BACKGROUND: Pneumatosis intestinalis (PI) and portal venous gas (PVG) are radiographic signs of underlying intra-abdominal pathology often associated with mesenteric ischemia (MI). Historically, PI and PVG mandated exploratory laparotomy due to the high mortality rate of untreated MI. The sensitivity and increased utilization of modern computed tomography (CT) frequently identifies PI and PVG from benign causes in patients who may be subjected to non-therapeutic laparotomies to rule out MI.METHODS: Consecutive adult patients presenting with either PI or PVG identified by CT were examined during the 5 year study. The clinical presentation, radiographic findings, treatment and outcome were reviewed. During the initial exploratory series (4 years), 74 cases were identified and utilized to generate a clinical algorithm capable of identifying MI from benign PI/PVG. The algorithm was then applied to 15 additional cases to confirm its clinical utility (1 year). RESULTS: PI and PVG were associated with three major clinical subgroups: mechanical gastrointestinal (GI) disease or injury (n=29); acute mesenteric ischemia (n=30); and benign idiopathic (n=26); (four were unable to be classified). In the exploratory series, patients with acute mesenteric ischemia were associated with abdominal pain (p=0.01), elevated lactate (>3.0) (p=0.006), small bowel PI (p=0.04) and Vascular Disease Score (calculated) (p<0.0005). We were able to distinguish the three clinical subgroups using a practical clinical algorithm with a sensitivity of 89%, specificity of 100%, positive predictive value of 100% and negative predictive value of 96%. The algorithm was 100% accurate when applied to the 15 additional cases.CONCLUSIONS: With greater sensitivity of modern CT scans, PI and PVG are being detected in patients with a wide range of surgical and non-surgical conditions. Using a clinical algorithm, we can identify important subgroups of patients with PI/PVG: mechanical diseases, acute mesenteric ischemia and benign idiopathic. Using this algorithm when treating patients with CT identified PI or PVG will improve treatment and can prevent non-therapeutic laparotomy in those with benign idiopathic findings.
Clinical Subgroups of Patients with PI or PVG

	Mechanical Causes	Mesenteric Ischemia	Benign Causes
Number (%)	29 (34%)	30 (35%)	26 (30%)
Vascular Disease Score(range)	3.29 (0-9.5)	6.9 (4-12)	2.0 (0-6)
VDS Greater or equal to 4.0	39%	100%	7%
Treatment	Surgery 65% Medical 35%	Surgery 69% Futility 31%	Surgery 38%(all non-therapeutic) Observation 62%
Outcome	Recovery 93% Mortality 7%	Recovered 24% Mortality 76%	Recovered 96% Relapse 8% Mortality 4%

VDS= Vascular Disease Score (Range 0 to 15)