Sigmoid volvulus occurs when the sigmoid colon, the S-shaped final segment of the large intestine just above the rectum, twists on its supporting tissue, cutting off the flow of stool and gas and sometimes choking its own blood supply. It accounts for roughly 15 percent of large bowel obstructions in the United States and is far more common in parts of Africa, Asia, and South America. The condition can resolve with a relatively simple endoscopic procedure, but left untreated it can lead to bowel death, perforation, and a surgical emergency with significant mortality.
What Actually Happens Inside the Abdomen
The sigmoid colon is anchored to the back wall of the abdomen by a fan-shaped piece of tissue called the mesosigmoid. In most people the sigmoid is mobile enough to shift around but not so mobile that it can flip over on itself. In people who develop sigmoid volvulus, the mesosigmoid tends to be longer and wider than average while the base where it attaches to the abdominal wall stays the same narrow width. That combination creates a kind of floppy pendulum: a heavy, mobile loop of bowel swinging on a narrow stalk.1PubMed Central. The role of the anatomy of the sigmoid colon in developing sigmoid volvulus: a case-control study When conditions are right, the loop rotates anywhere from 180 to over 360 degrees, pinching itself shut at both ends. Gas and stool become trapped inside the closed loop, which balloons outward. If the twist is tight enough, it also strangles the blood vessels running through the mesosigmoid, and that is when tissue starts dying.
Why Some People Are Vulnerable
Having a long, redundant sigmoid colon is a prerequisite, but several other factors raise the odds of an actual twist happening.
Chronic Constipation
Chronic constipation is one of the strongest risk factors and appears to create a vicious cycle. Stool that sits in the sigmoid for days at a time causes the bowel to stretch. Over months and years, that repeated stretching elongates and dilates the sigmoid, making it progressively more prone to twisting.2PubMed Central. Recurrence of Sigmoid Volvulus Associated With Constipation: A Retrospective Cohort Study Once a volvulus has occurred and been untwisted, the underlying constipation often persists, setting the stage for another episode.
Diet and Altitude
In regions where diets are very high in fiber and unprocessed vegetables, bulky stool and increased gas production can raise intraluminal pressure, gradually stretching the sigmoid wall. High altitude adds another layer: lower atmospheric pressure causes intestinal gases to expand, further distending the colon over time. Both factors contribute to the condition known as dolichosigmoid, an abnormally long sigmoid, which is why sigmoid volvulus rates are strikingly high in parts of East Africa, the Andes, and the Indian subcontinent.3Formosan Journal of Surgery. Sigmoid volvulus and concomitant clinical entities
Neuropsychiatric Conditions and Institutionalization
In the United States and other Western countries, sigmoid volvulus clusters in a somewhat different population: elderly men, often with neurological or psychiatric diagnoses, and frequently residents of nursing facilities.4Annals of Surgery. Colonic Volvulus in the United States: Trends, Outcomes, and Predictors of Mortality The connection is partly explained by the medications these patients take. Antipsychotics, opioids, and anticholinergic drugs all slow gut motility, promoting the same chronic constipation and sigmoid distension described above. Limited physical activity compounds the problem. African Americans and people with diabetes also appear at higher risk in U.S. data.
Chagas Disease
In Central and South America, infection with the parasite Trypanosoma cruzi causes Chagas disease, which can destroy the nerve cells that coordinate bowel contractions. The result is megacolon: an irreversibly dilated, dysfunctional segment of colon that is primed to twist.5IntechOpen. Digestive Disorders in Chagas Disease: Megaesophagus and Chagasic Megacolon This makes Chagas-related megacolon one of the most significant drivers of sigmoid volvulus in endemic regions.
Recognizing the Symptoms
The classic presentation is a triad of abdominal pain, abdominal distension, and inability to pass stool or gas.6PubMed Central. Sigmoid Volvulus and Ileosigmoid Knotting: An Update Distension can be dramatic, sometimes making the abdomen visibly asymmetric. The pain often starts as colicky cramping and can progress to constant, severe pain if the bowel’s blood supply is compromised. Tenderness on examination is another common finding.7PubMed Central. Sigmoid volvulus
The challenge is that many of the patients most vulnerable to sigmoid volvulus, elderly people with dementia or psychiatric illness, may not be able to describe their symptoms clearly. In these settings, unexplained abdominal distension that develops over hours should prompt urgent investigation, because delay can turn a straightforward case into one with dead bowel.
How It Looks on Imaging
A plain abdominal X-ray is often the first imaging study. The hallmark finding is the “coffee bean sign”: a massively distended, gas-filled loop of bowel that takes the shape of a coffee bean, with a central line where the walls of the twisted loop press together.8PubMed Central. Coffee bean sign: Its meaning and importance When present, this sign is considered essentially diagnostic of sigmoid volvulus.
CT scans provide more detail and have become the go-to study in most emergency departments. On CT, the twisted sigmoid and its mesentery create a “whirl sign,” a swirling pattern where the dilated bowel wraps around its blood vessels and supporting tissue. The point where the bowel narrows into the twist often has a “bird beak” appearance.9PubMed. Computed tomographic appearance of sigmoid volvulus CT is especially valuable because it can reveal signs of ischemia or perforation, features that change the treatment plan entirely. Radiologists look at the direction of rotation, the degree of distension, and whether the bowel wall shows evidence of compromised blood flow.10PubMed. Sigmoid volvulus-Can CT features predict outcomes and recurrence?
First-Line Treatment Is Usually Endoscopic
When there are no signs that the bowel has died or perforated, the initial treatment is endoscopic decompression. A flexible tube or a sigmoidoscope is passed through the rectum and into the twisted loop. The goal is to release the trapped gas and stool and, ideally, to untwist the bowel. The procedure is successful in most patients with uncomplicated sigmoid volvulus.11PubMed Central. Clinical outcome of patients treated with endoscopic decompression after failure of detorsion for uncomplicated sigmoid volvulus Interestingly, research suggests that even when the bowel does not fully untwist during the procedure, simple decompression, releasing the gas and stool, can be enough to resolve the obstruction with outcomes similar to full detorsion.
In a U.S. study from Minnesota, about four in five patients with sigmoid volvulus were successfully treated with nonoperative reduction initially.12Diseases of the Colon & Rectum. Colonic Volvulus: Presentation and Management in Metropolitan Minnesota, United States That high initial success rate can create a false sense of security, though, because recurrence rates after endoscopic decompression alone are notoriously high.
The Recurrence Problem
This is where the evidence gets blunt. Endoscopic decompression buys time, but it does not fix the underlying anatomy. The sigmoid is still redundant, the mesosigmoid is still long and floppy, and the constipation that contributed to the first episode often remains. In one series, five of seven patients managed with endoscopic decompression alone were readmitted with another volvulus, a recurrence rate above 70 percent.13PubMed Central. Recurrent sigmoid volvulus – early resection may obviate later emergency surgery and reduce morbidity and mortality Each recurrence carries the risk that the bowel will strangulate before the patient reaches the hospital, turning a manageable situation into a life-threatening one.
For this reason, the standard recommendation is to proceed to definitive surgery after the initial decompression, ideally during the same hospitalization or shortly after, once the patient has been stabilized and the bowel has had time to recover from its acute insult. The authors of that same study argued that all patients should be considered for surgery after initial decompression, regardless of how frail they appear, because the alternative is repeated emergency admissions with escalating risk.
Surgical Options
Definitive surgery for sigmoid volvulus means removing the redundant sigmoid colon (sigmoidectomy). The two main approaches are primary anastomosis, where the remaining ends of the colon are reconnected in the same operation, and Hartmann’s procedure, where the rectal stump is closed off and the upstream end of the colon is brought out through the abdominal wall as a temporary or permanent stoma (colostomy). Primary anastomosis is generally preferred when feasible because it avoids the need for a stoma and a potential second operation to reverse it. A retrospective study comparing the two approaches found that complication rates, including anastomotic leak, surgical-site infection, and mortality, were not significantly different between the groups, although hospital stays tended to be shorter with Hartmann’s procedure.14PubMed Central. Evaluating outcomes of primary anastomosis versus Hartmann’s procedure in sigmoid volvulus: A retrospective-cohort study
The timing of surgery matters enormously. When performed electively after successful endoscopic decompression, surgery can often be done laparoscopically (through small incisions), with fewer complications and a lower likelihood of needing a stoma. Emergency surgery, by contrast, more often requires an open approach and results in higher complication rates and more frequent stoma formation.15Annals of Coloproctology. Surgical Management of Sigmoid Volvulus: A Multicenter Observational Study This is the practical argument for not sending patients home after a successful decompression with a plan to “see how it goes.” Getting surgery done in the elective window, before the next twist, substantially improves outcomes.
When Surgery Is Too Risky
Many sigmoid volvulus patients are elderly, frail, and poor candidates for general anesthesia. For these individuals, a newer option called endoscopic-assisted percutaneous sigmoidopexy is gaining traction. In this procedure, the sigmoid colon is tacked to the abdominal wall using stitches or fixation devices placed through the skin under endoscopic guidance. It does not require general anesthesia and does not remove the redundant sigmoid, but it physically prevents the bowel from twisting again.16PubMed Central. Endoscopic-Assisted Percutaneous Sigmoidopexy: New Highlights on Technique and Outcomes The concept is similar to how a percutaneous endoscopic gastrostomy tube fixes the stomach to the abdominal wall, adapted for the sigmoid colon.17International Journal of Surgery Case Reports. Percutaneous endoscopic sigmoidopexy for sigmoid volvulus: A case report
A randomized controlled trial in high-risk elderly patients found endoscopic management to be both effective and safe for resolving obstruction and reducing recurrence.18PubMed Central. Endoscopic management of acute sigmoid volvulus in high risk surgical elderly patients: a randomized controlled trial Experience with the technique is still accumulating, but it fills a real gap for patients who previously had no good option between repeated decompressions and an operation they might not survive.
How Sigmoid Volvulus Differs from Cecal Volvulus
The colon can twist in other places too, most commonly the cecum (the pouch at the beginning of the large intestine). Despite both being forms of colonic volvulus, sigmoid and cecal volvulus are quite different in who they affect and how they are managed. Sigmoid volvulus predominates in older men, often with neurological conditions or a history of institutionalization. Cecal volvulus is more common in younger women.19Annals of Surgery. Colonic Volvulus in the United States: Trends, Outcomes, and Predictors of Mortality Crucially, cecal volvulus does not respond to endoscopic decompression, and all patients with cecal volvulus are treated surgically.20Diseases of the Colon & Rectum. Colonic Volvulus: Presentation and Management in Metropolitan Minnesota, United States So the endoscopy-first, surgery-later sequence that works for most sigmoid volvulus patients does not apply to cecal volvulus at all.
Sigmoid Volvulus in Pregnancy
Sigmoid volvulus is rare in pregnancy, but it is disproportionately dangerous when it does occur. The growing uterus displaces the bowel upward and can push a redundant sigmoid into an unfamiliar position, making it more susceptible to twisting. The condition is most common in the third trimester.21PubMed Central. Recurrent Sigmoid Volvulus in Pregnancy: Case Report Diagnosis is tricky because abdominal pain, distension, and constipation are common pregnancy complaints, and clinicians may not immediately think of a surgical emergency. The consequences of delay can be catastrophic, including fetal death and maternal death.22PubMed Central. Sigmoid volvulus in pregnancy: case report and review of literature Any pregnant patient presenting with signs of bowel obstruction should be evaluated urgently for volvulus, and treatment requires coordination between obstetricians and surgeons.
Geographic Patterns and Why They Matter
The epidemiology of sigmoid volvulus illustrates how geography, diet, and infrastructure interact in disease. In Western countries, sigmoid volvulus is the third most common cause of large bowel obstruction and is largely a disease of the elderly and institutionalized. In parts of sub-Saharan Africa, Central Asia, and South America, it is one of the most common surgical emergencies and can strike younger adults. The differences trace back to the dietary and altitude factors discussed earlier: high-fiber diets, elevation, and in South America, endemic Chagas disease all elevate the baseline rate of dolichosigmoid in the population.
These geographic patterns also matter for treatment access. Endoscopic decompression requires a flexible endoscope and a trained operator, resources that are readily available in urban hospitals but scarce in rural settings in low-income countries. Many patients in high-prevalence regions go straight to surgery, often arriving late with gangrenous bowel, which raises mortality dramatically. Improving access to endoscopy and training general practitioners to recognize the condition early could substantially reduce deaths in these regions.
Living with a Redundant Sigmoid
Many people have an unusually long sigmoid colon and never develop a volvulus. Having a dolichosigmoid is not itself a disease, and plenty of people live their entire lives without knowing theirs is longer than average. The problem arises when that anatomic variant combines with chronic constipation, reduced mobility, or medications that slow the gut. For someone who has already had one episode and undergone successful surgical resection, the recurrence risk drops dramatically because the redundant segment is gone. For those managed with decompression alone, aggressively treating constipation with dietary changes, adequate fluids, and sometimes laxatives may help reduce, though not eliminate, the chance of another twist. The underlying anatomy does not change without surgery, so patients and their families should understand the warning signs and seek prompt care if symptoms recur.