When to Order Imaging for Sepsis: ACR Appropriateness Decoded
When to Order Imaging for Sepsis: ACR Appropriateness Decoded
It’s 11 PM in the emergency department. A patient presents with fever, tachycardia, and hypotension, meeting criteria for sepsis. The source is unclear. You suspect an intra-abdominal process, but a basilar pneumonia is also on the differential. Do you order a CT of the abdomen and pelvis, a chest radiograph, or a combined chest/abdomen/pelvis CT scan? Choosing the right initial imaging study is critical for identifying the source of infection quickly while minimizing unnecessary radiation and cost. This guide decodes the American College of Radiology (ACR) Appropriateness Criteria for sepsis to help you make the most informed decision at the point of care.
What Does the ACR Appropriateness Criteria for Sepsis Cover?
This ACR guideline focuses on the use of diagnostic imaging to identify the source of infection in adult and pediatric patients with suspected or confirmed sepsis. The criteria are organized by clinical presentation, addressing common scenarios where the source may be localized to the chest or abdomen, or when the origin is entirely unknown. The primary goal of imaging in this context is to find a treatable source, such as an abscess, perforated viscus, or severe pneumonia, that requires specific intervention beyond systemic antibiotics.
These criteria do not cover the evaluation of septic complications, such as septic emboli to the brain or endocarditis, which are addressed in separate ACR guidelines. The focus here is on the initial diagnostic workup to locate the primary site of infection driving the systemic inflammatory response.
What Imaging Should I Order for Sepsis? Recommendations by Clinical Scenario
The optimal imaging strategy for sepsis depends entirely on the clinical signs and symptoms. The ACR provides clear guidance for several common presentations.
For a patient with suspected or confirmed sepsis and chest symptoms like cough, dyspnea, or chest pain, the initial imaging is straightforward. A chest radiograph is rated Usually appropriate. This is a fast, low-dose, and widely available test that can readily identify pneumonia, a common cause of sepsis. If the initial chest radiograph is normal, equivocal, or shows nonspecific findings, the next step is typically a chest CT. Both CT chest with IV contrast and CT chest without IV contrast are rated Usually appropriate in this scenario to evaluate for more subtle parenchymal disease, pleural effusions, or mediastinal pathology.
When a patient presents with suspected or confirmed sepsis and acute abdominal pain, the focus shifts. For initial imaging in this scenario, CT of the abdomen and pelvis with IV contrast is rated Usually appropriate. IV contrast is crucial for identifying abscesses, inflammatory changes, and vascular complications. While abdominal ultrasound is rated May be appropriate, it is often limited by body habitus and bowel gas. A non-contrast CT abdomen and pelvis is rated May be appropriate (Disagreement), reflecting a lack of consensus and its lower sensitivity for many infectious processes compared to a contrast-enhanced study.
In the challenging scenario of suspected or confirmed sepsis with no specific symptoms suggestive of origin, the workup begins with a broad but low-dose study. A chest radiograph is again rated Usually appropriate as the initial step to rule out a pulmonary source. If the chest radiograph is unrevealing, the next step is to search for an occult source. In this context, a CT of the abdomen and pelvis with IV contrast is rated Usually appropriate. A combined CT of the chest, abdomen, and pelvis with IV contrast is also an option, rated May be appropriate (Disagreement), and may be considered to provide a comprehensive single-study evaluation when the source is truly elusive.
ACR Imaging Recommendations for Sepsis Table
| 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
The ACR guidelines provide distinct relative radiation level (RRL) estimates for adult and pediatric patients, reflecting the critical importance of the As Low As Reasonably Achievable (ALARA) principle in children. Pediatric patients are more sensitive to the long-term risks of ionizing radiation due to their longer life expectancy and the increased radiosensitivity of their developing tissues. For example, a CT of the chest, abdomen, and pelvis is rated ☢ ☢ ☢ ☢ (10-30 mSv) for adults but may fall into a different dose range for children depending on the specific protocol and patient size.
This distinction underscores the need for careful consideration before ordering higher-dose studies like CT in pediatric patients. Non-ionizing modalities like ultrasound (US) or magnetic resonance imaging (MRI), when clinically appropriate, are often preferred. However, in the acute setting of sepsis, the diagnostic urgency and superior utility of CT in identifying a source of infection often outweigh the radiation risk, which can be mitigated by using pediatric-specific low-dose protocols.
Imaging Protocol Details for Sepsis
Once you’ve decided on the right study, the specific imaging protocol is essential for maximizing diagnostic yield. Our protocol guides provide detailed, scannable information on technique, contrast administration, and key interpretation principles for the studies recommended in the sepsis workup.
Tools to Help You Order the Right Study
Navigating imaging guidelines during a busy clinical shift can be challenging. GigHz offers a suite of reference tools designed to provide quick, reliable answers at the point of care, helping you adhere to evidence-based standards and communicate effectively with patients.
For clinical scenarios beyond sepsis, the ACR Appropriateness Criteria Lookup provides a searchable interface to the complete ACR guidelines, covering thousands of clinical variants across all specialties. It helps you quickly find the official recommendations for virtually any clinical presentation.
To ensure the selected study is performed correctly, the Imaging Protocol Library offers detailed, step-by-step protocols for hundreds of common and advanced imaging procedures. These guides are invaluable for trainees and practicing physicians who need to understand the technical details behind the order.
When discussing the risks and benefits of imaging with patients, especially concerning radiation, the Radiation Dose Calculator is an essential tool. It allows you to estimate effective dose for various studies and can help in tracking cumulative exposure for patients with chronic conditions requiring frequent imaging.
Why is CT with IV contrast so frequently recommended in the workup of sepsis?
Intravenous contrast is critical for evaluating infectious and inflammatory processes. It enhances the visibility of abscess walls, phlegmon, and areas of abnormal tissue perfusion. This allows radiologists to distinguish between simple fluid collections and complex, drainable abscesses, which is a key determination in managing a septic patient. Contrast also helps delineate vascular structures, identifying potential septic thrombophlebitis or other vascular complications.
When is a non-contrast CT appropriate for a patient with sepsis?
A non-contrast CT may be appropriate if a patient has a severe contraindication to IV contrast, such as a history of anaphylaxis or severe renal impairment. It can also be useful for identifying specific findings that do not require contrast, such as free intraperitoneal air from a perforated viscus, renal stones causing obstructive pyelonephritis, or calcifications. However, for most suspected intra-abdominal or soft tissue infections, a contrast-enhanced study is significantly more sensitive and specific.
Is there a role for MRI in the initial workup of sepsis?
For the initial, undifferentiated workup of a septic patient, MRI is rated Usually not appropriate. MRI scans are time-consuming, less accessible in an emergency setting, and more susceptible to motion artifact in an unstable patient. Its primary role is in follow-up imaging for specific clinical questions, such as evaluating for spinal epidural abscess, osteomyelitis, or complex deep soft tissue collections where its superior soft tissue contrast is advantageous.
What does the rating “May be appropriate (Disagreement)” signify?
This rating indicates that the ACR expert panel did not reach a consensus on the appropriateness of the procedure for that specific clinical scenario. This often occurs when the evidence is limited or when the risk-benefit profile may vary significantly based on patient-specific factors, available institutional expertise, and local practice patterns. In these cases, the ordering clinician should consider the specific clinical context and may benefit from a direct consultation with a radiologist.
For a patient with sepsis but no localizing signs, why is a chest radiograph the first step instead of a broad CT scan?
Pneumonia is one of the most common causes of sepsis. A chest radiograph is a very fast, low-cost, and low-radiation test that can quickly diagnose or exclude a significant pulmonary source of infection. Starting with this high-yield study avoids the higher radiation dose and cost of an immediate pan-scan (CT of the chest, abdomen, and pelvis). If the chest radiograph is negative, the guidelines then support proceeding to a more advanced study like a CT of the abdomen and pelvis to search for an occult source.
Reviewed by Pouyan Golshani, MD, Interventional Radiologist — May 12, 2026
