The Differential Diagnosis of Gas and Bloating

Purpose: To determine the prevalence of various disease processes accounting for the common complaint of gas and bloating in the outpatient setting. Methods: Electronic billing and medical records in an outpatient gastroenterology clinic from 2010-2012 were utilized. Patient visits with a presenting complaint coded as 787.3, “flatulence, eructation and gas pain,” were reviewed by three independent physicians. Patients under the age of 18 were excluded, as were patients with an existing diagnosis other than IBS. Only patients who underwent some form of evaluation (i.e., laboratory, biopsy, motility study, or breath testing) were included. Final diagnoses were divided into eight categories: Fructose Intolerance (FI), Lactose Intolerance (LI), Small Intestinal Bacterial Overgrowth (SIBO), Celiac Disease (CD), functional disorders, motility disorders, other and unknown. Diagnoses were not considered mutually exclusive, and presumptive diagnoses (i.e., improved with lifestyle changes alone) were counted as unknown in the absence of objective data. Summary statistics were applied using SPSS software. Results: Two hundred thirty-seven patients were included in the study population. 23.6% were male and 76.4% female. The average age was 55.4 ± 19.5. The most common diagnosis was FI (38.8%), followed by SIBO (32.9%). 23.2% of patients had functional disorders, most commonly IBS. 16.0% of patients were positive for LI. 13.9% of patients did not have a definitive diagnosis at the study's end, but the vast majority of those experienced symptom relief by changing their diet and lifestyle. 7.0% were found to have motility disorders, and 5.3% had celiac disease. Of the 10.4% patients with a diagnosis of “other”, the most frequent causes included GERD and microscopic colitis. 54% (n=15/28) of patients presenting with a diagnosis of IBS were found to have a different (or additional) diagnosis to explain their symptoms. Of the patients who underwent all three forms of breath testing (FI, LI, SIBO), 60.6% were positive for at least one test, and 22.3% were positive for all three. Consequently, one third (32.9%) of patients had more than one diagnosis, with some patients having as many as four. Conclusion: 1.) FI and SIBO were the most common causes of gas and bloating in the outpatient setting. 2.) Many patients, (33% in this population) have more than one etiology for their complaint, especially if they present with a history of IBS. 3.) A definitive diagnosis is attainable for >85% of patients with gas and bloating when proper testing is employed. 4. When used judiciously, breath testing can be an effective diagnostic tool.