14 Possible Causes of Bloody Stool (2024)

Blood in stool happens when there is bleeding in the gastrointestinal (GI) tract. Peptic ulcer disease, anal fissures,hemorrhoids, and cancer can cause blood in stool. Blood in stool for a woman is usually the same as it is for men since GI conditions affect people of all sexes.

Blood in stool looks red or maroonish. Blood that comes from the upper GI tract and is digested as it moves through the gut can look darker, often black and tar-like.

It can be a sign of something serious, so blood in your stool should never be ignored. You should always tell your provider if you have blood in your stool. They can do a physical exam, lab tests, and ask you about your health history to find out the cause.

This article discusses some of the possible reasons for blood in stool, as well as how these causes can be diagnosed and treated.

Upper GI Bleed

Blood in your stool may come from somewhere in your upper GI tract that is bleeding. The most common cause is peptic ulcer disease. In this condition, there are sores in the lining of the stomach or upper intestine that bleed.Blood from a peptic ulcer can be red or darker in color—even black and tarry.

An upper GI bleed can be diagnosed with a test called anendoscopy. During the procedure, a gastroenterologist looks at your upper GI tract with a camera attached to a narrow, flexible tube. The tube is put down your throat and looks at your gut.

If you have serious upper GI bleeding, you will need surgery to fix it.

Anal Fissure

Anal fissures are the most common cause of bloody stool in infants, but adults can get them, too.The blood in stool from anal fissures is bright red in color.

Anal fissures are cracks in the skin that can bleed. The tears are often caused byconstipation, or having large, firm stools that are hard to pass. The stretching skin of the anus makes fissures visible.

Anal fissures usually heal on their own. You can treat the pain and discomfort with petroleum jelly. Drinking more water and eating high-fiber foods can help soften your stools and prevent anal fissures from happening again.

Polyps

Apolypis a small growth on the lining of your intestines. There are a few types of polyps, butadenomatouspolypsare the most common. These polyps grow on the lining of the colon (large intestine). About 25% of adults aged 50 and over have this type of polyp.

Adenomatous polyps can turn intocolorectal cancer. Colorectal cancer is the third most common cause of cancer-related deaths in the United States.

Although most cases of colorectal cancer develop from adenomatous polyps, only around 5% of polyps will become cancerous.

Polyps often have no symptoms, but sometimes they can cause bloody stools. The blood can be red or dark and tarry.

Polyps can be removed before they become cancerous. If they do progress to cancer, the cancer is treatable if caught early. This is why all people age 45 and older should be regularly screened for colorectal cancer. This can be done with a colonoscopy or stool-based test.

Hemorrhoids

Hemorrhoids are swollen blood vessels that bulge from the anus.Hemorrhoids are often uncomfortable and can be painful or itchy. There are a lot of blood vessels around the anus and rectum, so hemorrhoids can bleed bright, red blood.

You might be more likely to have hemorrhoids if you:

• Have chronic diarrhea
• Are frequently constipated
• Do a lot of heavy lifting
• Sit for long periods of time
• Are pregnant

Most hemorrhoids do not require surgery. Eating more fiber or using a salve like Preparation H can help with symptoms. However, surgery is an option if your hemorrhoids are severe.

Gastroenteritis

Gastroenteritis is an illness of the stomach and intestines that causes inflammation. It can be caused by a virus, bacteria, or parasite.Sometimes, gastroenteritis causes bloody diarrhea—especially bacterial gastroenteritis.

Food poisoning is a type of gastroenteritis. Bacteria that commonly cause food poisoning include:

• Campylobacter
• E. coli
• Listeria
• Salmonella

Most of the time, gastroenteritis gets better on its own, but you should call your provider if symptoms last for more than one or two days.

Angiodysplasia

Blood in stool that cannot be explained is often caused byangiodysplasia.Angiodysplasia can happen as the blood vessels in the gut age or weaken.This type of blood in stool can be red or dark and tarry.

Angiodysplasia is common during end-stage renal disease (kidney disease) or renal failure. People with a genetic bleeding disorder calledvon Willebrand diseasecan also haveangiodysplasia.

Angiodysplasia can be treated in a few ways, including:

• Removal during endoscopy
• Hormone therapy
• Blood transfusions
• Iron supplements

For most people, angiodysplasia disappears on its own.

Inflammatory Bowel Disease (IBD)

Inflammatory bowel disease (IBD) is an autoimmune disease that affects the GI tract. With IBD, your immune system attacks and causes inflammation and damage to your intestines.Crohn's diseaseandulcerative colitisare the two most common types of IBD.Symptoms of IBD can include blood in stool which can be red or dark and tarry.

IBD can be treated in a few ways:

• Steroids
• Immune-modifying agents
• Surgery

Newer drugs are reducing the number of IBD patients who need surgery, but it can be necessary for people with more severe cases.

Cancer

Blood in stool can be a sign of colorectal cancer. Bloody stool related to cancer can be red or dark and tarry.

Providers used to think that colorectal cancer mostly happened to people over the age of 50. However, recent studies have shown that it’s also the third leading cause of cancer-related death in adults under the age of 50.

With earlier detection and treatment, the five-year survival rate for patients with colorectal cancer has been getting higher over time.

Diverticular Disease

Diverticulaare abnormal pouches that form in your lower intestine. There are two types ofdiverticular disease: diverticulosis and diverticulitis.Having diverticula is called diverticulosis. If the diverticula gets infected or inflamed, it’s calleddiverticulitis.

Both forms of diverticular disease can cause pain and blood in stool. When diverticular disease causes bleeding, it will usually start suddenly and be red or maroon in color.

Diverticula happens when the wall of your colon is weak. Sometimes, they can become very large—up to several centimeters in size. The disease is often blamed on a low-fiber diet, but the truecause of diverticulitisis unknown.

A surgeon can stop bleeding from diverticula during an endoscopy or abdominal surgery. Diverticula can be treated in or out of a hospital, depending on how sick a person is. Diverticulitis can often be successfully treated with antibiotics.

Ischemic Colitis

Ischemic colitishappens when the blood vessels that supply the large intestine are narrowed or blocked. Most cases of ischemic colitis happen in older adults. The condition can be short-term or long-term.

Blood in stool that’s bright red is a common symptom of ischemic colitis. Other symptoms include:

• Red blood in the stool
• Diarrhea
• An urgent need to defecate
• Abdominal pain and vomiting
  

Most cases of ischemic colitis do not last long and get better on their own. Sometimes, people with severe cases of ischemic colitis need to be hospitalized. Patients with severe disease may need intravenous (IV) fluids, antibiotics, bowel rest, and a restricted diet.

About 20% of people who develop ischemic colitis end up needing surgery. However, surgery for ischemic colitis is very dangerous—anywhere from 10%-65% of patients who have the surgery die.

Sexually Transmitted Infections (STIs)

Certain sexually transmitted infections (STIs) can cause blood in stool. STIs mostly affect the reproductive tract, but sometimes, they can also cause infection and inflammation in parts of the GI tract—especially the anus and rectum.

STIs that can cause blood in stool include:

• Syphilis
• Gonorrhea
• Chlamydia
• Herpes
• HIV/AIDS

STIs need different treatments, but antibiotics are common. Both partners may need treatment to prevent an STI from coming back.

Endometriosis

Endometriosis is a condition in which tissue that is similar to the kind that lines the uterus grows outside the uterus. If the tissue grows on or within the bowel, it can cause GI symptoms.

In rare cases, blood in stool in women is actually caused by deep endometriosis. For example, because there are lesions of tissue within the rectum. Sometimes, the blood in stool only shows up when a person is menstruating.

Endometriosis on the bowel often needs to be removed through surgery, though it can come back.

Esophageal Problems

Sometimes, blood in stool is actually caused by a problem higher up in the GI tract. Conditions that affect the food pipe (esophagus) can cause bleeding. If the bleeding gets bad enough, it travels through the digestive system and eventually makes its way out of the body in stool.

Tears in the esophagus (varices) are examples of conditions that can cause bleeding that may pass through the GI tract. Usually, blood in stool from higher up in the GI tract is darker colored rather than bright red (it may even look black).

Tears in the esophagus sometimes heal on their own. If they don’t or if there is a major tear, it might take surgery to get the bleeding to stop.

Red Food, Not Blood

Sometimes, what looks like bloody stool is really just red coloring from something you've eaten. Dyes used in foods and drinks like fruit punch and gelatin can make your stool red. Naturally red food like beets can also temporarily color your stool.

Summary

Blood in stool is never normal and is always a reason to call your provider. The causes of blood in stool vary but are often related to a problem somewhere in your GI tract. In some cases, conditions outside the GI system can lead to blood in stool. For example, some women have blood in stool because they have endometriosis on their bowel though this is rare. Certain STIs can also cause blood in stool. If you notice blood in your stool, do not wait to seek medical attention.