Pathophysiology
A volvulus occurs in parts of the bowel that have mesentery. The mesentery is the membranous peritoneal tissue allowing connections between the bowel and the anterior/posterior abdominal wall. This allows blood vessels to pass to the intestines by coursing through the mesentery. Once the mesentery weakens and the bowel twists around it then we get a volvulus which leads to a closed loop bowel obstruction and ischaemia → necrosis of the bowel & perforation.
There are 2 main types of volvulus:
- Sigmoid volvulus (80%) - most common as the mesentery of the sigmoid colon is longest and the sigmoid colon is more likely to twist on this segment of the bowel.
- Caecal volvulus (20%) - less common and affects younger patients more. In 80% of the population the caecum is retroperitoneal and is not at risk of twisting.
⚠️ Risk factors
Sigmoid volvulus associations
- Increasing age
- Chronic constipation
- Chagas disease
- Psychiatric and neurological conditions
- Delirium/dementia
Caecal volvulus associations
- Adhesions
- Pregnancy
- Any age group
😷 Presentation
Similar features to bowel obstruction.
As the sigmoid colon is very distant, vomiting (particularly bilious, green vomit) is usually quite a late sign.
- Colicky pain
- Abdominal distension - quite rapid in onset and progression compared to other causes of obstruction.
- Absolute constipation + lack of flatulence
On examination:
- Tympanic percussion
💭 Differential diagnosis
- Severe constipation
- Severe sigmoid diverticulitis
- Bowel obstruction
- Pseudo-obstruction - TFTs should be done to rule this out (for cases of hypothyroidism).
🔍 Investigations
🥇 CT abdomen-pelvis with contrast is the first investigation. It aids identification of the site and cause. We can see a whirl sign in the sigmoid colon.
A AXR may be done showing the coffee-bean sign in the LIF (for sigmoid volvulus). If there is an incompetent ileocaecal valve then the small bowel may be dilated. A caecal volvulus may show as distension from the RIF → left hypochondrium or epigastric regions.
🧰 Management
The initial management is that of any patient with bowel obstruction but we should asses ischaemia and give fluid resuscitation.
- 🏆 Sigmoidoscope + flatus tube - decompresses bowel. Patient is in the left lateral position for this procedure. The flatus tube is left in-situ for up to 24 hours.
- Supportive measures
- IV fluids
- Urinary catheter
- Broad-spectrum antibiotics - if there are any signs of sepsis
- Analgesia
- Anti-emetics if needed
💡 If the aetiology is adhesions due to a previous surgery, these will be treated conservatively too.
- Stenting of descending colon is also an option.
- Fluoroscopy should be performed if it doesn’t resolve within 24 hours and if the contrast does not reach the colon within 6 hours then the patient needs surgical management.
- Often the procedure is a laparotomy with Hartmann’s procedure.
- If resectioning is required, then a stoma will be needed.
Surgery is indicated if there is:
- Ischaemia
- Continuous failed attempts at decompression
- Necrotic bowel on endoscopy
🚨 Complications
- Bowel ischaemia and perforation
- Recurrence
- Mortality from surgery is high as patients are generally old and frail