Basics
Description
- Blockage of normal flow of air and other contents through the intestine
- May be partial or complete, mechanical or functional
- May arise from intrinsic abnormalities (e.g., meconium ileus, intestinal atresia) or extrinsic abnormalities (e.g., adhesions, bands, or volvulus)
- May also be caused by neuromotor dysfunction of the gastrointestinal tract (i.e. hypomotility or paralysis of the intestine)
- Most commonly involves the small bowel
- Untreated, obstruction can lead to intestinal ischemia.
Pathophysiology
- Pathophysiology depends on the mechanism of the obstruction.
- Functional obstruction (paralytic ileus)
- Failure of intestinal motor function without mechanical obstruction
- Common after abdominal surgery, following extensive manipulation of the bowel
- Other causes: infection (pneumonia, gastroenteritis, urinary tract infection, peritonitis, systemic sepsis), drugs (e.g., opiates, loperamide, vincristine), metabolic abnormalities (hypokalemia, hypomagnesemia, uremia, myxedema, and diabetic ketoacidosis)
- Mechanical obstruction
- Intestinal dilation proximal to site of obstruction as the bowel fills with intestinal contents and air
- Common after abdominal surgery following extensive manipulation of the bowel
- Buildup of intestinal contents results in further distention, nausea, and vomiting.
- Internal and external losses result in hypovolemia, oliguria, and azotemia.
- Bacteria proliferate in the small bowel and its contents can become feculent.
- "Closed loop"¯ obstruction occurs when contents cannot get in or out of an intestinal segment.
- Ischemic obstruction
- Occurs secondary to occlusion of intestinal blood supply
- Causes
- Twisting/kink of feeding blood vessels
- Increased intramural pressure in the setting of bowel distention can result in decreased perfusion to the affected area.
- With progression, gangrene, peritonitis, and perforation may occur.
- Damage to the normal gut barrier may enable bacteria, bacterial toxins, and inflammatory mediators to enter the circulation, causing sepsis.
Etiology
May be congenital (e.g., atresia, duplication), acquired (e.g., neoplastic, inflammatory), or iatrogenic (e.g., adhesions, radiation stricture)
Etiology varies by age:
- Neonates
- Intestinal atresia (most common cause in neonates)
- Obstructive meconium disorders (associated with cystic fibrosis)
- Meconium ileus
- Meconium plug syndrome
- Meconium peritonitis
- Duodenal atresia (associated with Down syndrome)
- Annular pancreas
- Anorectal malformation/Imperforate anus
- Necrotizing enterocolitis
- Hirschsprung disease
- Infants
- Pyloric stenosis (age: 1-2 months)
- Intussusception (age: 2 months to 2 years)
- Postoperative adhesions
- Incarcerated inguinal hernia
- Hirschsprung disease
- Duplications
- Meckel diverticulum
- Older children
- Postoperative or postinfectious intestinal adhesions (e.g., perforated appendicitis)
- Inflammatory bowel disease
- Malrotation with or without midgut volvulus
- Annular pancreas
- Meckel diverticulum
- Superior mesenteric artery syndrome
- Corrosive injury
- Foreign body ingestion
- Juvenile polyposis and related syndromes
- Distal intestinal obstruction syndrome (cystic fibrosis)
- Roundworm (Ascaris lumbricoides)
- Gastric and intestinal bezoars
- Colonic volvulus secondary to aerophagia and constipation (more common in neurodevelopmentally impaired)
- Cancer-related intestinal obstruction and radiotherapy-induced adhesions
Diagnosis
- Presentation may be acute and dramatic or chronic and subtle. Chronic or intermittent obstruction can be more challenging to diagnose.
- Careful history, physical examination, and consideration of age-related etiology will usually identify the specific cause.
History
- The classic symptoms of intestinal obstruction include vomiting, abdominal distention, colicky abdominal pain, and failure to pass flatus/stool (vomiting will be bilious if obstruction is distal to ampulla of Vater). Closed loop obstruction may present with pain and retching without emesis.
- Neonates
- History of maternal polyhydramnios and aspiration of >20 mL gastric fluid after birth may suggest high intestinal obstruction.
- Failure to pass meconium within 48 hours of birth is suggestive of a distal obstruction.
- Older children
- Commonly present with pain which can be poorly localized, colicky visceral pain or sharp peritoneal pain
- Nausea and vomiting: High intestinal obstruction results in bilious emesis; distal obstruction may lead to feculent emesis.
- Passage of blood or mucus per rectum may be a sign of intestinal ischemia or mucosal sloughing (e.g., intussusception and volvulus).
Alert
Due to potentially delayed diagnosis and reduced functional reserve, neonates with unrecognized intestinal obstruction deteriorate rapidly, with increased morbidity, mortality, and surgical complications.
Physical Exam
- General assessment and vital signs, signs of dehydration, sepsis, or malnutrition
- Palpation typically reveals abdominal distention. It may also reveal the presence of a hernia, a mass suggestive of stool, or intussusception.
- Tenderness denotes inflammation, significant distention, or ischemia and should raise concern for bowel compromise. Guarding and rigidity result from full-thickness bowel wall involvement or perforation/peritonitis.
- Bowel sounds are unreliable. They may be initially increased in hyperperistaltic obstructed loops. They may also become decreased, occasional, or even absent; typically absent sounds with ileus
- Anal inspection excludes anorectal malformation. Rectal examination reveals, at times, a palpable polyp or intussusceptum and blood (overt, occult, or "currant jelly,"¯ typical of intussusception).
- Fever, tachycardia, signs of peritonitis, and severe pain that persists after nasogastric decompression may indicate a need for surgical intervention.
Diagnostic Tests & Interpretation
Lab
- No laboratory studies are diagnostic, but CBC, electrolytes, and blood gas should be obtained to help optimize supportive treatment.
- Assess for hypochloremic, hypokalemic metabolic alkalosis.
- Bowel infarction may lead to marked leukocytosis, thrombocytopenia, and metabolic acidosis.
- Serum amylase and lipase should be determined to rule out pancreatitis (may be mildly elevated in intestinal obstruction).
Imaging
- Plain abdominal x-rays: supine and erect or decubitus views may identify the classic features: gasless abdomen or air-fluid levels and distended loops of intestine
- In small bowel obstruction: dilated small bowel, air-fluid levels without gas in the colon
- Paralytic ileus: distended loops of bowel throughout.
- Duodenal obstruction: "double-bubble"¯ sign
- Pneumoperitoneum in perforation
- Peritoneal calcifications in meconium peritonitis
- Right lower quadrant ground-glass appearance in meconium ileus
- High small bowel obstruction or ischemic obstruction (midgut volvulus) may present with normal or nearly normal X-rays.
- Ultrasonography: may identify a mass or phlegmon (e.g., perforated appendix), pyloric stenosis, malrotation (orientation of vessels), intussusception ("target sign"¯ or "Doughnut sign"¯), or pelvic pathology in adolescents
- CT or MRI: localize the obstruction "transition zone"¯; diagnosis of strangulation-ischemic segment does not perfuse with contrast; may demonstrate ileus-absence of transition zone, Crohn disease-terminal ileitis or stricture, and neoplasms
- Contrast enema: to confirm/treat intussusception or to evaluate for Hirschsprung; may show "microcolon"¯ of disuse in neonatal small bowel obstruction
- Upper GI series: for malrotation with or without volvulus.
- Water-soluble, low osmolarity materials should be preferred (risk of perforation). Effort should be made to minimize radiation exposure.
Alert
Evaluation for associated congenital anomalies is mandatory in some surgical conditions, as some are life threatening. The most frequent are cardiac and renal abnormalities.
Differential Diagnosis
Other causes of abdominal pain and vomiting should be considered and ruled out by history and physical examination:
- Appendicitis
- Torsion of testis or ovary
- Lower lobe pneumonia
- Pancreatitis
- Sickle cell crisis
- Henoch-Sch ¶nlein purpura
- Biliary colic
- Lead poisoning
- Acute adrenal insufficiency
- Diabetic ketoacidosis
- Acute intermittent porphyria
Alert
There is no spontaneous resolution of inguinal hernia. Surgery should be scheduled before incarceration occurs. Inguinal hernias have 10-28% risk for incarceration.
Treatment
Initial Stabilization
- Hold oral intake.
- Decompress the stomach by nasogastric tube.
- Administer IV fluids, correct electrolyte imbalance, and ensure adequate urine output.
- Cultures and broad-spectrum antibiotics (covering gram-negative aerobes and anaerobes) for sepsis or perforation/peritonitis
- Identify etiology of obstruction.
General Measures
- Paralytic ileus is usually self-limiting and resolves with supportive treatment.
- Nasogastric decompression and fluids alone initially for adhesions. Adhesive postoperative obstruction is less likely to resolve without surgery in a child younger than age 1 year old.
- In intussusception, hydrostatic or air enema reduction is successful in 90% of cases.
- Anti-inflammatory medication/steroids for inflammatory obstruction of IBD; persistent strictures may require resection
- Contrast enemas and direct enteral installation of N-acetylcysteine for uncomplicated meconium ileus
- Manual reduction of incarcerated inguinal hernias followed by repair
- Colonic volvulus may be treated with endoscopic decompression followed by elective surgery.
- Endoscopic removal of foreign bodies
Special Therapy
- Nonoperative management with decompression by nasogastric tube and IV fluids is the 1st-line approach in
- Early postoperative, partial, and recurrent adhesive obstructions
- Necrotizing enterocolitis
- Meconium ileus
- Duodenal hematomas
- Superior mesenteric artery syndrome
- Crohn disease
Surgery/Other Procedures
- Surgery may be required for definitive correction of bowel obstruction.
- Exceptions to this rule may include the above-mentioned conditions managed conservatively.
- In all situations: If no improvement within 12-24 hours, surgery is advisable.
- Additionally, bowel obstruction without a definitive causal diagnosis requires surgery.
- The surgical procedure is individualized according to the specific type, site, anatomy of the obstruction, and associated conditions.
- Laparoscopic surgery can be used for the diagnosis and repair of select intestinal obstructions and for adhesiolysis.
Ongoing Care
Prognosis
- Varies with different causes of intestinal obstruction, age of the patient, and associated conditions
- Extensive bowel resection or multiple repeat bowel resections can lead to short bowel syndrome, in which a requirement for long-term central access and parenteral nutrition is associated with significant morbidity and mortality.
Complications
- May result from delayed operation
- Dehydration, azotemia, renal failure
- Intestinal ischemia with sepsis and shock
- Bowel perforation and peritonitis
- Short-gut syndrome
Additional Reading
- McAteer JP, Kwon S, LaRiviere CA, et al. Pediatric specialist care is associated with a lower risk of bowel resection in children with intussusception: a population-based analysis. J Am Coll Surg. 2013;217(2):226-232. [View Abstract]
- Reid JR. Practical imaging approach to bowel obstruction in neonates: a review and update. Semin Roentgenol. 2012;479(1):21-31. [View Abstract]
- Young J, Kim DS, Muratore CS, et al. High incidence of postoperative bowel obstruction in newborns and infants. J Pediatr Surg. 2007;42(6):962-965. [View Abstract]
Codes
ICD09
- 560.9 Unspecified intestinal obstruction
- 777.1 Meconium obstruction in fetus or newborn
- 751.1 Atresia and stenosis of small intestine
- 560.2 Volvulus
- 560.81 Intestinal or peritoneal adhesions with obstruction (postoperative) (postinfection)
- 560.1 Paralytic ileus
ICD10
- K56.60 Unspecified intestinal obstruction
- P76.0 Meconium plug syndrome
- Q41.9 Congen absence, atresia and stenosis of sm int, part unsp
- K56.2 Volvulus
- P76.8 Other specified intestinal obstruction of newborn
- K56.5 Intestinal adhesions w obst (postprocedural) (postinfection)
- K56.0 Paralytic ileus
- P76.9 Intestinal obstruction of newborn, unspecified
SNOMED
- 81060008 Intestinal obstruction (disorder)
- 206523001 Meconium ileus (disorder)
- 93032003 Congenital atresia of intestinal tract (disorder)
- 9707006 intestinal volvulus (disorder)
- 67766009 Intestinal adhesions with obstruction (disorder)
- 55525008 Paralytic ileus (disorder)
FAQ
- Q: When should I consult a pediatric surgeon?
- A: If there is concern for bowel obstruction, a pediatric surgical consultation should be obtained early. In some cases, emergency surgery is necessary, whereas other times, it is more reasonable to place an NGT, administer IV fluids, and monitor for gradual resolution of the obstruction by clinical exam and radiographs.
- Q: Why are nasogastric tubes used in the treatment of intestinal obstruction?
- A: Tube decompression of the stomach allows for some symptomatic relief of nausea. In addition, it decreases the amount of fluid in obstructed intestine which may speed recovery. NGT output volume and character can guide management.
- Q: Is my child likely to have recurrent episodes of intestinal obstruction?
- A: It depends on the cause of the obstruction. Conditions associated with recurrence include intussusception, inflammatory conditions, and postoperative adhesions.