About this article
Medically reviewed- Written by
- Dr Paul Watson
- Medically reviewed by
- Dr Han Simpson
- Published
- August 23, 2026
- Medical review date
- September 8, 2026
- Evidence searched through
- September 8, 2026
- Next review due
- September 8, 2027
- Intended audience
- General Readers & Patients
- Geographic scope
- Worldwide
- Conflicts of interest
- None declared.
- Funding
- Website Owner
- Report a correction
- Report an error or editorial concern
- Medical disclaimer
- Read the medical disclaimer
If you searched for sigmoid colon, there’s a good chance you’re dealing with lower abdominal pain, a change in your bowel habits, blood in the stool, or a new test result that sounds more alarming than it should. I see this often in clinic. A patient hears a term they’ve never needed before, goes home, starts reading, and within minutes feels overwhelmed.
So let me talk to you the way I would in the exam room.
Most problems involving the sigmoid colon are understandable once you know where it is, what it does, and why this part of the bowel can be a trouble spot. Some issues are irritating but manageable. A few are urgent and need quick treatment. Knowing the difference matters.
Practical rule: If your symptoms are new, persistent, severe, or simply don’t feel like your “usual stomach upset,” it’s worth getting checked rather than trying to guess.
Understanding Your Sigmoid Colon
The sigmoid colon is the last curved part of your large intestine before the rectum. If the colon were a long hallway, the sigmoid colon would be the final bend just before the exit door. It’s a small section, but it causes a lot of confusion because it sits in an area where many different symptoms can overlap.
When patients ask me about it, they’re usually worried for one of three reasons. They’ve been told they might have diverticulitis, they’ve had a scan or colonoscopy mention the sigmoid colon, or they’re frightened by pain low on the left side of the belly. All three can feel scary at first.
Why this area gets attention
This section of bowel has a distinctive S-shape. It’s also more mobile than other parts of the colon, which is normal anatomy. That mobility helps it do its job, but it also explains why certain conditions happen here more often than people expect.
The sigmoid colon is also a common place for problems that range from everyday constipation to inflammation, twisting, polyps, and cancer. That sounds like a lot, but there’s a reason doctors focus on it. This part of the bowel acts a bit like a holding area for stool before a bowel movement, so anything that affects pressure, movement, or the bowel wall can show up here.
What patients usually notice first
Symptoms in this area often include:
- Lower left abdominal pain that may feel crampy, steady, or tender to touch
- Bloating or pressure that makes your abdomen feel tight
- Changes in bowel habits such as constipation, diarrhea, or going back and forth between both
- Blood or mucus in stool that needs medical attention
- A feeling of incomplete emptying after using the bathroom
One of the hardest parts is that these symptoms don’t point to one single diagnosis. Mild constipation can cause discomfort in the same general area as a more serious condition. That’s why the pattern matters. Is it sudden or gradual? Mild or intense? One day or ongoing? Is there fever, vomiting, or abdominal swelling?
Pain low in the abdomen doesn’t automatically mean something dangerous. But pain that is severe, persistent, or paired with fever, vomiting, or swelling should never be brushed off.
Your Colon’s Anatomy and Function
The colon is like your body’s final sorting and storage system. By the time digested material reaches this stage, most nutrients have already been absorbed higher up in the digestive tract. The colon’s job is to pull out more water, move waste along, and store stool until you’re ready to pass it.
The sigmoid colon is the last curved stretch before the rectum. It connects the descending colon to the rectum and sits in the left lower abdomen and pelvis.
Where it is and why it has that shape
Anatomically, the sigmoid colon is an S-shaped segment. It extends about 25 to 40 cm, or 10 to 15.75 inches, and it’s attached by the sigmoid mesocolon, which gives it significant mobility. That same mobility makes it the most mobile part of the colon and helps explain why it can be a frequent site for twisting, called volvulus, as described in Kenhub’s colon anatomy review.
In plain English, this means the sigmoid colon isn’t fixed tightly in place like a rigid pipe. It has some freedom to move. That’s useful for normal bowel function, but it also means it can sometimes fold, kink, or become more vulnerable to pressure-related problems.
A lot of people get hung up on the term “colon” and assume every section is basically the same. It isn’t. The sigmoid colon is built for the final stage of stool movement. Think of it as a waiting room just before departure. Stool collects there temporarily, more water is absorbed, and then muscular contractions push it toward the rectum.
What it actually does each day
Here are the main jobs of the sigmoid colon:
- Temporary storage: It holds stool before a bowel movement.
- Water handling: It continues absorbing water from waste, which affects how firm or loose the stool becomes.
- Propulsion: It uses coordinated muscle contractions to move stool into the rectum.
- Pressure management: Because it stores stool, it’s one of the places where pressure can build when bowel habits change.
That last point helps explain why constipation can make this area ache. If stool sits too long, the sigmoid colon can stretch and cramp. Some patients describe it as a dull pressure. Others say it feels like a stitch, a squeeze, or repeated waves of discomfort.
Why anatomy matters in real life
Doctors care about this segment’s shape and attachments because structure affects symptoms. A bendy, mobile section can work beautifully under normal conditions. But if there’s inflammation, trapped stool, a narrowing, or a twist, symptoms can escalate quickly.
I often tell patients not to think of abdominal anatomy as a list to memorize. Think of it as a map. Once you know the sigmoid colon is the final bend on the left side before the rectum, many symptoms make a lot more sense.
Common Sigmoid Colon Pains and Problems
The most common reason people learn this term is pain. Usually, they point to the lower left side of the belly and ask, “What’s there?” The answer is often the sigmoid colon.
Diverticulitis in plain language
One of the most frequent problems in this area is sigmoid colon diverticulitis. This happens when tiny pouches in the colon wall, called diverticula, get blocked with fecal matter or debris, leading to inflammation or infection that needs medical care to help prevent complications such as abscess or perforation, as explained by Colon & Rectal MD.
Patients usually understand it best when I compare diverticula to little pockets pushing out from the wall of the colon. If one of those pockets becomes irritated or infected, the area can become very sore.
Common clues include:
- Steady lower left abdominal pain
- Tenderness when pressing the area
- Fever or feeling unwell
- Nausea
- Constipation, diarrhea, or both
Not every case feels dramatic at first. Some people notice a nagging pain that doesn’t ease up after a bowel movement. Others feel bloated and think it’s “just gas” until the discomfort keeps building.
IBS and constipation can mimic it
Many readers often find this confusing. Irritable bowel syndrome, or IBS, can also cause cramping, bloating, and changes in bowel habits. Constipation can do the same. The difference is often in the overall pattern.
IBS tends to come and go and may be linked to stress, certain foods, or longstanding bowel sensitivity. Constipation often brings hard stools, straining, and a sense that things aren’t moving. Diverticulitis is more likely to cause localized pain and a generally sick feeling.
If the pain is fixed in one spot, getting worse, or accompanied by fever, don’t assume it’s IBS.
Symptom Checker Diverticulitis vs IBS vs Constipation
| Symptom | Diverticulitis | IBS | Constipation |
|---|---|---|---|
| Lower left abdominal pain | Often steady and localized | Often crampy and variable | Often pressure or cramping |
| Fever | Can happen | Not typical | Not typical |
| Bloating | Common | Common | Common |
| Nausea | Can happen | Sometimes | Sometimes |
| Bowel habit changes | May include constipation or diarrhea | Often diarrhea, constipation, or both | Usually fewer or harder stools |
| Tenderness to touch | More likely | Less typical | Mild if present |
| Needs prompt medical review | Yes, especially if pain persists or worsens | If symptoms are new or changing | If persistent, painful, or severe |
This table isn’t for self-diagnosis. It’s a simple guide to help you describe what you’re feeling more clearly when you speak with your doctor.
When common symptoms stop being “common”
Call a clinician promptly if you have:
- Persistent pain: especially on the lower left side
- Fever with abdominal symptoms: that combination deserves attention
- Vomiting or inability to pass stool or gas: this can suggest blockage
- Bleeding: even if it seems small
- Rapid worsening: a bad turn over hours matters
The sigmoid colon is often the source of manageable problems. It’s also a place where waiting too long can make treatment harder. When in doubt, let a professional sort it out.
When Things Get Serious Volvulus and Cancer
Some sigmoid colon conditions need urgent attention. The two that worry patients most are sigmoid volvulus and colon cancer involving the sigmoid colon. They’re very different problems, but both become easier to deal with when they’re recognized early.
Sigmoid volvulus
A volvulus means the bowel twists on itself. In the sigmoid colon, that twist can block the passage of stool and gas and may also compromise blood flow. When blood supply is affected, the situation becomes dangerous quickly.
This is not subtle in many cases. People may develop marked abdominal swelling, pain, constipation, and vomiting. The abdomen can become tight and distended.
What we do know is important. About 70% of sigmoid volvulus cases affect people over 60, it’s more common in men with a ratio of about 2:1 to 3:1, and after non-operative decompression the recurrence rate is about 50% to 60%, which is why surgery is often needed, according to this review in the Journal of Surgical Case Reports hosted on PMC.
Who can still be missed
Although many cases occur in older adults, clinicians also watch for people who don’t fit the classic pattern. The presentation can be overlooked when someone is younger or doesn’t have the long history of constipation people expect. Patient.info’s clinical review of sigmoid volvulus discusses this gap and notes that delayed treatment can be dangerous, particularly when there are signs of ischemia or perforation.
That’s why severe abdominal distension, worsening pain, and inability to pass stool or gas should never be treated as a wait-and-see problem.
Sudden swelling of the abdomen with pain and vomiting is an emergency until proven otherwise.
Cancer in the sigmoid colon
Cancer in this area often begins as a polyp, which is a small growth on the lining of the colon. Not every polyp becomes cancer, but some can change over time. That’s why screening matters so much.
Symptoms that raise concern include:
- Blood in the stool
- A lasting change in bowel habits
- Unexplained weight loss
- Fatigue
- A feeling that the bowel doesn’t empty properly
Many patients ask me if pain is always present. It isn’t. That’s one reason screening saves lives. The goal is to find polyps or early disease before symptoms become obvious.
The most reassuring truth here is that serious doesn’t mean hopeless. It means prompt evaluation matters.
How Doctors Investigate Your Symptoms
When symptoms point toward the sigmoid colon, the testing process usually feels more intimidating than the tests themselves. Once patients know what each test is for, anxiety usually drops.
A doctor starts with the basics. We listen to the story, examine the abdomen, ask about bowel habits, bleeding, fever, weight loss, and family history, and then decide which test best answers the question in front of us.
A visual overview can help before we talk through the details.
Flexible sigmoidoscopy and colonoscopy
For screening and direct visualization, doctors may recommend flexible sigmoidoscopy or colonoscopy. Current guidance recommends that people begin screening tests such as colonoscopy or flexible sigmoidoscopy at age 45, because the sigmoid colon is a frequent site for precancerous polyps, as noted by the Mayo Clinic overview of flexible sigmoidoscopy.
A flexible sigmoidoscopy looks at the rectum and sigmoid colon. A colonoscopy examines the whole colon. If your symptoms are focused low in the bowel, a sigmoidoscopy may be considered. If your doctor wants a complete look, especially for cancer screening or broader symptoms, colonoscopy is often preferred.
Patients usually ask me which one is “better.” The better test is the one that answers the clinical question safely and completely.
What the prep is really like
The prep matters because the camera can only see what isn’t covered by stool. For flexible sigmoidoscopy, preparation typically involves a low-fibre diet for 3 days, specific laxatives the day before, and enemas 1 to 2 hours before the procedure.
If you’re getting ready for a larger bowel exam, this guide on what to eat 2 days before colonoscopy can help make the preparation feel more manageable.
Many people dread the prep more than the procedure. That’s normal. My practical advice is simple:
- Follow the food instructions exactly: it gives the test the best chance of being complete
- Stay near a bathroom: the laxatives do their job quickly
- Use the written schedule: don’t rely on memory
- Call if instructions conflict with your medications: especially if you take blood thinners or diabetes medications
For a look at how bowel evaluation works in practice, this short video is useful:
CT scans and blood tests
If you have significant pain, fever, suspected diverticulitis, or possible bowel obstruction, a CT scan is often very helpful. It shows the bowel wall, surrounding tissues, inflammation, and complications outside the bowel itself. Blood tests may also check for infection, blood loss, or dehydration.
That combination of story, exam, imaging, and direct visualization usually gives a clear answer. And once the diagnosis is clear, treatment decisions become much less frightening.
Your Path to Feeling Better Treatment Options
Treatment depends on what’s causing the problem. I tell patients to think of sigmoid colon treatment as a ladder. We start with the simplest effective step and move upward only if needed.
Medication and daily habit changes
For some conditions, treatment begins with medicine and bowel support rather than procedures.
In diverticulitis, antibiotics may be used when infection is suspected. Doctors also pay attention to hydration, pain control, and how severe the attack seems. After recovery, many patients are advised to focus on a bowel routine that reduces straining and helps stool move more regularly.
For constipation-related symptoms, the plan may include:
- More fluid: dehydration can make stool harder and harder to pass
- Fiber changes: sometimes gradual increases help, though timing matters if you’re actively inflamed or preparing for a procedure
- Gentle bowel medications: your doctor may suggest a specific laxative rather than random over-the-counter trial and error
- Regular toilet habits: ignoring the urge to go can make things worse
Endoscopic treatment
Some problems can be treated without open surgery.
Doctors can remove polyps during a colonoscopy. In some cases of sigmoid volvulus, a specialist may try endoscopic detorsion, which means untwisting the bowel through a scope if there’s no sign that the bowel has become non-viable. That decision depends on the patient’s condition and the findings on exam and imaging.
This is one reason diagnosis comes before treatment. The same symptom, such as abdominal distension, can lead to very different treatment paths depending on whether the bowel is inflamed, blocked, twisted, or bleeding.
Surgery when it’s necessary
Sometimes the safest option is surgery. This may involve removing the affected part of the sigmoid colon, often called a sigmoidectomy or sigmoid colectomy. Surgery may be needed for recurrent volvulus, complicated diverticulitis, cancer, perforation, or severe obstruction.
I remember one patient who was terrified when she learned she needed surgery after repeated painful attacks. Her biggest fear wasn’t the operation itself. It was that life would never feel normal again. Months later, she told me the opposite was true. She could travel, eat without fear, and stop planning her day around pain.
Recovery after bowel treatment is rarely instant, but many people do get back to work, family life, and ordinary routines with good long-term results.
If you’re preparing for a flexible sigmoidoscopy as part of that journey, remember that good preparation matters. Clear visualization typically depends on a low-fibre diet for 3 days, laxatives the day before, and enemas 1 to 2 hours before the exam, as outlined in the earlier linked Medanta patient guide.
Key Takeaways for Your Gut Health Journey
The sigmoid colon is small compared with the whole digestive system, but it can create outsized worry. That’s understandable. It sits in a part of the body where pain, pressure, bloating, and bowel changes can feel vague at first and frightening once they persist.
The good news is that most of the mystery goes away when you pay attention to the pattern. Mild, brief discomfort is different from pain that stays put, builds, or comes with fever, bleeding, vomiting, or abdominal swelling.
When to call your doctor
Reach out promptly if you notice:
- Persistent lower abdominal pain: especially if it’s focused on the left side
- Blood in the stool: even if it seems minor
- Fever with bowel symptoms: that combination deserves medical review
- A major change in bowel habits: especially if it doesn’t settle
- Abdominal swelling or vomiting: particularly if you can’t pass stool or gas
Those are not symptoms to ignore or self-diagnose for long.
What helps you stay ahead
A few habits make a real difference:
- Keep up with screening: starting at the recommended age matters
- Notice changes early: your “normal” bowel pattern is useful information
- Follow prep instructions carefully: a clean bowel makes tests more accurate
- Ask direct questions: you deserve to understand what a scan or scope found
- Don’t minimize ongoing symptoms: if something persists, say so clearly
I’d also encourage you to keep learning from reliable reading rather than random message boards. For broader context on digestive concerns, you may find related articles in the Free Medical Journals blog helpful.
If you want more in-depth medical reading beyond patient education pages, open-access literature can also be useful. A good starting point is the NCBI Bookshelf overview of the sigmoid colon, which explains the anatomy and why this segment’s structure matters clinically.
The main message I want to leave you with is simple. Listen to your body. Don’t panic, but don’t dismiss persistent symptoms either. Individuals often feel better once they have a clear diagnosis and a plan, and that plan usually starts with one straightforward step: asking for help.