Can paralytic ileus be detected on ultrasound?

Ultrasound Detection of Paralytic Ileus

Yes, paralytic ileus can be detected on ultrasound with high sensitivity and specificity, characterized by dilated bowel loops with decreased or absent peristalsis activity.

Ultrasound Findings in Paralytic Ileus

• Ultrasound can identify paralytic ileus by showing dilated bowel loops (>2.5 cm) with decreased or absent peristalsis 1
• Real-time assessment of bowel motility on ultrasound is particularly valuable in differentiating paralytic ileus from mechanical obstruction 2
• In paralytic ileus, both small and large bowel appear dilated without a transition point, unlike mechanical obstruction 2
• Absence of peristalsis is a key diagnostic feature that can be directly visualized during ultrasound examination 2

Diagnostic Accuracy

• Ultrasound has 90% sensitivity and 96% specificity for detecting bowel obstruction, including paralytic ileus 1
• Duplex sonographical studies of intestinal peristalsis can help differentiate between mechanical obstruction (which shows hyperdynamic peristalsis proximal to obstruction) and paralytic ileus (which shows absent peristalsis) 2
• Early ultrasound examination is particularly valuable before massive fluid collection and meteorism develop, allowing for optimal visualization 2

Technical Considerations

• Patient preparation with a fasting period of 4-6 hours is recommended to reduce bowel gas that may interfere with visualization 1
• Systematic interrogation of the small bowel and colon using gentle graded compression technique is essential 1
• Administration of spasmolytic agents should be avoided as they may interfere with the real-time assessment of bowel peristalsis 1
• Ultrasound is most successful in non-obese patients due to its technical limitations 1

Additional Ultrasound Features

• Edema of the intestinal walls may be visible in paralytic ileus 2
• Sedimentation of intestinal contents can be observed 2
• Pearl string-like lined up gas bubbles under the ventral intestinal walls may be present 2
• Concomitant ascites can be detected 2

Advantages of Ultrasound

• Ultrasound can be performed at the bedside, making it particularly valuable for critically ill patients 1
• It allows for real-time assessment of bowel pliability and peristalsis, which is crucial for diagnosing paralytic ileus 1
• Ultrasound can help identify the underlying cause of paralytic ileus in many cases 2
• It can be performed earlier than X-rays, potentially allowing for earlier diagnosis (X-ray findings may take up to 6 hours to develop) 2

Limitations

• Gas-filled loops of bowel, commonly present in postoperative ileus, may obscure underlying pathology 1
• The sensitivity of ultrasound is particularly operator-dependent 1
• Patient factors such as obesity and guarding may preclude adequate compression with the ultrasound probe 1
• CT is superior to ultrasound in terms of providing information about the underlying cause of bowel obstruction 1

For optimal diagnosis of paralytic ileus, ultrasound should be considered as the initial imaging modality, particularly in patients where radiation exposure is a concern, with CT reserved for cases where ultrasound is inconclusive or additional information about etiology is needed 1.