Table 3 Published diagnostic criteria of SUO

Agarwal et al. 2006 [23]

“…suspected sepsis with no apparent infection at any site and negative blood cultures, along with the intensive care physician’s decision to start empiric antibiotics”

Contou et al. 2016 [16]

“septic shock and with no clear diagnosis (lack of both a source of infection and microbiological documentation) within the first 24 h of vasopressor introduction”

Fort et al. 2018 [25]

"radiological—including CT—and microbiological technology, and systematic diagnostic workups, the source of the sepsis is not always definitely identified"

Hulst et al. 2019 [88]

“clinical examination, extensive microbiological and diagnostic testing, such as computed tomography (CT), the septic focus cannot always be detected”

Kelly et al. 2000 [27]

"in patients with no physical or laboratory evidence of a source"

Kluge et al. 2012 [32]

"standardized diagnostic workup including microbiological evaluation (cultures of blood, urine, and respiratory secretions), chest X-rays, CT scanning, and transesophageal echocardiography according to the standard departmental protocol…when clinical signs and/or laboratory and/or imaging findings to identify the source of infection were inconclusive"

Lee et al. 1991 [33]

“complete clinical, imaging, and laboratory tests had ruled out other septic sources. Tests performed in all patients to exclude other sources of sepsis included multiple blood, urine, and sputum cultures; cultures of tips of central line catheters; abdominal CT scans; and serial chest radiographs”

Mandry et al. 2014 [28]

“after 48 h of extensive investigations. A unique procedure was not imposed for these diagnostic investigations, as they were dependent on clinical context. However, in addition to clinical examination, chest X-ray and conventional laboratory investigations (blood cultures, urine analysis, detection of soluble antigens, bronchoalveolar lavage fluid [BALF] culture, serology), most patients benefited from an echocardiography (transthoracic and/or transesophageal), an abdominal echography and whole body CT-scan before inclusion”

Minoja et al. 1996 [29]

“extensive diagnostic workup to localize infection, including a careful analysis of clinical and intraoperative findings, microbiological and serological data, X-rays, and US and CT images. Patients with suspected pneumonia underwent fiberoptic bronchoscopy, with bronchoalveolar lavage and protected specimen brush” and “radiologically identified deep-seated fluid collection, suspected of being but not demonstrated to be infected”

Velmahos et al. 1999 [31]

“no other test confirmed an infectious focus that could explain the clinical picture or if signs were not adequately explained by the existing evidence (persistent sepsis despite culture-specific antibiotics with adequate blood levels of known respiratory tract infection)”