Colonic volvulus: Clinical sciences

Colonic volvulus occurs when a redundant segment of the colon twists on its mesentery, causing a closed loop obstruction where the blood supply to the colon can become compromised. Now, in this closed loop, gas and secretions continue to build up with nowhere to go. This worsens the distension of the segment, and can lead to ischemia, necrosis, and ultimately perforation.

Colonic volvulus accounts for about 10% of large bowel obstructions and is more common in the elderly or in patients with chronic constipation. There are two major types of colonic volvulus depending on its anatomic location, which can involve the cecum or the sigmoid colon. Regardless of the type, timely diagnosis and treatment is very important to prevent necrosis and perforation of the involved bowel segment.

When assessing patients with a chief concern suggesting colonic volvulus, your first step is to perform an ABCDE assessment to determine if the patient is stable or unstable. If the patient is unstable, begin acute management immediately to stabilize the airway, breathing, and circulation. This means that you might need to intubate the patient, obtain IV access, administer fluids, and monitor vital signs. Additionally, keep the patient NPO and place a nasogastric tube for small bowel decompression. Next, quickly obtain a focused history and physical examination, and order labs such as CBC, CMP, and lactate, as well as an abdominal x-ray.

Okay, let’s discuss what you might find on history and physical examination. The history will typically reveal an acute onset of crampy abdominal pain, obstipation or constipation, and bloating. As the passage through the colon is blocked, the content of the intestine will start backing up. So over time, patients might develop nausea and vomiting as well. Be sure to ask about any previous episodes of colonic volvulus and what treatment they received at that time.

On physical exam, you might find altered mental status, tachycardia, and hypotension, which are signs of septic shock. Additionally, you can expect to see a distended tympanic abdomen with diffuse rebound tenderness with guarding. Finally, you should perform a digital rectal exam to rule out an obstructing rectal mass.

Now, let's talk about the lab results. You might see leukocytosis on CBC, electrolyte imbalances on CMP, and an elevated lactate level indicating metabolic acidosis.

Alright, abdominal x-ray findings depend if you’re dealing with cecal or sigmoid volvulus. As the bowel segment twists around its mesentery, it actually moves to a different area of the abdomen. So, cecal volvulus will be seen as a closed loop of bowel usually in the left upper quadrant. Since the blockage is at the very start of the large bowel, the small bowel might become distended, while distal areas of the large bowel are decompressed. Finally, there is only one air-fluid level.

On the flip side, sigmoid volvulus appears as a coffee bean sign. This is when the twisted bowel segment resembles a coffee bean on imaging. It is typically found in the right upper quadrant. Since the blockage is at the end of the large bowel, proximal areas of the large bowel might be distended, while the rectum appears decompressed. There might also be multiple air-fluid levels.

In both cases, you may possibly see pneumoperitoneum, or air under the diaphragm indicating bowel perforation. If you see these findings, you should suspect colonic volvulus with peritonitis from bowel ischemia, necrosis or perforation, which are all surgical emergencies.

Here’s a high-yield fact! Coffee bean sign is known by many other names including the omega sign, bent inner tube sign, inverted U sign, or kidney bean sign. So, don’t be confused if you hear any of these.

Alright, the next step is to immediately begin supportive care and obtain surgical consultation for an emergent laparotomy. Supportive care includes IV fluid resuscitation and consider vasopressor support if necessary, as well as electrolyte replacement, broad-spectrum IV antibiotics, and bowel rest. Exploratory laparotomy in this case is both diagnostic and therapeutic, so nothing should delay patients from going to the operating room.

Okay, now that unstable patients are treated, let's go back and talk about stable patients. Your first step in evaluating a stable patient is to obtain a focused history and physical exam, as well as labs like CBC, CMP, and lactate.

Stable patients typically report abdominal pain, bloating, obstipation or constipation, and sometimes nausea and vomiting. Patients might also report history of chronic constipation, as well as previous episodes of volvulus. Keep in mind that a lot of these patients are elderly, so some of them might not be able to provide history due to other concomitant conditions like dementia.

On physical exam, you can expect to find a distended and tympanic abdomen that is tender on palpation. Sometimes, you might hear hyperactive bowel sounds. As before, you should perform a digital rectal exam to rule out an obstructing rectal mass. Finally, labs might demonstrate leukocytosis, electrolyte imbalances, and elevated lactate causing metabolic acidosis. Based on these findings, you should suspect large bowel obstruction likely from colonic volvulus.