Paralytic ileus

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"paralytic ileus" OR "postoperative ileus" management

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paralytic ileus abdominal X-ray dilated bowel loops

This abdominal plain radiograph (supine X-ray) demonstrates marked gaseous distension of multiple small bowel loops, primarily located in the central abdomen. The loops are dilated significantly beyond the normal 3cm threshold, suggesting a small bowel obstruction or paralytic ileus. A notable clinical feature is the 'gasless' appearance or lack of significant dilatation in the large bowel (colon), which is characteristic of an obstructive process occurring proximal to the ileocecal valve. Key radiological landmarks include visible valvulae conniventes within the distended loops and a gastric bubble in the left upper quadrant. The absence of gas in the rectum or distal colon supports a diagnosis of mechanical small bowel obstruction. This imaging modality is a primary diagnostic tool for assessing acute abdominal pain and distension, providing evidence of intestinal transition zones and potential complications such as perforation (though no pneumoperitoneum is visible here).

Diagnostic Image: This abdominal radiograph (X-ray) panel displays a comparison between recumbent (A) and upright (B) views of a 19-year-old patient. The images demonstrate significant pathological dilatation of both small and large bowel loops, characteristic of generalized ileus. In the recumbent view (A), gas-filled intestinal segments are dispersed across the abdominal cavity, revealing prominent valvulae conniventes and haustral markings indicative of gaseous distension. In the upright view (B), multiple air-fluid levels are clearly visible within the dilated loops, manifesting as horizontal lines where gas interfaces with fluid due to gravity. These findings suggest a functional bowel obstruction or paralytic ileus. The imaging is critical for differentiating between mechanical obstruction and generalized dysmotility. Educational concepts illustrated include the radiographic signs of bowel distension, the diagnostic utility of positional X-rays in emergency medicine, and the identification of air-fluid levels as markers of impaired intestinal transit.

This abdominal radiograph (X-ray) shows a diagnostic image of the abdomen in a patient presenting with postoperative symptoms. The primary finding is the presence of several markedly dilated small bowel loops, primarily located in the upper and central abdominal regions. These loops exhibit significant gaseous distension and multiple air-fluid levels, characteristic of an intestinal obstruction or paralytic ileus. The degree of small bowel dilatation is disproportionate to the sparse amount of gas visible within the colon. Anatomical landmarks including the lumbar spine, sacrum, and pelvic bones (iliac crests and pubic symphysis) are clearly visible, providing spatial orientation. The radiographic presentation is highly suggestive of a mechanical small bowel obstruction, potentially related to postoperative adhesions or complications. This visual evidence serves as an educational tool for identifying typical radiological signs of bowel distension and air-fluid levels in acute surgical abdominal pathologies.

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Paralytic Ileus

Definition

Paralytic ileus (also called adynamic or functional ileus) is a non-mechanical failure of intestinal peristalsis caused by neuromuscular dysfunction of the myenteric (Auerbach's) and submucous (Meissner's) plexuses. There is no physical obstruction, yet the gut fails to propel its contents forward. The resultant stasis causes accumulation of fluid and gas within the bowel, leading to distension.

Bailey and Love's Short Practice of Surgery, 28th Ed.

Pathophysiology

The pathophysiology is complex and multifactorial:

Neurogenic factors: Disruption of the enteric nervous system (ENS) and central nervous system input
Inflammatory mediators: Surgical trauma triggers an inflammatory cascade that inhibits smooth muscle contractility
Enteric hormones and neuropeptides: Released in response to stress, they inhibit coordinated propulsion
Electrolyte disturbances: Hypokalemia, hypomagnesaemia, and hyponatraemia reduce smooth muscle excitability
Opioids: Bind to mu-receptors in the gut wall, directly suppressing motility
Hypoxia and bowel oedema: Relative splanchnic ischaemia (e.g., in pancreatitis) contributes via reflex vasoconstriction

The net result is impaired local neuromuscular function, failed coordinated contractility, and bowel wall oedema.

Sabiston Textbook of Surgery, 21st Ed.

Causes / Varieties

Category	Examples
Postoperative	Most abdominal procedures (self-limiting, 24-72 hours); prolonged if hypoproteinaemia or metabolic derangement present
Intra-abdominal sepsis	Peritonitis, anastomotic leak, abscesses - causes localised or generalised ileus
Reflex ileus	Spinal/rib fractures, retroperitoneal haemorrhage, plaster jacket application
Metabolic	Hypokalemia, uraemia, hypomagnesaemia, diabetic ketoacidosis
Drugs	Opioids, anticholinergics, tricyclic antidepressants
Pancreatitis	Regional ileus affecting the duodenum, proximal jejunum, or transverse colon due to proximity of inflammation
Systemic illness	Sepsis, myocardial infarction, pneumonia, trauma
Pseudo-obstruction (Ogilvie's syndrome)	A variant - massive colonic dilatation (especially the caecum) in patients with major non-abdominal illness; risk of perforation

Bailey and Love's, Pye's Surgical Handicraft, Maingot's Abdominal Operations

Return of Bowel Function After Surgery

After laparotomy, intestinal motility returns in a predictable order:

Small bowel - within hours (some contractile activity within hours)
Stomach - 24-48 hours
Colon - 3-5 days

This is clinically important: a patient may pass flatus/stool while still vomiting because the colon has recovered before the stomach.

Bailey and Love's; Sabiston Textbook of Surgery

Clinical Features

Nausea and vomiting
Abdominal distension (tympanic on percussion)
Loss of appetite
Absent or markedly reduced bowel sounds
Absolute constipation - failure to pass flatus or stool
Diffuse, non-colicky abdominal discomfort (no cramping, which would suggest mechanical obstruction)

Key distinguishing point: mechanical obstruction features colicky pain and high-pitched, tinkling bowel sounds early; paralytic ileus features silent abdomen and no colic.

Radiology

Plain Abdominal X-ray (AXR):

Dilatation of both small and large bowel (unlike mechanical obstruction, where dilatation is proximal to the block only)
Multiple air-fluid levels on erect views
In pancreatitis: "sentinel loop" (localised dilated loop near inflamed pancreas) and "colon cut-off sign" (abrupt loss of gas in transverse colon)
Sensitivity of AXR approximately 66% for small bowel obstruction vs ileus

CT Abdomen:

No transition point (the hallmark of mechanical obstruction - an abrupt calibre change)
Generalised dilatation without a defined obstruction site
Can exclude mechanical cause and identify intra-abdominal complications
Grainger & Allison's Diagnostic Radiology

Here are representative plain X-ray appearances:

Paralytic ileus - generalised small and large bowel dilatation with air-fluid levels

Supine (A) and erect (B) AXR showing generalised dilatation of both small and large bowel with multiple air-fluid levels - characteristic of paralytic ileus

Management

1. Treat the Underlying Cause

Correct electrolyte imbalances (especially K+, Mg2+, Na+)
Treat intra-abdominal sepsis (drainage, antibiotics)
Reduce/discontinue opioids where possible
Address pancreatitis, retroperitoneal pathology

2. Supportive Measures

IV fluid replacement and maintenance of adequate hydration
Nasogastric (NG) tube for gastric decompression (drainage purposes; relieves nausea and vomiting)
Nil by mouth initially; advance diet as tolerated
Early ambulation - promotes return of bowel motility

3. Nutritional Support

Nutrient absorption from the gut is impaired in paralytic ileus
Parenteral nutrition (TPN) should be considered in prolonged ileus to prevent malnutrition

4. Pharmacological Options

Neostigmine (a cholinesterase inhibitor): used in Ogilvie's syndrome/adynamic ileus to stimulate intestinal motility; also useful for urinary bladder atony
Prokinetics (e.g., metoclopramide) have limited evidence
Alvimopan (mu-opioid receptor antagonist): used to accelerate recovery of postoperative GI function after opioid-containing anaesthesia (not universally available)

5. Ogilvie's Syndrome (Pseudo-obstruction)

Enormous caecal dilatation (>12 cm) carries risk of perforation
Colonoscopic decompression is the treatment of choice
Neostigmine may avoid colonoscopy in some cases
Bailey and Love's; Sabiston Textbook of Surgery; Goodman & Gilman's Pharmacology; Pye's Surgical Handicraft

Paralytic Ileus vs. Mechanical Obstruction

Feature	Paralytic Ileus	Mechanical Obstruction
Pain	Dull, continuous	Colicky, intermittent
Bowel sounds	Absent/very reduced	High-pitched, tinkling
AXR	Generalised dilation (small + large)	Dilation proximal to obstruction
CT	No transition point	Clear transition point
Onset post-op	Expected, usually resolves 3-5 days	Unusual if bowel function had returned
Cause	Functional/neurogenic	Adhesions, hernia, volvulus, tumour

Key Points Summary

Paralytic ileus = failure of neuromuscular transmission (Auerbach's and Meissner's plexuses)
Most common cause is post-laparotomy (self-limiting, 24-72 h for small bowel; 3-5 days for colon)
Hypokalemia and opioids are major reversible contributing factors
Bowel sounds are absent; no colic (distinguishes from mechanical obstruction)
AXR shows generalised bowel dilatation; CT excludes mechanical cause
Management is largely supportive: fluids, electrolyte correction, NG tube, early ambulation, treat underlying cause
TPN for prolonged cases; neostigmine/colonoscopy for Ogilvie's syndrome

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