverticulum → Tc-99m pertechnetate scan

Delayed meconium >48h → Hirschsprung → rectal biopsy (absent ganglion cells)

Palpable purpura on legs/buttocks + abdominal pain + arthralgia → HSP → monitor UA

Bloody diarrhea → MAHA + thrombocytopenia + AKI → HUS → supportive care, NO antibiotics

RLQ pain + migration + anorexia + leukocytosis → appendicitis → US first

Abdominal pain + Kussmaul + glucose 500 → new-onset DKA → fluids cautiously, insulin, watch for cerebral edema

Adolescent + amenorrhea + unilateral pelvic pain + positive β-hCG → ectopic pregnancy

Boy + abdominal pain + high-riding testis + absent cremasteric reflex → testicular torsion → 6-hour window

Painless abdominal mass + hematuria + hypertension, age 2–5 → Wilms tumor

Abdominal mass crossing midline + opsoclonus-myoclonus → neuroblastoma

Ileocecal mass in older child with rapid growth → Burkitt lymphoma → tumor lysis precautions

Recurrent periumbilical pain, normal exam, normal growth, no nocturnal symptoms → functional abdominal pain (Rome IV)

Chronic constipation with palpable stool + withholding behavior → functional constipation → PEG 3350 maintenance

Lower lobe pneumonia can present as abdominal pain — always get CXR if respiratory signs

Sickle cell + RUQ pain → cholelithiasis (pigment stones from chronic hemolysis)

Strep pharyngitis + abdominal pain → mesenteric adenitis (or scarlet fever)

Ceftriaxone in infants → biliary sludge, pseudocholelithiasis

Rotavirus vaccine → small intussusception risk (1–5/100,000) — still recommended

Cerebral edema during DKA treatment → mannitol or 3% saline; leading DKA mortality

Board pearl: When a stem says "lethargic infant with no obvious source," think intussusception — lethargy can be the sole presenting feature and may mimic sepsis or meningitis. Abdominal ultrasound has high sensitivity and should be obtained liberally.

Board Question Stem Patterns

Stem 1: 3-week-old firstborn boy with progressive non-bilious projectile vomiting after feeds, hungry afterward, weight loss, palpable epigastric mass, labs show Na 132, K 3.0, Cl 90, HCO₃ 32. → Answer: pyloric stenosis; next step: IV fluids to correct alkalosis, then pyloromyotomy. Trap: choosing immediate surgery before electrolyte correction.

Stem 2: 8-month-old with episodes of crying and drawing up legs, lethargy between episodes, bloody mucousy stool. US shows target sign. → Air enema reduction; admit for observation 12–24 h.

Stem 3: 5-day-old with bilious emesis, abdominal distension. → Upper GI series urgently; suspect malrotation/volvulus; surgical consult. Trap: choosing abdominal US first.

Stem 4: 6-year-old with fever, periumbilical pain migrating to RLQ over 18 h, anorexia, WBC 16,000. US shows non-compressible appendix 9 mm. → Laparoscopic appendectomy; perioperative antibiotics.

Stem 5: 7-year-old with palpable purpura on buttocks, knee arthralgia, severe colicky abdominal pain, microscopic hematuria. → HSP; supportive care + prednisone for severe abdominal pain; monitor UA weekly.

Stem 6: 4-year-old with bloody diarrhea 1 week ago, now pale, oliguric, petechiae, Cr 2.5, platelets 40,000, schistocytes on smear. → HUS (post-EHEC); supportive care, dialysis if needed, NO antibiotics, NO antimotility agents.

Stem 7: 14-year-old girl with 6 h of severe RLQ pain, nausea, last menses 7 weeks ago. β-hCG positive. US shows tubal mass. → Ectopic pregnancy; OB/GYN consult, methotrexate vs. surgery.

Stem 8: 12-year-old boy with 4 h sudden abdominal/scrotal pain, vomiting, high-riding right testis, no cremasteric reflex. → Testicular torsion; immediate urology consult and surgical exploration — don't wait for imaging.

Stem 9: 10-year-old with abdominal pain, Kussmaul breathing, glucose 480, ketones positive, pH 7.15. → New-onset DKA; cautious fluids, insulin infusion, watch for cerebral edema.

Stem 10: 9-year-old with 6 months of periumbilical pain, normal exam, normal growth, no nocturnal symptoms, attends school regularly but with anxiety. → Functional abdominal pain (Rome IV); reassurance, CBT, avoid extensive workup.

Step 3 management: Question vignettes will often offer CT abdomen as a tempting answer in children — usually wrong. Default to ultrasound first for appendicitis and intussusception; upper GI for malrotation; clinical diagnosis + UA for HSP. Pick CT only when US is non-diagnostic and clinical concern persists.

One-Line Recap

Pediatric abdominal pain demands age-stratified red-flag triage that separates surgical emergencies — bilious emesis (volvulus), colicky pain with currant-jelly stool (intussusception), projectile non-bilious vomiting in a young infant (pyloric stenosis), migratory RLQ pain (appendicitis), and acute scrotal or pelvic pain (torsion) — from benign mimics like constipation, gastroenteritis, mesenteric adenitis, and functional pain, using ultrasound-first imaging, targeted labs including a pregnancy test in every post-menarchal female, and early surgical consultation rather than reflexive CT.

Never-miss red flags: bilious vomiting at any age, pain before vomiting, peritoneal signs, hemodynamic instability, scrotal/genital pain, palpable purpura, blood in stool, abdominal pain + acidosis (DKA)

Imaging hierarchy in children: ultrasound first for appendicitis, intussusception, pyloric stenosis, ovarian/testicular torsion; upper GI for malrotation; MRI before CT when feasible — "Image Gently"

Mandatory exam elements: genital exam in every boy with abdominal pain, skin exam for purpura/bruising, pregnancy test in every post-menarchal female, glucose check in any child with tachypnea

Management mantras: correct electrolytes before pyloromyotomy; air enema for stable intussusception; no antibiotics/antimotility agents in EHEC/HUS; cautious fluids in DKA to prevent cerebral edema; analgesia does not mask surgical abdomen

Board pearl: When stuck, ask: "Is this child sick or not sick, surgical or not surgical, and have I checked the genitals, the glucose, and the β-hCG?" These three checks rescue more pediatric abdominal pain question stems than any imaging study.