When to Order Imaging for Sepsis: ACR Appropriateness Decoded
When to Order Imaging for Sepsis: ACR Appropriateness Decoded
It’s 11 p.m. in the emergency department, and you’re evaluating a patient with a fever, tachycardia, and hypotension. The lactate is elevated, and you’ve initiated sepsis protocols. Now, the critical question: what is the source? The patient’s symptoms are nonspecific, and you need to decide on the right imaging study to guide treatment without delay or unnecessary radiation. Do you start with a chest radiograph, or is a CT of the abdomen and pelvis with contrast the better first step? Choosing the most effective initial imaging is crucial for identifying the source of infection and directing therapy. This guide decodes the American College of Radiology (ACR) Appropriateness Criteria for sepsis to help you make evidence-based decisions at the point of care.
What Does the ACR Appropriateness Criteria for Sepsis Cover?
The ACR Appropriateness Criteria for Sepsis, developed by the Gastrointestinal panel, provides guidance for imaging adult and pediatric patients with suspected or confirmed sepsis. The recommendations are stratified based on the patient’s clinical presentation, helping clinicians select the most suitable initial and subsequent imaging studies. These guidelines focus on identifying the infectious source when it is not clinically apparent.
This topic specifically covers common clinical scenarios, including:
- Sepsis with pulmonary symptoms (e.g., cough, dyspnea).
- Sepsis with acute abdominal pain.
- Sepsis with no localizing signs or symptoms.
- Next-step imaging after a normal or nonspecific initial chest radiograph.
These criteria are intended for the acute setting to find a treatable source of infection. They do not cover the evaluation of known or suspected endocarditis, osteomyelitis, or central nervous system infections, which have their own dedicated guidelines.
What Imaging Should I Order for Sepsis? Recommendations by Clinical Scenario
The optimal imaging strategy for a patient with sepsis depends entirely on the clinical context. The ACR provides specific recommendations for different presentations to maximize diagnostic yield while minimizing risks.
For a patient with suspected or confirmed sepsis presenting with cough, dyspnea, or chest pain, the initial imaging is straightforward. A Radiography chest is rated as Usually appropriate. This is a fast, low-dose, and widely available study that can readily identify common thoracic sources of infection like pneumonia. If the initial chest radiograph is normal, equivocal, or nonspecific, the guidelines recommend follow-up imaging. In this scenario, both CT chest with IV contrast and CT chest without IV contrast are considered Usually appropriate to evaluate for more subtle pneumonia, empyema, or pulmonary abscesses.
When a patient with sepsis presents with acute abdominal pain, the focus shifts to the abdomen and pelvis. A CT abdomen and pelvis with IV contrast is rated as Usually appropriate. This study is highly sensitive for identifying common intra-abdominal sources such as abscess, appendicitis, diverticulitis, cholecystitis, and bowel perforation. While US abdomen May be appropriate, particularly for right upper quadrant pathology, it is less comprehensive than CT. A non-contrast CT of the abdomen and pelvis is rated May be appropriate (Disagreement), reflecting its utility when IV contrast is contraindicated but its lower sensitivity for many inflammatory processes.
In the challenging scenario of suspected or confirmed sepsis with no specific symptoms suggestive of origin, the initial imaging approach is broader. A Radiography chest is still Usually appropriate as a first step, given that pneumonia is a very common cause of sepsis. If the chest radiograph is unrevealing, the next step is typically cross-sectional imaging. A CT abdomen and pelvis with IV contrast is rated Usually appropriate as the next imaging study to search for an occult abdominal or pelvic source. A comprehensive CT chest abdomen pelvis with IV contrast May be appropriate (Disagreement) in this situation, offering a single, all-encompassing study, though with a higher radiation dose.
ACR Imaging Recommendations Table for Sepsis
| Clinical Scenario | Top Procedure | ACR Rating | Adult RRL | Pediatric RRL |
|---|---|---|---|---|
| Suspected or confirmed sepsis. Cough or dyspnea or chest pain. Initial imaging. | Radiography chest | Usually appropriate | ☢ <0.1 mSv | ☢ <0.03 mSv [ped] |
| Suspected or confirmed sepsis. Cough or dyspnea or chest pain. Normal or equivocal or nonspecific chest radiograph. Next imaging study. | CT chest with IV contrast | Usually appropriate | ☢ ☢ ☢ 1-10 mSv | ☢ ☢ ☢ ☢ 3-10 mSv [ped] |
| Suspected or confirmed sepsis. Acute abdominal pain. Initial imaging. | CT abdomen and pelvis with IV contrast | Usually appropriate | ☢ ☢ ☢ 1-10 mSv | ☢ ☢ ☢ ☢ 3-10 mSv [ped] |
| Suspected or confirmed sepsis. No specific symptoms suggestive of origin, or symptoms cannot be assessed. Initial imaging. | Radiography chest | Usually appropriate | ☢ <0.1 mSv | ☢ <0.03 mSv [ped] |
| Suspected or confirmed sepsis. No specific symptoms suggestive of origin, or symptoms cannot be assessed. Normal or equivocal or nonspecific chest radiograph. Next imaging study. | CT abdomen and pelvis with IV contrast | Usually appropriate | ☢ ☢ ☢ 1-10 mSv | ☢ ☢ ☢ ☢ 3-10 mSv [ped] |
Adult vs. Pediatric Sepsis Imaging: Radiation Dose Tradeoffs
Imaging pediatric patients with sepsis requires careful consideration of radiation dose due to their increased radiosensitivity and longer life expectancy, which increases the lifetime risk of radiation-induced malignancy. The ACR guidelines reflect this by providing distinct Relative Radiation Level (RRL) categories for pediatric patients, often placing them in a higher tier than adults for the same CT examination. This highlights the greater effective dose received by smaller bodies.
The principle of ALARA (As Low As Reasonably Achievable) is paramount. While CT is a powerful tool for identifying the source of sepsis, its use in children must be judicious. For example, a CT of the abdomen and pelvis is rated ☢ ☢ ☢ (1-10 mSv) for adults but ☢ ☢ ☢ ☢ (3-10 mSv [ped]) for children. This difference underscores the importance of using pediatric-specific CT protocols that are optimized to reduce dose. In some cases, non-ionizing modalities like ultrasound (US) or Magnetic Resonance Imaging (MRI) may be considered, although their use in the acute sepsis workup is limited by availability, time, and patient cooperation. The decision to use CT should always balance the diagnostic benefit of finding a life-threatening infection against the long-term risks of radiation exposure.
Imaging Protocol Details for Sepsis
Once you’ve decided on the right study based on the clinical scenario, ensuring it is performed correctly is the next critical step. The specific imaging protocol—including contrast timing, slice thickness, and reconstruction parameters—can significantly impact diagnostic quality. Our protocol guides provide detailed, practical information for the key studies recommended in the sepsis workup.
Tools to Help You Order the Right Study
Navigating imaging guidelines in a fast-paced clinical environment can be challenging. GigHz offers a suite of reference tools designed to support evidence-based decision-making at the point of care, helping you select the most appropriate study and communicate effectively with patients and colleagues.
The ACR Appropriateness Criteria Lookup provides a searchable interface for the complete ACR guidelines, extending far beyond sepsis. It allows you to quickly find recommendations for hundreds of clinical variants, ensuring you are aligned with national standards for any patient presentation.
Our Imaging Protocol Library offers detailed, step-by-step guides for performing a wide range of diagnostic imaging studies. These protocols are invaluable for trainees and technologists and serve as a reference for ordering physicians who want to understand the technical aspects of the examinations they select.
The Radiation Dose Calculator is an essential tool for discussing the risks and benefits of imaging with patients. It helps you estimate cumulative radiation exposure from various studies and provides clear, understandable context for conversations about dose, supporting the principles of informed consent and shared decision-making.
Why is CT with IV contrast so frequently recommended for sepsis workup?
Intravenous contrast is crucial for evaluating sepsis because it enhances the visibility of inflammatory processes and vascular abnormalities. It opacifies blood vessels, allowing for the detection of perfusion defects, and it leaks into inflamed tissues, highlighting abscess walls, phlegmon, and organ inflammation. This makes it superior to non-contrast CT for identifying many common sources of sepsis, such as a perforated appendix, diverticular abscess, or pyelonephritis.
When is a non-contrast CT appropriate for a patient with sepsis?
A non-contrast CT may be appropriate in specific situations. The primary indication is a strong contraindication to IV contrast, such as a severe prior allergic reaction or, in some cases, advanced renal failure where the risks are deemed to outweigh the benefits. Non-contrast CT is also useful for identifying specific findings that do not require contrast, such as free intraperitoneal air from a bowel perforation, renal stones causing obstruction, or certain types of hemorrhage. However, for a general sepsis workup, it is significantly less sensitive than a contrast-enhanced study.
Is there a role for MRI in the initial workup of sepsis?
According to the ACR Appropriateness Criteria, MRI is ‘Usually not appropriate’ for the initial evaluation of sepsis. This is due to several practical limitations in the acute setting: MRI scans are longer, less available, and require a stable, cooperative patient. Critically ill, septic patients are often difficult to monitor in the MRI scanner. MRI is typically reserved as a problem-solving tool for specific indications once the patient is stabilized, such as evaluating for spinal epidural abscess or complex soft tissue infections.
What if my septic patient has renal failure and I’m hesitant to give IV contrast?
This is a common clinical dilemma that requires a careful risk-benefit analysis. The risk of contrast-induced nephropathy (CIN) must be weighed against the risk of missing a life-threatening, treatable source of sepsis. In a critically ill patient, identifying and controlling the source of infection is the highest priority. Modern iodinated contrast agents and hydration protocols have reduced the risk of CIN. The decision should be made in consultation with the radiology team. Alternative studies like ultrasound or non-contrast CT can be considered, but their lower diagnostic yield must be acknowledged.
Why is abdominal radiography rated ‘Usually not appropriate’ for suspected abdominal sepsis?
Plain abdominal radiographs have very low sensitivity for most intra-abdominal sources of sepsis. They cannot visualize solid organs, the bowel wall, or the mesentery effectively. While they can detect signs of bowel obstruction (air-fluid levels) or perforation (free air), CT is far more sensitive for both of these findings and can also identify the underlying cause. For suspected abscess, appendicitis, diverticulitis, or cholecystitis, an abdominal radiograph is not a useful diagnostic test.
Reviewed by Pouyan Golshani, MD, Interventional Radiologist — May 12, 2026
