Contents · 12 sections
In a nutshell. Acute intestinal obstruction (AIO) is a disruption of intestinal transit that requires differentiating between mechanical (strangulated — incarceration + impaired blood supply; obstructive — without ischemia) and dynamic (paralytic, spastic) obstruction. By level: high (small bowel) and low (large bowel). Key diagnostics: plain radiography (Kloiber's air-fluid levels, gas-fluid arches) and contrast-enhanced CT. Strangulation requires emergency surgery; adhesive small bowel obstruction is often managed conservatively for 24–48 hours; malignant colonic obstruction requires a stoma/stent/resection.
1. Classification
- Mechanical: strangulated (volvulus, knotting, incarcerated hernia, intussusception), obstructive (tumor, gallstone, foreign body, coprostasis, bezoar, helminth ball), mixed (adhesive).
- Dynamic: paralytic (postoperative, peritonitis, electrolyte disturbances, mesenteric ischemia), spastic (rare — lead colic, porphyria).
- By level: high (small intestine) and low (large intestine).
- By degree: complete and partial.
- By course: acute and chronic.
2. Etiology
- Small bowel: adhesions (60–75%), incarcerated hernias (10–20%), tumors (5%), Crohn's disease, intussusception, volvulus, foreign bodies.
- Large bowel: colorectal cancer (60%), sigmoid volvulus (10–15%), diverticular disease, coprostasis, intussusception (rare in adults).
- In children: intussusception (peak 6–36 months), pyloric stenosis, atresias, meconium ileus, Hirschsprung's disease.
3. Pathogenesis
Proximal to the obstruction — accumulation of fluid and gas, increased luminal pressure, impaired lymphatic and venous outflow → wall edema, transudation, third-space fluid loss up to 6–8 L → hypovolemia, electrolyte shifts (hypokalemia, hypochloremic alkalosis in high vomiting).
In strangulation — additional compromise of arterial blood supply → ischemia → necrosis within 6–12 hours → perforation and peritonitis. In obstructive colonic obstruction with a competent ileocecal valve — a "closed loop" with the risk of cecal perforation at a diameter of > 12 cm.
4. Clinical presentation
Characteristic features
- Colicky pain — pathognomonic for mechanical obstruction; intense, constant, without pain-free intervals — in strangulation and ischemia.
- Vomiting: early in high obstruction, late "fecaloid" in low obstruction.
- Cessation of stool and flatus.
- Abdominal distension — markedly pronounced in low and paralytic obstruction.
- Hyperactive "tinkling" peristalsis (succussion splash — Sklyarov's sign) in mechanical obstruction; "grave silence" — in paralytic obstruction and necrosis.
Symptoms
- Wahl's sign — asymmetric distension with visible peristalsis over the affected loop.
- Spasokukotsky's sign — "falling drop" sound.
- Obukhov hospital sign — an empty, relaxed rectal ampulla (in sigmoid volvulus).
- Hegar's sign / Cege-Manteuffel sign — inability to introduce > 0.5 L of water during a siphon enema.
5. Diagnostics
- Plain abdominal radiography standing/supine: Kloiber's signs (air-fluid levels), gas-fluid arches, "staircase" pattern, mucosal folds of the small bowel (Kerckring's folds), "coffee bean" sign in sigmoid volvulus.
- IV contrast-enhanced CT (gold standard): obstruction point, transition zone, ischemic signs (wall thickening, pneumatosis, portal venous gas, lack of enhancement), free air/fluid.
- Water-soluble contrast per os (Gastrografin): diagnostic and therapeutic in adhesive SBO — passage into the colon within 24 hours rules out complete obstruction.
- Ultrasound — diagnosis in pregnant women and children (to-and-fro movements, pseudokidney sign).
- Barium enema / colonoscopy when colonic tumor is suspected.
- Laboratory tests: CBC (leukocytosis, left shift), ABG and lactate (↑ lactate — early marker of ischemia), electrolytes, creatinine, urea, amylase.
6. Differential diagnosis
| Condition | Key differentiator |
|---|---|
| Acute pancreatitis | Shingles-like pain, ↑↑ amylase/lipase, CT |
| Perforation of a hollow viscus | "Dagger-like" pain, free gas under the diaphragm |
| Mesenteric ischemia | Disproportion between pain and physical findings, ↑↑ lactate, history of atrial fibrillation |
| Ogilvie's syndrome | Colonic dilation without mechanical obstruction; CT shows no transition zone |
| Paralytic AIO | Postoperative, peritonitis, hypokalemia; "silent" abdomen, uniform distension |
| Renal colic | Radiating pain, hematuria, ultrasound/CT |
7. Management strategy
Conservative
- NPO, nasogastric tube for gastric decompression.
- Crystalloid infusion — rehydration, electrolyte correction.
- Urinary bladder catheterization, monitoring diuresis.
- Antibiotics if ischemia/perforation is suspected.
- Analgesia (without masking the clinical dynamics!).
- Water-soluble contrast per os — diagnostic and therapeutic in adhesive small bowel obstruction.
- Duration — up to 24–48 h; if no resolution or in case of worsening — surgery.
Emergency surgery
- Strangulation (hernia incarceration, volvulus, knotting).
- Peritonitis, free gas.
- Large bowel obstruction with signs of ischemia.
- Closed-loop obstruction (cecal diameter > 12 cm).
- Worsening during conservative management.
Types of surgery
- Adhesiolysis for adhesive obstruction.
- Bowel resection for necrosis.
- Herniorrhaphy.
- For colorectal tumor: resection with primary anastomosis (right colon) or Hartmann's procedure/stoma/stent (left colon).
- Detorsion and mesosigmopexy for sigmoid volvulus; resection in case of necrosis.
- Reduction (hydrostatic in children — within 24 h from onset).
8. Specifics of large bowel obstruction
- 70% — colorectal cancer (more frequently left-sided).
- Colonoscopy + SEMS stenting as a bridge to surgery — allows elective resection in 1–2 weeks.
- Sigmoid volvulus in the elderly — endoscopic detorsion + elective resection thereafter.
- Ogilvie's syndrome (acute colonic pseudo-obstruction) — neostigmine 2 mg IV (under cardiac monitoring!), decompressive colonoscopy; surgery only in case of perforation.
9. Postoperative management
- Early mobilization, ERAS protocols.
- Early enteral nutrition (per os or via a jejunal tube).
- Prokinetics for ileus: metoclopramide, erythromycin.
- Chewing gum — safely ↑ peristalsis.
- Electrolyte correction — especially K⁺ and Mg²⁺.
- VTE prophylaxis: LMWH, compression stockings.
10. Complications
- Bowel necrosis, perforation, peritonitis.
- Abdominal sepsis, septic shock.
- ARF, multiple organ failure.
- Anastomotic leak (5–10%).
- Short bowel syndrome (with extensive resection < 150 cm).
- Recurrence of adhesive SBO (up to 30% within 10 years).
11. Prognosis
- Mortality 5–10% with timely care; up to 30% in strangulation.
- Key predictor — time to surgery in ischemia (> 24 h sharply worsens outcome).
- Elderly age, comorbidities, peritonitis — risk factors.
12. FAQ
When is conservative management sufficient in adhesive SBO?
In the absence of peritonitis, ischemia, tachycardia, progressive leukocytosis, and elevated lactate. Monitor every 4–6 h. Passage of water-soluble contrast into the cecum within 24 h is a predictor of resolution.
How do small bowel and large bowel Cloiber's air-fluid levels differ?
Small bowel levels — narrow, high, located more centrally, with circular folds (Kerkckring folds). Large bowel levels — wide, low, peripheral, with haustra.
What is the «double-barrel» sign on ultrasound?
In intussusception — concentric layers of bowel loops (target sign in transverse view, double-barrel in longitudinal view). Sensitivity 98% in children.
When is a colorectal stent placed?
For obstructing left-sided tumor obstruction in patients at high surgical risk or as a bridge to surgery. Do not use in perforation, ischemia, or proximal tumor.
What does the «coffee bean» sign mean?
Characteristic radiological finding of sigmoid volvulus — a giant coffee-bean-shaped loop directed toward the right upper quadrant.
See also: Peritonitis · Appendicitis · Colorectal cancer · Hernias · Surgery Catalog