Many people see blood in the toilet when they have a bowel movement, but don’t do anything about it. Most won’t even tell a doctor.
Bleeding when you poop, also called rectal bleeding, has several causes, some more worrisome than others. But particularly as cases of colorectal cancer rise in younger adults, it’s an important symptom that warrants medical attention. Knowing what the bleeding might mean and what to do next is crucial.
“Rectal bleeding is very common. It’s one of the most common complaints that comes up in primary care and [gastroenterology] visits,” said Samir Gupta, a gastroenterologist and professor of medicine at UC San Diego Health.
But it can be a danger symptom.
“Any blood in the stool is abnormal. It doesn’t automatically mean cancer, but it’s definitely not something to be assumed is normal and warrants no further attention,” said Sophie Balzora, a gastroenterologist and clinical professor in the department of medicine at NYU Grossman School of Medicine.
“It’s important to remember that benign conditions of the anus and rectum that can cause bloody stools are exceedingly more common than colon or rectal cancer, especially in young people at average risk for the disease. But that doesn’t mean the issue should be ignored,” Balzora added.
Bleeding comes in several forms. The blood, for example, may be bright red or maroon, in the toilet bowl or on the toilet paper, and could be barely noticeable or pouring out, the latter of which would constitute a medical emergency.
And then there are other symptoms that may be associated with the bleeding, including constipation, urgency to have a bowel movement and abdominal pain. It’s projected that there will be approximately 150,000 new cases of colorectal cancer in the United States in 2023 alone.
“There are a few things that might give a doctor or a person a better idea of whether their bleeding might be more likely due to a benign cause or due to a tumor growth, but these clues are not very accurate,” said Gupta. “It really is not so straightforward to try and diagnose yourself in terms of figuring out whether the rectal bleeding is due to a benign cause or not.”
Range of severity
There are different causes of rectal bleeding that range in severity. “The list is long,” said Balzora.
Among the most common structural causes of benign bleeding are hemorrhoids, which are enlarged veins in the anus and rectum often caused by straining. While not an exhaustive list, other examples of things that can cause bleeding include small tears in the skin of the anus, called anal fissures, bleeding from outpouchings in the wall of the colon called diverticula, inflammatory bowel disease and cancer.
Unfortunately, even doctors aren’t very good at determining the cause of bleeding without a colonoscopy. “Studies indicate that based on rectal exam and clinical findings, clinicians aren’t perfect at distinguishing hemorrhoids from other sources of blood loss,” said Lisa Strate, a gastroenterologist and professor of medicine at the University of Washington.
To complicate things further, multiple causes of rectal bleeding can coexist. “You can have hemorrhoids or an anal fissure and colorectal cancer at the same time,” said Balzora.
What to do if you see blood
If you notice blood in your stool, the first thing to do is to ask yourself whether you need immediate evaluation at an emergency department.
“If people feel lightheaded or weak, those could be signs that they’ve lost a significant amount of blood,” Strate said.
Other signs that probably indicate the need to go to an emergency room include passing large amounts of blood, frequent bloody bowel movements, severe abdominal pain, passing out, feeling short of breath, having a fever along with bloody stools, or experiencing low blood pressure.
Even if there isn’t an emergency, you still should make an appointment with a primary care doctor or gastroenterologist. During the appointment, you can expect them to take a thorough history and potentially do bloodwork, which could evaluate for low red blood count or inflammation, and perform a rectal exam to look for any obvious external causes of bleeding. Sometimes, the physician will refer you for a colonoscopy.
“These days I have a much lower threshold to proceed with an endoscopic study given the increased rates of colorectal cancer in those under 50,” said Balzora, referring to colonoscopies and other similar procedures to see inside the colon.
In her view, it’s reasonable to first try to treat the bleeding conservatively, assuming there aren’t red-flag symptoms, but with a plan to follow up. This means that, if a clinician suspects a benign cause of bleeding is likely, they might first use noninvasive methods to treat it. If the bleeding continues, however, they’re likely to pursue an endoscopy.
Gupta agreed.
“All benign causes of rectal bleeding should get better with treatment,” he said. If the bleeding does not improve, this might indicate that there is something more worrisome. People with rectal bleeding who do not initially have colonoscopies “should have a follow-up clinic visit within 60 days to close the clinical loop and make sure that the symptoms have resolved. And all other people need to go on to” colonoscopy, he said.
“It’s easy to dismiss symptoms. It’s human nature,” said Balzora. “Your health is the absolute priority and blood in stool is never normal. You shouldn’t be afraid of what it might be. Take that next step and talk about it with a health-care professional.”