Intestinal Gas (Belching, Bloating, Flatulence)

  • Medical Author:
    Jay W. Marks, MD

    Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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What causes bloating?

It is important to distinguish between bloating and distention.

  • Bloating is the subjective sensation (feeling) that the abdomen is full or larger than normal. Thus, bloating is a symptom akin to the symptom of discomfort.
  • In contrast, distention is the objective determination (physical finding) that the abdomen is larger than normal. Distention can be determined by such observations as the inability to fit into clothes, the need to loosen the belt or looking down at the stomach and noting that it is clearly larger than normal.

In some instances, bloating may represent a mild form of distention since the abdomen does not become physically (visibly or measurably) enlarged until its volume increases by one quart. Bloating and even mild cases of distention may be caused by relaxation of the muscles of the abdominal wall and downward movement of the diaphragm.

There are three ways in which abdominal distention can arise. The causes are an increase in air, fluid, or tissue within the abdomen. The diseases or conditions that cause an increase of air, fluid, or tissue are very different from one another. Therefore, it is important to determine what (air, fluid, tissue) is distending the abdomen.

There are two types of distention; continuous and intermittent.

  • Continuous distention may be caused by the enlargement of an intra-abdominal (within the abdomen) organ, an intra-abdominal tumor, a collection of fluid within the peritoneal cavity, the space that surrounds the intra-abdominal organs (ascites), or just plain obesity.
  • Intermittent distention is usually due to the accumulation of gas and/or occasionally, fluid within the stomach, small intestine, or colon.
Medically Reviewed by a Doctor on 10/29/2015

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