.Describe causes, clinical features and treatment of chronic intestinal obstruction
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I now have sufficient information from multiple authoritative textbooks to compose a comprehensive answer on chronic intestinal obstruction. Let me compile this.
Chronic Intestinal Obstruction
Chronic (or recurrent/subacute) intestinal obstruction refers to a persistent or intermittent impairment of intestinal transit over weeks to months, in contrast to the acute, rapidly progressive form. It may be mechanical (a structural lesion physically blocking the lumen) or functional/pseudo-obstruction (dysmotility without a mechanical occlusion).
1. Causes
A. Mechanical Causes
Mechanical obstruction accounts for the majority of chronic cases. Hernias, intestinal adhesions, intussusception, and volvulus together account for ~80% of mechanical obstructions, with tumors and infarction comprising most of the remainder.
| Extrinsic (outside bowel wall) | Intrinsic (within the wall) | Intraluminal |
|---|---|---|
| Adhesions (post-surgical — most common cause of SBO) | Strictures: Crohn's disease, radiation enteritis, ischaemic | Gallstone ileus |
| Incarcerated hernia (inguinal, femoral, incisional) | Neoplasm (colorectal, small bowel: adenocarcinoma, lymphoma, carcinoid) | Bezoars |
| Peritoneal/omental carcinomatosis (ovarian, colorectal, gastric, pancreatic) | Congenital atresia/stenosis | Faecal impaction |
| Volvulus (sigmoid most common; cecal) | Intussusception | Foreign bodies |
| External compression by pelvic masses, retroperitoneal tumours | Diverticulitis with scarring | — |
| Radiation fibrosis | Hirschsprung disease (congenital aganglionic megacolon) | — |
Key points by site:
- Small bowel: Adhesions predominate (particularly after previous abdominal or pelvic surgery). Crohn's disease produces transmural inflammation → fibrotic strictures. Peutz-Jeghers hamartomatous polyps cause obstruction in patients aged 10–30 years. Radiation enteritis causes fibrotic strictures.
- Large bowel: Colorectal carcinoma is by far the most common cause, especially in the elderly; incidence is rising in younger patients. Diverticulitis with chronic inflammation can produce strictures. Sigmoid volvulus is characteristic in elderly, institutionalised, or anticholinergic-medicated patients. Fecal impaction is common in debilitated patients.
B. Functional (Pseudo-obstruction)
Chronic intestinal pseudo-obstruction (CIPO) — a syndrome of recurrent obstructive symptoms without a mechanical lesion — results from dysfunction of intestinal smooth muscle, the myenteric plexus, or the extraintestinal nervous system. Causes include:
- Visceral myopathies (e.g., scleroderma, systemic lupus)
- Visceral neuropathies (e.g., diabetes mellitus, Parkinson's disease)
- Paraneoplastic neuropathy (especially small-cell lung cancer — IgG antibodies reactive to myenteric/submucosal plexus neurons)
- Infiltration of mesentery or bowel muscle by tumour
- Drug-induced (opioids, vinca alkaloids, anticholinergics, tricyclic antidepressants)
2. Clinical Features
Symptoms
| Feature | Character |
|---|---|
| Abdominal pain | Most common symptom; typically colicky (crescendo-decrescendo), periumbilical or diffuse for small bowel, hypogastric for large bowel; more episodic and paroxysmal (30 sec–2 min) in proximal SBO; longer intervals and lasting longer episodes with distal obstruction |
| Vomiting | Prominent early in high/proximal obstruction (bilious); delayed and feculent in distal ileal or colonic obstruction; intermittent or continuous |
| Constipation / obstipation | Common in complete obstruction; partial obstruction may allow passage of flatus and stool |
| Abdominal distension | Characteristic; increases over time |
| Bloating / early satiety | Especially in pseudo-obstruction and partial obstruction |
| Weight loss / malabsorption | In longstanding partial obstruction, malabsorption and nutritional deficiency may develop |
Symptoms in chronic/partial obstruction tend to be insidious in onset, waxing and waning, and may mimic other GI conditions including CIPO.
Physical Examination
- Distension — most reliable sign; tympanitic on percussion
- Bowel sounds — high-pitched, metallic "rushes" with mechanical obstruction; diminished or absent in ileus/pseudo-obstruction; may diminish if obstruction persists for hours
- Visible peristalsis — may be present with chronic partial SBO
- Tenderness — variable; peritonism (localized or rebound) signals strangulation, perforation, or gangrene and demands urgent intervention
- Rectal examination — may reveal fecal impaction, rectal carcinoma, blood, or stricture
- Fever, tachycardia, leukocytosis — suggest strangulation or secondary infection
3. Investigations
Laboratory
- CBC: Leukocytosis suggests strangulation/gangrene (WBC >20,000/mm³ = suspect bowel gangrene; >40,000/mm³ = suspect mesenteric vascular occlusion)
- Electrolytes: Deranged with dehydration, prolonged vomiting
- BUN/creatinine: Elevated with volume depletion
- Lactate / serum bicarbonate: Metabolic acidosis and elevated lactate are markers of ischaemia
Imaging
- Plain abdominal X-ray (AXR): Multiple air-fluid levels, dilated loops of bowel; upright and supine views (limited utility in ED but useful initially)
- CT abdomen/pelvis (with IV contrast): Investigation of choice — identifies site, level, and cause of obstruction; differentiates benign (smooth transition, mesenteric vascular changes) from malignant obstruction (mass at obstruction site, lymphadenopathy, abrupt transition, irregular wall thickening); evaluates for strangulation (decreased bowel wall enhancement)
- CT enteroclysis: For low-grade SBO — water-soluble contrast infused via naso-enteric tube provides bowel distension for better assessment
- Colonoscopy / flexible sigmoidoscopy: For colonic strictures, tumours
- Water-soluble contrast enema: Useful to differentiate pseudo-obstruction from mechanical in large bowel; therapeutic in sigmoid volvulus
4. Treatment
Management depends on the underlying aetiology, degree of obstruction (partial vs. complete), presence of strangulation, and overall patient status.
General/Initial (All Mechanical Obstructions)
- IV fluid resuscitation — correct dehydration and electrolyte abnormalities
- Nasogastric (NG) decompression — relieves distension, reduces vomiting; mandatory for acute presentations; uncomfortable for long-term use
- Opioid discontinuation — opioids worsen dysmotility
- Urinary catheter — to monitor fluid balance
- Close monitoring — vital signs, urine output, serial abdominal examination
Conservative (Non-operative) Management
Appropriate for most cases of partial mechanical obstruction in the absence of signs of strangulation or deterioration:
- Trial for 12–24 hours with observation, IV fluids, NG suction
- Water-soluble contrast study (Gastrografin) administered via NG tube: if contrast reaches caecum within 8 hours → remove NG, commence liquids; if not in 24 hours → proceed to surgery
- Contraindications: suspected ischaemia, closed-loop obstruction, strangulated hernia, perforation
Surgical Management
Indications: complete obstruction, failed conservative management, signs of strangulation (fever, tachycardia, peritonism, leukocytosis), perforation, closed-loop obstruction.
Options:
- Adhesiolysis — for adhesive SBO
- Hernia repair — with or without bowel resection (if strangulated/gangrenous bowel)
- Bowel resection with primary anastomosis — for tumours, Crohn's strictures, ischaemic or radiation strictures, diverticular stricture
- Defunctioning stoma (colostomy/ileostomy) — where primary anastomosis is unsafe
- Laparoscopy — can diagnose and treat in selected cases (adhesive SBO, malignant bowel obstruction)
Endoscopic/Minimally Invasive Options
- Self-expanding metal stents (SEMS) — placed in gastric outlet, duodenum, colon, or rectum to palliate obstructive cancer; effective bridge to definitive surgery in colorectal cancer
- Endoscopic balloon dilatation / stricturoplasty — for Crohn's strictures (short, fibrotic, non-inflamed strictures)
- Endoscopic decompression — for sigmoid/cecal volvulus (colonoscopic decompression ± rectopexy)
- Percutaneous endoscopic gastrostomy (PEG) / venting gastrostomy — for palliative nausea/vomiting in inoperable malignant obstruction; allows enteral nutrition and symptom relief
Pharmacological Management
Particularly relevant for inoperable malignant obstruction or CIPO:
| Drug class | Examples | Role |
|---|---|---|
| Antisecretory | Octreotide, anticholinergics (hyoscine) | Reduce intestinal secretions, relieve colicky pain |
| Antiemetics | Dopamine antagonists (metoclopramide, haloperidol, phenothiazines) | Nausea and vomiting control |
| Analgesics | Opioids (for pain, with caution) | Pain management |
| Anti-inflammatory | Glucocorticoids (dexamethasone) | May help resolve partial/inflammatory obstruction; anti-oedema effect |
| Prokinetics | Metoclopramide, neostigmine | Only for incomplete or functional obstruction; contraindicated in complete mechanical obstruction |
Special notes:
- Metoclopramide can be trialled in incomplete or functional obstruction only
- Octreotide reduces GI secretions and may relieve obstructive symptoms without surgery
- SEMS are preferred over long-term NG tubes in patients with weeks-to-months life expectancy
- Long-term NG tubes are undesirable; a venting gastrostomy is a more comfortable alternative
Disease-Specific Treatment
| Cause | Specific Treatment |
|---|---|
| Crohn's disease stricture | Corticosteroids (active inflammation), biologics (anti-TNF/anti-integrin), endoscopic balloon dilatation, stricturoplasty or resection |
| Colorectal cancer | Surgical resection (curative or palliative) ± adjuvant chemo/RT; SEMS for palliation or bridge to surgery |
| Sigmoid volvulus | Colonoscopic decompression first; semi-elective sigmoid resection to prevent recurrence |
| Hirschsprung disease | Surgical resection of aganglionic segment with coloanal anastomosis |
| Radiation stricture | Endoscopic dilatation; surgical resection if refractory |
| CIPO | Treat underlying cause; prokinetics (neostigmine for acute colonic pseudo-obstruction); nutritional support (enteral/parenteral); low-residue diet |
| Adhesive SBO | Conservative first; laparoscopic or open adhesiolysis for failure/recurrence; anti-adhesion barriers (e.g., Seprafilm) at surgery |
| Faecal impaction | Disimpaction (manual, enema, polyethylene glycol); long-term bowel regimen |
Summary
Chronic intestinal obstruction requires systematic assessment of the level (small vs. large bowel), degree (partial vs. complete), and aetiology (mechanical vs. functional). Adhesions, hernias, and colorectal tumours dominate, but inflammatory, radiation, vascular, and functional causes must always be considered. Management centres on resuscitation, decompression, and definitive treatment of the underlying cause — surgical for most mechanical obstructions, pharmacological/endoscopic for palliation or functional disease.
Sources: Sleisenger & Fordtran's Gastrointestinal and Liver Disease; Harrison's Principles of Internal Medicine 22e; Robbins & Kumar Basic Pathology; Tintinalli's Emergency Medicine; Sabiston Textbook of Surgery
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