What is the definition, causes, manifestations, diagnosis, and treatment of intestinal obstruction in children?

INTESTINAL OBSTRUCTION IN CHILDREN

Definition

Intestinal obstruction in children is a mechanical or functional blockage of the intestinal lumen that prevents normal passage of intestinal contents, requiring urgent recognition and intervention to prevent life-threatening complications including ischemia, perforation, and septic shock. 1, 2

The condition manifests differently based on the level of obstruction (proximal versus distal) and can be complete or partial. 1

Causes

Neonatal Period (First Days of Life)

Proximal Obstructions:

• Duodenal atresia presents with the classic "double bubble" sign on radiography with no distal gas 1
• Jejunal atresia shows a "triple bubble" pattern with absent distal bowel gas 1
• Annular pancreas can cause duodenal obstruction 2

Distal Obstructions:

• Ileal atresia is the most common distal atresia, showing multiple dilated bowel loops with microcolon on contrast enema 1
• Meconium ileus (associated with cystic fibrosis) requires therapeutic enema 1
• Meconium plug syndrome and neonatal small left colon syndrome are functional obstructions requiring observation 1
• Hirschsprung's disease requires rectal biopsy for diagnosis 1

Life-Threatening Emergency:

• Malrotation with midgut volvulus is the most critical diagnosis requiring emergent surgery, can present with bilious vomiting and normal or minimal bowel gas pattern 1

Beyond Neonatal Period

Small Bowel Obstruction:

• Adhesions from prior surgery account for 55-75% of cases 3
• Intussusception is the leading cause in infants and young children 4
• Incarcerated/strangulated hernias (umbilical, inguinal, femoral) are the second most common cause 1, 4
• Neoplasia, Crohn's disease, duplication cysts, and trauma are less common 3, 2

Large Bowel Obstruction:

• Hirschsprung's disease in undiagnosed cases 5
• Neoplasia (rare in children) 5
• Inflammatory bowel disease strictures 5

Functional Obstruction (Ileus)

• Necrotizing enterocolitis in premature and stressed full-term infants, presenting with abdominal distension, bloody stools, bilious emesis, and sepsis 1
• Postoperative ileus from surgical manipulation and opioids 6
• Sepsis and peritonitis 6
• Electrolyte disturbances (hypokalemia, hypocalcemia, hypomagnesemia) 6
• Medications: opioids, anticholinergics 6

Clinical Manifestations

Warning Signs Requiring Immediate Action

Examine ALL hernia orifices (umbilical, inguinal, femoral) and surgical scars carefully—incarcerated hernias are a leading cause and easily missed. 1

Key Clinical Features by Obstruction Level:

Proximal Obstruction (Duodenum/Proximal Jejunum):

• Bilious vomiting within first 2 days of life is malrotation with midgut volvulus until proven otherwise 1
• Earlier and more prominent nausea/vomiting 1
• Less abdominal distension 1

Distal Obstruction (Ileum/Colon):

• Multiple distended bowel loops 1
• Progressive abdominal distension (positive likelihood ratio 16.8) 1
• Delayed or absent vomiting 1
• Feculent gastric aspirate indicates distal small bowel or large bowel obstruction 1

Signs of Ischemia/Perforation (Surgical Emergency):

• Peritoneal signs on examination 1
• Tachycardia, tachypnea, cool extremities, mottled skin 1
• Low serum bicarbonate, low arterial pH, elevated lactate, marked leukocytosis 1
• Bloody stools (especially in necrotizing enterocolitis) 1
• Portal venous gas or pneumatosis intestinalis 1

Necrotizing Enterocolitis Specific:

• Increased apnea and bradycardia episodes 1
• Focal abdominal wall erythema 1
• Thrombocytopenia and neutropenia 1

Diagnosis

Initial Evaluation

Immediate resuscitation takes priority: IV crystalloids, nasogastric decompression, nil per os, Foley catheter, and correction of electrolyte abnormalities before any imaging. 1

Laboratory Tests:

• Complete blood count, renal function, electrolytes (assess for pre-renal failure) 1
• Liver function tests 1
• Low bicarbonate, low pH, elevated lactate, marked leukocytosis, hyperamylasemia suggest ischemia 1
• Coagulation profile for potential emergency surgery 1

Imaging Algorithm

Plain Abdominal Radiography (First-Line):

• Sensitivity 74% for small bowel obstruction, 84% for large bowel obstruction 1
• Classic "double bubble" with no distal gas = duodenal atresia, no further imaging needed before surgery 1
• Multiple dilated loops with no/minimal distal gas = distal obstruction, proceed to contrast enema 1
• Bilious vomiting with nonclassic double bubble or normal gas pattern = malrotation/volvulus, proceed URGENTLY to upper GI series 1

Upper GI Series (Fluoroscopy):

• Gold standard for malrotation/midgut volvulus with 96% sensitivity 1
• Abnormal position of duodenojejunal junction (ligament of Treitz) confirms malrotation 1
• False-positive rate 10-15% due to redundant duodenum, bowel distension, jejunal position—meticulous technique required 1
• NOT indicated for classic double bubble with no distal gas or suspected distal obstruction 1

Contrast Enema (Fluoroscopy):

• Diagnostic procedure of choice for suspected distal obstruction with 96% sensitivity and 98% specificity for large bowel obstruction 1
• Microcolon indicates ileal/jejunal/colonic atresia 1
• Can be therapeutic in meconium plug syndrome and meconium ileus 1
• Less accurate than UGI for malrotation (20% false-negative rate, 15% false-positive from high mobile cecum) 1

Water-Soluble Contrast Administration:

• In adhesive small bowel obstruction, if contrast doesn't reach colon by 24 hours, predicts need for surgery 1
• Reduces need for surgery and shortens hospital stay in adhesive obstruction 1
• Administer only after adequate gastric decompression to avoid aspiration pneumonia and pulmonary edema 1

CT Scan:

• Most accurate diagnostic tool with ~90% accuracy for identifying site, severity, and etiology 1, 5
• Sensitivity 75-100% and specificity 61-93% for identifying ischemia/necrosis 1
• Evaluates bowel wall, vessels, mesentery for ischemia 1
• Pneumatosis indicates ischemia/infarction 1
• Oral contrast NOT needed—intraluminal fluid/gas in obstructed bowel provides excellent contrast 1

Magnetic Resonance Imaging:

• Preferred over CT in children and pregnant women to minimize radiation with 95% sensitivity and 100% specificity 1

Ultrasound:

• Limited role in postnatal diagnosis of intestinal obstruction 1
• Can evaluate SMV/SMA relationship for malrotation but less reliable than UGI 1

Treatment

Immediate Management (All Cases)

Begin resuscitation immediately before definitive diagnosis:

• Isotonic crystalloids with supplemental potassium to replace losses 1
• Nasogastric decompression to prevent aspiration pneumonia 1
• Nil per os 1
• Foley catheter for urine output monitoring 1
• Anti-emetics 1

Surgical Indications (Emergent)

Operate immediately for:

• Malrotation with midgut volvulus (mortality approaches 100% if bowel necrosis occurs) 1
• Signs of ischemia/perforation: peritoneal signs, shock, elevated lactate, pneumatosis 1
• Complete mechanical obstruction from atresia 1, 2
• Incarcerated/strangulated hernia 1, 4
• Necrotizing enterocolitis with perforation (peritoneal drainage or bowel resection) 1

Non-Operative Management

Adhesive Small Bowel Obstruction:

• 72-hour trial of conservative management is safe unless signs of ischemia/perforation 1
• Nasogastric or long intestinal tube decompression 1
• Water-soluble contrast administration reduces surgery need and hospital stay 1
• 12% recurrence at 1 year, 20% at 5 years 1

Meconium Plug/Meconium Ileus:

• Therapeutic contrast enema 1

Necrotizing Enterocolitis:

• Nonoperative management successful ~70% of time with antibiotics and bowel rest 1
• Survival rate 95% unless entire bowel involved (mortality 40-90% with total involvement) 1

Antibiotic Therapy

For complicated intra-abdominal infection or necrotizing enterocolitis:

• Broad-spectrum empiric therapy: carbapenems (imipenem, meropenem), piperacillin-tazobactam, ticarcillin-clavulanate, or extended-spectrum cephalosporin (cefotaxime, ceftriaxone, ceftazidime, cefepime) with metronidazole 1
• Traditional pediatric regimen: gentamicin, ampicillin, and clindamycin (or metronidazole) 1
• Individualized aminoglycoside dosing based on lean body mass and extracellular fluid volume 1

Critical Pitfalls to Avoid

Bilious vomiting in a neonate is malrotation with midgut volvulus until proven otherwise—delay in diagnosis is the major risk factor for mortality. 1, 7

Do not obtain UGI series for classic double bubble with no distal gas—this delays necessary surgery for duodenal atresia. 1

Do not administer water-soluble contrast without adequate gastric decompression—risk of aspiration pneumonia and pulmonary edema. 1

Examine all hernia orifices and surgical scars—incarcerated hernias are easily missed and are the second leading cause of obstruction in children. 1, 4

Neonates deteriorate rapidly with unrecognized obstruction—early diagnosis and prompt surgical intervention are critical, with delays being the major risk factor for mortality. 2, 7

Prematurity is not a contraindication to surgery—premature infants tolerate operative procedures well, and delay increases mortality. 7

Overall mortality should be <5% with specialized care—higher mortality indicates delays in diagnosis/treatment or associated major congenital anomalies (especially cardiac). 2, 7