Intestinal Obstruction

Definition

Intestinal obstruction is a condition where there is an impairment of the normal flow of intestinal contents due to either a mechanical or functional cause.
It can occur at any level of the gastrointestinal tract, but it is most common in the small intestine and colon.

Classification

1. Dynamic (Mechanical) Obstruction

Caused by a physical blockage preventing intestinal transit.
Examples: Adhesions, hernias, malignancies, volvulus, intussusception.

2. Adynamic (Functional) Obstruction

No mechanical blockage, but peristalsis is absent or inadequate.
Examples: Paralytic ileus, pseudo-obstruction.

3. Simple vs. Strangulated Obstruction

Simple obstruction: No compromise to bowel blood supply.
Strangulated obstruction: Blood supply is compromised, leading to ischemia and necrosis.

Etiology

A. Small Bowel Obstruction (SBO)

Adhesions (40%) – Most common cause, often post-surgical.
Hernias (12%) – Incarcerated inguinal, femoral, or umbilical hernias.
Malignancies (15%) – Primary or metastatic tumors.
Intussusception – Common in children.
Volvulus – Twisting of the bowel (less common in small bowel).
Foreign Bodies – Bezoars, gallstones (gallstone ileus).

B. Large Bowel Obstruction (LBO)

Colorectal Cancer (60%) – Most common cause in adults.
Diverticular Disease (15%) – Inflammatory strictures from diverticulitis.
Volvulus (10%) – Sigmoid or caecal volvulus.
Fecal Impaction (5%) – Elderly, immobile patients.
Strictures – From inflammatory bowel disease (Crohn’s, ischemic colitis).

C. Functional (Adynamic) Obstruction

Paralytic Ileus – Common postoperatively, seen in peritonitis, electrolyte imbalances.
Ogilvie’s Syndrome – Acute colonic pseudo-obstruction, seen in elderly and critically ill patients.

4 Cardinal Symptoms

1. Abdominal Pain (Colicky Pain)

First symptom, sudden onset.
Colicky in nature (due to increased peristalsis).
Location varies by site of obstruction:
- Small bowel obstruction (SBO) → Periumbilical pain.
- Large bowel obstruction (LBO) → Lower abdominal pain.
Continuous, severe pain suggests strangulation.

2. Vomiting

Early and severe in proximal (high) SBO.
Delayed in distal (low) SBO.
Late or absent in LBO unless the ileocaecal valve is incompetent.
Nature of vomitus:
- High SBO → Bile-stained, greenish vomitus.
- Low SBO → Foul-smelling, feculent vomiting.

3. Abdominal Distension

More pronounced in LBO than SBO.
Mild distension in high SBO, marked distension in low SBO or LBO.
"Closed-loop" obstruction (competent ileocaecal valve) → Massive caecal distension, high risk of perforation.

4. Absolute Constipation (Obstipation)

No passage of faeces or flatus.
Occurs early in LBO, but may be delayed in SBO.

Physical Examination

Inspection

Abdominal distension (more in LBO than SBO).
Visible peristalsis may be seen in thin patients with SBO.

Palpation

Tenderness → More pronounced if strangulation or peritonitis is present.
Localized mass → Suggests malignancy or volvulus.

Percussion

Tympanic abdomen due to gas accumulation.
Dullness in flanks → Suggests free fluid (perforation or peritonitis).

Auscultation

Early obstruction → Hyperactive, high-pitched, "tinkling" bowel sounds.
Late obstruction or ileus → Absent bowel sounds.

Signs of Dehydration & Shock (late presentation)

Dry mucous membranes
Reduced urine output
Tachycardia
Hypotension (common in SBO due to fluid loss).

Investigations

Imaging

1. Erect Abdominal X-ray:

SBO → Multiple air-fluid levels with "stepladder" appearance.
LBO → Dilated colon with haustra still visible.
Sigmoid Volvulus → "Coffee bean" sign, "bird’s beak" sign
Caecal Volvulus → caecum is intraperitoneal and 'mobile', able to displaced away from RIF, susceptible to twisting or folding.

2. CT Abdomen with Contrast (Gold Standard):

Identifies transition point, cause, and signs of ischemia (bowel wall thickening, pneumatosis intestinalis).

3. Water-soluble Contrast Study (Gastrografin):

Helps in differentiating mechanical from paralytic ileus.
Bird's beak sign - tapering of contrast at the site of the twist

Management

1. Initial Resuscitation & Supportive Care

Airway & Breathing:

Ensure adequate oxygenation and assess for signs of aspiration risk.

Circulation:

Insert two large-bore IV cannulas (14G/16G).
Fluid resuscitation: Use Hartmann’s solution or normal saline to correct dehydration and electrolyte imbalances.
Monitor urine output: Insert a Foley catheter (goal: >0.5 mL/kg/hr).

Nasogastric Tube (NGT):

Decompression with Ryle’s or Salem tube to reduce vomiting and prevent aspiration.

Pain Control:

IV opioids (morphine) cautiously used in non-strangulating obstruction.
Avoid excessive opioids in paralytic ileus, as they reduce gut motility.

Broad-Spectrum IV Antibiotics:

If suspected strangulation or perforation, start ceftriaxone + metronidazole or piperacillin-tazobactam.

2. Conservative (Non-Operative) Management

Indications:

Only for partial or adhesive obstruction
No signs of strangulation (no peritonism, no leukocytosis, no lactate elevation).
Adhesive small bowel obstruction (may resolve in 72 hours).

Protocol:

NGT decompression + NPO (nil by mouth).
IV fluids + electrolyte correction.
Serial abdominal exams every 4-6 hours.
Gastrografin challenge may accelerate resolution in adhesive obstructions.

Operative Management

1. Absolute Indications (Emergency Surgery Required):

Suspected strangulation (peritonism, fever, tachycardia, acidosis, leukocytosis, raised lactate).
Closed-loop obstruction (e.g., volvulus, obstructed hernia).
Failed conservative management - Obstruction not resolving after 72 hours of conservative therapy.
Intestinal perforation (free air on X-ray/CT).

2. Surgical Approaches

1. Laparotomy (Open Surgery)

Used for perforation, strangulation, ischemia.
Procedure:
- Exploration of obstruction site.
- Resection of non-viable bowel.
- Primary anastomosis if the patient is stable.
- Stoma formation (colostomy/ileostomy) in unstable cases.

2. Laparoscopic Adhesiolysis

**For stable adhesive SBO.
Reduces risk of recurrent adhesions.

3. Segment-Specific Procedures

Sigmoid Volvulus → Endoscopic decompression, then elective resection.
Caecal Volvulus → Right hemicolectomy.
Malignant Large Bowel Obstruction → Stenting (palliative) or segmental resection.

3. Postoperative Care & Long-Term Management

NGT decompression until bowel function resumes.
Gradual reintroduction of diet (clear liquids → soft foods).
IV fluids & electrolyte monitoring.
Prophylaxis against deep vein thrombosis (DVT) (compression stockings, LMWH).
Bowel stimulation (early mobilization, stool softeners).
Management of underlying cause (e.g., avoiding NSAIDs for Crohn’s, post-op adhesiolysis for recurrent cases).

Prognosis & Complications

Poor Prognostic Indicators

Elderly patients (>75 years).
Delayed presentation (>24 hours of symptoms).
Shock at admission (tachycardia, hypotension).
Bowel ischemia/perforation on imaging.

Potential Complications

Bowel Necrosis → Perforation → Sepsis (if untreated).
Postoperative Adhesions → Recurrent Obstruction.
Short Bowel Syndrome (if extensive resection).
Wound infection/Intra-abdominal abscess.

Reference