CCS Integrated Cases

CCS case: severe abdominal pain with peritoneal signs

Clinical Overview and When to Suspect Surgical Abdomen

— Perforated viscus (peptic ulcer, sigmoid diverticulum, appendix, colon cancer)

— Acute appendicitis with rupture

— Mesenteric ischemia with infarction

— Acute cholecystitis with gallbladder perforation

— Strangulated bowel obstruction

— Spontaneous bacterial peritonitis (SBP) in cirrhotics — usually lacks rigidity; subtle exam

— Ruptured ectopic, ruptured AAA, ovarian torsion (surgical mimics)

— Hemodynamic instability not responding to 2 L crystalloid

— Free air on upright CXR with rigid abdomen

— Pulsatile mass + hypotension (AAA)

— Peritonitis after recent endoscopy or colonoscopy

— Elderly (blunted exam, on beta-blockers masking tachycardia)

— Diabetics, immunosuppressed, chronic steroid users

— Cirrhotics and dialysis patients

— Postoperative patients (anastomotic leak)

CCS pearl: On the CCS interface, the first three orders for any peritonitis stem should be IV access × 2, NS or LR bolus 1–2 L, and NPO, followed within minutes by labs, lactate, type & screen, and a surgery consult — order the consult before imaging returns if the abdomen is rigid.

Definition: Acute abdominal pain with peritoneal signs (involuntary guarding, rigidity, rebound, percussion tenderness) implies inflammation of the parietal peritoneum and mandates urgent surgical evaluation

Core CCS trigger: Adult presenting to ED with severe, constant abdominal pain >6 hours, fever, tachycardia, and a "board-like" or focally rigid abdomen — your clock starts immediately

Top etiologies driving peritonitis on Step 3:

Why Step 3 cares: This is a time-sensitive CCS case testing your ability to resuscitate, image, consult surgery, and start antibiotics in parallel — not sequentially. Delays in source control increase mortality ~7%/hour in fecal peritonitis

Red-flag features pushing toward immediate OR over CT:

High-risk hosts (atypical presentations, lower threshold to image and admit):

Presentation Patterns and Key History

— Sudden onset, "worst ever" within seconds: perforation, ruptured AAA, mesenteric embolism, ovarian torsion

— Gradual crescendo over hours: appendicitis, cholecystitis, diverticulitis, SBO progressing to ischemia

— Pain out of proportion to exam: acute mesenteric ischemia until proven otherwise

— Migratory periumbilical → RLQ: classic appendicitis

— Epigastric → diffuse rigidity: perforated peptic ulcer

— Vomiting before pain → gastroenteritis; vomiting after pain → surgical

— Obstipation (no flatus/stool) → obstruction or ileus from peritonitis

— Hematochezia/melena → ischemia, ulcer, diverticular bleed (rarely peritonitic)

— Fever, chills, rigors → established intra-abdominal sepsis

— Anorexia is nearly universal in surgical abdomen — its absence argues against

— NSAID or chronic steroid use → perforated ulcer

— Atrial fibrillation, recent MI, CHF → embolic mesenteric ischemia

— Cirrhosis with ascites → SBP (paracentesis, not laparotomy)

— Prior abdominal surgery → adhesive SBO with strangulation

— Immunosuppression → atypical, blunted presentation

— LMP, contraception, prior ectopic, IUD → ruptured ectopic in any woman of reproductive age

— Beta-blockers blunt tachycardia

— Opioids, steroids, and immunosuppressants blunt pain and fever

— Anticoagulants increase rectus sheath hematoma and retroperitoneal bleed risk

Board pearl: In any reproductive-age woman with acute abdominal pain, β-hCG comes before imaging and before opioids — ruptured ectopic kills, and pregnancy changes both imaging modality (US first) and surgical approach. On CCS, order urine β-hCG within the first 5 simulated minutes.

Pain quality and progression narrows the differential rapidly:

Associated symptoms to elicit on CCS history:

Critical PMH that reframes the case:

Medications that mask findings:

Physical Exam Findings and Hemodynamic Assessment

— Tachycardia + hypotension + narrow pulse pressure → sepsis or hemorrhage

— Fever >38.5°C with rigors → established peritonitis

— Tachypnea (RR >22) → early SIRS/sepsis criterion, also splinting from diaphragmatic irritation

— qSOFA ≥2 (RR ≥22, SBP ≤100, AMS) flags septic shock risk → ICU triage

— Distension + visible peristalsis → SBO

— Absent bowel sounds → diffuse peritonitis or late ileus

— High-pitched, tinkling → mechanical obstruction

— Tympany over liver (loss of dullness) → free air from perforation

— Involuntary guarding and rigidity = peritonitis; voluntary guarding is not

— Rebound tenderness — less specific than percussion tenderness or cough tenderness

— Murphy: RUQ arrest on inspiration → cholecystitis

— McBurney point tenderness, Rovsing, psoas, obturator: appendicitis

— Carnett sign: pain worsens with abdominal wall tensing → abdominal wall, not intraperitoneal

— Cullen/Grey-Turner: retroperitoneal hemorrhage (severe pancreatitis, ruptured AAA)

— Rectal exam: gross/occult blood, mass, tenderness in pouch of Douglas

— Pelvic exam in women: cervical motion tenderness, adnexal mass

— Hernia orifices: incarcerated/strangulated hernia is easy to miss

— Pulses and skin: mottling, livedo → mesenteric ischemia

Key distinction: A rigid, silent abdomen with free air is an OR diagnosis — CT is not required to operate. A soft, tender abdomen with ascites in a cirrhotic is a paracentesis diagnosis — surgery would harm.

General appearance: Patient with peritonitis lies completely still, knees flexed; colicky pain (renal, biliary) makes patients writhe. Stillness is a peritonitis tell

Vital sign patterns:

Abdominal exam sequence — inspect, auscultate, percuss, palpate:

Localizing signs to know cold:

Mandatory adjunct exams:

Diagnostic Workup — Initial Labs, Imaging, and Bedside Tests

— CBC with differential, BMP, LFTs, lipase, lactate, coagulation panel

— Type and screen (type and cross 2–4 units if unstable or surgical)

— Venous blood gas (faster than ABG, gives pH and lactate)

— Blood cultures × 2 before antibiotics if not delaying them

— Urinalysis, urine β-hCG (every woman 12–55)

— ECG — rule out inferior MI presenting as epigastric pain, detect AF (embolic source)

— Troponin if epigastric pain in patient >50 or with CAD risk factors

— Leukocytosis with left shift (may be normal or low in elderly/immunosuppressed — do not be reassured)

— Lactate >2 mmol/L → tissue hypoperfusion; >4 → severe sepsis/ischemia

— Metabolic acidosis with anion gap → ischemic bowel, sepsis

— Elevated lipase >3× ULN → pancreatitis (but mild elevations occur in perforation, ischemia)

— Transaminitis + alk phos → biliary

— Cr rise → AKI from hypoperfusion; affects contrast decisions

— Upright CXR and supine abdominal film: detects free air under the diaphragm (perforation) and obstruction patterns — fast, cheap, available in minutes

— Bedside ultrasound (FAST/RUQ): free fluid, AAA, gallbladder, pregnancy — operator-dependent but immediate

— CT abdomen/pelvis with IV contrast: the workhorse — sensitivity >95% for perforation, appendicitis, diverticulitis, ischemia, abscess. Use oral contrast selectively (not in suspected perforation or ischemia)

— Cr ≤1.5 or eGFR ≥30: IV contrast acceptable

— Hold metformin 48h after contrast if eGFR <30 or AKI

CCS pearl: On an unstable patient, upright CXR + bedside US in the trauma bay beats waiting for CT — free air or free fluid plus rigidity sends them to OR.

CCS initial order set (simulated time 0–15 min), all "Stat":

Expected lab patterns:

Initial imaging:

Contrast pitfalls:

Diagnostic Workup — Advanced and Confirmatory Studies

— Perforation: extraluminal free air, free fluid, fat stranding, wall thickening at site

— Appendicitis: appendix >6 mm, wall enhancement, periappendiceal stranding, appendicolith

— Diverticulitis: sigmoid wall thickening, pericolic fat stranding, ± abscess (Hinchey staging)

— Mesenteric ischemia: bowel wall pneumatosis, portal venous gas, lack of mucosal enhancement, SMA/SMV thrombus on CTA

— SBO: transition point, dilated proximal/decompressed distal loops, closed-loop or whirl sign → strangulation

— Cholecystitis: wall thickening >3 mm, pericholecystic fluid, distension, sonographic Murphy

— Order specifically when mesenteric ischemia is suspected (AF, pain out of proportion, lactic acidosis with soft abdomen)

— Also for suspected ruptured AAA in stable enough patient — unstable goes straight to OR

— Pregnancy with non-diagnostic ultrasound (appendicitis, biliary)

— Suspected choledocholithiasis without cholangitis

— Send cell count with differential, culture in blood culture bottles at bedside, albumin, total protein

— PMN ≥250/µL = SBP — start ceftriaxone 2 g IV and albumin 1.5 g/kg day 1, 1 g/kg day 3

— Total protein <1 g/dL, glucose <50, multiple organisms → think secondary bacterial peritonitis (perforation) → CT and surgery

— Reserved for equivocal cases (young woman with possible appendicitis vs gynecologic) or for both diagnosis and therapy

Key distinction: SBP vs secondary peritonitis — both have PMN ≥250, but secondary has polymicrobial culture, low ascitic glucose, high LDH, and high protein. Missing this sends a perforated cirrhotic to floor instead of OR.

CT abdomen/pelvis with IV contrast — interpretation pearls by etiology:

CT angiography (arterial + venous phases):

MRI/MRCP:

Diagnostic paracentesis (cirrhotic with ascites and any abdominal pain or fever):

Diagnostic laparoscopy:

Risk Stratification and First-Line Management Logic

— Two large-bore IVs (16–18 g) or central access if peripheral fails

— Crystalloid bolus: balanced solution (LR or Plasma-Lyte) 30 mL/kg over the first 3 hours for sepsis-induced hypoperfusion (Surviving Sepsis Campaign)

— Reassess after each 500–1000 mL: HR, BP, MAP target ≥65, urine output ≥0.5 mL/kg/h, lactate clearance

— Foley catheter for UOP monitoring

— NG tube if vomiting, obstruction, or planned OR

— NPO, supplemental O2 to keep SpO2 ≥94%

— Lactate

— Blood cultures × 2 before antibiotics

— Broad-spectrum antibiotics within 1 hour

— 30 mL/kg crystalloid for hypotension or lactate ≥4

— Vasopressors if hypotensive during/after resuscitation

— Immediate OR (no further imaging): hemodynamic instability + peritonitis, free air + rigidity, ruptured AAA, ischemic bowel with peritonitis

— CT then OR: stable peritonitis, localized findings

— Source control by IR: drainable abscess (Hinchey II diverticulitis, periappendiceal abscess >3 cm) — percutaneous drain, antibiotics, interval surgery

— Medical only: SBP, uncomplicated diverticulitis without abscess, pancreatitis without infection

CCS pearl: On the simulation, advance the clock in 15-minute intervals during resuscitation, reassess vitals and exam each time, and call surgery consult before the first liter finishes in any rigid abdomen.

Parallel-track resuscitation — do not wait for diagnosis to treat shock:

Vasopressors: start norepinephrine peripherally or centrally if MAP <65 after adequate fluids; add vasopressin 0.03 U/min as second agent

Sepsis bundle (1-hour bundle on CCS clock):

Surgical vs medical decision tree:

Pain control: Do not withhold analgesia — IV opioids (morphine 0.1 mg/kg or hydromorphone 0.5–1 mg) do not obscure surgical decision-making (evidence-based since 2000s)

Pharmacotherapy — First-Line Antibiotic Regimens

— Community-acquired, mild–moderate: ceftriaxone 2 g IV q24h + metronidazole 500 mg IV q8h; or ertapenem 1 g IV q24h; or moxifloxacin 400 mg IV (if beta-lactam allergy)

— Community-acquired, severe (ICU, peritonitis with shock): piperacillin-tazobactam 4.5 g IV q6h (extended infusion) or meropenem 1 g IV q8h

— Healthcare-associated/postop/recent antibiotics: meropenem 1 g IV q8h + vancomycin 15–20 mg/kg IV (cover MRSA if risk factors) ± echinocandin (micafungin 100 mg IV) if Candida risk (perforated upper GI, immunosuppressed, recent broad-spectrum, parenteral nutrition)

— SBP: ceftriaxone 2 g IV q24h × 5–7 days

— Antibiotics within 1 hour of recognition of septic shock; mortality rises ~7% per hour of delay

— Draw cultures first only if it does not delay the dose

— STOP-IT trial: 4 days of antibiotics after adequate source control is non-inferior to 8 days for complicated intra-abdominal infection

— If source control is inadequate or impossible: 7–10 days, guided by clinical course

— PPI (pantoprazole 40 mg IV q12h) for perforated peptic ulcer

— VTE prophylaxis (enoxaparin 40 mg SC daily or heparin 5000 U SC q8h) once bleeding controlled and within 24h of surgery

— Antiemetics: ondansetron 4 mg IV

— Stress-dose steroids only if known adrenal insufficiency or chronic steroid use (hydrocortisone 100 mg IV then 50 mg q6h)

— Aminoglycosides as first-line (nephrotoxicity, no mortality benefit)

— Anti-motility agents in suspected ischemia/obstruction

— NSAIDs (renal, bleeding)

Step 3 management: For a hemodynamically unstable patient with peritonitis: piperacillin-tazobactam 4.5 g IV within 1 hour, after blood cultures, alongside 30 mL/kg LR and norepinephrine if MAP <65.

Empiric antibiotic selection — cover gram-negatives, anaerobes, enterococci (in healthcare-associated or biliary):

Timing — every hour matters:

Antibiotic duration after source control:

Adjunctive pharmacology:

Avoid:

Procedures and Surgical Source Control

— Perforated peptic ulcer: exploratory laparotomy (or laparoscopy if stable) with Graham omental patch; biopsy edges to rule out malignancy; H. pylori eradication postop

— Perforated appendicitis: laparoscopic appendectomy; if phlegmon/abscess and stable → IR drain + antibiotics + interval appendectomy 6–8 weeks (controversial, but board-favored in walled-off disease)

— Perforated diverticulitis (Hinchey III/IV): Hartmann procedure (sigmoid resection + end colostomy) traditionally; primary anastomosis with proximal diversion in selected stable patients (LADIES/DIVA data)

— Acute mesenteric ischemia: emergent laparotomy with embolectomy/revascularization + resection of frankly necrotic bowel; second-look laparotomy 24–48h later for marginal segments

— Strangulated SBO: laparotomy with lysis of adhesions, resection of non-viable bowel

— Gangrenous/perforated cholecystitis: emergent cholecystectomy; percutaneous cholecystostomy if too unstable

— Ruptured AAA: OR or endovascular (EVAR) if anatomy permits

— Percutaneous drainage of abscesses ≥3 cm

— Cholecystostomy for high-risk surgical candidates

— Mesenteric angiography with thrombolysis/thrombectomy in early SMA occlusion without peritonitis

— Type and cross 2–4 units PRBC, FFP available

— Correct INR if >1.5 (vitamin K, FFP, or 4-factor PCC for warfarin)

— Hold and reverse DOACs if available (andexanet, idarucizumab)

— Platelets >50k for surgery, >100k for neuraxial

— Glucose 140–180; insulin drip if needed

— Antibiotic redosing intraop based on half-life and blood loss

CCS pearl: Order "Surgery consult, STAT" as a discrete order — the case advances when surgery accepts. Then order "Transfer to OR" when the consult recommends operation; do not keep ordering labs once the decision is made.

Source control is the definitive therapy — antibiotics alone fail in established peritonitis with a controllable source

Operative approaches by etiology:

Interventional radiology source control:

Perioperative checklist:

Special Populations — Elderly and Renal/Hepatic Impairment

— Blunted pain, absent fever, normal or low WBC in up to 30% of perforations

— Higher baseline mortality from intra-abdominal sepsis (up to 30–40%)

— Lower threshold to obtain CT even with mild findings

— Beta-blockers mask tachycardia; rely on lactate, mental status, UOP

— Polypharmacy: NSAIDs → perforation; anticoagulants → retroperitoneal bleed mimicking acute abdomen

— Mesenteric ischemia disproportionately affects elderly with AF, CHF, vascular disease — always on the differential for "pain out of proportion"

— Code status discussion before OR if frail; consider goals-of-care if multiple comorbidities

— Adjust dosing: piperacillin-tazobactam 3.375 g q8h if CrCl 20–40; meropenem 500 mg q8h if CrCl 25–50

— Avoid nephrotoxins: aminoglycosides, NSAIDs, contrast if avoidable (use non-contrast CT or MRI; weigh diagnostic urgency against renal risk — perforation usually wins)

— Vancomycin: target trough 15–20 or AUC 400–600; consider levels q24–48h

— LMWH dose-adjust (enoxaparin 30 mg SC daily if CrCl <30) or switch to unfractionated heparin

— Coagulopathy is real bleeding risk only with active bleeding or invasive procedure; do not over-correct INR

— SBP prophylaxis after first episode: norfloxacin 400 mg PO daily (or ciprofloxacin, TMP-SMX)

— Avoid: aminoglycosides (HRS risk), large-volume paracentesis without albumin (>5 L → albumin 6–8 g/L removed)

— Hepatic encephalopathy worsens with sepsis; lactulose, rifaximin

— MELD score predicts perioperative mortality — MELD >15 carries high surgical risk; multidisciplinary discussion

Step 3 management: In a cirrhotic with ascites and abdominal pain, paracentesis comes before antibiotics if it can be done in <30 min; PMN ≥250/µL confirms SBP → ceftriaxone 2 g IV + albumin 1.5 g/kg day 1, 1 g/kg day 3 (reduces hepatorenal syndrome and mortality).

Elderly (>65) — atypical and dangerous:

Renal impairment:

Hepatic impairment / cirrhosis:

Special Populations — Pregnancy and Pediatrics

— Appendicitis is the most common non-obstetric surgical emergency in pregnancy; appendix migrates superiorly with gestational age (RLQ → RUQ by third trimester)

— Leukocytosis is physiologic (up to 15k); do not anchor on it

— Imaging: ultrasound first; if non-diagnostic, MRI without gadolinium is preferred; CT only if MRI unavailable and benefit outweighs radiation risk — do not let pregnancy delay diagnosis of surgical abdomen

— Operate when indicated: maternal mortality from delayed appendectomy with perforation > risk of surgery to fetus; fetal loss rises from 3% (uncomplicated) to 20–35% (perforation/peritonitis)

— Antibiotics: ceftriaxone + metronidazole are category B and safe; avoid fluoroquinolones, tetracyclines

— Left lateral decubitus tilt during transport and OR to relieve IVC compression

— Obstetric consult mandatory; fetal monitoring per gestational age (>24 weeks: continuous intraop if feasible)

— Always exclude ruptured ectopic in first trimester with peritonitis — ultrasound, β-hCG; ectopic is OR not antibiotics

— Appendicitis peak age 10–19; perforation rates higher in <5 (delayed presentation, communication)

— Alvarado or Pediatric Appendicitis Score to risk-stratify; ultrasound first in children to avoid CT radiation; MRI if equivocal

— Intussusception (3 months – 3 years): "currant jelly" stool, sausage mass, target sign on US → air or contrast enema (diagnostic and therapeutic), surgery if perforation or failed reduction

— Malrotation with midgut volvulus in neonates: bilious vomiting → emergent upper GI study → Ladd procedure

— Meckel diverticulum: painless GI bleeding more common; can perforate

— Antibiotic dosing weight-based; fluid resuscitation 20 mL/kg boluses, reassess after each

— Always consider non-accidental trauma in unexplained pediatric peritonitis

Board pearl: A pregnant woman with peritoneal signs gets MRI, not CT, and the OR before the obstetric viability discussion delays surgery — maternal survival is the fetal survival strategy.

Pregnancy:

Pediatrics:

Complications and Adverse Outcomes

— Refractory hypotension despite fluids + vasopressors

— ARDS: bilateral infiltrates, PaO2/FiO2 <300; lung-protective ventilation (6 mL/kg IBW, plateau <30)

— AKI from hypoperfusion + nephrotoxins; may require CRRT

— DIC: prolonged PT/PTT, low fibrinogen, thrombocytopenia, schistocytes; treat underlying cause, replace products

— Acute liver injury (shock liver) — transaminases in thousands, recover with perfusion

— Anastomotic leak (postop day 5–7): new fever, tachycardia, peritoneal signs, leukocytosis → CT with rectal/oral contrast, return to OR or IR drainage

— Wound dehiscence, evisceration (postop day 7–10) — salmon-colored drainage is a warning sign

— Surgical site infection — superficial vs deep vs organ-space

— Postoperative ileus vs early mechanical obstruction

— Intra-abdominal abscess (postop day 5–14): fever, leukocytosis, localized pain → CT, percutaneous drain

— Fistula formation (enterocutaneous, colovesical)

— Short bowel syndrome if extensive resection

— VTE: PE risk elevated; prophylaxis essential

— C. difficile colitis from broad-spectrum antibiotics

— Stress ulcer / GI bleed

— ICU delirium

— Adrenal insufficiency in critical illness

— Refeeding syndrome when nutrition reintroduced after prolonged NPO

— Adhesive SBO risk lifelong after laparotomy (~10% within 10 years)

— Incisional hernia (10–20%)

— Ostomy-related issues (skin, electrolytes, dehydration in high-output stomas)

— Psychological: PTSD after ICU, depression

CCS pearl: A postoperative patient on day 5 with new tachycardia and fever is an anastomotic leak until proven otherwise — order CT abdomen/pelvis with contrast, blood cultures, broaden antibiotics, and call surgery before assuming pneumonia or UTI.

Septic shock and multi-organ failure:

Surgical complications:

Non-surgical complications:

Long-term:

When to Escalate Care — ICU, Consult, and Disposition

— Septic shock (vasopressor requirement)

— Lactate ≥4 or persistent lactic acidosis after resuscitation

— Respiratory failure (intubation, FiO2 >0.5, NIV)

— AKI requiring CRRT

— Postoperative after extensive resection, prolonged OR time, or significant blood loss

— Bowel ischemia post-revascularization

— Age + comorbidity + severe physiology (APACHE II, qSOFA ≥2)

— Hemodynamically stable on antibiotics but with significant comorbidity

— Postoperative day 1 from uncomplicated laparotomy without ICU need

— Hemodynamically stable, controlled source, low APACHE, no organ dysfunction

— Uncomplicated diverticulitis, SBP responding to therapy

— General surgery — any peritonitis

— Critical care — septic shock, organ failure

— Interventional radiology — drainable collection

— Gastroenterology — upper GI bleed, suspected ischemic colitis without peritonitis

— Obstetrics — pregnant patients

— Nephrology — RRT need

— Infectious disease — multidrug-resistant organisms, fungal peritonitis, prosthetic infections

— Community ED without surgical capability → transfer to tertiary center; stabilize first (airway, IV access, fluids, first dose of antibiotics), then transfer with EMTALA-compliant documentation

— Pediatric or obstetric cases without specialty support → transfer

— Discharging a patient with "resolved" pain after opioids without imaging

— Admitting peritonitis to a non-monitored bed

— Delaying surgical consult while waiting for CT in an unstable patient

Step 3 management: In CCS, the location order ("Move to ICU," "Transfer to OR") is a graded action — move to the appropriate level as soon as the criteria are met, not at the end of the case.

ICU admission criteria:

Step-down/telemetry:

Floor admission:

Mandatory consults (order early on CCS):

Transfer to higher level of care:

Disposition mistakes to avoid:

Key Differentials — Same-Category (Intra-Abdominal) Causes

— Sudden epigastric pain → diffuse rigidity; NSAID/steroid/H. pylori history

— Free air on upright CXR in ~75%; CT for the rest

— Treatment: omental patch, IV PPI, H. pylori testing

— Migratory periumbilical → RLQ pain; anorexia, low fever

— Ultrasound or CT; appendectomy

— LLQ pain, fever, leukocytosis; >50 years; CT shows pericolic stranding ± abscess

— Hinchey staging guides management

— Pain out of proportion; AF or vascular disease; elevated lactate

— CTA mesenteric vessels; emergent revascularization + resection

— Prior surgery, hernia; vomiting, obstipation, distension

— CT: transition point, whirl sign, pneumatosis if late

— Operative

— RUQ pain, Murphy sign, fever

— Ultrasound first; HIDA if equivocal

— Cholecystectomy or cholecystostomy

— Charcot triad (RUQ pain, fever, jaundice), Reynolds pentad with shock and AMS

— ERCP for decompression + antibiotics

— Epigastric pain radiating to back, lipase >3× ULN

— Sterile vs infected necrosis; step-up approach (drain, debridement)

— Cirrhosis with ascites; often subtle exam without rigidity

— Paracentesis PMN ≥250; ceftriaxone + albumin

— Colon >6 cm, systemic toxicity; risk of perforation

— Medical optimization, colectomy if no response in 48–72h or perforation

Key distinction: "Pain out of proportion" with a soft abdomen + lactic acidosis + AF = mesenteric ischemia (CTA, OR), not gastroenteritis. Missing this is a classic Step 3 trap.

Perforated peptic ulcer:

Acute appendicitis (perforated or not):

Acute diverticulitis with perforation:

Acute mesenteric ischemia:

Strangulated/closed-loop SBO:

Acute cholecystitis / gallbladder perforation:

Ascending cholangitis / gallbladder gangrene:

Severe acute pancreatitis with necrosis:

Spontaneous bacterial peritonitis:

Toxic megacolon (IBD or C. difficile):

Key Differentials — Other-Category (Extra-Abdominal) Causes

— Inferior MI: epigastric pain, nausea, vomiting → ECG, troponin in any patient >40 with epigastric pain

— Acute aortic dissection (Type B with mesenteric involvement): tearing pain, BP differential, widened mediastinum → CTA

— Ruptured AAA: abdominal/back pain, pulsatile mass, hypotension → bedside US, OR/EVAR; do not delay for CT in unstable

— Pericarditis with referred pain (rare)

— Lower lobe pneumonia or empyema: referred upper abdominal pain, especially in children/elderly → CXR

— Pulmonary embolism: pleuritic pain, sometimes RUQ from hepatic congestion or referred

— Renal colic / obstructing stone with pyelonephritis: flank pain, hematuria → CT without contrast

— Pyelonephritis with abscess or emphysematous pyelonephritis (diabetics): sepsis source

— Testicular torsion: referred lower abdominal pain in adolescents → exam testes, Doppler US

— Ruptured ectopic pregnancy: β-hCG, transvaginal US, OR

— Ovarian torsion: sudden adnexal pain, nausea; Doppler US; OR detorsion

— Tubo-ovarian abscess / severe PID: fever, CMT, adnexal mass; antibiotics ± drainage

— Ovarian cyst hemorrhage

— DKA: abdominal pain in 30%; check glucose, anion gap, ketones

— Adrenal crisis: abdominal pain, hypotension, hyperkalemia, hyponatremia

— Acute intermittent porphyria: colicky pain, neuropsych symptoms, dark urine; PBG

— Sickle cell vaso-occlusive crisis with abdominal/splenic sequestration

— Hereditary angioedema with bowel wall edema

— Lead poisoning, black widow envenomation, scorpion sting

— Strep pharyngitis in children with referred pain

— Herpes zoster (pre-eruptive dermatomal pain)

— Rectus sheath hematoma (anticoagulated patients): Carnett sign positive, CT confirms

— Hernia incarceration without obstruction yet

Board pearl: Always order ECG, lipase, β-hCG, glucose, and lactate on any acute abdomen — these five tests catch the most-missed mimics (MI, pancreatitis, ectopic, DKA, ischemia).

Cardiovascular mimics:

Pulmonary:

Genitourinary:

Gynecologic (always rule out in women):

Metabolic/systemic:

Toxic / infectious:

Abdominal wall:

Postoperative Course, Discharge Medications, and Secondary Prevention

— Early ambulation (POD 0–1) to reduce VTE, ileus, atelectasis

— Multimodal analgesia: scheduled acetaminophen, NSAIDs if renal function permits, gabapentinoids selectively, opioid-sparing strategy; PCA for first 24–48h then transition

— Diet advancement when bowel function returns (flatus, soft abdomen, hunger) — clear liquids → regular as tolerated

— Foley out POD 1–2 unless contraindicated

— Drains removed when output <30 mL/day serous

— VTE prophylaxis throughout admission; consider extended prophylaxis (28 days) after cancer surgery or high-risk laparotomy

— Complete oral antibiotic course (typically total 4–7 days post-source control per STOP-IT)

— PPI for perforated PUD: pantoprazole 40 mg daily × 8 weeks

— H. pylori eradication if positive: triple/quadruple therapy

— Stool softener + bowel regimen while on opioids

— Resume home medications selectively (hold ACEi/ARB until renal stable; restart beta-blockers; resume anticoagulation per surgical clearance, usually 24–72h post-op)

— VTE prophylaxis prescription if extended

— PUD: H. pylori test-and-treat, NSAID avoidance or co-prescribe PPI, smoking cessation, alcohol moderation

— Diverticulitis: high-fiber diet, hydration, smoking cessation; colonoscopy 6–8 weeks after first complicated episode to exclude malignancy; elective sigmoidectomy considered after complicated or recurrent episodes (shared decision)

— Appendicitis: no specific prevention; counsel on incisional hernia signs

— Cholecystitis: definitive cholecystectomy if temporized with cholecystostomy

— Mesenteric ischemia: antiplatelet/anticoagulation, risk factor control, statin, smoking cessation, AF management

— SBP: secondary prophylaxis with norfloxacin/cipro indefinitely; transplant evaluation

— Cancer-related perforation: oncology referral, staging

Step 3 management: After complicated diverticulitis, schedule outpatient colonoscopy in 6–8 weeks — this is a frequently tested discharge order on Step 3.

Postoperative recovery milestones (ERAS-aligned):

Discharge medication checklist:

Secondary prevention by etiology:

Follow-Up, Monitoring, and Counseling

— Surgical clinic visit at 1–2 weeks for wound check, staple/suture removal, drain assessment, pathology review

— PCP visit within 1–2 weeks for medication reconciliation, comorbidity management, VTE prophylaxis review, return to work/activity counseling

— Subspecialty follow-up as indicated: GI (for diverticulitis colonoscopy at 6–8 weeks; for PUD reassessment), hepatology (cirrhosis with SBP), cardiology (new AF found during workup), vascular surgery (mesenteric ischemia)

— Wound: signs of SSI (erythema, drainage, fever) → urgent return

— Bowel function: obstipation, distension, vomiting → possible adhesive SBO

— Nutrition: weight, albumin/prealbumin if extensive resection; B12 if terminal ileal resection

— Ostomy education and high-output management (>1500 mL/day → dehydration risk, anti-motility agents like loperamide)

— CBC and BMP at 1–2 weeks if anemic or AKI during admission

— Fever >38°C, worsening pain, persistent vomiting, no flatus/stool, wound drainage, shortness of breath, calf swelling/pain, blood in stool or vomit

— Activity: no lifting >10 lb for 4–6 weeks after laparotomy; lighter restrictions after laparoscopy

— Driving: when off opioids and able to perform emergency stop, usually 1–2 weeks

— Sexual activity: when comfortable, usually 2 weeks

— Smoking cessation counseling — improves wound healing and reduces recurrence in PUD/diverticulitis

— Alcohol moderation, weight management, fiber for diverticulitis

— Psychological support: depression/PTSD screening at follow-up after ICU stay

— Confirm receipt of pathology results

— Medication reconciliation to prevent duplication (especially anticoagulants)

— Confirm primary care has hospital discharge summary within 48 hours

CCS pearl: On final disposition, order both "Follow up in surgery clinic in 1–2 weeks" and "Follow up with PCP in 1–2 weeks" plus any condition-specific test (colonoscopy, H. pylori test) — Step 3 rewards explicit longitudinal planning.

Discharge handoff and follow-up cadence:

Outpatient monitoring parameters:

Return precautions (give in writing):

Counseling and rehabilitation:

Quality and safety follow-up:

Ethical, Legal, and Patient Safety Considerations

— Standard: discuss diagnosis, proposed procedure, risks, benefits, alternatives, and consequences of refusal

— Emergency exception (implied consent): life-threatening condition + patient unable to consent + no surrogate immediately available → proceed in patient's best interest; document the emergency rationale

— Surrogate hierarchy varies by state but generally: spouse → adult children → parents → siblings

— Capacity must be assessed before accepting refusal of life-saving surgery — pain, opioids, sepsis-induced delirium can impair capacity transiently

— Capacitated adult may refuse even life-saving surgery (Jehovah's Witnesses, advance directives)

— Explore reasons, ensure understanding, document, offer alternatives (cell-saver, fractionated products); do not coerce

— Pediatric refusal by parents of life-saving care → court order; emergent treatment may proceed under emergency exception

— Non-accidental trauma in children with peritonitis → CPS report

— Elder abuse → APS report

— Penetrating trauma, gunshot/stab wounds → law enforcement notification per state law

— Handoff is the highest-risk moment — use structured tools (SBAR, I-PASS)

— Medication reconciliation at every transition; missed reinitiation of home meds (e.g., levothyroxine, antiepileptics, immunosuppressants) is a common Step 3 vignette

— Pending labs and imaging must be explicitly assigned to a follow-up provider before discharge

— Discharge to skilled nursing facility requires accurate problem list, medications, follow-up appointments, and pending studies

— Universal protocol: site marking, time-out, verification

— Surgical count to prevent retained foreign body

— Postoperative SBP-style "never events" reporting if they occur

— VTE prophylaxis is a CMS quality measure

— Ethical and legal obligation to disclose harm (e.g., wrong-site surgery, retained sponge); honest disclosure reduces litigation and aligns with professionalism

Step 3 management: A septic patient brought in altered without family who needs emergent laparotomy → proceed under the emergency exception, document the urgency and the attempt to reach surrogates, and assess capacity on recovery to consent for subsequent procedures.

Informed consent for emergency surgery:

Refusal of treatment:

Mandatory reporting and legal triggers:

Transitions of care safety:

Patient safety in the OR and ICU:

Disclosure of medical error:

High-Yield Associations and Rapid-Fire Facts

Board pearl: Step 3 loves the timing details — antibiotics within 1 hour, 30 mL/kg in 3 hours, paracentesis before antibiotics if it doesn't delay them, colonoscopy at 6–8 weeks, follow-up in 1–2 weeks.

Free air under the diaphragm + rigid abdomen → perforated viscus → OR, no further imaging needed if unstable

Pain out of proportion to exam + AF + lactic acidosis → acute mesenteric ischemia → CTA + emergent vascular surgery

Cirrhosis + ascites + abdominal pain or fever → paracentesis; PMN ≥250 = SBP → ceftriaxone + albumin

LLQ pain + fever + leukocytosis in >50 → diverticulitis; CT; Hinchey stage drives management

RLQ pain after migration from periumbilical + anorexia → appendicitis; US/CT; appendectomy

Sudden epigastric pain with NSAID use → perforated PUD; upright CXR for free air

Sausage-shaped RUQ mass + currant jelly stool in toddler → intussusception; air enema

Bilious vomiting in neonate → malrotation/volvulus until proven otherwise; emergent upper GI

β-hCG positive + hypotension + adnexal pain → ruptured ectopic; OR

Charcot triad / Reynolds pentad → ascending cholangitis → ERCP decompression

STOP-IT trial → 4 days of antibiotics post-source control = 8 days

Surviving Sepsis → antibiotics within 1 hour, 30 mL/kg balanced crystalloid, lactate-guided resuscitation

MELD >15 → high perioperative mortality in cirrhotics

Pregnancy + RLQ/RUQ pain → US first, MRI second; do not delay surgery

Anastomotic leak typically POD 5–7 with new fever, tachycardia, peritoneal signs

Hinchey IV diverticulitis (fecal peritonitis) → Hartmann procedure

Closed-loop SBO, whirl sign, pneumatosis → strangulation → emergent OR

Loss of liver dullness to percussion → pneumoperitoneum (Jobert sign)

Carnett sign positive → abdominal wall pain (rectus sheath hematoma, hernia) — not peritonitis

Avoid aminoglycosides as first-line for intra-abdominal sepsis

Echinocandin coverage for Candida in upper GI perforation, immunosuppressed, prior antibiotic exposure

Colonoscopy 6–8 weeks after complicated diverticulitis to exclude malignancy

H. pylori test-and-treat for any PUD perforation

Norfloxacin daily for secondary SBP prophylaxis

Board Question Stem Patterns

— Best next step: upright CXR (free air under diaphragm) → IV fluids, broad-spectrum antibiotics, surgery consult for emergent laparotomy and omental patch

— Diagnosis: acute mesenteric ischemia (embolic)

— Best next step: CT angiography of abdomen, emergent vascular surgery consult, fluids, broad-spectrum antibiotics

— Best next step: diagnostic paracentesis with cell count and culture

— If PMN ≥250: ceftriaxone 2 g IV + albumin 1.5 g/kg day 1

— Best initial imaging: abdominal ultrasound, then MRI without gadolinium if non-diagnostic

— Definitive management: laparoscopic appendectomy; ceftriaxone + metronidazole

— Diagnosis: anastomotic leak

— Best next step: CT abdomen/pelvis with contrast, broaden antibiotics, surgery consult for return to OR

— Management: percutaneous IR drainage + antibiotics, interval colonoscopy 6–8 weeks, consider elective sigmoidectomy

— Diagnosis: intussusception

— Next step: air contrast enema (diagnostic and therapeutic); surgery if perforation or failure

— Diagnosis: ruptured AAA

— Next step: immediate vascular surgery / OR or EVAR, type and cross 6–10 units; bedside US only if it doesn't delay

— Ruptured ectopic until proven otherwise → OB/GYN, OR

Step 3 management: Recognize the disposition-defining detail in each stem — instability mandates OR over CT, cirrhosis mandates paracentesis over laparotomy, pregnancy mandates US/MRI over CT, AF mandates CTA for mesenteric ischemia.

Stem: "Sudden epigastric pain in a 62-year-old on chronic NSAIDs, now rigid abdomen, BP 90/60..."

Stem: "78-year-old with AF on no anticoagulation, severe diffuse abdominal pain × 4 hours, soft abdomen, lactate 6.2..."

Stem: "55-year-old with cirrhosis and ascites, fever 38.6, mild diffuse abdominal tenderness, no rigidity..."

Stem: "30-year-old G2P1 at 22 weeks with RLQ → RUQ pain, fever, leukocytosis..."

Stem: "Postop day 6 after sigmoidectomy with primary anastomosis, new tachycardia, fever, diffuse abdominal pain..."

Stem: "65-year-old with LLQ pain × 3 days, fever, CT shows 5-cm pericolic abscess..."

Stem: "Toddler with episodic crying, drawing legs up, currant jelly stool..."

Stem: "Pulsatile abdominal mass, syncope, BP 70/40..."

Stem: "Acute abdomen, pregnancy test pending, hypotension, free fluid on FAST..."

One-Line Recap

Tight high-yield recap bullets:

CCS pearl: The winning CCS rhythm for severe peritonitis is resuscitate → image (or skip to OR) → antibiotics → consult surgery → ICU/OR disposition → source control → de-escalate antibiotics → discharge with structured follow-up — execute these in parallel, not sequence.

The bottom line: Severe abdominal pain with peritoneal signs is a surgical emergency requiring parallel resuscitation, broad-spectrum antibiotics within 1 hour, urgent imaging or direct-to-OR triage based on hemodynamic stability, and definitive source control — with population-specific tweaks for pregnancy, cirrhosis, and the elderly.

Resuscitate while diagnosing: 2 large-bore IVs, 30 mL/kg balanced crystalloid, blood cultures, lactate, antibiotics within 1 hour, vasopressors (norepinephrine first) if MAP <65 after fluids — do not wait for CT to start

Image smartly: Upright CXR + bedside US for unstable; CT abd/pelvis with IV contrast for stable; MRI for pregnant; CTA for suspected mesenteric ischemia; paracentesis (not CT first) for cirrhotic with ascites

Source control wins: Antibiotics alone fail in established peritonitis with a controllable source — surgery or IR drainage is the definitive therapy; STOP-IT supports 4 days of antibiotics after adequate source control

Special populations change the algorithm: Elderly present blandly with high mortality (low threshold to image), pregnant patients get US/MRI and operate when indicated (maternal mortality drives fetal outcomes), cirrhotics need paracentesis first to distinguish SBP from secondary peritonitis, and pediatric peritonitis demands consideration of intussusception, malrotation, and non-accidental trauma

Don't miss the mimics: Inferior MI, ruptured AAA, DKA, ruptured ectopic, adrenal crisis, and lower-lobe pneumonia all mimic acute abdomen — ECG, β-hCG, glucose, lactate, and lipase on every patient

Discharge is part of the case: Antibiotic course, H. pylori test-and-treat after PUD, colonoscopy 6–8 weeks after complicated diverticulitis, SBP prophylaxis after first episode, surgery and PCP follow-up in 1–2 weeks, VTE prophylaxis, return precautions in writing