Diverticula are outpouchings in the wall of the bowel and may manifest in several ways.
Terms
- Diverticulum (pl. diverticula): Outpouching in the bowel wall.
- Diverticulosis: Diverticula are present but do not cause symptoms.
- Diverticular disease: Diverticula are symptomatic.
- Diverticulitis: Diverticula are inflamed.
Epidemiology
Diverticulosis is most common in the Western world and tends to affect individuals of older age, usually over the age of 50.[i]
Pathophysiology
- A diverticulum is an outpouching of the bowel wall. The vasa recta are arteries which supply the intestines.
- The point at which these vessels penetrate through the colon can form as a point of weakness.
- Thus, layers of the bowel may herniate through this weakness, forming a diverticulum. Due to the close proximity to the vasa recta, diverticula may bleed.
- One potential theory describing the pathogenesis is abnormal colonic motility. It is thought abnormal motility of the colon can result in high intraluminal pressures which can force parts of the intestinal wall to herniate through the weakened parts of the wall (where the vasa recta penetrate).[ii]
- False diverticula are far more common and involve the herniation of the mucosa and submucosa through the muscularis of the bowel.
- True diverticula are uncommon and will involve the mucosa, submucosa, muscularis and serosa (i.e. all the layers of the bowel wall).
- Diverticula are most commonly found in the sigmoid colon though it is possible to find them elsewhere.
Diverticulitis is inflammation of these outpouchings and is thought to occur due to obstruction of a diverticulum by faeces or a faecolith (basically a stone of faeces). This leads to stagnation within the diverticulum, thus allowing bacterial proliferation and subsequent inflammation. It is possible for inflamed diverticula to perforate.
Clinical Features
Diverticulosis
Diverticular Disease
- Bloating
- Flatulence
- Altered bowel habits
- Rectal bleeding
- Lower abdominal pain (typically left iliac fossa pain)
Diverticulitis
- Same for diverticular disease but patients appear generally unwell
- Pyrexia
- Guarding/rigidity on examination
- Nausea/vomiting
- Left iliac fossa pain
- There may also be a palpable mass in the lower left quadrant on examination of the abdomen
Investigations
Diverticulosis is usually an incidental finding on colonoscopy. If patients are symptomatic they have diverticular disease.
If we’re trying to judge the difference between diverticular disease and diverticulitis, the following investigations can be helpful in the acute setting:
Bloods
- FBC, U&E, LFT, Bone Profile: As a baseline + infection markers and haemoglobin in the FBC
- CRP: Inflammation
- VBG: Baseline + lactate level in case of perforation/peritonitis
Imaging
- Chest X-ray +/- Abdominal X-ray: Looking for pneumoperitoneum as evidence of perforation
- CT abdomen and pelvis with contrast: Can identify diverticulitis as well as any complications such as abscess formation.
Endoscopy is not performed in the acute setting due to a risk of perforation, but can be organised in the outpatient setting.
Management
Diverticular Disease
- NICE guidance states individuals with diverticular disease can be advised to follow a high-fibre diet and good fluid intake.
- Bulk-forming laxatives can also be offered if patients have constipation or they cannot tolerate a high-fibre diet.
- Analgesia: NSAIDs and opiates are avoided as they may increase risk of perforation
- Antispasmodics for patients with cramping pain
- Patients with significant rectal bleeding/haemodynamic instability should receive emergency referral to secondary care as they may require a blood transfusion.
Acute Diverticulitis
Depending on the severity of the disease, it may be possible to manage patients in primary care/as an outpatient. However, if patients are unwell, they'll likely require admission.
General Considerations
- Fluids
- Blood transfusion if significant bleed
- Analgesia
Antibiotics
- Systemically well: Can consider not prescribing antibiotics
- Systemically unwell: Oral antibiotics based on how unwell they are.
- First line: Co-amoxiclav, or cefalexin + metronidazole/trimethoprim + metronidazole if penicillin allergic
- Complicated diverticulitis: IV antibiotics
Surgery
- Surgery in uncomplicated cases usually is not needed but complications such as peritonitis may require surgery.[iii] There may also be indication for bowel resection e.g. where there is significant bleeding.
- A Hartmann’s procedure is a common emergency procedure used in the management of severe acute diverticulitis. It involves removal of the sigmoid colon with the formation of an end colostomy. It may be possible to then do a reversal of the colostomy i.e. joining the colostomy back to the rectal stump at a later date.
Complications
- Fistula formation: Can occur between the bladder or the vagina. Patients may present with faecaluria,or notice faeces coming from the vagina.
- Abscess: Can be drained via CT-guided percutaneous drainage.
- Perforation: Perforation of the diverticulum can lead to peritonitis.
- Bleeding: Due to proximity of vasa recta. This can be quite substantial, and patients may require resuscitation.
- Bowel Obstruction: Secondary to the formation of a diverticular stricture – these can form due to repeated episodes of diverticulitis resulting in scarring and a stricture.
References
[i] https://www.ncbi.nlm.nih.gov/books/NBK430771/
[ii] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5832336/
[iii] Oxford Handbook of Clinical Medicine
[iv] https://www.nice.org.uk/guidance/ng147/chapter/Recommendations#diverticulosis
