Volvulus refers to the rotation of a portion of the gastrointestinal tract on its own mesentery leading to issues such as obstruction, ischaemia and perforation.
In this document we will cover volvulus as well as intestinal malrotation in children
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. The mesentery 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.
The twisting effect also compromises the blood flow as the vessels that travel through the mesentery are twisted. This leads to ischaemia and subsequent necrosis of the bowel if not managed in time.
The increase in pressure that occurs due to the obstruction, coupled with inflammation and ischaemia may then lead to perforation of the bowel.
🔢 Classification
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
🔍 Investigations
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
Intestinal malroation is a spectrum of disorders that occur during the development of the embryo. Intestinal malrotation is a risk factor for a volvulus (especially a midgut volvulus).
🥚 Embryology
Around week 3, the gut begins to form from the endoderm layer. It initially starts off as a straight tube from the stomach to rectum. Around week 4 it begins to elongate and it forms a U-shaped loop which then rotates 90º counterclockwise at around week 5-6. It then undergoes a physiological herniation into the umbilical cord temporarily. When in the umbilical cord, it rotates another 90º counterclockwise. With this subsequent rotation. The caecum and ascending colon end up on the right-hand side and the transverse colon is on the left-hand side.
Around week 10, the midgut begins to return into the abdominal cavity while simultaneously folding on itself to create bowel loops. It undergoes a further rotation counterclockwise. The mesentery also fuses with the posterior abdominal wall
Pathophysiology
When there are abnormalities with this counterclockwise rotation (either it fails to occur or is incomplete) the intestines become abnormally positioned in the abdominal cavity. If there is inadequate rotation, this leads to inadequate fixation ultimately which may lead to increased mobility of the intestines within the abdominal cavity.
Defects in the mesentery may also be associated with malrotation which once again increases risk of bowel hypermobility. If the bowels are too mobile it poses a risk of a volvulus formation.
Ladd’s bands may also be present in cases of incomplete rotation. They are fibrous connective tissue bands that extend from the caecum → retroperitoneum. They can compress and obstruct the intestines (particularly the duodenum). They also anchor the bowl at anomalous locations which may promote mobility and increase the risk of volvulus once again.
There are 2 common rotational abnormalities that may present:
- Complete non-rotation - in this case the small bowel is on the right and the large bowel on the right. There may be a narrow base of the mesentery as a result. This poses a high risk for a midgut volvulus.
- Incomplete rotation - in this instance some rotation has occurred and the caecum is in the mid-upper abdomen and is fixed with Ladd’s bands which may obstruct the duodenum as they cross it. It can also result in w as well as hernias.
If there is nonrotation of the bowel loops, the the duodenum will be on the right-hand side and the colon on the left-hand side. The fixation points may be quite narrow and provide a pivot point on which the bowel begins to twist around. The superior mesenteric artery (SMA) lies in between these two fixation points, running through the mesentery. As the bowel twists, it then leads to compression of the SMA → ischaemia and necrosis.
🔍 Investigations
- 🏆 Upper GI contrast series - provides visualisation of the small intestines, and information on the relationship between the small bowel and caecum. It will show a corkscrew duodenum.
- Abdominal X-rays - may show distended small bowel loops and stomach.
- Bloods - these may be used to identify ischaemia and necrosis with a raised WCC (if it has been happening for a while).
🧰 Management
- Ladd procedure - this is a laparotomy + detorsion of the volvulus. It may be done electively or in as an emergency procedure.
- Known intestinal malrotation → elective procedure.
- Midgut volvulus → emergency procedure.
The procedure involves untwisting and repositioning the bowel (such that it does not twist again). Ladd’s bands are removed and the appendix may also be removed. If there is any necrotic bowel it will be resected and anastomosed or a stoma will be constructed.
💡 Post-operative adhesions may be beneficial after midgut volvulus as they prevent recurrence of the issue.
