Why Your Poop Might Look Narrow

Stool should typically look like a sausage or snake. But what your stool (poop) looks like can change from time to time. Sometimes, stool can be narrower than usual. There are various reasons why your stool may have a smaller diameter. Some causes, like constipation, might be less concerning, while others, like cancer, may be more severe. A healthcare provider can determine what is causing the change in stool shape and provide any needed treatment.

What Causes Narrow Stools?

Depending on factors like what you eat or what conditions you have, you might experience some variation in the shape of your stool.

Constipation

Constipation is a condition that makes it so that you have infrequent bowel movements, difficulty making a bowel movement, or both. The regular shape of your stool can change when you're constipated, causing it to look narrower than usual after you strain to get it out.

Constipation is very common. It's usually caused by a lack of fiber in your diet, though some medications and conditions like Parkinson's disease can also contribute to constipation.

Signs of constipation include:

• Having fewer than three bowel movements in a week
• Producing stool that is hard, dry, and difficult to pass
• Experiencing stomach bloating
• Straining during a bowel movement

Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a group of digestive symptoms that can cause stomach pain as well as diarrhea, constipation, or both. IBS can occur because of a problem with the movement of the intestines, an issue with the intestinal nerves, or a problem with how the brain controls intestinal functions. Even though there is an issue with the functioning of the intestines, there aren't any structural abnormalities in your intestines.

Healthcare providers diagnose IBS from your symptoms. IBS can lead to a change in your stool's appearance, including making it narrower than usual. Other symptoms of IBS are:

• Relief from abdominal pain after a bowel movement
• Abdominal pain with a change in stool frequency and consistency
• A dull ache or cramp-like pain in the lower abdomen
• Bloated stomach
• Mucus in your stool
  
• The feeling of having had an incomplete bowel movement

You may even experience symptoms that do not seem to be related to the intestines, like fatigue and difficulty sleeping.

Diverticular Disease

The lining of the intestine wall is usually smooth. When pouches develop in the wall of the intestine, it is known as diverticular disease. These small balloon-like pouches usually form from weakened areas of the intestine muscles. When the pouches become inflamed repeatedly, it can lead to scarring that narrows the inside of the intestines. The narrowing of the intestines can make it difficult for stool to come out, potentially causing narrow stools.

Other symptoms of diverticular disease are:

• Pain in the lower left side of the abdomen
• Changes in bowel habits, such as diarrhea or constipation
• Symptoms that get worse after eating and better after a bowel movement
• Pain that gets worse when someone places pressure on your stomach
• Symptoms that come and go or remain constant

Colorectal Cancer

Colorectal cancer develops in the tissues of your colon or rectum. At first, you might not experience any symptoms. As the disease progresses, you might start having some symptoms. One symptom of colorectal cancer is narrowed stool. The stool can become so narrow that it is sometimes described as pencil-thin.

Other signs of colorectal cancer are:

• Fatigue
• Blood in stool
• Diarrhea or constipation
• Unexplained weight loss
• A feeling like your bowels are not empty
  

Anal Stenosis

Anal stenosis is a rare condition that happens when the anal canal becomes narrow from scarring. This condition usually happens after surgeries hemorrhoid removal, also known as a hemorrhoidectomy, or other surgeries of the anus. Other causes of anal stenosis are chronic diarrhea, long-term laxative use, trauma, radiotherapy, tuberculosis, and other infections.

Besides narrow stools, other symptoms of anal stenosis are:

• Painful bowel movements
• An inability to pass stool
• Bleeding with bowel movements
  

When to See a Healthcare Provider

Having stool that's typically normal but occasionally narrow is not usually something to worry about. However, you'd want to see a healthcare provider if your narrow stool lasts for more than two weeks or if your stool continuously gets thinner, especially to the point that's it's pencil-thin.

Other signs that may indicate you should have an evaluation are:

• Unexplained weight loss
• Bloody stools
• A feeling as though there is a mass in your rectum
• No bowel movement in three days
• Abdominal bloating and pain
• A feeling as though your bowel isn't emptying

If you are experiencing any concerning symptoms and have certain risk factors that make you more likely to develop colorectal cancer, it is even more critical to see a healthcare provider. These risk factors include being older, having a history of polyps, having inflammatory bowel disease, and having a family history of colon cancer.

Diagnosis

Healthcare providers usually diagnose narrow stools based on your symptoms and a physical exam. Depending on what symptoms you are experiencing and your risk factors for certain conditions, there may be a need for further diagnostic testing, like imaging scans. 

Your healthcare provider may perform the following tests:

• Digital rectal exam: Healthcare providers insert a gloved finger into your rectum. The purpose of this exam is so your healthcare provider can feel for any irregularities, like masses, in the area.
• Complete blood cell count (CBC): A CBC is a blood test that can help detect certain conditions like infections, anemia, cancers, and diseases that affect the immune system.
• Imaging tests: Some scans, like an abdominal ultrasound or an abdominal X-ray, can show intestinal problems. 
• Endoscopy: An endoscopy is a type of test where a healthcare provider will guide a tube with a camera on it through your intestines. There are different types of endoscopies used for which part of the body needs exploration. A flexible sigmoidoscopy can give providers a view of your rectum and lower colon while a colonoscopy can view your entire colon. The procedures can be used to check for tumors or polyps, and a biopsy can be taken from the intestines to check for cancer.
• Fecal occult blood test: This test will help detect any bleeding in your intestines that the human eye can not see. It can help diagnose different intestinal disorders, such as ulcers, colitis, and colorectal cancer.

A healthcare provider may also use different criteria and charts to help classify symptoms. For instance, the Rome criteria help healthcare providers diagnose IBS. The requirements to meet the criteria include having had abdominal pain for at least one day a week in the last three months, along with two or more signs of additional symptoms that occur with abdominal pain.

Meanwhile, the Bristol stool chart is an assessment tool covering the seven different stool types. It helps healthcare providers diagnose intestinal problems such as constipation and diarrhea.

How to Get Your Stool Back to Normal

Treatment will vary based on the exact cause of your narrow-shaped stool. For example, if constipation is causing the stool change, you can try increasing your fiber intake. This can include eating whole grains, legumes, berries, apples, vegetables, and nuts. You should also drink more water to help your stool become softer. If you need additional help to relieve your constipation, talk with your healthcare provider about medications like stool softeners or laxatives.

If IBS is causing the narrow stools, you can try managing your IBS. This might include eating smaller, more frequent meals and eating meals more slowly. You can also avoid foods that cause gas and bloating, like cabbage and beans. You can consider implementing a low-FODMAP diet since the diet avoids certain carbohydrates that increase gas. Certain foods and stress can make IBS symptoms worse, so you'll want to take note of foods or situations that induce symptoms and try to avoid them if possible. Increasing physical activity may help keep you regular too.

Diverticular disease, colorectal cancer, and anal stenosis need to be managed by a healthcare provider. Treatment would depend on which condition you have and how advanced the disease is. Diverticular disease may benefit from probiotics, fiber supplements, or anti-inflammatory medications. Colorectal cancer may require surgery, radiation, or chemotherapy. Anal stenosis might need surgery.

A Quick Review

Narrow stool is not usually a concern when it happens occasionally. The temporary change in stool shape might be due to constipation or irritable bowel syndrome. If the stool stays narrow or continues to get narrower, you should contact a healthcare provider. Stool that is very thin might be a sign of colorectal cancer. Narrow stool may also be a sign of diverticular disease or anal stenosis. A healthcare provider can determine what is causing your stool to be narrow and provide proper treatment, if necessary.