Labs
None are diagnostic
Check electrolytes to assess for dehydration
Leukocytosis could indicate gangrene or perforation
Anemia could indicate malignancy as source of<unk> 
ABG may help assess if the patient has respiratory compromise from diaphragmatic compression 
Imaging 
Use the 3/6/9 rule for bowel imaging
Upper limit of 3cm for small bowel, 6cm for colon, and 9cm for cecum
XR
Sensitivity of 69% to 80% for detecting bowel<unk> , but insensitive for diagnosing cause or location
Upright films can detect pneumoperitoneum, hollow viscus perforation
Distended colon (small bowel may appear distended as well if the ileocecal valve is competent)
Cecal diameter of ≥12cm is associated with higher risk of perforation, ≥9cm is associated with<unk> <unk>  bowel diameter ≥5-6cm is associated with<unk> 
CT
Can usually identify the cause of<unk> , except in cases of pseudo-obstruction
Sensitivity for diagnosing<unk>  as high as 90% (not as high as for small bowel<unk> 
Can also diagnose intestinal ischemia
Colonoscopy
Can be used to rule-out pseudo-obstruction in patients who are not candidates for urgent surgical intervention
None are diagnostic
Check electrolytes to assess for dehydration
Leukocytosis could indicate gangrene or perforation
Anemia could indicate malignancy as source of<unk> 
ABG may help assess if the patient has respiratory compromise from diaphragmatic compression 
Use the 3/6/9 rule for bowel imaging
Upper limit of 3cm for small bowel, 6cm for colon, and 9cm for cecum
XR
Sensitivity of 69% to 80% for detecting bowel<unk> , but insensitive for diagnosing cause or location
Upright films can detect pneumoperitoneum, hollow viscus perforation
Distended colon (small bowel may appear distended as well if the ileocecal valve is competent)
Cecal diameter of ≥12cm is associated with higher risk of perforation, ≥9cm is associated with<unk> <unk>  bowel diameter ≥5-6cm is associated with<unk> 
CT
Can usually identify the cause of<unk> , except in cases of pseudo-obstruction
Sensitivity for diagnosing<unk>  as high as 90% (not as high as for small bowel<unk> 
Can also diagnose intestinal ischemia
Colonoscopy
Can be used to rule-out pseudo-obstruction in patients who are not candidates for urgent surgical intervention
Upper limit of 3cm for small bowel, 6cm for colon, and 9cm for cecum
Sensitivity of 69% to 80% for detecting bowel<unk> , but insensitive for diagnosing cause or location
Upright films can detect pneumoperitoneum, hollow viscus perforation
Distended colon (small bowel may appear distended as well if the ileocecal valve is competent)
Cecal diameter of ≥12cm is associated with higher risk of perforation, ≥9cm is associated with<unk> <unk>  bowel diameter ≥5-6cm is associated with<unk> 
Can usually identify the cause of<unk> , except in cases of pseudo-obstruction
Sensitivity for diagnosing<unk>  as high as 90% (not as high as for small bowel<unk> 
Can also diagnose intestinal ischemia
Can be used to rule-out pseudo-obstruction in patients who are not candidates for urgent surgical intervention
Large bowel obstruction
Abdominal aortic aneurysm
Small bowel obstruction
Aortocaval fistula
Malignant bowel obstruction
Acute gastroenteritis
Epiploic appendagitis
Aortoenteric fisulta