Traumatic Adynamic (Paralytic) Ileus

Definition

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

• POI is a physiologic, self-limiting response involving mainly the stomach and colon (not the small intestine), lasting 2-4 days after abdominal surgery.
• True adynamic ileus is a pathologic, generalized motor disorder involving the entire gut - stomach, small intestine, and colon - and is the more severe, clinically significant entity.

Varieties / Causes (with focus on traumatic)

1. Postoperative - A degree of ileus usually follows any abdominal procedure, self-limiting at 24-72 hours. Prolonged if hypoproteinaemia or metabolic abnormalities are present. Intraoperative handling of bowel loops disturbs peristaltic activity and provokes adynamic ileus.
2. Infective - Intra-abdominal sepsis may give rise to localised or generalised ileus.
3. Reflex ileus (Traumatic) - This is the key traumatic variety. It may occur following:
   • Fractures of the spine or ribs
   • Retroperitoneal haemorrhage (e.g., from vertebral fractures, pelvic fractures, aortic injury)
   • Application of a plaster jacket
   • Retroperitoneal conditions such as haematoma
   • Retroperitoneal operations (e.g., kidney transplantation)
   • Adynamic ileus is common after thoracolumbar spine injuries (fractures of the thoracic spine are specifically associated with it)
4. Metabolic - Uraemia and hypokalaemia are the most common contributory factors.
5. Systemic inflammatory - Sepsis, pancreatitis (regional self-limiting ileus affecting the duodenum, proximal jejunum, or transverse colon via direct proximity and reflex splanchnic vasoconstriction).

• Bailey and Love's 28th ed.; Current Surgical Therapy 14th ed.; Pye's Surgical Handicraft 22nd ed.; Maingot's Abdominal Operations

Pathophysiology

• The sympathetic nervous system exerts a predominantly inhibitory effect on small intestinal contractile activity. Retroperitoneal trauma, haematoma, or irritation interferes with the autonomic nervous innervation to the gut - specifically disrupting the splanchnic sympathetic pathways that modulate intestinal motor activity.
• In the context of spinal fractures, disruption of autonomic pathways at the thoracolumbar level directly removes central control over gut motility.
• Retroperitoneal haemorrhage causes direct irritation of the autonomic ganglia and plexuses lying on the posterior abdominal wall.
• Splanchnic ischaemia secondary to reflex vasoconstriction in response to systemic hypotension (as in trauma with haemorrhagic shock) further contributes.
• The result is a secondary, neurally mediated blockade of effective contractile activity across the entire gut.
• Current Surgical Therapy 14th ed., p. 201

Clinical Features

• No return of bowel sounds on auscultation
• No passage of flatus
• Progressive abdominal distension that is tympanic
• Vomiting (effortless, without colic) - colicky pain is NOT a feature; its presence suggests mechanical obstruction
• Absolute constipation
• Nausea, loss of appetite

Diagnosis and Differential

Management

1. Treat the primary cause - address retroperitoneal haematoma, spinal injury, infection, or sepsis. The ileus is transient and resolves when the systemic cause is controlled.
2. Nasogastric suction - decompression of the distended gut; restriction of oral intake until bowel sounds and flatus return.
3. Fluid and electrolyte balance - close attention is essential. Correct hypokalaemia (a major contributor) and uraemia.
4. Parenteral nutrition - if ileus is prolonged, nutrient absorption is impaired and parenteral nutrition must be considered.
5. Prokinetic drugs - there is no convincing evidence for their use in adynamic ileus; they are not effective and should not be relied upon.
6. CT scanning - if ileus is prolonged, CT should be performed to exclude intra-abdominal sepsis or mechanical obstruction.
7. Return to theatre - the need for laparotomy becomes increasingly likely if bowel inactivity persists beyond 7 days, or if bowel activity recommences and then ceases (suggesting a secondary mechanical or infective cause).

• Bailey and Love's 28th ed.; Current Surgical Therapy 14th ed.

Key Points Summary

• Traumatic adynamic ileus is a reflex/neurogenic phenomenon caused by retroperitoneal trauma (haematoma, spinal/rib fractures) interfering with autonomic innervation to the gut.
• It involves the entire GI tract (unlike postoperative ileus, which spares the small bowel).
• The mechanism is sympathetic-mediated inhibition of gut contractility.
• Diagnosis requires ruling out mechanical obstruction - absence of colicky pain and a diffuse, non-transitioned dilation on imaging are key.
• Management is conservative - treat the cause, decompress, correct electrolytes, and wait. Prokinetics are ineffective.
• Adynamic ileus after thoracolumbar spine fractures is well-documented; it is also seen after pelvic fractures with retroperitoneal haematoma.