Sigmoid volvulus is a serious medical condition involving a segment of the large intestine, specifically the sigmoid colon. This part of the bowel can twist around its supporting tissue, known as the mesentery. When this twisting occurs, it creates a closed-loop obstruction, which can prevent the passage of stool and gas. This condition requires prompt medical attention due to its potential for severe complications if not addressed quickly.
How Sigmoid Volvulus Occurs
Sigmoid volvulus occurs when the sigmoid colon, a mobile, S-shaped section of the large intestine, twists around its supporting mesentery. This twisting creates a closed-loop obstruction, preventing the passage of stool and gas and potentially compromising blood supply. The rotation can range from partial to a full turn, trapping gas and fluid.
Certain factors increase the likelihood of this twisting. Chronic constipation, leading to an elongated and distended sigmoid colon from stool accumulation, is common. An unusually long or mobile sigmoid colon also makes it more prone to twisting. Advanced age, especially in bedridden or institutionalized individuals with neurological or psychiatric conditions affecting bowel motility, is another risk factor.
Dietary habits, such as a high-fiber diet, can contribute to an elongated sigmoid colon, increasing volvulus risk. Abdominal adhesions from previous surgeries are another less common factor, creating points where the bowel might twist. These factors, combined with a mobile colon and distension from trapped gas or stool, facilitate the colon’s rotation and acute obstruction.
Identifying the Symptoms
Sigmoid volvulus typically presents with distinct and rapidly progressing symptoms. Severe abdominal pain, often colicky or cramping, is common and can be sudden in onset, intensifying as the condition progresses. Abdominal distension is another prominent sign, where the abdomen appears visibly swollen and feels tight.
Constipation, specifically the inability to pass both stool and gas, is a key indicator of intestinal obstruction. Nausea and vomiting may also occur, especially as the obstruction becomes more severe and proximal to the twisted segment.
Diagnosis and Treatment Options
Diagnosing sigmoid volvulus typically begins with a physical examination, where the healthcare provider may note significant abdominal distension that sounds tympanitic (drum-like) upon percussion. Tenderness in the lower abdomen may also be present, raising concern for the condition. An empty rectal ampulla on digital rectal examination can further support the suspicion.
Initial imaging often involves plain abdominal X-rays, which can reveal a characteristic “coffee bean sign” or “bent inner tube sign,” indicating a massively distended, air-filled loop of the sigmoid colon. This sign, representing the twisted colon and its compressed walls, is diagnostic in 50% to 75% of cases. Computed tomography (CT) scans offer higher diagnostic accuracy, exceeding 90%, and can show a “whirl sign,” where the bowel and its mesentery twist around a central point, along with dilated bowel loops and air-fluid levels. CT scans are also valuable for assessing potential complications like ischemia.
In stable patients without signs of bowel damage, initial management often includes endoscopic detorsion. This procedure uses a flexible tube (sigmoidoscope or colonoscope) guided into the rectum to gently untwist the colon, providing immediate relief by decompressing it and evacuating gas and liquid stool. While effective for immediate relief, endoscopic detorsion alone carries a high risk of recurrence (18-90%). Therefore, definitive surgical intervention is often recommended after successful detorsion to prevent future episodes.
Surgical options typically involve sigmoid colectomy, which is the removal of the affected portion of the colon. This may be followed by a primary anastomosis, where the remaining healthy bowel ends are reconnected, or in more complex cases, a Hartmann procedure, which creates a temporary or permanent colostomy. Emergency surgery is necessary if there are signs of peritonitis, bowel ischemia, or perforation.
Understanding Potential Outcomes
When the twisted colon’s blood supply is cut off, it results in bowel ischemia, a lack of blood flow to the tissue. Prolonged ischemia can cause gangrene, leading to tissue death in the affected bowel segment. If the compromised bowel wall perforates, intestinal contents can leak into the abdominal cavity, causing peritonitis, a widespread infection. This can rapidly progress to sepsis, a severe body-wide inflammatory response that can lead to organ failure and death.
After successful treatment, particularly surgical resection, the prognosis generally improves. Elective sigmoid colectomy, performed after initial decompression, significantly reduces the risk of recurrence. However, if only endoscopic detorsion is performed without subsequent surgery, the recurrence rate can be high, with some studies reporting recurrence in over 80% of cases within months. Managing underlying conditions like chronic constipation is also important to minimize recurrence risk. Recovery time varies but often involves a period of hospitalization and gradual return to normal bowel function.