2024 Clinical Practice Guideline Update by the Infectious Diseases Society of America on Complicated Intra-abdominal Infections: Risk Assessment, Diagnostic Imaging, and Microbiological Evaluation in Adults, Children, and Pregnant People 

Robert A Bonomo,  Anthony W Chow,  Morven S Edwards,  et al

Clinical Infectious Diseases, Volume 79, Issue Supplement_3, October 2024, Pages S81–S87, https://doi.org/10.1093/cid/ciae346

RESULTS: RECOMMENDATIONS AND REMARKS

In adults and children with complicated intra-abdominal infection, which severity of illness score for risk stratification calculated within 24 hours of hospital or ICU admission best predicts 30-day or in-hospital mortality?

Recommendation: Risk stratification according to severity of illness is important for management of complicated intra-abdominal infection. For adults with complicated intra-abdominal infection, if a severity of illness score is used, the panel suggests APACHE II; http://www.globalrph.com/apacheii.htm) as the preferred severity of illness score for risk stratification within 24 hours of hospitalization or ICU admission (conditional recommendation, low certainty of evidence).

In adults with suspected acute appendicitis, should ultrasound (US), computed tomography (CT), or magnetic resonance imaging (MRI) be obtained as the initial imaging modality?

In adults with suspected appendicitis, if initial imaging is inconclusive, should US, CT, or MRI be obtained for subsequent imaging?

Recommendation: In non-pregnant adults with suspected acute appendicitis, the panel suggests obtaining an abdominal CT as the initial imaging modality to diagnose acute appendicitis (conditional recommendation, very low certainty of evidence).

In children with suspected acute appendicitis, should US, CT, or MRI be obtained as the initial imaging modality?

In children with suspected appendicitis, if initial imaging is inconclusive, should US, CT, or MRI be obtained for subsequent imaging?

Recommendation: In children and adolescents with suspected acute appendicitis, the panel suggests obtaining an abdominal US as the initial imaging modality to diagnose acute appendicitis (conditional recommendation, very low certainty of evidence).

Recommendation: In children and adolescents with suspected acute appendicitis, if initial US is equivocal/non-diagnostic and clinical suspicion persists, the panel suggests obtaining an abdominal MRI or CT as subsequent imaging to diagnose acute appendicitis rather than obtaining another US (conditional recommendation, very low certainty of evidence).

In pregnant people with suspected acute appendicitis, should US or MRI be obtained as the initial imaging modality?

In pregnant people with suspected appendicitis, if initial imaging is inconclusive, should US or MRI be obtained for subsequent imaging?

Recommendation: In pregnant people with suspected acute appendicitis, the panel suggests obtaining an abdominal US as the initial imaging modality to diagnose acute appendicitis (conditional recommendation, very low certainty of evidence).

Recommendation: In pregnant people with suspected acute appendicitis, if initial US is equivocal/non-diagnostic and clinical suspicion persists, the panel suggests obtaining an MRI as subsequent imaging to diagnose acute appendicitis (conditional recommendation, very low certainty of evidence).

In adults with suspected acute cholecystitis or acute cholangitis, should abdominal US or CT be obtained as the initial imaging modality?

In adults with suspected acute cholecystitis or acute cholangitis, if initial imaging is inconclusive, should CT, MRI/MRCP (magnetic resonance cholangiopancreatography), or HIDA (hepatobiliary iminodiacetic acid) be obtained for subsequent imaging?

Recommendation: In non-pregnant adults with suspected acute cholecystitis or acute cholangitis, the panel suggests abdominal US as the initial diagnostic imaging modality (conditional recommendation, very low certainty of evidence).

Recommendation: In non-pregnant adults with suspected acute cholecystitis or acute cholangitis, if initial US is equivocal/non-diagnostic and clinical suspicion persists, the panel suggests obtaining an abdominal CT scan as subsequent imaging to diagnose acute cholecystitis or acute cholangitis (conditional recommendation, very low certainty of evidence).

Recommendation: In non-pregnant adults with suspected acute cholecystitis, if both US and CT are equivocal/non-diagnostic and clinical suspicion persists, the panel suggests obtaining either an abdominal MRI/MRCP or HIDA scan as subsequent imaging to diagnose acute cholecystitis (conditional recommendation, low certainty of evidence for HIDA, knowledge gap for MRI/MRCP).

In pregnant people with suspected acute cholecystitis or acute cholangitis, should abdominal US or MRI be obtained as the initial imaging modality?

Recommendation: In pregnant people with suspected acute cholecystitis or suspected acute cholangitis, US or MRI can be considered as the initial diagnostic imaging modality; however, the panel is unable to recommend one imaging modality versus the other (knowledge gap).

In adults with suspected acute diverticulitis, should CT, US, or MRI be obtained as the initial imaging modality?

Recommendation: In non-pregnant adults with suspected acute diverticulitis, the panel suggests obtaining an abdominal CT as the initial diagnostic modality (conditional recommendation, very low certainty of evidence).

Recommendation: In non-pregnant adults with suspected acute diverticulitis, if CT is unavailable or contraindicated, the panel suggests obtaining an US or MRI as the initial diagnostic modality (conditional recommendation, very low certainty of evidence).

In pregnant adults with suspected acute diverticulitis, should CT, US, or MRI be obtained as the initial imaging modality?

Recommendation: In pregnant adults with suspected acute diverticulitis, US or MRI can be considered for imaging; however, the panel is unable to recommend one imaging modality versus the other (knowledge gap).

In adults with suspected acute intra-abdominal abscesses, should abdominal US or CT be obtained as the initial imaging modality?

In adults with suspected acute intra-abdominal abscesses, if initial imaging is inconclusive, should MRI be obtained for subsequent imaging?

Recommendation: In nonpregnant adults and adolescents with suspected acute intra-abdominal abscess, the panel suggests obtaining an abdominal CT scan as the initial diagnostic imaging modality (conditional recommendation, very low certainty of evidence).

In children with suspected acute intra-abdominal abscesses, should abdominal US or CT be obtained as the initial imaging modality?

In children with suspected acute intra-abdominal abscesses, if initial imaging is inconclusive, should MRI be obtained for subsequent imaging?

Recommendation: In children with suspected acute intra-abdominal abscess, the panel suggests obtaining an abdominal US as the initial diagnostic imaging modality (conditional recommendation, very low certainty of evidence).

Recommendation: In children with suspected acute intra-abdominal abscess, if initial US is negative/equivocal/non-diagnostic and clinical suspicion persists, the panel suggests either CT or MRI as subsequent imaging to diagnose acute intra-abdominal abscess (conditional recommendation, very low certainty of evidence).

In pregnant people with suspected acute intra-abdominal abscesses, should abdominal US or MRI be obtained as the initial imaging modality?

Recommendation: In pregnant people with suspected acute intra-abdominal abscess, US or MRI can be considered as the initial diagnostic imaging modality; however, the panel is unable to recommend one versus the other (knowledge gap).

In adults and children with known or suspected intra-abdominal infection (uncomplicated or complicated), should blood cultures be obtained to effect a meaningful change in antimicrobial therapy?

Recommendation: In adults and children with suspected intra-abdominal infections who have an elevated temperature AND: hypotension and/or tachypnea and/or delirium, OR there is concern for antibiotic-resistant organisms that would inform the treatment regimen, the panel suggests obtaining blood cultures (conditional recommendation, very low certainty of evidence).

Recommendation: In non-immunocompromised adults and children with suspected intra-abdominal infections who have a normal/elevated temperature but do not have hypotension, tachypnea, or delirium, and there is no concern for antibiotic-resistant organisms that would inform the treatment regimen, the panel suggests not routinely obtaining blood cultures (conditional recommendation, very low certainty of evidence for adults/low certainty of evidence for children).

In adults and children with known or suspected intra-abdominal infection (uncomplicated or complicated), should cultures of intra-abdominal fluid be obtained to effect a meaningful change in antimicrobial therapy?

Recommendation: In adults and children with complicated intra-abdominal infection who are having a procedure for source control, the panel suggests obtaining intra-abdominal cultures to guide antimicrobial therapy (conditional recommendation, moderate certainty of evidence).

Recommendation: In adults and children with uncomplicated appendicitis undergoing an appendectomy, the panel suggests not routinely obtaining intra-abdominal cultures (conditional recommendation, low certainty of evidence).