Inclusion Criteria:  Patients with radiologically confirmed acute colonic pseudo obstruction (ACPO).  Plain abdominal radiograph or computed tomography imaging Cecal diameter of >9 cm or transverse colon diameter of >6 cm Distal obstruction ruled out on imaging (Contrast enema, endoscopy, CT scan)  Exclusion Criteria:  Patients with previous neostigmine administration during current hospitalization Patients with prior attempt at endoscopic decompression on this admission. Patients with base-line heart rate of less than 60 beats per minute or on beta blocker medication Patients with systolic blood pressure of less than 90 mm Hg Signs of bowel perforation, with peritoneal signs on physical examination or free air on radiographs Active bronchospasm requiring medication Treatment with prokinetic drugs such as cisapride or metoclopramide in the 24 hours before evaluation A history of colon cancer or partial colonic resection Signs concerning for colonic obstruction Active gastrointestinal bleeding Pregnancy Serum creatinine concentration of more than 3 mg per deciliter (265μmol per liter).