What Is Irritable Bowel Syndrome? Even though irritable bowel syndrome, or IBS, is one of the most common gastrointestinal disorders encountered by doctors, a lot of people still do not know much about the illness. This could probably be because it is not given as much attention when compared to other illnesses. It could also be that irritable bowel syndrome itself has not been properly defined and explained to people. Irritable Bowel Syndrome: Basic Definition Irritable bowel syndrome or spastic colon is considered a functional bowel disorder. Two of the most common manifestations of IBS are abdominal pain from cramps and apparent changes in bowel habits. Some of the principal signs of this syndrome are a pain in the lower abdomen and a sensation of being bloated, which are most often relieved by defecating. Irritable bowel syndrome, statistically speaking, is very common. It makes up 20% to 50% of all gastroenterology cases every year. Diagnosing Irritable Bowel Syndrome. The cause of irritable bowel syndrome is not that fully known. And because of this, there are no specific laboratory tests that would be able to detect whether a person is positive for irritable bowel syndrome.