Clinical Mimics: An Emergency Medicine–Focused Review of Sepsis Mimics

Brit Long, MD; Alex Koyfman, MD


J Emerg Med. 2017;52(1):34-42. 

In This Article

Abstract and Introduction


Background: Sepsis is a common clinical condition, and mortality and morbidity may be severe. The current definition of sepsis involves systemic inflammatory response syndrome (SIRS) criteria, which is met by many conditions.

Objective: This review evaluates the SIRS continuum, signs and symptoms of sepsis, mimics of sepsis, and an approach to management for sepsis mimics.

Discussion: The current emergency medicine definition of sepsis includes SIRS, a definition that may be met by many conditions. Because of common pathophysiologic responses, these diseases present in a similar manner. These conditions include anaphylaxis, gastrointestinal emergency, pulmonary disease, metabolic abnormality, toxin ingestion/withdrawal, vasculitis, and spinal injury. Many of these conditions can be deadly if they are not diagnosed and managed. However, differentiating between sepsis and mimics can be difficult in the emergency setting. Laboratory abnormalities in isolation do not provide a definitive diagnosis. However, a combination of history, physical examination, and adjunctive studies may assist providers. For the patient in extremis, resuscitation must take precedence while attempts to differentiate sepsis from mimics are underway.

Conclusions: SIRS and sepsis exist along a continuum, with many other conditions overlapping because of a common physiologic response. A combination of factors will assist providers in differentiating sepsis from mimics rather than using diagnostic studies in isolation. Resuscitation should be initiated while attempting to differentiate sepsis from its mimics.


Emergency physicians are well versed in the care of sepsis, as close to 750,000 patients per year are admitted for sepsis in the United States.[1–4] A wide range of estimates for prevalence exists, with 300 to 1000 cases per 100,000 persons per year. More than half of admitted septic patients will require at least step-down unit care or greater. Mortality rates vary from 20% to 50%.[1–4] Not only is the mortality severe, but studies have shown increasing costs of care for these patients.[1–4]

Systemic inflammatory response syndrome (SIRS) and sepsis are common clinical entities, and these conditions exist along a spectrum.[2,5,6] The definition of sepsis has undergone several modifications with the Surviving Sepsis Campaign.[2] The clinical syndromes involving SIRS, sepsis, severe sepsis, and septic shock are shown in Table 1. Unfortunately, these criteria are nonspecific, and the criteria alone do not provide a diagnosis or predict outcome.[7] A recent intensive care unit study found a sensitivity of 88% for SIRS in patients with confirmed sepsis. However, associated organ dysfunction does predict poorer outcome.[7]

Sepsis is a commonly investigated condition in the literature because of its potential for severe mortality and morbidity and its high prevalence. Emergency physicians are considered first-line for resuscitating patients in extremis, and septic patients can rapidly decline clinically. Resuscitation includes source evaluation, antimicrobials, ensuring adequate preload with intravenous (IV) fluids, and vasopressors if necessary as key components.[2,5] The SIRS criteria were established to diagnose sepsis quickly to begin management.[2,5–7] A deficit of studies is present in the current literature detailing conditions that mimic sepsis. This review provides an overview of these mimics and an approach to these conditions.