Perioperative & Surgical Care

Preoperative antibiotic prophylaxis: SCIP measures

Clinical Overview and When to Suspect SCIP-Driven Prophylaxis Need

— SCIP Inf-1: Prophylactic antibiotic received within 1 hour before incision (2 hours for vancomycin or fluoroquinolones)

— SCIP Inf-2: Appropriate antibiotic selection for the specific surgery

— SCIP Inf-3: Prophylactic antibiotic discontinued within 24 hours after surgery end (48 hours for cardiothoracic)

— SCIP Inf-4: Cardiac surgery patients with 6 AM postop glucose <180 mg/dL on POD 1 and 2

— SCIP Inf-9: Urinary catheter removed by POD 2

— SCIP Inf-10: Perioperative normothermia (≥36°C) for colorectal surgery

— Any clean procedure with prosthetic implant (joint, mesh, vascular graft, valve)

— All clean-contaminated cases (GI, GU, GYN, head/neck entering aerodigestive mucosa)

— Contaminated cases (treatment, not just prophylaxis)

— High-risk clean cases: cardiac, breast with implant, neurosurgery

Board pearl: The single most-tested SCIP metric is antibiotic timing — within 60 minutes of incision (120 min for vanco/FQ). Earlier than 60 min or after incision = SCIP failure, even if the "right" drug was given.

Step 3 management: On CCS, when you "Order surgery," also order "prophylactic antibiotic" and document time relative to incision — the simulator credits proper timing.

Surgical Care Improvement Project (SCIP) measures were CMS quality metrics (2006–2015) that standardized perioperative infection prevention. Although retired as standalone reporting, the core principles are now embedded in NSQIP, Joint Commission, and CMS value-based purchasing — and remain heavily tested on Step 3.

Core antibiotic-related SCIP measures:

When to suspect prophylaxis is indicated:

Procedures not requiring routine prophylaxis: clean dermatologic excision, simple hernia without mesh in low-risk patient, diagnostic endoscopy without intervention, cataract surgery (topical only).

Presentation Patterns and Key History

— "A 68-year-old man is scheduled for elective total knee arthroplasty at 0800. At 0600 he receives 2 g cefazolin IV. Incision is made at 0815. Is timing appropriate?" → Yes if within 60 min; here 135 min before incision = failure.

— "Patient with MRSA nasal colonization going for CABG" → add vancomycin to cefazolin, do not replace it.

— "Patient reports penicillin allergy with rash as a child" → clarify reaction; non-severe rash ≠ contraindication to cefazolin (cross-reactivity <1%).

— "Anaphylaxis to penicillin" → use clindamycin or vancomycin depending on procedure.

— Allergy details: specific drug, reaction type, timing, severity, prior tolerance of cephalosporins

— MRSA status: prior infection, colonization, healthcare exposure, nursing home residence

— Recent antibiotic use (last 90 days) — affects resistance risk

— Weight — dosing is weight-based; cefazolin 2 g if <120 kg, 3 g if ≥120 kg

— Renal function — affects vancomycin and aminoglycoside dosing

— Diabetes and glycemic control — links to SCIP Inf-4

— Procedure type, duration, expected blood loss — drives redosing

— Colorectal: bowel prep status, mechanical + oral antibiotic prep (neomycin/metronidazole) reduces SSI

— Cardiac: sternal wound risk factors (DM, obesity, smoking, BIMA harvest)

— Ortho implant: prior joint infection, skin condition at incision site

Key distinction: Prophylaxis ≠ treatment. A patient with active cellulitis at the surgical site needs therapeutic antibiotics and case delay/redirection — not a single preop dose. Stem clues like "erythema, warmth, purulent drainage" demand you postpone elective surgery.

Board pearl: Always ask about β-lactam allergy nature before defaulting to vancomycin — overuse of vanco prophylaxis increases SSI from gram-negatives and is a tested pitfall.

Step 3 vignettes rarely show a "sick" patient — they show a preoperative or intraoperative decision point. Recognize these stems:

Key history elements to elicit preop:

Surgical-site-specific history:

Physical Exam Findings and Preoperative Assessment

— Skin at incision site: check for active dermatitis, cellulitis, open wounds, recent shaving abrasions. Clipping > shaving; razor shaving the night before doubles SSI rates.

— Nasal exam / MRSA swab result for cardiac and orthopedic implant cases — decolonization with mupirocin × 5 days + chlorhexidine baths reduces S. aureus SSI.

— Dentition: poor oral hygiene before cardiac valve or prosthetic joint surgery raises bacteremia risk.

— BMI and body habitus: obese patients need higher cefazolin dose (3 g) and may need redosing sooner.

— Indwelling devices: existing Foley, central line, drains — sources of contamination.

— Fever or tachycardia preop → delay elective surgery, work up source

— Hyperglycemia (random glucose >200) → optimize before elective case; cardiac surgery requires tight intraop/postop control

— Hypothermia risk: assess for thin habitus, long case duration → plan forced-air warming (SCIP Inf-10)

— Antibiotic ordered, dose appropriate for weight, scheduled to infuse within 60 min of incision

— Allergy verified and reconciled

— Hair management plan (clip in OR)

— Glucose check if diabetic

— Foley necessity assessed; if placed, plan for removal by POD 2

Step 3 management: If the vignette shows a patient shaved at home the night before for hernia repair, document and proceed — but on CCS, order chlorhexidine skin prep and counsel the patient that this is a modifiable risk for next time.

CCS pearl: Always order "chlorhexidine-alcohol skin prep" (superior to povidone-iodine for most clean and clean-contaminated cases per NEJM 2010 trial) when setting up a surgical case in the simulator — it's a credited intervention.

Board pearl: Normothermia, normoglycemia, and supplemental O₂ are the "triple S" SSI bundle beyond antibiotics.

The preop exam for antibiotic prophylaxis focuses on modifiable infection risk factors and site readiness:

Vital signs and systemic clues:

Documentation checklist before sending patient to OR:

Diagnostic Workup — Preop Labs and Risk Screening

— CBC: baseline WBC; leukocytosis preop suggests occult infection, delay elective case

— BMP: creatinine/eGFR required before vancomycin or aminoglycoside dosing

— Glucose / HbA1c: A1c >8% predicts SSI; cardiac surgery target preop A1c <7%. POD 1 and 2 glucose <180 mg/dL is the SCIP cardiac target.

— Albumin <3.5 g/dL and prealbumin: nutritional marker predicting SSI and dehiscence

— Coags if regional anesthesia planned (affects timing of antibiotic and block)

— MRSA nares PCR or culture — standard before cardiac, orthopedic implant, neurosurgical implant cases at most US institutions

— Urinalysis before urologic procedures, prosthetic joint, or vascular surgery; treat asymptomatic bacteriuria only if instrumentation of GU tract or implant placement

— Stool screening is not routine

— CXR if pulmonary symptoms, smoker, or thoracic case

— Dental panoramic before cardiac valve replacement at some centers

Key distinction: Asymptomatic bacteriuria generally does not warrant treatment except in pregnancy, prior to urologic procedure with mucosal trauma, or before prosthetic joint/heart valve implantation. Treating it otherwise is a tested pitfall (drives resistance, C. difficile, no SSI reduction).

Board pearl: A preop MRSA-positive nasal swab in a CABG patient mandates vancomycin + cefazolin (dual coverage), mupirocin nasal × 5 days, and chlorhexidine baths × 5 days — all three are tested as a bundle.

Step 3 management: Don't cancel surgery for mild anemia or stable CKD — but do delay elective surgery for uncontrolled hyperglycemia, untreated UTI before urologic instrumentation, or active skin infection at incision site.

Antibiotic prophylaxis itself doesn't require diagnostic testing, but risk stratification labs drive SCIP-aligned decisions:

Screening swabs and cultures:

Imaging supports the surgical plan, not antibiotic choice — but note:

ECG: not infection-related but part of standard preop workup for age ≥65 or known CV disease

Diagnostic Workup — Confirmatory and Targeted Studies

— MRSA nasal PCR: rapid (1–2 hr); positive → add vancomycin and decolonize. Negative predictive value ~96% for S. aureus SSI.

— Wound or tissue culture if revising prior surgical site (e.g., revision arthroplasty for suspected indolent infection) — guides directed prophylaxis

— Synovial fluid analysis (cell count, alpha-defensin, culture) before revision joint surgery to rule out periprosthetic infection masquerading as aseptic loosening

— C. difficile PCR if recent diarrhea — affects choice and risk

— Local antibiogram — institutional gram-negative resistance rates may shift first-line choice (e.g., cefazolin failure rates for E. coli in colorectal cases)

— Prior culture data in the chart — if the patient grew ESBL E. coli from a recent UTI, urologic prophylaxis may require ertapenem

— Pre-infusion serum creatinine

— Weight-based dose (15 mg/kg, max ~2 g for prophylaxis)

— Infuse over ≥60 minutes (faster → red man syndrome — histamine release, not allergy)

— Start infusion 120 minutes before incision to complete on time

— Renal function and ideal body weight for dosing

— Single preop dose for prophylaxis avoids cumulative toxicity

Key distinction: Red man syndrome (flushing, pruritus during vanco infusion) is not an allergy — slow the rate, premedicate with antihistamine, continue use. Anaphylaxis (hypotension, bronchospasm, urticaria after dose) is a true allergy — switch agents.

Board pearl: A revision arthroplasty stem with elevated ESR/CRP and synovial WBC >3000 with PMN predominance signals chronic prosthetic joint infection — these patients need culture-directed therapy and possibly two-stage revision, not standard cefazolin prophylaxis.

CCS pearl: Order vancomycin trough only for therapeutic dosing, not single-dose prophylaxis — overordering wastes credit.

When standard prophylaxis may be insufficient, targeted studies guide escalation:

Antimicrobial stewardship inputs:

Vancomycin-specific monitoring:

Aminoglycoside-specific:

Risk Stratification and Prophylaxis Decision Logic

— Class I (clean): prophylaxis only if implant, high-risk host, or high-morbidity infection (cardiac, neuro, ortho implant, breast with implant, vascular)

— Class II (clean-contaminated): always prophylax (GI, biliary, GU with mucosal entry, head/neck, gyn, thoracic entering airway)

— Class III (contaminated): prophylaxis + often extended therapy (gross spillage, fresh trauma <4 hr, acute non-purulent inflammation)

— Class IV (dirty/infected): therapy, not prophylaxis (perforated viscus, abscess, devitalized tissue)

— Age >65, DM, obesity, smoking, malnutrition, immunosuppression, prior SSI, prolonged preop hospitalization, ASA ≥3

— Goal: therapeutic tissue concentration at incision and throughout case

— Cefazolin, cefuroxime, ampicillin-sulbactam, clindamycin: infuse within 60 min before incision

— Vancomycin, fluoroquinolones: within 120 min because of longer infusion

— Tourniquet cases (ortho): complete antibiotic infusion before tourniquet inflation

— Procedure duration exceeds 2 half-lives of the drug (cefazolin: redose at 4 hours)

— Blood loss >1500 mL or massive fluid resuscitation

— Adult cardiopulmonary bypass run

Step 3 management: A 5-hour open AAA repair with 2 L blood loss given a single 2 g cefazolin at induction is a SCIP failure — the correct answer is redose cefazolin at hour 4 and again if bleeding ongoing.

Board pearl: Dirty wounds get treatment, not prophylaxis. A vignette of perforated diverticulitis going to OR receives piperacillin-tazobactam or ceftriaxone + metronidazole as therapy, continued postop, not a single dose.

Key distinction: Postop antibiotic continuation beyond 24 hours (48 for cardiac) does not reduce SSI and increases C. difficile and resistance — a SCIP Inf-3 failure.

Decide prophylaxis using wound class + implant + host factors:

Host factors elevating risk and influencing agent choice:

Timing principle:

Intraoperative redosing — give a second dose if:

Pharmacotherapy — First-Line Regimens by Procedure

— Cardiac, vascular, orthopedic (including hip/knee arthroplasty), neurosurgery, head/neck (clean), thoracic (non-esophageal), plastic with implant, hernia with mesh, hysterectomy (with metronidazole), C-section

— Covers skin flora (S. aureus MSSA, S. epidermidis, streptococci) and some gram-negatives

— Colorectal: cefazolin + metronidazole OR cefoxitin OR ceftriaxone + metronidazole; add oral neomycin + metronidazole or erythromycin with mechanical bowel prep the day before

— Appendectomy (uncomplicated): cefoxitin or cefazolin + metronidazole, single dose

— Hysterectomy (vaginal or abdominal): cefazolin (some add metronidazole)

— C-section: cefazolin within 60 min before skin incision (changed from "after cord clamp" — reduces endometritis and SSI; add azithromycin for non-elective/laboring)

— Cholecystectomy (high-risk): cefazolin; low-risk elective lap chole — no prophylaxis needed

— GU with bowel involvement (cystectomy): cefoxitin or cef + metronidazole

— Transurethral prostate procedures: ciprofloxacin or TMP-SMX (treat preop bacteriuria first)

— Head/neck cancer with mucosal incision: ampicillin-sulbactam or cefazolin + metronidazole (covers oral anaerobes)

— Known MRSA colonization/infection

— High institutional MRSA rate

— Prosthetic implant + recent healthcare exposure

— Always co-administered with cefazolin (vanco has poor MSSA and gram-negative coverage)

Board pearl: The 2010 ACOG change: give cefazolin BEFORE skin incision for C-section, not after cord clamp. Tested repeatedly.

Step 3 management: Never substitute vancomycin alone for cefazolin in routine prophylaxis — vanco is inferior to cefazolin against MSSA and has narrower gram-negative coverage. Dual therapy if MRSA risk.

Key distinction: Cefoxitin (2nd-gen with anaerobic activity) is preferred where anaerobes matter and you want single-agent simplicity (colorectal, appy).

Cefazolin 2 g IV (3 g if ≥120 kg; pediatric 30 mg/kg) is the workhorse for most procedures:

Procedure-specific first-line:

MRSA add-on: vancomycin 15 mg/kg IV (max ~2 g) for:

Procedures, Allergy Pathways, and Special Pharmacology

— Non-severe reaction (rash, GI upset, family history, unknown): cefazolin is safe — true cross-reactivity with penicillin is <1% (older 10% figure was overstated, contamination-driven). Use cefazolin.

— Severe IgE-mediated reaction (anaphylaxis, angioedema, bronchospasm, hypotension) or severe delayed (SJS/TEN, DRESS, AGEP, interstitial nephritis): avoid all β-lactams

— Alternative agents by procedure:

– Cardiac, vascular, ortho, neuro: vancomycin (± aztreonam or gentamicin if gram-negative coverage needed)

– Colorectal, GYN, GI: clindamycin + (gentamicin or aztreonam or ciprofloxacin) or metronidazole + (gent/aztreonam/cipro)

– Head/neck: clindamycin alone

— Cefazolin: 4 h

— Cefoxitin: 2 h

— Ampicillin-sulbactam: 2 h

— Clindamycin: 6 h

— Vancomycin: 8–12 h (rarely needed in single-dose prophylaxis)

— Metronidazole: not redosed in standard cases

— ≤24 hours post-op for most procedures

— ≤48 hours for cardiothoracic surgery

— Drains, catheters, packing are not indications to extend prophylaxis

— Intranasal mupirocin × 5 days + chlorhexidine bathing × 5 days for S. aureus decolonization in cardiac/ortho

— Vancomycin powder in wound in some spine cases (controversial, not standard)

— Wound irrigation with saline standard; antibiotic irrigation not routinely recommended

Board pearl: Continuing prophylactic antibiotics "until the drain comes out" is a classic SCIP failure — does not reduce SSI, increases C. difficile and resistance.

CCS pearl: On the simulator, after an uncomplicated colectomy, write "discontinue antibiotics" at 24 hours postop — credited stewardship action.

Step 3 management: A patient with "penicillin allergy — hives as a child, never tested" going for hip arthroplasty: order cefazolin, document shared decision and absence of severe reaction history.

β-lactam allergy management is the highest-yield Step 3 branch point:

Redosing thresholds (from incision time):

Discontinuation (SCIP Inf-3):

Topical and adjunctive:

Special Populations — Elderly and Renal/Hepatic Impairment

— Same prophylaxis agents and timing apply; no age-based dose reduction for cefazolin

— Higher baseline SSI risk → strict adherence to bundle (timing, normothermia, glucose, hair clipping)

— Greater C. difficile susceptibility → strict SCIP Inf-3 discontinuation

— Polypharmacy: review for QT-prolonging agents before fluoroquinolone use

— Delirium risk with anticholinergic adjuncts

— Cefazolin: standard 2 g preop dose unchanged; redosing interval extended (eGFR 10–50: every 8 h instead of 4 h; eGFR <10: typically no redose needed in single-day case)

— Vancomycin: dose by actual body weight, no preop dose reduction for single use, but avoid redosing if eGFR <30; check trough if therapy continues

— Aminoglycosides: single preop dose generally safe; avoid in eGFR <30 when alternatives exist

— Fluoroquinolones: dose-adjust for eGFR <50

— Aztreonam: adjust for eGFR <30

— Metronidazole: reduce dose by 50% in severe (Child-Pugh C) cirrhosis

— Clindamycin: caution; monitor LFTs in prolonged use, single dose usually fine

— Ceftriaxone: caution in combined hepatic + renal failure (biliary sludge, displaces bilirubin)

— Albumin <3 g/dL predicts SSI; defer elective surgery for nutritional optimization when feasible

— Pressure injury risk → SCIP-adjacent: skin assessment, padding, positioning

Board pearl: Cefazolin is renally cleared but is rarely the culprit in AKI — most "renal" concerns in cefazolin use are about redosing frequency, not dose reduction of the preop dose itself.

Step 3 management: An 82-year-old with eGFR 35 going for total hip arthroplasty: give standard cefazolin 2 g preop; if case >4 hours, redose at 6–8 hours instead of 4. No need to substitute vancomycin unless MRSA risk.

Key distinction: Vancomycin nephrotoxicity is dose- and trough-dependent — a single prophylactic dose rarely causes AKI; avoid prolonged empiric use postop.

Elderly (≥65):

Renal impairment:

Hepatic impairment:

Frail/malnourished:

Special Populations — Pregnancy, Pediatrics, Obesity, Immunocompromise

— C-section: cefazolin 2 g IV (3 g if ≥120 kg) within 60 minutes BEFORE skin incision — single most-tested OB prophylaxis fact

— Add azithromycin 500 mg IV for non-elective (laboring or ruptured membranes) C-section — reduces endometritis, wound infection

— β-lactam severe allergy: clindamycin + gentamicin

— Avoid: fluoroquinolones, tetracyclines, sulfonamides near term, aminoglycosides when alternatives exist

— Postpartum tubal ligation, D&C for retained products, cerclage: case-specific, often cefazolin

— Cefazolin 30 mg/kg (max 2 g) within 60 min of incision; redose every 4 h

— Vancomycin 15 mg/kg

— Clindamycin 10 mg/kg

— Weight-based dosing critical; underdosing common pitfall

— Cefazolin 3 g (some recommend 2 g if <120 kg, 3 g if ≥120 kg, with adult literature supporting up to 3 g for morbid obesity)

— Adequate dosing matters more than agent choice — underdosing predicts SSI

— Higher SSI baseline → strict bundle adherence

— Standard agents, but threshold to extend coverage for gram-negatives or fungi if indicated by surgery type

— Coordinate with transplant or oncology team for biologic timing (hold TNF-α inhibitors perioperatively per ACR/AAOS guidance)

— Maintain prophylaxis duration per SCIP — do not extend "just because immunocompromised" unless contamination

— Tight perioperative glucose (<180 mg/dL); SCIP Inf-4 for cardiac

— Hold SGLT2 inhibitors 3–4 days preop (DKA risk)

Board pearl: Cefazolin before skin incision in C-section is a near-guaranteed exam point — paired with azithromycin for non-elective cases.

Step 3 management: A 145 kg patient for ventral hernia repair with mesh: order cefazolin 3 g (not 2 g) within 60 min of incision; redose at 4 h if case extends.

Pregnancy:

Pediatrics:

Obesity (BMI ≥35 or weight ≥120 kg):

Immunocompromised (solid organ transplant, chemotherapy, biologics, HIV with low CD4):

Diabetes:

Complications and Adverse Outcomes

— Superficial incisional: skin/subcutaneous, within 30 days

— Deep incisional: fascia/muscle, within 30–90 days

— Organ/space: within 30–90 days (or 1 year if implant)

— Most common organisms: S. aureus (MSSA > MRSA), coagulase-negative staph, E. coli, Enterococcus, Pseudomonas (procedure-dependent)

— C. difficile infection (CDI): risk rises with each unnecessary postop day of antibiotics — primary reason for SCIP Inf-3

— Allergic reactions: anaphylaxis, urticaria, rash; red man syndrome (vanco infusion rate) is non-allergic

— Nephrotoxicity: vancomycin, aminoglycosides

— AKI: vancomycin + piperacillin-tazobactam combination carries elevated AKI risk

— QT prolongation: fluoroquinolones, macrolides

— Tendinopathy and aortic dissection risk: fluoroquinolones (especially in elderly, steroid users)

— Antimicrobial resistance: selection of MDR organisms

— Wrong drug (e.g., vanco alone for clean cardiac in non-MRSA patient → MSSA breakthrough)

— Wrong dose (under-dosed obese patient)

— Wrong timing (>60 min preop, or after incision)

— Missed redose in long case

— Continued beyond 24/48 h

— Hypothermia → coagulopathy, increased SSI, cardiac events

— Hyperglycemia → impaired neutrophil function, sternal wound infection

— CAUTI from delayed Foley removal (SCIP Inf-9)

— VTE from missed prophylaxis (separate SCIP VTE measures)

Board pearl: A postop fever pattern: POD 0–1 atelectasis or drug fever, POD 3–5 UTI or pneumonia, POD 5–7 wound infection, POD >7 DVT/PE or abscess — the "5 Ws" mnemonic remains testable.

Key distinction: C. difficile presenting as postop diarrhea after "routine" prophylaxis extended to 5 days = iatrogenic, SCIP-preventable.

Step 3 management: Suspected SSI → open and drain, culture, then targeted antibiotics — don't escalate empirically without source control.

Surgical site infection (SSI) — primary outcome prophylaxis prevents:

Antibiotic-related complications:

Prophylaxis failure patterns to recognize:

Systemic and procedural complications related to bundle failures:

When to Escalate Care — Consults, ICU, and Inpatient Triage

— Anaphylaxis during antibiotic infusion → stop infusion, epinephrine IM, IV fluids, secure airway, consider postponing elective surgery; allergy consult before next exposure

— Severe red man syndrome → slow infusion, antihistamines; not an escalation unless airway involvement

— Suspected SJS/TEN, DRESS → ICU or burn unit, dermatology, discontinue agent, no rechallenge ever

— Massive bleeding during long case → anesthesia communicates need for antibiotic redose; surgical team responsibility to track

— Sepsis from SSI or anastomotic leak: ICU admit, broad-spectrum empiric therapy (often piperacillin-tazobactam or meropenem + vancomycin), urgent source control (IR drainage or reoperation), surgical consult

— Mediastinitis after cardiac surgery: cardiac surgery consult, ICU, broad gram-positive + gram-negative coverage, washout

— Necrotizing soft tissue infection at wound: immediate surgical debridement, piperacillin-tazobactam + vancomycin + clindamycin (anti-toxin), ICU

— C. difficile fulminant (ileus, megacolon, shock): ICU, IV metronidazole + PO/PR vancomycin, surgical consult for colectomy

— Infectious disease for resistant organisms, prosthetic joint/valve infection, recurrent SSI

— Antimicrobial stewardship — institutional resource for de-escalation

— Allergy/immunology for verified severe β-lactam allergy needing future surgery (consider skin testing or graded challenge)

CCS pearl: When a postop patient spikes a fever and you suspect SSI, on the simulator: examine wound, open and culture if fluctuant, obtain blood cultures × 2, start empiric antibiotics based on local antibiogram, consult surgery — sequence credited.

Step 3 management: A patient develops hypotension and diffuse urticaria 5 minutes into vancomycin infusion → stop infusion, IM epinephrine 0.3–0.5 mg, IV fluids, diphenhydramine, methylprednisolone, secure airway, defer elective surgery, document true vancomycin allergy for future avoidance.

Board pearl: Always document and reconcile allergy events in the chart and EHR allergy list — transition-of-care failures kill.

Escalation triggers in the preop and intraop antibiotic context:

Postoperative escalation:

Specialty consults:

Key Differentials — Same-Category Causes (Surgical Site Issues)

— Superficial SSI: erythema, warmth, tenderness, purulent drainage from incision, fever; within 30 days. Treat with open-and-drain ± oral antibiotics if cellulitis surrounds.

— Deep incisional SSI: fascial dehiscence risk, deeper drainage; often requires OR washout.

— Organ/space SSI: intra-abdominal abscess after colorectal; CT + IR drainage + IV antibiotics.

— Anastomotic leak (POD 3–7): tachycardia, fever, leukocytosis, peritonitis or rising drain output that changes character. CT with oral/rectal contrast or surgery. Antibiotics alone don't substitute for source control.

— Seroma: painless, fluctuant, clear fluid; aspirate if symptomatic; no antibiotics

— Hematoma: painful, ecchymotic, expanding; evacuate if large; no antibiotics unless infected

— Suture reaction / stitch abscess: local, sterile; remove offending suture

— Fat necrosis: firm, indurated, slow resolution

— Wound dehiscence: mechanical failure; may or may not be infected — rule out fascial dehiscence (salmon-colored fluid = "pink fluid sign" → emergent OR)

— CLABSI, CAUTI, ventilator-associated pneumonia — different bundles, different antibiotics, but they masquerade as "SSI" in early postop fever

— Sternal wound infection / mediastinitis post-cardiac

— Periprosthetic joint infection — acute (<3 mo) vs chronic (>3 mo) → different surgical strategy (DAIR vs two-stage revision)

— Mesh infection after hernia repair — often requires mesh removal

Key distinction: Cellulitis vs. abscess: cellulitis = nonpurulent → β-lactam (cephalexin, dicloxacillin); abscess = purulent → I&D first, then antibiotics if surrounding cellulitis, immunocompromise, or systemic signs.

Board pearl: Salmon-colored "pink" serosanguinous drainage from a clean abdominal incision = impending fascial dehiscence, not infection — go to OR.

Step 3 management: Don't treat a postop seroma with antibiotics — aspirate and observe.

Differentiating SSI subtypes and mimics is core Step 3 surgery content:

Non-infectious wound mimics:

Catheter and device-related infection in postop patient:

Specific by procedure:

Key Differentials — Other-Category Causes of Postop Fever

— Atelectasis (controversial as a fever cause but classically taught)

— Drug fever / transfusion reaction

— Malignant hyperthermia (intraop/immediate postop, masseter rigidity, hypercarbia) — dantrolene

— Pre-existing infection (UTI, pneumonia)

— UTI (especially if Foley in place — SCIP Inf-9 emphasizes removal by POD 2)

— Pneumonia / aspiration

— IV line-related phlebitis or CLABSI

— Early SSI (especially streptococcal or clostridial — onset <48 h with severe pain, crepitus, hypotension demands emergent debridement)

— Wound infection (typical SSI window)

— Anastomotic leak

— Intra-abdominal abscess

— C. difficile colitis from antibiotic exposure

— DVT / PE — fever, tachycardia, hypoxia

— Deep abscess, late SSI

— Drug-induced hepatitis, transfusion-associated infections

— Acalculous cholecystitis in critically ill

— Adrenal insufficiency in chronic steroid users without stress dosing

— Withdrawal syndromes (alcohol, benzodiazepine)

— Pancreatitis from medications or hypoperfusion

— Thyroid storm in undiagnosed Graves

Key distinction: Early-onset severe pain at the wound (POD 1–2) with crepitus and systemic toxicity → necrotizing fasciitis or clostridial myonecrosis, not routine SSI — emergent surgical debridement + broad antibiotics + ICU. Antibiotic prophylaxis would not have reliably prevented this in a contaminated case.

Board pearl: The 5 Ws of postop fever: Wind (POD 1–2 atelectasis/pneumonia), Water (POD 3 UTI), Walking (POD 4–5 DVT), Wound (POD 5–7 SSI), Wonder drugs (POD 7+ drug fever, C. diff).

Step 3 management: Postop fever without localizing signs on POD 1 → exam, basic labs, avoid reflex broadening of antibiotics; reassess in 24 h.

POD 0–2 — early fever, usually not infectious:

POD 3–5:

POD 5–7:

POD >7:

Non-surgical mimics during admission:

Secondary Prevention, Discharge, and Long-Term Plan

— Most procedures: stop within 24 h of surgery end

— Cardiothoracic: stop within 48 h

— Do not continue for drains, packing, catheters, or "just in case"

— Most clean and clean-contaminated cases: no antibiotic on discharge

— Contaminated/dirty cases or established infection: continue per source-specific guidelines (e.g., 4–7 days for perforated appendicitis with source control)

— Wound care instructions, infection warning signs (fever, increasing pain, drainage, opening of wound)

— Glycemic management for diabetics

— Mupirocin and chlorhexidine bath protocols ended preop unless prior known recurrent S. aureus infections — coordinate with ID

— Patients with prosthetic joints no longer require routine antibiotic prophylaxis for dental procedures per AAOS/ADA 2015 — case-by-case for immunocompromised

— Patients with prosthetic heart valves, prior IE, congenital cyanotic heart disease, cardiac transplant with valvulopathy still require endocarditis prophylaxis before high-risk dental/respiratory mucosal procedures per AHA

— Amoxicillin 2 g PO 30–60 min before dental work (clindamycin no longer first-line allergy alternative per 2021 update — use azithromycin or doxycycline)

— Document indication, agent, duration in discharge summary

— Flag any allergies developed perioperatively in EHR

— Communicate any positive cultures and follow-up plan to primary care

Key distinction: Surgical prophylaxis ≠ endocarditis prophylaxis. A patient with a mechanical mitral valve undergoing colonoscopy with biopsy needs no antibiotics (GI/GU procedures not in 2007/2021 AHA endocarditis prophylaxis indications).

Board pearl: Clindamycin is no longer recommended for endocarditis prophylaxis in penicillin-allergic patients (2021 AHA) due to C. difficile risk — use cephalexin (non-severe allergy), azithromycin, or doxycycline.

Step 3 management: Discharge summary must specify antibiotic stop date — transition-of-care safety issue.

Discontinuation orders (SCIP Inf-3):

Discharge prescriptions:

Decolonization continuation:

Long-term and repeat surgery considerations:

Antimicrobial stewardship handoff:

Follow-Up, Monitoring, and Counseling

— Vital signs, wound check on rounds

— Daily WBC trend not mandatory; check if clinical concern

— Glucose checks for diabetics and all cardiac surgery patients (target <180 mg/dL — SCIP Inf-4)

— Foley assessment daily; remove by POD 2 unless documented indication (urology, strict I/O for hemodynamics, sacral wound, comfort care)

— Drain output character and volume

— Temperature curve interpretation per "5 Ws"

— Postop visit 1–2 weeks with surgeon for wound check, suture/staple removal

— Longer-term visit per procedure (6 weeks for joint replacement rehab milestone, 30 days for SSI surveillance, 90 days for organ/space SSI in implant procedures)

— Primary care reconciliation within 1–2 weeks for chronic disease optimization

— Warning signs: fever >38.3°C, increasing pain or redness, wound drainage, opening, systemic symptoms

— Diabetes: continued tight glucose, A1c follow-up

— Smoking cessation: strongly tied to wound healing; offer pharmacotherapy

— Nutrition: protein intake, supplements if malnourished

— Activity: procedure-specific weight-bearing and lifting restrictions

— Catheter care if any indwelling device remains

— Institutions track 30-day SSI rates (NSQIP), readmissions for SSI, CDI rates

— Surgeon-level outcome feedback is part of value-based purchasing

Step 3 management: Postop wound check at 2 weeks reveals a 2 cm area of erythema without fluctuance, fever, or systemic symptoms in an otherwise healthy patient — mark borders, oral cephalexin × 5–7 days, return in 48 h or sooner if worsening — outpatient management appropriate.

Board pearl: Smoking cessation ≥4 weeks preop measurably reduces SSI and pulmonary complications — counsel and refer at every visit.

CCS pearl: On the simulator, order "smoking cessation counseling" and "nicotine replacement" during preop visits — both credit.

Inpatient monitoring during prophylaxis window:

Discharge follow-up cadence:

Patient counseling at discharge:

Quality and outcome tracking:

Ethical, Legal, and Patient Safety Considerations

— Antibiotic administration is usually covered under broad surgical consent, but allergy disclosure and shared decision-making matter when using an agent with elevated risk (vancomycin in patient with renal disease, fluoroquinolone in elderly with QT prolongation)

— If a patient refuses prophylaxis, document capacity assessment, risks discussed (increased SSI), alternative non-pharmacologic measures, and proceed with their informed choice

— EHR allergy fields must specify drug, reaction, severity, date; vague "PCN allergy" entries lead to unnecessary vancomycin, more C. difficile, and higher SSI rates

— When a vague allergy is clarified preop (e.g., "rash as a child"), update the chart to reduce future overuse

— Handoffs between OR → PACU → floor → home are high-risk for missed antibiotic discontinuation orders (perpetuating beyond 24 h)

— Discharge summary must specify antibiotic stop date and any pending cultures

— Failure to communicate a positive MRSA swab or intraoperative culture to outpatient providers is a sentinel-event-level safety lapse

— Wrong-site surgery (time-out)

— Retained foreign object

— Mediastinitis after CABG — CMS non-payment trigger; reinforces glucose, decolonization, prophylaxis bundle

— CAUTI and CLABSI after hospital admission

— Inappropriate prophylaxis harms future patients via resistance — collective harm

— Stewardship programs are required by Joint Commission accreditation

— SSI rates publicly reported via NHSN/CMS Hospital Compare

— Adverse drug events to FDA MedWatch when serious

Step 3 management: A patient signed out from the OR team to the floor team with "continue antibiotics" but no stop date — the receiving team's responsibility is to review indication, check SCIP timing, write a stop order at 24 h unless documented reason to continue. Transition-of-care safety mandates closing this loop.

Board pearl: "PCN allergy" carries real morbidity — relabeling/de-labeling programs reduce SSI and C. difficile.

Informed consent for prophylaxis:

Allergy documentation — a major patient safety domain:

Transitions of care — Step 3 favorite:

Never events relevant to SCIP domain:

Antimicrobial stewardship as an ethical duty:

Mandatory reporting:

High-Yield Associations and Rapid-Fire Facts

Board pearl: If the question gives a time for antibiotic infusion start, calculate whether it lands within 60 min (or 120 for vanco) of incision — this is the single most-tested SCIP fact.

Cefazolin within 60 minutes of incision — the SCIP timing rule.

Vancomycin and fluoroquinolones within 120 minutes — longer infusion exception.

Discontinue prophylaxis within 24 hours (48 hours for cardiothoracic).

C-section: cefazolin BEFORE skin incision, not after cord clamp.

Non-elective C-section: add azithromycin to cefazolin.

Colorectal: mechanical bowel prep + oral neomycin/metronidazole the day before, plus IV cefazolin + metronidazole (or cefoxitin) preop.

MRSA-colonized patient before cardiac/ortho implant: cefazolin + vancomycin + mupirocin nares + chlorhexidine bath.

Cefazolin dose: 2 g; 3 g if ≥120 kg; pediatric 30 mg/kg.

Redose cefazolin every 4 hours intraop or after >1500 mL blood loss.

Tourniquet must be inflated AFTER full antibiotic infusion in extremity surgery.

Red man syndrome = infusion rate, not allergy → slow rate, give antihistamine.

Mild PCN allergy ≠ contraindication to cefazolin (cross-reactivity <1%).

Severe PCN/cephalosporin allergy: clindamycin or vancomycin ± gentamicin/aztreonam.

Normothermia (≥36°C) required, especially colorectal surgery — SCIP Inf-10.

POD 1 and 2 glucose <180 mg/dL after cardiac surgery — SCIP Inf-4.

Foley removal by POD 2 — SCIP Inf-9.

Clip, don't shave hair, in the OR — not the night before.

Chlorhexidine-alcohol skin prep preferred over povidone-iodine for most cases.

Endocarditis prophylaxis indications (AHA 2021): prosthetic valve/material, prior IE, unrepaired cyanotic CHD, CHD repair with prosthetic material × 6 months or with residual defect, cardiac transplant with valvulopathy — for high-risk dental and respiratory mucosal procedures only.

Prosthetic joints don't routinely need dental prophylaxis (AAOS/ADA 2015).

Clindamycin no longer recommended for IE prophylaxis allergy alternative (2021 AHA) — use azithromycin or doxycycline.

Elective lap chole in low-risk patient: no prophylaxis needed.

Dirty wound (perforated viscus, established abscess): therapy, not prophylaxis.

Smoking cessation ≥4 weeks preop reduces SSI.

SSI surveillance: 30 days (90 days with implant).

Board Question Stem Patterns

Board pearl: Stems with explicit clock times are almost always testing timing of prophylaxis — calculate the interval before reading answer choices.

Stem 1 — Timing: "Patient receives cefazolin at 0630; incision at 0815." → 105 minutes elapsed = SCIP failure. Correct: infuse within 60 min of incision.

Stem 2 — Allergy clarification: "PCN allergy — rash as a child." Going for THA. → Cefazolin is appropriate; cross-reactivity <1%.

Stem 3 — Severe allergy: "Anaphylaxis to amoxicillin." Going for total knee. → Vancomycin preop (with attention to infusion start 120 min before incision).

Stem 4 — MRSA carrier: "Nasal swab positive for MRSA, scheduled for CABG." → Cefazolin + vancomycin, mupirocin × 5 d + chlorhexidine baths × 5 d preop.

Stem 5 — C-section timing: "G3P2 for repeat C-section." → Cefazolin before skin incision, not after cord clamp.

Stem 6 — Non-elective C-section: "Laboring with ROM 18 hours, going for emergent C-section." → Cefazolin + azithromycin.

Stem 7 — Colorectal prep: "Sigmoid colectomy tomorrow." → Mechanical bowel prep + oral neomycin/metronidazole day before + IV cefoxitin or cefazolin/metronidazole within 60 min of incision.

Stem 8 — Duration error: "POD 3 after appendectomy, still on cefoxitin." → Stop antibiotics (single dose was sufficient for uncomplicated appy; SCIP Inf-3 violation).

Stem 9 — Redosing: "5-hour open AAA, 1800 mL blood loss, given one cefazolin dose at induction." → Redose at 4 h and after major blood loss — failure to do so.

Stem 10 — Obesity: "145 kg patient for ventral hernia with mesh." → Cefazolin 3 g, not 2 g.

Stem 11 — Lap chole: "Healthy 35-year-old, elective lap chole." → No prophylaxis needed.

Stem 12 — Dirty wound: "Perforated diverticulitis." → Therapy (pip-tazo or ceftriaxone + metronidazole), continue postop, not single-dose prophylaxis.

Stem 13 — Endocarditis prophylaxis vs surgical prophylaxis: "Mechanical mitral valve, going for colonoscopy with polypectomy." → No prophylaxis (GI procedure not in AHA indications).

Stem 14 — Tourniquet: "TKA with tourniquet inflated 5 minutes after cefazolin started." → SCIP/best-practice failure — antibiotic must be fully infused before inflation.

Stem 15 — Red man syndrome: "Hypotension, flushing during vanco infusion." → Slow rate, antihistamine, continue — not an allergy.

One-Line Recap

Give the right antibiotic, at the right dose, within 60 minutes of incision (120 for vancomycin/fluoroquinolones), redose for long cases or blood loss, and stop within 24 hours (48 for cardiothoracic) — that is the heart of SCIP-aligned surgical antibiotic prophylaxis.

Board pearl: When in doubt on a Step 3 surgical vignette — check the clock, the drug, the dose, the duration, and the allergy chart. Those five anchors capture nearly every testable SCIP point.

Timing: Cefazolin (and most β-lactams, clindamycin) within 60 min of incision; vanco/FQ within 120 min; C-section before skin incision; complete infusion before tourniquet inflation.

Selection: Cefazolin is the workhorse for most clean and clean-contaminated cases; add metronidazole or use cefoxitin when anaerobes matter (colorectal, appy); add vancomycin (don't replace cefazolin) for MRSA carriers in cardiac/ortho implant; clindamycin or vanco ± gent/aztreonam for severe β-lactam allergy.

Dose and redose: 2 g cefazolin, 3 g if ≥120 kg, pediatric 30 mg/kg; redose at 4 h or after >1500 mL blood loss.

Duration: Stop within 24 h (48 h cardiac); drains, catheters, and "just in case" are not indications to extend.

Bundle: Normothermia ≥36°C, glucose <180 mg/dL POD 1–2 in cardiac, Foley out by POD 2, clip don't shave, chlorhexidine-alcohol prep, MRSA decolonization when indicated.

Allergy nuance: Mild PCN allergy does not preclude cefazolin; clarify and de-label whenever possible — overuse of vanco worsens outcomes.

Special cases: Dirty wounds get therapy, not prophylaxis; lap chole in low-risk patient needs none; prosthetic joints don't routinely need dental prophylaxis; endocarditis prophylaxis is a separate, narrower indication list.

Safety/transition: Document allergies precisely, write a stop date in the discharge summary, and treat antimicrobial stewardship as an ethical obligation.