When to Order Imaging for Sepsis: ACR Appropriateness Decoded
It’s late in a busy shift, and you have a patient with a fever, tachycardia, and hypotension. You suspect sepsis, but the source is unclear. Do you order a chest radiograph, a comprehensive computed tomography (CT) scan of the chest, abdomen, and pelvis, or start with an abdominal ultrasound? Rapidly identifying the source of infection is critical for targeted therapy, but unnecessary imaging can delay care and expose the patient to radiation. This guide decodes the American College of Radiology (ACR) Appropriateness Criteria for sepsis to help you make the right call, fast.
What Does the ACR Appropriateness Criteria for Sepsis Cover?
The ACR Appropriateness Criteria for Sepsis, published by the Gastrointestinal panel, provides evidence-based guidelines for imaging patients with suspected or confirmed sepsis. The criteria are designed to help clinicians select the most appropriate initial and subsequent imaging studies to identify the source of infection. This document focuses on common clinical presentations, including patients with pulmonary symptoms, abdominal pain, or those with no localizing signs or symptoms (sepsis of unknown origin).
These guidelines specifically address the initial diagnostic workup. They do not cover follow-up imaging for known infections, imaging for specific conditions that can lead to sepsis (like neutropenic fever or post-procedural complications), or the evaluation of end-organ damage from septic shock. The recommendations are intended for the general adult and pediatric populations where an infectious source is sought.
What Imaging Should I Order for Sepsis? Recommendations by Clinical Scenario
Choosing the right imaging study depends entirely on the clinical context. The ACR provides specific recommendations based on the patient’s signs and symptoms to guide the diagnostic pathway.
For a patient with suspected or confirmed sepsis presenting with cough, dyspnea, or chest pain, the initial imaging study is straightforward. A chest radiograph is rated Usually appropriate. This is a low-dose, readily available first step to evaluate for pneumonia, empyema, or other thoracic sources of infection. If the initial chest radiograph is normal, equivocal, or nonspecific, the next step is typically a CT of the chest with or without IV contrast, both of which are rated Usually appropriate in this scenario. Contrast-enhanced CT is particularly useful for evaluating for pulmonary embolism, abscess, or complex pleural effusions.
When the clinical picture points to an intra-abdominal source, such as in a patient with suspected or confirmed sepsis and acute abdominal pain, the guidelines are different. A CT of the abdomen and pelvis with IV contrast is rated Usually appropriate. This study provides a comprehensive evaluation of the solid organs, bowel, and peritoneal space, and is highly sensitive for identifying sources like abscess, appendicitis, diverticulitis, or cholecystitis. An abdominal ultrasound (US) May be appropriate, often used as an initial test in the right upper quadrant for suspected biliary pathology or in patients where radiation is a primary concern. A non-contrast CT of the abdomen and pelvis May be appropriate, but there is panel disagreement, as IV contrast is often crucial for identifying inflammatory changes and abscess collections.
The most challenging scenario is the patient with suspected or confirmed sepsis with no specific symptoms suggestive of origin. As a first step, a chest radiograph is Usually appropriate to quickly rule out a pulmonary source. If the source remains elusive, several other studies May be appropriate, including CT of the chest (with or without contrast), CT of the abdomen and pelvis with IV contrast, or a combined CT of the chest, abdomen, and pelvis with IV contrast. The choice depends on subtle clinical clues, lab values, and institutional protocols. If the initial chest radiograph in this non-localizing patient is normal or nonspecific, a CT of the abdomen and pelvis with IV contrast becomes Usually appropriate as the next step to search for a common occult source.
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 suspected sepsis requires careful consideration of radiation dose. Children are more radiosensitive than adults, and cumulative radiation exposure is a significant concern over their longer expected lifespan. The principle of As Low As Reasonably Achievable (ALARA) is paramount.
The ACR guidelines reflect this by providing separate Relative Radiation Level (RRL) estimates for pediatric patients. For example, a CT of the abdomen and pelvis has an adult RRL of ☢ ☢ ☢ (1-10 mSv) but a pediatric RRL of ☢ ☢ ☢ ☢ (3-10 mSv [ped]). While the absolute dose in millisieverts (mSv) may be in a similar range (and often lower due to size-based protocols), the higher RRL category for children signifies a greater relative biological risk. This underscores the importance of justifying every CT scan in a pediatric patient and considering non-ionizing alternatives like ultrasound or MRI when clinically appropriate. For sepsis of unknown origin, starting with chest radiography and targeted ultrasound can often obviate the need for broad CT imaging in children.
Imaging Protocol Details for Sepsis
Once you’ve decided on the right study, the specific imaging protocol is critical for diagnostic accuracy. A poorly timed contrast bolus or incorrect slice thickness can obscure the findings you’re looking for. Our protocol guides provide detailed, scannable instructions for technologists and trainees on how to perform the key studies recommended in these guidelines.
Tools to Help You Order the Right Study
Navigating imaging guidelines in real-time can be challenging. GigHz provides a suite of free reference tools designed to support clinical decision-making at the point of care, helping you select the most appropriate study and communicate effectively with patients about radiation dose.
The Imaging Appropriateness Selector provides a searchable interface for the complete ACR guidelines, covering hundreds of clinical variants beyond sepsis. It’s designed for quick access when you need to justify an imaging order or explore options for a complex presentation.
Our Imaging Protocol Library offers detailed, step-by-step protocols for a wide range of CT, MRI, and ultrasound examinations. These guides are essential for ensuring studies are performed correctly to maximize diagnostic yield.
The Radiation Dose Calculator helps you estimate effective dose for common imaging studies. This tool is invaluable for tracking cumulative exposure and for having informed conversations with patients and their families about the risks and benefits of medical imaging.
Frequently Asked Questions About Imaging for Sepsis
Why is CT with IV contrast generally preferred for suspected abdominal sepsis?
Intravenous contrast is crucial for evaluating abdominal and pelvic infections. It enhances the visibility of organ parenchyma, blood vessels, and inflammatory changes. Specifically, IV contrast helps delineate abscess walls, identify phlegmon (diffuse inflammation without a drainable fluid collection), and assess for complications like septic thrombophlebitis or organ ischemia. A non-contrast CT can miss or underestimate the severity of these findings.
When is an abdominal ultrasound a good first choice for sepsis?
Ultrasound is an excellent first-line imaging modality when the clinical suspicion is high for a specific source that is well-visualized with sonography. This most commonly includes the hepatobiliary system (cholecystitis, cholangitis, liver abscess) or the kidneys (pyelonephritis, renal abscess). It is also preferred in pregnant patients and children to avoid ionizing radiation. However, its utility can be limited by patient body habitus and the presence of overlying bowel gas, and it is less comprehensive than CT for a diffuse or unknown source.
Is there a role for MRI in the initial workup of sepsis?
For the initial, acute evaluation of a septic patient, MRI is rated Usually not appropriate by the ACR. This is primarily due to longer acquisition times, patient monitoring challenges in the MRI suite, and more limited availability compared to CT and ultrasound. MRI may have a role in specific follow-up situations, such as evaluating for spinal epidural abscess, complex soft tissue infections, or as a problem-solving tool when CT findings are equivocal, but it is not a first-line test for undifferentiated sepsis.
Why is a chest radiograph the first step even if I suspect an abdominal source?
A chest radiograph is recommended as a first-line study in most septic patients, even with abdominal symptoms or no localizing signs, for several reasons. First, pneumonia is a very common cause of sepsis and can present with atypical symptoms. Second, the chest radiograph is fast, inexpensive, and uses a very low radiation dose. Third, it can reveal findings related to abdominal pathology, such as a pleural effusion secondary to a subphrenic abscess or free air under the diaphragm from a perforated viscus. It’s a high-yield screening tool that can quickly confirm or exclude a thoracic source.
What does “(Disagreement)” next to an ACR rating mean?
The “(Disagreement)” tag indicates that while the final numerical rating for a procedure fell into a certain category (e.g., “May be appropriate”), there was a notable lack of consensus among the expert panelists who developed the guidelines. This often occurs for procedures where the evidence is less definitive or where practice patterns vary regionally. It signals to the ordering clinician that the appropriateness of this particular study is more debatable and may depend heavily on the specific clinical details and local expertise.
Reviewed by Pouyan Golshani, MD, Interventional Radiologist — May 26, 2026
