Diverticula with wall thickening and fat stranding
No abscess or free air
Complicated
Abscess
Extraluminal air or contrast
Sepsis risk stratification adjunct
qSOFA elements
RR >= 22/min
Altered mental status
qSOFA limitations
Not a diagnostic test
Not a replacement for clinical judgment
MRI
MRI considerations
Pregnancy and radiation avoidance
MRI abdomen and pelvis without gadolinium as alternative
Gadolinium avoidance unless essential
Diagnostic performance
Useful when CT contraindicated
Limited availability and longer acquisition time
Practical limitations
Motion artifact with severe pain
Access delays in unstable patients
CT
CT abdomen and pelvis with IV contrast
Indications
First episode with significant tenderness
Concern for complicated disease
Key CT findings
Colonic wall thickening
Pericolic fat stranding
Complication findings
Abscess
Extraluminal free air
Contrast considerations
IV contrast improves abscess and complication detection
Oral contrast not required in most ED pathways
CT performance characteristics
Diagnostic accuracy
High sensitivity for acute diverticulitis
High specificity for acute diverticulitis
Pitfalls
Early disease with minimal stranding
Colitis overlap in diffuse inflammatory changes
Ultrasound
Ultrasound role
Point-of-care adjunct
Localized bowel wall thickening
Pericolic hyperechoic fat
Abscess screening
Superficial or pelvic collections sometimes detectable
Limited for deep retroperitoneal collections
Limitations
Operator dependence
Reduced sensitivity with obesity or bowel gas
Disposition
Level of care decisions
Discharge pathway candidates
Uncomplicated disease on imaging or high-confidence clinical recurrence
No abscess or perforation features
No obstruction
Clinical stability
Normal or improving vitals
No sepsis physiology
Functional stability
Tolerating oral fluids
Pain controlled with oral medications
Admission indications
Complicated diverticulitis
Abscess
Perforation or peritonitis
High-risk host factors
Immunocompromised state
Frailty or limited supports
Treatment failure
Persistent vomiting
Worsening pain or fever despite ED therapy
ICU or monitored setting triggers
Septic shock physiology
Vasopressor requirement
Rising lactate despite resuscitation
Severe comorbidity decompensation
Acute kidney injury with instability
Respiratory failure
Follow-up planning
Post-episode evaluation
Colonoscopy consideration after resolution
No colonoscopy within recommended screening interval
Complicated diverticulitis episode
Surgical follow-up consideration
Recurrent episodes impacting quality of life
Persistent symptoms after resolution
Treatment
Supportive care
Symptom control bundle
Analgesia strategy
Acetaminophen PO 650-1000 mg every 6-8 hours
NSAID avoidance consideration if bleeding or renal risk
Antiemetic options
Ondansetron ODT 4-8 mg every 8 hours as needed
Metoclopramide PO or IV 10 mg every 6-8 hours as needed
Hydration
Oral rehydration for mild cases
IV crystalloid for dehydration or inability to tolerate PO
Diet progression
Clear liquids initially if nausea or significant pain
Advance as tolerated within 24-48 hours
No requirement for prolonged bowel rest in mild uncomplicated cases
NPO status triggers
Peritonitis
Severe vomiting or ileus
Antibiotics
Antibiotic decision framework
Uncomplicated diverticulitis
Selective antibiotics in immunocompetent mild disease
Antibiotics favored if systemic signs or significant comorbidity
Complicated diverticulitis
IV antibiotics for abscess, perforation, obstruction, fistula
Source control planning with surgery or IR
Outpatient oral regimens
Amoxicillin-clavulanate PO
875 mg amoxicillin with 125 mg clavulanate every 12 hours
Typical duration 4-7 days when used
Ciprofloxacin plus metronidazole PO
Ciprofloxacin 500 mg every 12 hours
Metronidazole 500 mg every 8-12 hours
TMP-SMX plus metronidazole PO
TMP-SMX DS 1 tablet every 12 hours
Metronidazole 500 mg every 8-12 hours
Inpatient IV regimens
Ceftriaxone plus metronidazole IV
Ceftriaxone 2 g every 24 hours
Metronidazole 500 mg every 8 hours
Piperacillin-tazobactam IV monotherapy
4.5 g every 6-8 hours
Renal dose adjustment for reduced eGFR
Ertapenem IV monotherapy
1 g every 24 hours
Useful for once-daily dosing pathways
Severe sepsis or resistant organism risk
Meropenem IV
1 g every 8 hours
Renal dose adjustment required
Add MRSA coverage only if specific risk
Prior MRSA colonization or infection
Healthcare-associated infection context
Procedures and source control
Abscess management
Small abscess approach
Antibiotics alone for selected small collections
Close reassessment and repeat imaging if worsening
Larger abscess approach
If abscess >= 3 cm, IR drainage consideration
Culture-directed antibiotic adjustment
Perforation and peritonitis
If generalized peritonitis, emergent operative management pathway
Broad-spectrum IV antibiotics
Hemodynamic resuscitation and vasopressors if needed
Obstruction or fistula
Surgical evaluation
Partial obstruction with significant symptoms
Colovesical or colovaginal fistula suspicion
Special Populations
Pregnancy
Pregnancy-specific considerations
Diagnostic approach
Ultrasound or MRI preference when feasible
CT use if benefits outweigh risks in severe disease
Antibiotic selection
Avoid fluoroquinolones
Beta-lactam based regimens preferred
Obstetric collaboration triggers
Viable gestation with systemic illness
Preterm labor symptoms
Geriatric
Older adult considerations
Presentation differences
Less fever and leukocytosis
Higher baseline constipation and atypical pain
Higher complication risk
Lower threshold for CT imaging
Lower threshold for admission
Medication safety
Opioid sparing strategy
Renal dosing for antibiotics
Pediatrics
Pediatric considerations
Epidemiology
Rare diagnosis
Consider alternative etiologies first
Imaging approach
Ultrasound first strategy when possible
CT reserved for unclear or severe cases
Antibiotic dosing
Weight-based dosing per local pediatric references
Early pediatric surgery involvement if complicated
Background
Epidemiology
Epidemiologic features
Prevalence
Diverticulosis prevalence increases with age
Only a minority develop diverticulitis
Recurrence
Recurrent episodes possible after first event
Complicated recurrence less common after uncomplicated course
Burden of illness
Common cause of acute left lower quadrant pain in adults
Significant healthcare utilization for imaging and admissions
Pathophysiology
Disease mechanism
Diverticular microperforation
Localized inflammation in pericolic fat
Phlegmon formation
Progression pathways
Abscess formation
Free perforation with peritonitis
Fistula formation
Colovesical fistula
Colovaginal fistula
Therapeutic Considerations
Antibiotic rationale
Uncomplicated disease
Inflammation-driven syndrome in many cases
Selective antibiotics supported by modern guideline trends
Complicated disease
Polymicrobial coverage targeting gram-negative and anaerobes
Source control as primary determinant of outcomes
Procedural rationale
Abscess drainage
Improved clinical resolution with drainage when appropriate
Culture data supports narrowing therapy
Surgery
Indicated for generalized peritonitis
Indicated for refractory obstruction or fistula complications
Evidence framing
Selective antibiotics in mild uncomplicated immunocompetent patients
Class IIa recommendation based on guideline consensus
Shared decision-making emphasized
CT imaging as preferred modality for first or complicated presentations
ACEP Level C style evidence label for ED diagnostic strategy pragmatics
High diagnostic accuracy supports complication detection
Patient Discharge Instructions
Copy discharge instructions
Discharge instructions packet
Diagnosis explanation
Diverticulitis as inflammation of colon outpouchings
Uncomplicated versus complicated explanation if applicable
Home care
Clear liquids for 24 hours if nauseated
Advance diet as pain improves
Medications
Take prescribed antibiotics exactly as directed if given
Acetaminophen as first-line pain control
Return to ED now
Worsening abdominal pain
Persistent vomiting or inability to keep fluids down
Return to ED now
Fever or chills after initial improvement
Fainting, severe weakness, or confusion
Return to ED now
New blood in stool or black stools
New shortness of breath or chest pain
Follow-up
Primary care visit within 48-72 hours if not improving
Colonoscopy discussion after recovery if not up to date
References
Guidelines and key sources
Guideline sources
American Gastroenterological Association clinical practice updates on diverticulitis management
Selective antibiotics in uncomplicated disease
Colonoscopy timing after an episode
American Society of Colon and Rectal Surgeons guidelines on left-sided diverticulitis
Complicated diverticulitis pathways
Elective surgery decision-making
World Society of Emergency Surgery guidelines on acute colonic diverticulitis
CT-based classification
Abscess drainage thresholds
Evidence sources
Randomized trials and meta-analyses on antibiotics versus no antibiotics in uncomplicated diverticulitis
Similar complication rates in selected patients
Emphasis on patient selection and follow-up
Diagnostic accuracy studies of CT for acute diverticulitis
High sensitivity and specificity reported across studies
Strong performance for abscess and perforation detection
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.