What Is Constipation Predominant IBS?

Constipation-predominant irritable bowel syndrome (IBS-C) is a subtype of irritable bowel syndrome (IBS) in which the patient experiences chronic constipation accompanied by recurrent abdominal pain. IBS-C is considered a functional gastrointestinal disorder (FGD) in that no visible sign of illness is uncovered during standard diagnostic testing, but rather symptoms are a reflection in a dysfunction in the way that the digestive system is functioning. 

IBS-C manifests itself in approximately one-third of all IBS patients. Older individuals and those who have lower socioeconomic status are at higher risk for IBS-C. Compared to the other IBS subtypes, people who have IBS-C are more likely to experience anxiety, depression and a lowered quality of life.

IBS-C and chronic idiopathic constipation (also known as functional constipation) share many of the same symptoms. According to the Rome III criteria for FGDs, the disorders differ in that IBS-C patients experience abdominal pain and discomfort alongside constipation. However, most gastroenterologists and some researchers believe that the two disorders are one and the same.

The symptoms of IBS-C include some or all of the following:

• Infrequent bowel movements
• Lumpy or hard stools
• Abdominal pain
• Gas and bloating
• A feeling of incomplete evacuation
• Mucus in or on the stool
• Sensation of blockage in the anus and/or rectum
• Straining
• Use of the fingers to remove stool (digital evacuation)

Constipation is typically defined as experiencing fewer than three bowel movements in a week. With IBS-C, loose stools are rarely experienced without the use of a laxative.

The Rome III criteria spell out that symptoms must be experienced 3 days per month over the past three months, with stool changes occurring in at least 25% of stools.

IBS-C is diagnosed after other disorders have been ruled out. Your doctor is likely to do a physical examination, run some blood work and conduct a stool sample analysis. Other tests will be recommended depending on your symptoms and your medical history. If your symptoms match the diagnostic criteria for IBS-C, and there is no evidence of any red-flag symptoms or other illness, IBS-C will be diagnosed.

There is no single treatment protocol for IBS-C. Your doctor may recommend that you slowly increase the amount of fiber in your diet. They may recommend the use of an osmotic laxative, such as Miralax or lactulose.

There are also several medications available designed to target the underlying causes of chronic constipation, including:

• Amitiza
• Prucalopride (Canada and Europe only)
• Linzess (Constella)
• Zelnorm (strict criteria for use)

If your doctor believes that dyssynergic defecation is a contributing factor to your IBS-C symptoms, they may recommend that you try biofeedback.