Synopsis
Distinguish incidental diverticulosis, symptomatic diverticular disease and acute diverticulitis, identify complicated infection early, and choose conservative, antimicrobial, radiological or surgical care proportionately.
- Diverticulosis means the presence of diverticula, diverticular disease means attributable chronic symptoms, and diverticulitis is acute inflammation that may be uncomplicated or complicated.
- Typical acute diverticulitis produces constant left lower-quadrant pain and tenderness with fever or raised inflammatory markers, but right-sided disease and atypical presentations occur.
- Peritonitis, abscess, fistula, obstruction, perforation or sepsis defines complicated disease and changes the setting, imaging urgency and treatment.
- For a systemically well person with uncomplicated acute diverticulitis, NICE supports considering no antibiotics, simple analgesia and clear re-presentation advice.
- Use antibiotics when the person is systemically unwell, immunosuppressed or significantly comorbid, following current local choices, allergies, renal function and resistance policy.
- Contrast CT within twenty-four hours of admission is recommended when complicated diverticulitis is suspected and inflammatory markers are raised; it maps abscess and alternative diagnoses.
- A CT-confirmed abscess larger than 3 cm prompts consideration of percutaneous drainage if feasible or surgery; deterioration warrants re-imaging and source-control review.
- After recovery, do not promise that seeds, nuts or popcorn must be avoided. Encourage a healthy balanced fibre-containing diet once the acute episode settles, adjusted for tolerance.
Key red flags
Persistent fever, focal mass, sepsis, failure to improve or CT fluid collection and extraluminal gas suggests a complication requiring hospital antibiotics and radiological or surgical source-control planning.
Sudden diffuse pain, involuntary guarding or rigidity, shock and free intraperitoneal contamination indicate a surgical emergency. Analgesia and imaging should not delay resuscitation and senior colorectal review.
Pneumaturia, faecaluria or recurrent unusual urinary infection suggests colovesical fistula, while progressive distension, vomiting and obstipation raises an inflammatory or malignant stricture.
Anaemia, mass, progressive bowel change, weight loss or an irregular shouldered stenosing lesion must not be assumed to be diverticular. Apply cancer pathways and obtain tissue or interval evaluation appropriately.
Investigation priorities
Detect physiological deterioration, dehydration and organ dysfunction that determines admission and urgency.
Management branches
Focal symptoms suggest acute diverticulitis but the person is systemically well with no complication signal.
- Check observations, hydration, peritonism, oral intake, immune status and comorbidity, considering urinary, gynaecological and malignant alternatives.
- Offer simple analgesia, consider a no-antibiotic strategy and give practical oral fluid and short-term diet advice without imposing prolonged restriction.
- Provide explicit same-day escalation triggers including worsening pain, fever, vomiting, inability to drink, distension, bleeding or new systemic symptoms.
- Arrange timely review and reconsider examination, bloods or imaging if improvement does not follow the expected course.