Objective: To assess the value of a parasympathomimetic drug(neostigmine) in the early resolution of acute colonic pseudo-obstruction(Ogilvie′s syndrome).Methods: To study 42 patients in Hawler Teaching Hospital with the diagnosis of acute colonic pseudo-obstruction between years 2004 and 2008.All had abdominal distention and radiographic evidence of colonic dilation,with a cecal diameter of more than 10 cm,and had had no response to at least 36 hours of conservative treatment.We randomly assigned 22 to receive 2.5 mg of neostigmine intravenously and 20 to receive intravenous saline.A physician who was unaware of the patients′ treatment assignments recorded clinical response(defined as prompt evacuation of flatus or stool and a reduction in abdominal distention),abdominal circumference,and measurements of the colon on radiographs.Patients who had no response to the initial injection were received another dose of neostigmine three hours later.Results: Twenty of the 22 patients who received neostigmine had prompt colonic decompression,as compared with none of the 20 patients who received placebo(P<0.001).The median time to response was 5 minutes(range,2 to 30).Fourteen patients in the placebo group and the two patients in the neostigmine group without an initial response received open-label neostigmine;all had colonic decompression.Four patients who had an initial response to neostigmine required colonoscopic decompression for recurrence of colonic distention;two eventually underwent subtotal colectomy.Side effects of neostigmine included abdominal pain,excess salivation,and vomiting.Symptomatic bradycardia developed in four patients and was treated with atropine.Conclusions: In patients with acute colonic pseudo-obstruction who have not had a response to conservative therapy,treatment with neostigmine rapidly decompresses the colon. Objective: To assess the value of a parasympathomimetic drug (neostigmine) in the early resolution of acute colonic pseudo-obstruction (Ogilvie’s syndrome). Methods: To study 42 patients in Hawler Teaching Hospital with the diagnosis of acute colonic pseudo-obstruction years 2004 and 2008. All had abdominal distention and radiographic evidence of colonic dilation, with a cecal diameter of more than 10 cm, and had had no response to at least 36 hours of conservative treatment. We randomly assigned 22 to receive 2.5 mg of neostigmine intravenously and 20 to receive intravenous saline. A physician who was unaware of the patients’ treatment assignments recorded clinical response (defined as prompt evacuation of flatus or stool and a reduction in abdominal distention), abdominal circumference, and measurements of the colon on radiographs. Patients who had no response to the initial injection were received another dose of neostigmine three hours later. Results: Twenty of the 22 patients who r eceived neostigmine had prompt colonic decompression, as compared with none of the 20 patients who received placebo (P <0.001). median time to response was 5 minutes (range, 2 to 30) .Fourteen patients in the placebo group and the two patients in the neostigmine group without an initial response received open-label neostigmine; all had colonic decompression. Four patients who had an initial response to neostigmine required colonoscopic decompression for recurrence of colonic distention; two eventually underwent subtotal colectomy. Side effects of neostigmine included abdominal pain , excess salivation, and vomiting. Symptomatic bradycardia developed in four patients and was treated with atropine. Conclusions: In patients with acute colonic pseudo-obstruction who have not had a response to conservative therapy, treatment with neostigmine rapidly decompresses the colon.