Cholecystitis
Clinical Snapshot
Acute cholecystitis is inflammation of the gallbladder wall. In the great majority of cases (90-95%), a gallstone impacts in the cystic duct, obstructing outflow and triggering distension, venous congestion, bacterial overgrowth and a secondary inflammatory response — calculous cholecystitis. A distinct minority (roughly 5-10%) occurs without any gallstone at all — acalculous cholecystitis — almost always in critically ill patients (prolonged fasting or parenteral nutrition, mechanical ventilation, major trauma or burns, sepsis) where gallbladder stasis and ischemia, rather than mechanical obstruction, drive the same inflammatory cascade. Acalculous disease carries a higher rate of gangrene and perforation than calculous disease and is easy to miss in a sedated or ventilated patient who cannot report pain.[1]
Gallstones affect a substantial proportion of adults in North America and Western Europe, the large majority of whom remain asymptomatic for life; acute cholecystitis is the most common serious complication in those who do become symptomatic.[2] Untreated, the sequence is predictable: obstruction leads to distension, ischemia, and, without intervention, gangrene and perforation. The internationally adopted Tokyo Guidelines (TG18) define explicit diagnostic criteria and a 3-tier severity grade (I mild, II moderate, III severe) that together drive nearly every decision in this chapter, from which imaging to order to whether a patient goes to the operating room today or is stabilized first.[3]
Definitive treatment is cholecystectomy, and the single biggest change in management over the last decade is timing: early laparoscopic cholecystectomy, performed within the same hospital admission rather than after a course of antibiotics and a planned return in 6-8 weeks, is now the guideline-endorsed standard of care wherever a patient's overall condition and local surgical resources allow it — a position adopted by the World Society of Emergency Surgery's 2020 update, whose panel includes a Canadian co-author (Andrew W. Kirkpatrick, Foothills Medical Centre, Calgary, Alberta).[2] This chapter also covers the pharmacist-relevant work of choosing and stopping biliary antibiotics correctly, differentiating cholecystitis from the more dangerous entity of ascending cholangitis, and supporting patients through the now much shorter window between diagnosis and surgery.
Recognize the Condition
The classic pattern
Right upper quadrant (RUQ) or epigastric pain, often severe and constant — distinguishing it from the waxing-and-waning pain of simple biliary colic (see Assessment & Diagnosis) — that may radiate to the right scapula or interscapular back. Nausea, vomiting, and anorexia are common, fever is frequent but not universal (especially early), and a history of similar but self-limited episodes after fatty meals is typical: biliary colic that this time "didn't go away."[3]
Murphy's sign
Ask the patient to take a deep breath while palpating the right subcostal margin; inspiratory arrest from pain as the inflamed gallbladder descends onto the examiner's fingers is a positive Murphy's sign. It is the single most useful individual physical finding for this diagnosis, but — like every other individual history, exam, or basic laboratory finding studied — it is not sensitive or specific enough on its own to rule the diagnosis in or out. A systematic review of the history and physical examination found a positive Murphy's sign carried a positive likelihood ratio of only 2.8 (95% CI 0.8-8.6), and even normal right-upper-quadrant tenderness could not reliably exclude the diagnosis (negative likelihood ratio 0.4, 95% CI 0.2-1.1). Clinical gestalt plus imaging — not any single finding — makes the diagnosis.[4]
Acalculous cholecystitis looks different
In a critically ill, sedated, or ventilated patient, none of the above may be reportable or elicitable. Suspect acalculous cholecystitis in this population with otherwise-unexplained fever, sepsis, leukocytosis, or abnormal liver enzymes, and image early — this variant progresses to gangrene and perforation more often, and more quickly, than calculous disease.[1]
Risk Factors
- The classic "4 F's" for gallstone disease — Female, Forty (increasing age), Fertile (multiparity/pregnancy), and Fat (obesity) — remains a genuinely useful bedside teaching mnemonic, though gallstones and cholecystitis occur across every age, sex, and body habitus.
- Rapid or substantial weight loss, including after bariatric surgery or very-low-calorie diets, which increases cholesterol saturation of bile and gallbladder stasis.
- Pregnancy — elevated estrogen increases cholesterol secretion into bile, and progesterone reduces gallbladder motility.
- Total parenteral nutrition and prolonged fasting — a specific driver of acalculous cholecystitis through gallbladder stasis when the gallbladder is never stimulated to empty.
- Critical illness generally — mechanical ventilation, major trauma or burns, sepsis, and post-cardiac-surgery states are the classic settings for acalculous cholecystitis.
- Medications that promote biliary sludge or stasis: ceftriaxone (forms a calcium-ceftriaxone precipitate causing reversible "biliary pseudolithiasis," typically after several days of therapy) and octreotide (reduces gallbladder motility and cholecystokinin release with ongoing use).
- Hemolytic conditions (e.g., sickle cell disease, hereditary spherocytosis) producing pigment stones through chronic bilirubin overproduction.
- Diabetes mellitus, cirrhosis, and a family history of gallstone disease.
- Older age broadly increases gallstone prevalence and the risk of a complicated (gangrenous, emphysematous, or perforated) presentation.
Red Flags & Refer
Escalate urgently — beyond routine cholecystitis management — for any of the following:
- Signs of gangrenous or emphysematous cholecystitis — a markedly tender, tense gallbladder; crepitus or gas on imaging (emphysematous cholecystitis, more common in diabetes and carrying a higher mortality); or a patient who looks far sicker than the exam alone would suggest. A delayed or missed diagnosis here is a leading cause of perforation.
- Suspected perforation — diffuse peritonitis, free air, or a pericholecystic/subhepatic collection on imaging, or hemodynamic instability. This is a surgical emergency.
- Charcot's triad (RUQ pain, fever, jaundice) or, more ominously, Reynolds' pentad (Charcot's triad plus hypotension and altered mental status) — this is ascending cholangitis, not simple cholecystitis, and needs urgent biliary drainage (usually ERCP), not just antibiotics and a cholecystectomy booking. See Assessment & Diagnosis for how to tell the two apart.[5]
- TG18 Grade III (severe) disease — any new organ dysfunction (hypotension needing vasopressor support, altered mental status, a PaO2/FiO2 ratio under 300, oliguria or a creatinine over 2.0 mg/dL [177 μmol/L], an INR over 1.5, or a platelet count under 100 x 10⁹/L) — needs concurrent critical-care-level support alongside biliary source control.[3]
- Jaundice, or a bilirubin/ALP substantially higher than expected for simple cholecystitis — raises concurrent choledocholithiasis and needs imaging of the common bile duct before assuming cholecystitis is the whole picture.
- Pregnancy with suspected acute cholecystitis — needs prompt surgical involvement; see Special Populations.
- A critically ill, sedated, or ventilated patient with otherwise-unexplained sepsis — actively rule out acalculous cholecystitis rather than waiting for a classic history this population often cannot provide.[1]
Assessment & Diagnosis
The Tokyo Guidelines (TG18) diagnostic criteria
| Category | Findings |
|---|---|
| A. Local signs of inflammation | Murphy's sign, or right-upper-quadrant mass, pain, or tenderness |
| B. Systemic signs of inflammation | Fever, elevated CRP, or an elevated white cell count |
| C. Imaging findings | Findings characteristic of acute cholecystitis on ultrasound, CT, MRI, or cholescintigraphy |
- Suspected diagnosis — 1 item from A plus 1 item from B.
- Definite diagnosis — 1 item from A plus 1 item from B plus C (imaging confirmation).
Severity grading — this, not just the diagnosis, drives the management plan
| Grade | Definition |
|---|---|
| Grade I (mild) | Does not meet the criteria for Grade II or III. Mild gallbladder inflammation in an otherwise healthy patient with no organ dysfunction — cholecystectomy is a low-risk procedure. |
| Grade II (moderate) | Any one of: a white cell count over 18 x 10⁹/L; a palpable, tender right-upper-quadrant mass; duration of symptoms over 72 hours; or marked local inflammation (biliary peritonitis, a pericholecystic or hepatic abscess, or gangrenous or emphysematous cholecystitis). |
| Grade III (severe) | Dysfunction of any one organ system: cardiovascular (hypotension needing vasopressor support), neurological (decreased level of consciousness), respiratory (a PaO2/FiO2 ratio under 300), renal (oliguria, or a creatinine over 2.0 mg/dL [177 μmol/L]), hepatic (an INR over 1.5), or hematological (a platelet count under 100 x 10⁹/L). |
Distinguishing biliary colic, acute cholecystitis, and choledocholithiasis/ascending cholangitis
| Feature | Biliary colic | Acute cholecystitis | Choledocholithiasis / ascending cholangitis |
|---|---|---|---|
| Pain pattern | Episodic RUQ/epigastric pain, typically resolving within a few hours | Persistent RUQ pain, often over 6 hours, with true local and systemic inflammation | RUQ pain with jaundice; in cholangitis, fever is prominent |
| Fever / systemic signs | Absent | Present (meets TG18 local plus systemic criteria) | Charcot's triad (pain, fever, jaundice); Reynolds' pentad adds hypotension and altered mental status in severe cholangitis |
| Liver enzymes / bilirubin | Normal | Normal or mildly elevated | Bilirubin, ALP, and GGT more substantially elevated, reflecting bile-duct obstruction |
| Imaging | Gallstones without gallbladder wall changes | Gallstones with wall thickening, pericholecystic fluid, or a sonographic Murphy's sign | A dilated common bile duct, often with a visible stone; the gallbladder itself may or may not show acute changes |
| Priority intervention | Analgesia; elective outpatient work-up toward elective cholecystectomy | Admission, antibiotics if indicated, early cholecystectomy (see Choose Initial Treatment) | Urgent biliary drainage (usually ERCP) takes priority over cholecystectomy — see Choose Initial Treatment |
Laboratory testing
White cell count is often mildly to moderately elevated with a left shift, and CRP is typically elevated — both feed directly into the TG18 systemic-inflammation criterion and severity grade above.[3] Liver enzymes and bilirubin are usually normal or only mildly elevated in isolated cholecystitis; a more substantial rise in bilirubin, ALP, or GGT should prompt evaluation for concurrent choledocholithiasis rather than being attributed to cholecystitis alone.
Imaging
| Modality | Sensitivity | Specificity | Role and practical notes |
|---|---|---|---|
| Right-upper-quadrant ultrasound | 81% (95% CI 75-87%) | 83% (95% CI 74-89%) | First-line in essentially every patient — fast, no radiation, no contrast, though operator-dependent. Look for gallstones, gallbladder wall thickening (3 mm or more), pericholecystic fluid, and a sonographic Murphy's sign. |
| Cholescintigraphy (HIDA scan) | 96% (95% CI 94-97%) | 90% (95% CI 86-93%) | The single most accurate study for this diagnosis; reserve for an equivocal ultrasound when suspicion remains high. Non-visualization of the gallbladder indicates cystic duct obstruction and is itself diagnostic. Slower to obtain and involves a radiotracer. |
| MRI / MRCP | 85% (95% CI 66-95%) | 81% (95% CI 69-90%) | No ionizing radiation; particularly useful for evaluating the common bile duct (MRCP) and in pregnancy. |
| CT | 94% (95% CI 73-99%, single study) | 59% (95% CI 42-74%) | Lower specificity than ultrasound for cholecystitis itself; most useful for identifying complications (perforation, abscess, emphysematous change) or when the diagnosis is unclear and another intra-abdominal cause is being excluded. |
[6] A practical pathway: RUQ ultrasound first in essentially every patient with suspected acute cholecystitis.[2][3] If ultrasound is equivocal but suspicion remains high, cholescintigraphy is the most accurate confirmatory test.[6] Add MRCP, CT, or proceed toward ERCP if there is concern for a bile-duct stone (an elevated bilirubin, ALP, or GGT, or a dilated common bile duct on ultrasound) — see Choose Initial Treatment for the cholangitis pathway.
Treatment Targets
- Confirm the diagnosis and assign a TG18 severity grade efficiently — grade, not just "cholecystitis, yes or no," drives the whole plan.
- Control pain and nausea while keeping the patient NPO pending a surgical or interventional decision.
- Start appropriate empiric antibiotics promptly for anything beyond the mildest, non-toxic presentations, and stop them on schedule once source control is achieved rather than by default.
- Achieve definitive source control — early laparoscopic cholecystectomy for the great majority of patients — rather than defaulting to a prolonged antibiotics-then-interval-surgery approach that current evidence no longer supports for most patients.
- Identify concurrent choledocholithiasis or ascending cholangitis promptly, since it changes the plan to urgent biliary drainage ahead of cholecystectomy.
- Recognize and escalate gangrenous, emphysematous, or perforated disease immediately rather than treating it as routine cholecystitis.
- Select a genuinely safe path — percutaneous cholecystostomy plus antibiotics, with cholecystectomy deferred or never performed — for patients too unwell for surgery, rather than pushing an unsafe operation.
- Set patients up with clear counselling on fat restriction, warning signs, and the plan for surgery, whether same-admission or interval.
Choose Initial Treatment
Confirm the diagnosis, grade severity, then choose the pathway
Once TG18 criteria confirm acute cholecystitis (see Assessment & Diagnosis), grade severity (I mild, II moderate, III severe) — this is what determines whether a patient goes for surgery this admission, needs gallbladder drainage first, or needs organ-support before either.[7]
Management by TG18 severity grade
Grade I (mild)
1st line early laparoscopic cholecystectomy — safe and preferred, performed as soon as reasonably possible after diagnosis, ideally within 72 hours of symptom onset and generally no later than about 1 week, at centres with appropriate laparoscopic experience.[2][8][9]
Grade II (moderate)
Early laparoscopic cholecystectomy remains preferred at centres experienced with acute inflammatory disease. Local inflammation too severe for safe immediate surgery gallbladder drainage (percutaneous cholecystostomy) plus antibiotics, with cholecystectomy performed once inflammation has settled.[7]
Grade III (severe)
Manage organ dysfunction (critical-care-level supportive care) in parallel with urgent biliary source control — not sequentially. If the patient's physiologic reserve and comorbidity burden support it, early cholecystectomy at an experienced centre is reasonable; if not, percutaneous cholecystostomy is the safer initial step, with cholecystectomy — if ever appropriate — deferred to full recovery.[7]
Why "early" changed from a debate to a default
The randomized ACDC trial compared immediate surgery (within 24 hours of admission) with delayed surgery (7-45 days later, after initial antibiotics): immediate surgery reduced overall morbidity with no difference in mortality, and shortened both hospital stay and cost.[8] A Cochrane review pooling multiple randomized trials of early (within 1 week of diagnosis) versus delayed (6-12 weeks later) laparoscopic cholecystectomy found shorter total hospital stay with early surgery and no meaningful difference in bile-duct injury or conversion-to-open rate — evidence that overturned the older default of "cool it down with antibiotics, operate electively months later."[9]
Charcot's triad, Reynolds' pentad, or imaging showing a dilated common bile duct with a visible stone means this is ascending cholangitis, not simple cholecystitis. The priority is urgent biliary decompression — usually ERCP — which takes precedence over cholecystectomy; broad-spectrum antibiotics are started immediately but are not a substitute for drainage. Cholecystectomy, once indicated, generally follows once cholangitis is controlled, often during the same admission.[5]
Antibiotic selection and stewardship
Choose empiric antibiotics targeting enteric gram-negatives — and, where biliary instrumentation or a healthcare-associated source is likely, anaerobes and Enterococcus — based on TG18 grade and any resistance risk factors (recent hospitalization, prior antibiotic exposure, known ESBL colonization).[10] See Pharmacologic Treatment Options and Drug Tables for specific regimens.
Adequate source control achieved stop antibiotics within about 24 hours after cholecystectomy for mild-to-moderate (Grade I-II) disease with the gallbladder fully removed — this is an explicit TG18 management-bundle recommendation, not a judgment call, and unnecessary continuation adds cost and resistance pressure without benefit.[11] Incomplete source control, or Grade III disease continue a longer course, commonly 4-7 days and guided by clinical response — see Drug Tables.[10]
Percutaneous cholecystostomy — for whom, and what happens after
Reserve for patients whose surgical or physiologic risk is judged too high for even early laparoscopic cholecystectomy, and for Grade II/III disease with local inflammation too severe for safe immediate surgery. It achieves source control (drainage) without removing the gallbladder, buying time for acute inflammation and any organ dysfunction to resolve. A Cochrane review found insufficient high-quality evidence to define precisely which high-risk patients benefit most, or whether cholecystostomy improves survival over antibiotics alone — treat it as a bridge, or as a definitive option for a genuinely poor surgical candidate, not as an automatic substitute for surgery in someone who could otherwise tolerate an operation.[12] Reassess for interval cholecystectomy once the patient has recovered, since the gallstones — and the risk of recurrence — remain unless the gallbladder is eventually removed.
Non-Pharmacologic Treatment
- NPO (nothing by mouth) while a surgical or interventional decision is pending, with IV fluid resuscitation.
- Early laparoscopic cholecystectomy is preferred over open surgery and over delayed/interval surgery for the great majority of patients — shorter stay, faster recovery, and, per current trial evidence, no increase in bile-duct injury or conversion-to-open rate compared with delayed surgery.[9]
- Percutaneous cholecystostomy (image-guided, under local anesthesia) for patients too unwell for surgery — see Choose Initial Treatment.
- Urgent ERCP for confirmed choledocholithiasis or ascending cholangitis, ahead of cholecystectomy — see Choose Initial Treatment.
- Correct coagulopathy and optimize hemodynamics before any procedure.
- Nasogastric decompression only for significant vomiting or ileus, not routinely.
- For patients ultimately not undergoing cholecystectomy — a poor surgical candidate managed definitively with drainage alone, or awaiting an interval operation — counsel on a low-fat diet to reduce symptomatic biliary colic episodes; this does not treat the underlying gallstone disease itself.
Special Populations
Pregnancy
Acute cholecystitis is the second most common non-obstetric surgical emergency of pregnancy after appendicitis. Ultrasound remains first-line imaging throughout pregnancy given its safety profile. Do not delay indicated surgery for suspected acute cholecystitis on the basis of gestational age alone — laparoscopic cholecystectomy is considered safe in every trimester where expertise is available, and unresolved intra-abdominal inflammation carries its own risks to the pregnancy. For antibiotic selection, beta-lactams (penicillins, cephalosporins, carbapenems) are generally preferred and considered compatible throughout pregnancy; avoid fluoroquinolones and tetracyclines.
Breastfeeding
Cefazolin, ceftriaxone, piperacillin-tazobactam, ertapenem, meropenem, and metronidazole at standard multidose regimens are all considered compatible with breastfeeding; confirm specifics against each drug's own Drug Database entry. Avoid fluoroquinolones (ciprofloxacin) when a suitable alternative exists.
Pediatrics
Acute cholecystitis is uncommon in children and, when it occurs, is disproportionately linked to hemolytic disease (pigment stones, e.g., sickle cell disease, hereditary spherocytosis) or to acalculous disease following a systemic viral or bacterial illness. The same TG18 diagnostic and severity framework applies, adapted with pediatric surgical and imaging expertise and weight-based antibiotic dosing.
Older adults
Presentation is more often atypical and blunted — less pronounced fever and pain than the underlying severity would suggest — and gangrenous, emphysematous, and perforated disease are more common at presentation. Maintain a lower threshold for imaging and for early surgical involvement. Frailty and comorbidity burden, not age alone, should determine the choice between early cholecystectomy and a cholecystostomy-first approach in the Grade III pathway.
Critically ill / ICU patients
This is the population at real risk of acalculous cholecystitis: presentation is frequently limited to unexplained sepsis, and diagnosis relies on a lower threshold for imaging rather than a classic history the patient cannot provide. Gangrene and perforation are more common than in calculous disease, and percutaneous cholecystostomy is frequently the preferred initial step given the high surgical risk typical of this population.[1]
Renal impairment
Dose-adjust piperacillin-tazobactam, the carbapenems (ertapenem, meropenem), ciprofloxacin, and ketorolac (avoid in significant impairment) for reduced renal function; monitor vancomycin levels or AUC closely. Ceftriaxone and cefazolin typically need little to no adjustment. Consult a renal dosing reference or pharmacist for the specific adjustment.
Hepatic impairment
Reduce the metronidazole dose in severe hepatic impairment given reduced clearance of active metabolites, and use acetaminophen cautiously (lower total daily dose) in significant hepatic impairment. Note that mild transaminase or bilirubin elevation is common in cholecystitis itself and does not necessarily indicate drug-related hepatotoxicity. Most cephalosporins and carbapenems do not require specific hepatic dose adjustment.
Monitoring & Follow-Up
After laparoscopic cholecystectomy for uncomplicated (Grade I-II) disease, routine postoperative monitoring (vitals, wound check, tolerance of oral intake) is generally all that is needed, and same-day or next-day discharge is standard. Track the antibiotic stop date explicitly — about 24 hours after surgery with adequate source control — rather than defaulting to a longer "standard" course left over from an earlier era of practice.[11]
After percutaneous cholecystostomy: monitor drain output, plan a tube cholangiogram before removal, and explicitly schedule reassessment for interval cholecystectomy once the patient has recovered, rather than leaving the drain (or a drain-free but gallbladder-in-situ state) as the default long-term plan.
Watch specifically for new fever, worsening pain, or jaundice in the days after cholecystectomy — these suggest a retained common bile duct stone, a bile leak, or a missed injury, and warrant reimaging rather than an assumption of ordinary post-surgical discomfort (see Treatment Failure / Next Step). Confirm routine histopathology is reviewed on every cholecystectomy specimen — unexpected findings, though uncommon, do occur and change follow-up. Complete medication reconciliation at discharge, including the antibiotic end date and any analgesic taper.
Common Errors to Avoid
- Treating "gallstones on ultrasound" alone as diagnostic of acute cholecystitis without true local and systemic inflammatory signs — gallstones are common and often entirely asymptomatic.
- Defaulting to "antibiotics now, elective surgery in 6-8 weeks" — current trial evidence supports early, same-admission laparoscopic cholecystectomy for the great majority of patients.
- Continuing antibiotics on a fixed multi-day schedule after adequate source control instead of stopping at about 24 hours per the TG18 management-bundle recommendation.
- Missing ascending cholangitis by treating jaundice, RUQ pain, and fever as simply "a bad cholecystitis" rather than recognizing Charcot's triad and pursuing urgent biliary drainage.
- Failing to consider acalculous cholecystitis in a critically ill patient with unexplained sepsis, simply because no gallstones were mentioned on a prior scan.
- Reflexively avoiding morphine for biliary pain over outdated sphincter-of-Oddi-spasm concerns, while reaching for meperidine instead, which carries a real toxicity risk and is not preferred.
- Missing emphysematous or gangrenous cholecystitis by anchoring on "the patient doesn't look that sick," particularly in a patient with diabetes.
- Choosing percutaneous cholecystostomy reflexively in a patient who could actually tolerate early laparoscopic cholecystectomy, rather than reserving it for genuinely high-risk patients or severe local inflammation.
- Forgetting to schedule interval-cholecystectomy reassessment after cholecystostomy in a patient whose condition later improves.
Clinical Decision Algorithm
Drug Tables
How to use this table: Doses are adult doses and require patient-specific confirmation (renal/hepatic function, weight, allergy history). Pediatric dosing is weight-based per the current product monograph unless stated. Drug pricing is intentionally omitted. Select any drug name to open its complete Pharmasist Drug Database page.
Empiric Antibiotics — Grade I/II (Mild-to-Moderate) Community-Acquired Disease
Stop within about 24 hours after cholecystectomy once source control is adequate; a full listed course applies only when the gallbladder is not removed promptly.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Ceftriaxone | Adults: 2 g IV once daily | Hypersensitivity, biliary sludging, transient LFT elevation | Do not co-administer with calcium-containing IV solutions | Combine with metronidazole; dual therapy is a standard, cost-effective first choice. |
| Cefazolin | Adults: 1-2 g IV every 8 hours | Hypersensitivity, rare interstitial nephritis | Possible increased INR with warfarin | Reserve for genuinely mild, low-resistance-risk community-acquired disease; add metronidazole if anaerobic coverage is needed. |
| Metronidazole | Adults: 500 mg IV every 8 hours | GI upset, metallic taste, peripheral neuropathy with prolonged use | Disulfiram-like reaction with alcohol | Added to a cephalosporin (or another agent without reliable anaerobic activity) when anaerobic coverage is indicated. |
Empiric Antibiotics — Grade III (Severe) or Healthcare-Associated / High Resistance-Risk Disease
Broader single-agent or combination coverage; continue for a defined course (commonly 4-7 days) guided by clinical response and adequacy of source control.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Piperacillin-tazobactam | Adults: 3.375-4.5 g IV every 6 hours, renally adjusted | GI upset, rash, interstitial nephritis | May increase methotrexate levels | Single-agent broad coverage including most anaerobes; a reasonable first choice for Grade II-III or resistance-risk disease. |
| Ertapenem | Adults: 1 g IV once daily | Diarrhea, hypersensitivity reactions | May decrease valproic acid levels | Convenient once-daily dosing for ESBL risk; does not cover Pseudomonas — avoid as a default in septic shock. |
| Meropenem | Adults: 1 g IV every 8 hours, renally adjusted | GI upset, hypersensitivity, rare seizures at high doses or in renal impairment | May decrease valproic acid levels | Broadest routine coverage including Pseudomonas; reserve for Grade III, ICU, or high resistance-risk disease. |
| Vancomycin | Adults: 15-20 mg/kg IV every 8-12 hours, level- or AUC-guided | Nephrotoxicity, infusion-related "red man" reaction | Additive nephrotoxicity with other nephrotoxic agents | Add-on, not monotherapy, for suspected Enterococcus/MRSA in severe or healthcare-associated disease. |
Beta-Lactam Allergy Alternative
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Ciprofloxacin | Adults: 400 mg IV every 12 hours | GI upset, tendinopathy risk, QTc prolongation | Chelation with antacids/metal cations reduces absorption; avoid with other QTc-prolonging drugs | Paired with metronidazole; reserve fluoroquinolones for confirmed allergy given resistance and toxicity concerns. |
| Metronidazole | Adults: 500 mg IV every 8 hours | GI upset, metallic taste, peripheral neuropathy with prolonged use | Disulfiram-like reaction with alcohol | Paired with ciprofloxacin for anaerobic coverage. |
Analgesia and Antiemesis
Scheduled multimodal analgesia (acetaminophen plus an NSAID where appropriate) is preferred over an opioid-first approach; reserve opioids for breakthrough pain.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Acetaminophen | Adults: 975-1000 mg PO/IV every 6 hours, maximum 4 g/day (lower in hepatic impairment) | Hepatotoxicity with overdose or in significant hepatic impairment | None significant at standard doses | First-line, scheduled — not only as-needed. |
| Ketorolac | Adults: 15-30 mg IV every 6 hours | GI bleeding, renal impairment, platelet inhibition | Increased bleeding risk with anticoagulants; avoid with other NSAIDs | Limit to 5 days total; avoid in significant renal impairment or active GI bleeding risk. A randomized trial found early NSAID analgesia (diclofenac) in biliary colic reduced progression to overt cholecystitis.[13] |
| Morphine | Adults: 2-4 mg IV every 3-4 hours PRN | Respiratory depression, sedation, constipation, nausea | Additive CNS/respiratory depression with other sedatives | The older concern about sphincter of Oddi spasm is not a reason to withhold morphine; avoid meperidine instead. |
| Hydromorphone | Adults: 0.2-0.5 mg IV every 3-4 hours PRN | Respiratory depression, sedation, constipation, nausea | Additive CNS/respiratory depression with other sedatives | Preferred over morphine in significant renal impairment given more predictable metabolite handling. |
| Ondansetron | Adults: 4 mg IV/PO, may repeat per the product monograph | Headache, QTc prolongation at higher/repeated doses | Additive QTc prolongation with other QTc-prolonging drugs | First-line for nausea and vomiting. |
References
- Acute acalculous cholecystitis: a review — Clinical Gastroenterology and Hepatology (Huffman JL, Schenker S). Clin Gastroenterol Hepatol 2010;8(1):15-22
- 2020 World Society of Emergency Surgery updated guidelines for the diagnosis and treatment of acute calculus cholecystitis — World Journal of Emergency Surgery, World Society of Emergency Surgery (Pisano M, Allievi N, Gurusamy K, et al.). World J Emerg Surg 2020;15:61
- Tokyo Guidelines 2018: diagnostic criteria and severity grading of acute cholecystitis (with videos) — Journal of Hepato-Biliary-Pancreatic Sciences (Yokoe M, Hata J, Takada T, et al.). J Hepatobiliary Pancreat Sci 2018;25(1):41-54
- Does this patient have acute cholecystitis? — JAMA (Trowbridge RL, Rutkowski NK, Shojania KG). JAMA 2003;289(1):80-86
- Tokyo Guidelines 2018: diagnostic criteria and severity grading of acute cholangitis (with videos) — Journal of Hepato-Biliary-Pancreatic Sciences (Kiriyama S, Kozaka K, Takada T, et al.). J Hepatobiliary Pancreat Sci 2018;25(1):17-30
- A systematic review and meta-analysis of diagnostic performance of imaging in acute cholecystitis — Radiology (Kiewiet JJ, Leeuwenburgh MM, Bipat S, Bossuyt PM, Stoker J, Boermeester MA). Radiology 2012;264(3):708-720
- Tokyo Guidelines 2018: flowchart for the management of acute cholecystitis — Journal of Hepato-Biliary-Pancreatic Sciences (Okamoto K, Suzuki K, Takada T, et al.). J Hepatobiliary Pancreat Sci 2018;25(1):55-72
- Acute cholecystitis: early versus delayed cholecystectomy, a multicenter randomized trial (ACDC study, NCT00447304) — Annals of Surgery (Gutt CN, Encke J, Köninger J, et al.). Ann Surg 2013;258(3):385-393
- Early versus delayed laparoscopic cholecystectomy for people with acute cholecystitis — Cochrane Database of Systematic Reviews (Gurusamy KS, Davidson C, Gluud C, et al.). Cochrane Database Syst Rev 2013;(6):CD005440
- Tokyo Guidelines 2018: antimicrobial therapy for acute cholangitis and cholecystitis — Journal of Hepato-Biliary-Pancreatic Sciences (Gomi H, Solomkin JS, Schlossberg D, et al.). J Hepatobiliary Pancreat Sci 2018;25(1):3-16
- Tokyo Guidelines 2018: management bundles for acute cholangitis and cholecystitis — Journal of Hepato-Biliary-Pancreatic Sciences (Mayumi T, Okamoto K, Takada T, et al.). J Hepatobiliary Pancreat Sci 2018;25(1):96-100
- Percutaneous cholecystostomy for high-risk surgical patients with acute calculous cholecystitis — Cochrane Database of Systematic Reviews (Gurusamy KS, Rossi M, Davidson BR). Cochrane Database Syst Rev 2013;(8):CD007088
- Treatment of biliary colic with diclofenac: a randomized, double-blind, placebo-controlled study — Gastroenterology (Akriviadis EA, Hatzigavriel M, Kapnias D, Kirimlidis J, Markantas A, Garyfallos A). Gastroenterology 1997;113(1):225-231
Professional reference only. Apply clinical judgment and verify patient-specific decisions against current authoritative guidance and product information.