What to Know About Left-Sided Ulcerative Colitis

A sub-type of UC, this disease can cause pain and permanent damage without proper treatment. Here’s how to stay one step ahead.

by Jeanine Barone Health Writer

Editor's Note: This story is part of a new series on HealthCentral called "Get Your Ph.D.!", which is geared toward people who've got the basics of their condition down and want to up their expertise. Who's ready to go pro?!

If you’re familiar with the irritable bowel disease known as ulcerative colitis (UC), you probably know that it’s characterized by chronic inflammation of the rectum and large intestine (colon). People with UC are battling a number of unpleasant symptoms, including rectal bleeding, diarrhea, abdominal pain, and an urgent need to go to the bathroom. Fun times! But despite what you may think, UC doesn’t always affect the entire colon. In certain cases, it can be restricted to specific areas.

One of these sub-types of UC is known as left-sided ulcerative colitis. It gets its name from the colon’s upside-down “U” shape. On the right side of the abdomen is what’s referred to as the ascending colon, because digested food moves up from the small intestine. Then, going across the top of the inverted U, from right to left, is the middle colon (also called the transverse colon). Once it reaches the left side of your body, the colon bends downward—the splenic flexure. As it travels down the left side of the abdomen toward your rectum, it’s known as the descending colon.

“Ulcerative colitis starts in the rectum. If it goes beyond that—but not beyond the splenic flexure—that’s left-sided colitis,” says Berkeley Limketkai, M.D, Ph.D., an associate clinical professor at the David Geffen School of Medicine at the University of California, Los Angeles.

You may never have heard of it, but “left-sided ulcerative colitis is not rare,” says Dr. Limketkai. “About 34% of our ulcerative colitis patients have left-sided colitis—that’s not a small number.” Some research indicates that people who develop UC late in life (usually 60 years of age or older) are more likely to have left-sided colitis compared with younger individuals. And while it shares much in common with the more general UC (also called pancolitis or extensive colitis) crowd, left-sided colitis can have its own (fun!) set of side effects and symptoms. Let’s take a closer look.

Left-Sided Colitis and Poop

You can’t talk about any kind of gut issue without first talking about poop. Diarrhea is often cited as one of the most typical symptoms of UC, according to Dr. Limketkai, “About 90% of individuals with UC, including left-sided, have diarrhea. But colitis can alter bowel habits and there can be constipation as well.”

Some people with left-sided UC can experience constipation; and when they do need to go to the bathroom, they may spend a long time on the toilet defecating or they may have to go many times in one day because the stool had piled up in their colon.

How Serious Is Left-Sided Colitis?

It’s logical to reason that if your UC is restricted to just the left side, it’s probably not as severe as UC that affects your entire colon. Not true. It all depends on the degree of inflammation—not where the inflammation is located—as well as how well a person responds to medication.

“If a patient has refractory [unmanageable] left-sided colitis, they can be quite ill, with debilitating bloody diarrhea leading to anemia, malnutrition, and weight loss,” says Jeffry A. Katz, M.D., a professor of medicine at Case Western Reserve University School of Medicine in Cleveland, OH.

Diagnosing Left-Sided Colitis

As with other forms of ulcerative colitis, left-sided colitis is most likely diagnosed by a colonoscopy. During this procedure, a thin, fiber-optic camera is inserted into the anus and threaded into the rectum and colon to capture images of the lining. “When performing a colonoscopy, sometimes it’s like someone drew a sharp line in the colon and the disease stops at that line and doesn't cross,” says Dr. Katz. In the case of left-sided colitis, the inflammation with redness and other irregularities in the gut’s lining are visible up to the splenic flexure (that “bend in the road”), but these signs disappear once the scope goes beyond that point. (If the inflammation in your colon continues after the splenic flexure, your doctor will make a diagnosis of pancolitis.)

It’s not clear why UC works in this manner. “It could be genetic, or immune mediated, or related to gut bacteria, or gut blood supply—or something else,” says Dr. Katz.

Unfortunately, just because your left-sided colitis is contained to one area right now doesn’t mean things will stay this way. Left-sided colitis can progress to pancolitis, particularly if it’s not properly treated. “One of the biggest factors of progression is whether it was adequately controlled with medication,” says Dr. Limketkai, “If left-sided colitis is adequately controlled, then progression is less common.”

The good news: Some 70% of people who have left-sided colitis stay that way. Over about a 10-year period of treatment, 12% of patients will regress to UC of the rectum or the sigmoid, (part of the colon connected to the rectum), says Dr. Katz. Another 17% will go on to develop pancolitis.

Treatments for Left-Sided Colitis

In general, treatment for left-sided ulcerative colitis is not too different from other forms of ulcerative colitis—with a few exceptions. The initial treatment of choice is 5-ASA, a category of medication that reduces inflammation.

“There is good data that patients with mild-to-moderate left-sided colitis do better with a combination of both topical (enema or rectal suppository) and oral 5-aminosalicylates together (5-ASA) compared to treatment with either oral 5-ASA or topical 5-ASA alone,” says Dr. Katz. “This is perhaps the one treatment difference in patients with left-sided colitis compared to patients with more extensive or more limited colitis.”

Where other areas of the colon can’t be reached by suppository or enema, the proximity of left-sided colitis makes it easier (but no less awkward) to treat with topical meds that can be injected or inserted. That’s an advantage, because by administering medication in this way, the drugs can be directly delivered to the inflamed tissues for potentially more effective results. The challenge, of course, is with compliance: Many patients shy away from a topical regimen that involves regularly using an enema or a rectal suppository because they find it cumbersome and embarrassing.

In other ways, treatment for left-sided UC, especially severe cases, is similar to those with severe pancolitis or extensive UC. If the case is moderate to severe, the big guns are used early and aggressively to get the inflammation under control, says Dr. Limketkai. These medications are referred to as biologics, drugs that target specific proteins in the body that are causing inflammation. Therapies include:

  • Entyvio (vedolizumab)

  • Humira (adalimumab)

  • Remicade (infliximab)

  • Stelara (ustekinumab)

Another drug that may be used is Xeljanz (tofactinib), which acts differently by inhibiting an enzyme that activates the body’s immune response. “We don’t do this aggressive treatment for mild to moderate cases because it can be too much, says Dr. Limketkai.

“You could develop antibodies to the medication, [making the medication ineffective.] You don’t want to burn your bridge.” Still, between this option and a growing list of other therapies that have shown success, you’re bound to find a treatment that works for your left-sided UC.

Jeanine Barone
Meet Our Writer
Jeanine Barone

Jeanine Barone is a scientist and journalist with an eclectic background. She’s a nutritionist and exercise physiologist who regularly writes about travel, health, fitness, and food for numerous top-tier publications. Jeanine enjoys active travel, especially long-distance cycling and cross-country skiing.