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. Dietary changes, supplements, medication, and behavioral interventions may reduce the symptoms.

Symptoms

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

Criteria

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% of stools can be described as hard and less than 25% of stools described as soft.

Associated Symptoms

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 vs. Chronic Idiopathic Constipation (CIC)

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 questioned 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.

Risk Factors

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.

Diagnosis

IBS-C has traditionally been a diagnosis of exclusion, meaning that it's only diagnosed after ruling out other disorders that may be causing your symptoms. However, diagnostic guidelines released in 2021 by the American College of Gastroenterology (ACG) aim to make it a "positive" diagnosis instead.

The ACG says its recommended diagnostic method will make the process faster, which means getting you on proper treatments sooner. It's not yet clear how these guidelines will change the typical doctor's IBS diagnostic process. Rest assured that either method can diagnose you accurately.

Diagnosis of Exclusion

In the older method, if your doctor suspects IBS-C, they'll likely get a list of your symptoms, examine you, 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 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, you can be diagnosed with IBS-C.

Positive Diagnosis

The ACG's recommended diagnostic method includes focusing on your medical history and physical exam plus key symptoms, including:

• Abdominal pain
• Altered bowel habits
• Minimum of six months of symptom duration
• The absence of alarm features of other possible conditions
• Possible anorectal physiology testing if a pelvic floor disorder is suspected or if constipation doesn't respond to standard treatments

No further testing is recommended for IBS-C.

Treatment

The ACG treatment protocol for IBS-C includes dietary modifications, supplements, prescription medications, and lifestyle/behavioral changes.

Diet and Supplements

• Dietary changes: A short-term trial of a low-FODMAP diet can help you identify foods that contribute to your symptoms.
• Fiber: Slowly increasing the amount of fiber, and especially soluble fiber, in your diet (or through supplements) may promote more frequent bowel movements.
• Peppermint oil: Enteric-coated capsules of peppermint oil may help your intestinal muscles relax, lower pain and inflammation, and eliminate harmful bacteria.

Prescription Medications

• Amitiza (lubiprostone): Increases fluid secretion in the intestines
• Linzess (linaclotide) or Trulance (plecanatide): Increase bowel movements
• Zelnorm (tegaserod): Speeds digestion and reduces hypersensitivity in the digestive organs (recommended for women under 65 with no cardiovascular risk factors and no response to other medications)
• Tricyclic antidepressants: Prescription medications that may affect the nerves of the GI system through changing activity of the neurotransmitters norepinephrine and dopamine

Behavioral Interventions

• Cognitive behavioral therapy/gut-directed hypnotherapy: May help establish healthier habits and overcome emotional components of IBS
• Biofeedback: Recommended for those with dyssynergic defecation

Not Recommended

The ACG says some common IBS-C treatments don't have enough evidence of their effectiveness to be recommended. These include:

• Antispasmodic drugs
• Probiotic supplements
• Polyethylene glycol (PEG, an ingredient in some OTC laxatives)
• Fecal transplant