Ileus: causes 
MD SPUGERS:
Mesenteric ischemia
Drugs (see below)
Surgical (post-op)
Peritonitis/ Pancreatitis (sentinnel loop)
Unresolved mechanical obstruction (eg mass, intussusception, blockage)
Gram negative sepsis
Electrolyte imbalance (eg hypokalemia)
Retroperitoneal bleed or hematoma
Spinal or pelvic fracture
Drugs are Aluminum hydroxide, Ba++, Ca carbonate, opiates, TCA, verapamil