Constipation Predominant IBS (IBS-C) Overview

Constipation-predominant irritable bowel syndrome (IBS-C) is a condition characterized by chronic constipation with associated abdominal pain. It is a subtype of irritable bowel syndrome (IBS), and approximately one-third of people who have IBS manifest the IBS-C type.

IBS-C is one of the functional gastrointestinal disorders (FGD), which are gastrointestinal (GI) disorders that produce signs and symptoms without an identifiable cause despite standard diagnostic testing. These disorders can cause significant distress. Lifestyle modifications and medication may reduce the symptoms.

The predominant symptoms of IBS-C are frequent constipation accompanied by pain when having a bowel movement.

It is normal to have one or two bowel movements per day, but it is also normal to have less than one per day. Generally speaking, characteristics that denote constipation include:

• Having fewer than three bowel movements in a week
• Lumpy or hard stools
• The need to strain during a bowel movement

The Rome IV criteria define FGD based on specific signs and symptoms. According to the Rome IV criteria, IBS-C is specifically defined as a condition in which:

• Constipation associated with pain occurs at least three days per month.
• Symptoms have persisted over the past three months.
• At least 25 percent of stools can be described as hard and less than 25 percent of stools described as soft.

In addition to the criteria for IBS-C, there are some other symptoms you may experience if you have constipation-predominant IBS.

Common symptoms of IBS-C include:

• Abdominal pain
• Gas and bloating
• A feeling of incomplete evacuation
• Mucus on the stool
• A sensation of blockage in the anus and/or rectum
• Need to use fingers to remove stool (digital evacuation)

With IBS-C, loose stools are rarely experienced, unless using a laxative.

IBS-C and chronic idiopathic constipation (also known as functional constipation) share many of the same symptoms. According to the Rome IV criteria, the biggest difference is that IBS-C causes abdominal pain and discomfort alongside constipation, while idiopathic constipation is typically painless.

Gastroenterologists have questions whether the two conditions are manifestations of the same disorder along a single disease spectrum rather than two completely separate disorders. However, the two conditions tend to respond to different treatments, which suggests that they may be accurately considered two different conditions. At this point, the answer is not completely clear.

There is no known cause of IBS-C. The symptoms occur because the digestive system does not function as it should, but there is no identifiable cause for this. Dyssynergic defecation, which is dysfunction of the pelvic floor muscles, is often present in people with IBS-C.

IBS-C is a diagnosis of exclusion, meaning that it is only diagnosed after other disorders that could cause your signs and symptoms have been ruled out.

If you are being evaluated for IBS-C, your doctor is likely to do a physical examination, run some blood work, and conduct a stool sample analysis. Other tests, including imaging tests and interventional tests such as colonoscopy, may 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.

Treatment for IBS-C includes dietary and lifestyle modifications, over-the-counter laxatives, and prescription medications.

• Diet and lifestyle: Your doctor may recommend that you slowly increase the amount of fiber in your diet to promote more regular bowel movements.
• Laxatives: Over-the-counter laxatives such as Miralax or lactulose may help your constipation. Use only as directed and based on the advice of your doctor, as laxative overuse can cause serious side effects.
• Amitiza (lubiprostone): A prescription medication that is FDA approved for treatment of IBS-C, lubiprostone increases fluid secretion in the intestines. Other FDA prescription medications include linaclotide and plecanatide which work by increasing bowel movements.
• Medications used for IBS: Antidepressants may have an effect on the nerves of the GI system, and antispasmodics can relax the muscles within it. These medications are not formally indicated for the treatment of IBS, but they are frequently prescribed to reduce the symptoms of IBS.
• Behavioral interventions: Cognitive behavioral therapy may be recommended for the treatment of IBS. If dyssynergic defecation is a contributing factor to your IBS-C symptoms, your doctor may recommend that you try biofeedback.