What Is the Sigmoid Colon, and What Does It Have to Do With Diverticulitis? Everything You Need to Know

Every piece of food that goes into your mouth passes through your digestive system, which includes the esophagus, the stomach, the small intestine, the large intestine, and the rectum.

The colon (or large intestine) is the final stop for digested food before it exits the body as fecal waste. And here, the colon absorbs any remaining water, nutrients, and electrolytes. (1)

But while you might think of your colon as nothing more than a continuous waste tunnel, it actually consists of four parts: the ascending colon, the transverse colon, the descending colon, and the sigmoid colon. (1)

Most people don’t give much thought to the innermost functions of their colon, and in most cases, they prefer not to. But if you have diverticulitis, getting to know your sigmoid colon may provide a better understanding of your condition.

What Is the Sigmoid Colon Exactly, and Why Is It Important?

The sigmoid colon is the lower section of your large intestine and connects the descending colon to your rectum. (1)

Also called the pelvic colon, its name comes from its S shape. (2) The sigmoid colon performs the same function as other sections of your colon, in that it absorbs water and nutrients from digested foods. But along with this role, the sigmoid colon serves as a storage area for waste until it leaves the body. (3)

How Does Diverticulitis Affect the Sigmoid Colon?

Because of the sigmoid colon's location, near the rectum, this area is also a high pressure zone, particularly when you’re constipated and struggling to have a bowel movement. (4)

While straining may occur naturally, it can also trigger problems like hemorrhoids and anal fissures, which are tears in the lining of the anus. The more you strain, the more pressure you’ll have in the sigmoid colon, and this pressure can cause the formation of small, harmless (and often symptom-free) pouches called diverticula that protrude outward from the colon wall. (5)

As if these problems weren't bad enough, a diverticulum can sometimes rupture and become inflamed or infected, giving rise to the condition diverticulitis. (6)

Because the sigmoid colon is the most common area for diverticula to develop, this also happens to be the most common area affected by diverticulitis. (7)

Potential Signs of a Problem With Your Sigmoid Colon

That’s not to say that you’ll get diverticulitis if you have one or more diverticula, but there’s always the possibility of a rupture.

A diverticulum that doesn’t cause a problem is known as diverticulosis. You could have one or more diverticula and never know it. (6) But sharp pain can occur suddenly, and at this point, there’s no doubting a problem.

“Signs of problems in the sigmoid colon, such as diverticulitis, may include fever, left lower quadrant pain, nausea, vomiting, and changes in bowel habit (often constipation),” says Daniel Motola, MD, PhD, a gastroenterologist with Gotham Medical Associates in New York City. “Bleeding diverticular disease can also result in a significant amount of bright red blood from the rectum.”

Typically with problems in the digestive tract, a doctor may recommend a colonoscopy to view the colon and help diagnose digestive conditions. But for good reason, your doctor won’t put your body through a colonoscopy when you’re dealing with diverticulitis pain, at least not at first. (8)

Rather, you’ll complete other testing such as a blood and urine test to rule out problems with your kidneys or liver, and your doctor may perform an MRI or CT scan of the abdominal area to check for diverticulitis. (8)

Depending on the findings, treatment may include oral or intravenous antibiotics, pain medication, or your doctor might bring up the topic of surgery. (8)

Although your doctor may initially delay a colonoscopy, you’re not completely off the hook. If you’re diagnosed with diverticulitis, you will need a colonoscopy about six weeks after you recover to rule out other possible causes of symptoms. (8)

What Other Conditions Affect the Sigmoid Colon?

Diverticulitis can affect the sigmoid colon, but other problems can also develop in this area.

“Generally speaking, inflammation from diverticulitis can cause scar tissue formation and breakdown of the colon wall, and if the colon wall develops a hole, then an abscess will form,” warns Will Bulsiewicz, MD, a gastroenterologist and gut health expert in Mount Pleasant, South Carolina.

Scar tissue refers to adhesions that can form anywhere on the body after trauma or surgery. (9) Bands of scar tissue developing between the abdomen and other organs can create abnormal connections (fistulas), resulting in pain, constipation, and intestinal blockage. And when a fistula develops near another organ, such as the bladder, you may experience urinary tract infections, difficulty urinating, or frequent urination, explains Dr. Bulsiewicz. (10)

An abscess, on the other hand, is a collection of pus caused by an infection.

“In mild cases, an abscess may be small and may only require antibiotics. In severe cases, there can be a larger abscess or even peritonitis, meaning infection of the peritoneum that lines the abdominal cavity,” says Bulsiewicz.

Peritonitis isn’t anything to play with. This infection occurs when a rupture in the abdomen causes intestinal waste to leak into the abdominal cavity. This is a life-threatening medical emergency. (11)

Signs of peritonitis include fever, increased thirst, and an inability to pass stools and gas. (11)

Surgery is an unfortunate reality of some problems affecting the sigmoid colon. Surgery may involve a procedure to drain an abscess, or to remove diseased sections of the sigmoid colon (bowel resection) with or without a colostomy. (8) A colostomy is an operation to create an opening in the colon through the abdomen. (12)

It’s important to realize, however, that not all problems with the sigmoid colon are related to diverticulitis, notes Dr. Motola.

“Obstruction of the sigmoid colon by mass or cancer can lead to difficulty having bowel movements despite laxatives, and if severe enough, can also result in abdominal pain, nausea, and vomiting.”

Keeping Your Sigmoid Colon in Proper Working Order

Because diverticula don’t usually cause symptoms, you may be unaware of a problem with your sigmoid colon until you’re struck with stomach pain. (6) The good news is that keeping your sigmoid colon in good working order may head off problems. Here are some tips to help keep your sigmoid colon healthy.

Eat more fiber. A low-fiber diet increases the risk of developing diverticula, which of course, can lead to diverticulitis. The more fiber you eat, the easier it’ll be for stools to pass through the colon, thus alleviating pressure and strain. Ideally, you should eat between 21 and 38 grams of fiber per day. (13) If this feels like too much, supplement with fiber tablets.

Limit red meat. You don’t have to give up cheeseburgers and steaks entirely, but you should aim to eat red meat in moderation (that includes pork!). Prepare a few meatless meals each week and make a conscious effort to snack on more vegetables during the day. “Quite simply, by eating more plants and less meat, you can dramatically reduce your risk of developing diverticulitis,” says Bulsiewicz.

Get moving. Exercise can feel like a chore, and you might use any and every excuse to avoid physical activity. No one is suggesting spending an hour in the gym every day. But you should aim for at least 30 minutes of moderate-intensity exercise five days a week. (13)

Take a probiotic. Probiotics — which are good bacteria — may also help your digestive tract run smoothly. Good sources of probiotics include yogurt and sauerkraut; or take a probiotic supplement. (13)

Drink plenty of fluids. Proper hydration helps keep stool soft and prevents straining, thus alleviating pressure in the sigmoid colon. (8)

The Takeaway on the Function of the Sigmoid Colon and Warding Off Related Health Issues

While the sigmoid colon plays a role in waste removal from the body, too much pressure in this area can take your colon on a roller coaster. But with the right diet, habits, and improved bowel habits, you can keep your colon healthy and avoid the ride.