01Approach to the Critical Patient/attcp48

Immediate priorities

›Life-threatening presentations

›Generalized peritonitis

›Diffuse abdominal rigidity

›Septic shock physiology

›Perforated viscus concern

›Free air on imaging

›Acute surgical abdomen

›Septic shock

›SBP < 90 mmHg

›MAP < 65 mmHg

›Lactate >= 2 mmol/l

›Resuscitation steps

›Large bore IV access bilaterally

›Fluid resuscitation 30 ml/kg crystalloid if shock

›Reassess after initial bolus

›Nil by mouth immediately

›Surgical preparation

›Aspiration risk reduction

›Blood cultures before antibiotics when septic

›Two sets peripheral

›Within 45 minutes of recognition

Escalation triggers

›Surgical consultation triggers

›Generalized peritonitis

›Emergent surgical evaluation mandatory

›Operating room preparation

›Failed non-operative management

02History/hx67

Presentation pattern

›Core symptoms

›Left lower quadrant pain

›Gradual onset typical

›Localized to sigmoid region

›Fever

›Low grade to high grade

›Rigors in complicated disease

›Altered bowel habits

›Constipation or diarrhea

›Tenesmus

›Associated symptoms

›Nausea and vomiting

›Frequency and duration

›Inability to tolerate oral intake

›Urinary symptoms

›Colovesical fistula clue

›Pneumaturia or fecaluria

›Vaginal symptoms in women

›Colovaginal fistula concern

›Discharge character

Risk factors

›Demographic and lifestyle factors

›Age > 65 years

›Diverticulosis prevalence increases with age

›> 60% prevalence over age 60

›Obesity

›BMI >= 30 as independent risk factor

03Physical Exam/exam44

Vitals and general

›Stability assessment

›Temperature

›>= 38.5 C as significant fever

›Absence of fever does not exclude complicated disease

›Heart rate

›Tachycardia as severity marker

›Persistent tachycardia despite analgesia concerning

›Blood pressure

›SBP < 90 mmHg as shock threshold

›Orthostatic hypotension in volume depleted patients

›Respiratory rate

›Elevation with peritonitis

›Diaphragmatic splinting

Abdominal exam

›Tenderness localization

›Left lower quadrant point tenderness

›Maximum tenderness over sigmoid colon

›Absent in right-sided diverticulitis

›Peritoneal signs

›Rebound tenderness

›Guarding and rigidity

›Murphy sign

›Absent in typical diverticulitis

›Positive suggests cholecystitis mimic

›Palpable mass

›Phlegmon

›Tender ill-defined induration

04Differential Diagnosis/ddx37

Life threats and urgent mimics

›Immediate threats

›Colonic perforation with peritonitis

›ICD-10 K57.20 or K57.80

›Surgical emergency

›Colorectal carcinoma

›ICD-10 C18.7 sigmoid

›Colonoscopy required after acute episode

›Mesenteric ischemia

›ICD-10 K55.0

›Elevated lactate, out of proportion pain

›Common mimics

›Appendicitis

›ICD-10 K37

›Right lower quadrant pain, younger patients

›Irritable bowel syndrome

›ICD-10 K58.9

›No fever or leukocytosis

›Infectious colitis

›ICD-10 A09

›Diarrhea predominant, diffuse cramping

Gynaecologic and urologic differentials

›Gynaecologic

›Ovarian cyst or torsion

›ICD-10 N83.2 or N83.5

›Pelvic ultrasound for exclusion

›Pelvic inflammatory disease

›ICD-10 N73.9

05Laboratory Tests/lt43

Core infection labs

›Complete blood count

›Leukocytosis typical

›WBC > 15 x 10^9/L high-risk feature

›Left shift with bands in complicated disease

›Normocytic anaemia

›Chronic inflammation

›Occult bleeding from malignancy

›Inflammatory markers

›C-reactive protein

›CRP > 140 mg/L high-risk feature for complicated disease

›Useful for risk stratification when CT not immediately available

›Erythrocyte sedimentation rate

›Elevated but nonspecific

›Less useful in acute setting than CRP

Metabolic and organ function

›Basic metabolic panel

›Electrolytes

›Sodium and potassium for IV fluid management

›Dehydration and vomiting effects

›Renal function

›Creatinine for antibiotic dosing

›Contrast CT dosing threshold

›Glucose

›Diabetes management

›Stress hyperglycaemia

›Liver function tests

›Alkaline phosphatase elevation

06Diagnostic Tests/dt74

Scoring Systems

›Hinchey classification for complicated diverticulitis

›Stage I

›Pericolic or mesenteric abscess

›Non-operative management typical

›Stage II

›Pelvic, retroperitoneal, or distant abscess

›Percutaneous drainage often feasible

›Stage III

›Generalised purulent peritonitis

›Surgery usually required

›Stage IV

›Generalised faecal peritonitis

›Emergent surgery mandatory

›ACEP and AGA risk stratification criteria

›High-risk features for complicated disease

›CRP > 140 mg/L

›WBC > 15 x 10^9/L

›Symptoms > 5 days

›Immunocompromise

›Low-risk uncomplicated criteria

›First episode, no comorbidities

›CRP < 140 mg/L, tolerating oral intake

›Outpatient treatment may be appropriate

MRI

›MRI abdomen and pelvis role

›Preferred in pregnancy

›No ionising radiation

07Disposition/dispo44

Admission indications

›Inpatient admission required

›High fever > 38.5 C with systemic toxicity

›Rigors

›Unable to tolerate oral intake

›Leukocytosis with complicated imaging findings

›Abscess

›Free air or free fluid

›Immunocompromise

›Chemotherapy recipients

›Transplant patients

›High-dose corticosteroids

›Failed outpatient management

›No improvement after 48 to 72 hours of oral antibiotics

›Worsening symptoms on oral therapy

›ICU admission indications

›Septic shock

›Vasopressor requirement

›Lactate > 4 mmol/l despite resuscitation

›Post-operative monitoring

›Emergency colonic resection

›Hartmann procedure

Discharge criteria

›Outpatient criteria for uncomplicated diverticulitis

›First episode in immunocompetent patient

›No comorbidities

›Reliable follow-up

›Tolerating oral intake

08Treatment/t93

Supportive care

›Immediate supportive measures

›Nil by mouth or clear liquids

›Clear liquid diet 1 to 2 days in uncomplicated disease

›NPO when surgery or drainage likely

›Analgesia

›Paracetamol (acetaminophen) 1 g IV or PO every 6 hours

›First-line analgesic for uncomplicated diverticulitis

›JAMA 2025 recommendation

›Avoid NSAIDs

›Increase risk of complicated diverticulitis

›Impair healing

›IV fluid resuscitation

›Normal saline or lactated Ringer's

›Rate guided by clinical response

Antibiotic therapy - uncomplicated

›Selective antibiotic use strategy

›Antibiotics NOT routine for all uncomplicated cases

›Observation with pain management supported by AGA 2021 and ACP 2022 guidelines

›Class I recommendation for selective antibiotic use

›Antibiotics indicated for uncomplicated disease when

›Persistent fever or systemic symptoms

›Temperature > 38.5 C not resolving

›Rigors present

›Age > 80 years

›Pregnancy

›Immunocompromise

›Chemotherapy, high-dose steroids, organ transplant

›Chronic medical comorbidities

›Cirrhosis, chronic kidney disease, heart failure, poorly controlled diabetes

›High-risk CRP or WBC

›CRP > 140 mg/L

›WBC > 15 x 10^9/L

›Oral antibiotic regimens for outpatient uncomplicated disease

›Amoxicillin-clavulanate PO

›875 mg PO twice daily

›Duration 7 to 10 days

›First-line oral option (JAMA 2025)

›Ciprofloxacin plus metronidazole PO

›Ciprofloxacin 500 mg PO twice daily

›Combined with metronidazole 500 mg PO three times daily

›Duration 7 to 10 days

›Alternative when amoxicillin-clavulanate not tolerated

›Cephalexin plus metronidazole PO

›Cephalexin 500 mg PO four times daily

›Combined with metronidazole 500 mg PO three times daily

›Duration 7 to 10 days

Antibiotic therapy - complicated

›IV antibiotic regimens for complicated or inpatient disease

›Ceftriaxone plus metronidazole IV

›Ceftriaxone 2 g IV every 24 hours

›Duration guided by clinical response

›Step down to oral when tolerating

›Metronidazole 500 mg IV every 8 hours

›Anaerobic coverage

›Oral equivalent when tolerating

›Piperacillin-tazobactam IV

›4.5 g IV every 6 to 8 hours

›Broad spectrum single agent option

›Preferred when resistant organisms suspected

›Extended infusion 4.5 g IV over 4 hours every 8 hours per local protocol

›Ampicillin-sulbactam IV

›3 g IV every 6 hours

›Renal dose adjustment when eGFR impaired

›Alternative single agent option

›Ertapenem IV

›1 g IV every 24 hours

›For polymicrobial or ESBL concern

›Renal dose adjustment required

Interventional and surgical management

›Percutaneous drainage

›Abscess >= 3 to 5 cm

›CT or ultrasound guided drainage

›Reduces need for emergency surgery

›Bridge to elective resection

›Repeat CT at 48 to 72 hours to assess response

›Smaller abscesses < 3 cm

›May resolve with antibiotics alone

›Close monitoring mandatory

›Emergency surgery

›Indications

›Generalised peritonitis (Hinchey III or IV)

›Mortality 0.5% elective vs 10.6% emergent resection

›JAMA 2025 data

›Failed percutaneous drainage

›Haemodynamic instability from perforation

›Surgical options

›Hartmann procedure

›Sigmoid resection with end colostomy

›Reversal in 6 to 12 months

›Primary anastomosis with diverting ileostomy

›Selected cases in stable patients

›Surgeon and patient dependent

›Elective resection

›After recurrent complicated episodes

›Individualised risk-benefit discussion

›Laparoscopic sigmoid colectomy preferred

09Special Populations/sp70

Pregnancy

›Pregnancy-specific considerations

›Incidence and timing

›Right-sided diverticulitis more common in pregnancy

›Diagnosis delayed due to displaced anatomy

›Imaging approach

›Ultrasound first-line

›No radiation risk

›Adequate sensitivity when experienced sonographer

›MRI second-line

›No ionising radiation

›Preferred over CT when ultrasound inconclusive

›CT reserved for surgical emergencies

›Radiation risk discussed with patient

›Fetal shielding when feasible

›Antibiotic selection

›Amoxicillin-clavulanate PO generally safe

›Category B/compatible in most trimesters

›Review with obstetrics

›Metronidazole

›Use cautiously in first trimester

›Generally considered acceptable in second and third trimesters

›Avoid ciprofloxacin

›Fluoroquinolone cartilage risk

›Use only when no alternative

›Obstetric co-management

›Fetal monitoring when viable gestation

›Preterm labour risk with intra-abdominal sepsis

10Background/b64

Epidemiology

›Incidence and burden

›Approximately 180 per 100,000 persons per year in the US

›Approximately 200,000 hospitalisations annually in the US

›JAMA 2025 data

›Prevalence increases with age

›> 60% of people over age 60 have diverticulosis

›Only 4% of those with diverticulosis develop diverticulitis per lifetime

›Uncomplicated vs complicated distribution

›Approximately 85% uncomplicated (localised inflammation without abscess, perforation, fistula, or obstruction)

›12 to 15% complicated at presentation

›Geographic and demographic patterns

›More common in Western countries

›Low fibre diet contribution

›Sedentary lifestyle association

›Male predominance under age 50

›Female predominance over age 50

›Postmenopausal hormonal factors implicated

Pathophysiology

›Diverticula formation

›Pulsion diverticula

›False diverticula involving mucosa and submucosa

›Herniation through colonic wall at vasa recta points

›Elevated intraluminal pressure

›Low fibre diet reduces stool bulk

›Segmental colonic hypercontractility

›Predominant location

›Sigmoid colon in Western populations

11Patient Discharge Instructions/pdi31

copy discharge instructions

›Diverticulitis home care

›Clear liquid diet for first 1 to 2 days

›Water, broth, clear juice

›Advance to low-fibre soft diet as tolerated

›Medications as prescribed

›Take antibiotics for the full course even if feeling better

›Avoid NSAIDs including ibuprofen and naproxen

›Rest

›Light activity as tolerated

›Avoid strenuous exertion until cleared

›Warning signs to return to ER

›Sudden severe worsening abdominal pain

›Rigid or board-like abdomen

›High fever > 38.5 C not improving

›Vomiting and unable to keep fluids down

›Chills or shaking

›Blood in stool or rectal bleeding

›Confusion or feeling very unwell

›Passing gas or stool through urine or vagina

›Follow-up instructions

›Colonoscopy appointment in 6 to 8 weeks

›To check for colon cancer or polyps

›Do not skip this appointment

›Family doctor follow-up within 5 to 7 days

›Dietary consultation if recommended

›Long-term prevention

›Gradually increase dietary fibre after recovery

12References/r25

Guidelines and key sources

›Primary guidelines

›Brown RF, Lopez K, Smith CB, Charles A. Diverticulitis. JAMA 2025

›Comprehensive management algorithm

›Selective antibiotic strategy

›Peery AF, Shaukat A, Strate LL. AGA Clinical Practice Update on Medical Management of Colonic Diverticulitis: Expert Review. Gastroenterology 2021

›Observation-first strategy for uncomplicated disease

›Selective antibiotic use framework

›Qaseem A et al. Diagnosis and Management of Acute Left-Sided Colonic Diverticulitis: ACP Clinical Guideline. Annals of Internal Medicine 2022

›Outpatient management evidence base

›CT imaging role

›Supporting evidence

›Young-Fadok TM. Diverticulitis. NEJM 2018

›Pathophysiology and surgical management review

›Hinchey classification staging

›You H et al. Management of Diverticulitis: A Review of Guidelines. Medical Journal of Australia 2019

›Comparative guideline synthesis

›Percutaneous drainage evidence

›Peery AF. Management of Colonic Diverticulitis. BMJ 2021

›Non-operative management evidence

›Colonoscopy follow-up rationale

›Coding references

›ICD-10 K57.32 diverticulitis of large intestine without perforation or abscess

›K57.20 diverticulitis of large intestine with perforation and abscess

›K57.80 diverticulitis of intestine part unspecified without perforation or abscess

›SNOMED CT colonic diverticulitis disorder concept

Evidence & Review

Evidence & Review