Complicated Intra-abdominal Infections: Risk Assessment, Diagnostic Imaging, and Microbiological Evaluation in Adults, Children, and Pregnant People

• Because the WSES (World Society of Emergency Surgery) Sepsis Severity Score is specific to complicated intra-abdominal infection and performs well, it is an acceptable alternative to APACHE II for adults with complicated intra-abdominal infection.
• No severity of illness scoring system specific to complicated intra-abdominal infection can be recommended to guide management of pediatric patients with complicated intra-abdominal infection at present.

• Intravenous (IV) contrast is usually appropriate whenever a CT is obtained in adults with suspected acute appendicitis; however, CT without IV contrast also has high diagnostic accuracy in detecting acute appendicitis and may be appropriate.
• Because of CT’s accuracy, immediate additional imaging studies beyond CT are usually not necessary. If a CT is negative but clinical suspicion for acute appendicitis persists, consider observation and supportive care, with or without antibiotics; if clinical suspicion is high, consider surgical intervention.
• Ultrasound (US), when definitively positive or definitively negative, and magnetic resonance imaging (MRI) are also reasonably accurate and may precede CT, depending on the patient and clinical circumstances.

• US is generally readily available but is also operator-dependent and can yield equivocal results. MRI is not always readily available, and sedation may be required for young children. CT is generally readily available but involves radiation exposure and may require use of IV contrast or sedation.

Remarks:

• US is generally available but is also operator-dependent and can yield equivocal results. MRI is not always readily available, and sedation may be required for young children. CT is generally readily available but involves radiation exposure and may require use of IV contrast or sedation.
• CT with IV contrast is usually appropriate when performed in children with suspected acute appendicitis after equivocal ultrasound; however, CT without IV contrast may be appropriate.
• Depending on the clinical situation, observation may be appropriate instead of subsequent imaging.
• If there is a strong clinical suspicion for appendicitis after equivocal imaging, exploratory laparoscopy or laparotomy may also be considered if subsequent imaging delays appropriate management.

• It would also be reasonable to initially obtain an MRI in pregnant people with suspected acute appendicitis if access to an MRI is readily available. The conditional imaging strategy suggested (US, then MRI for equivocal results) would likely yield the same results as an MRI only.

Remarks:

• It would also be reasonable to initially obtain an MRI in pregnant people with suspected acute appendicitis if access to an MRI is readily available. The conditional imaging strategy suggested (US, then MRI for equivocal results) would likely yield the same results as an MRI only.

Remarks:

• The diagnosis of acute cholangitis should include clinical signs (jaundice, fever, chills, and right upper quadrant [RUQ] abdominal pain), laboratory findings (indicators of inflammation and biliary stasis), and imaging findings (biliary dilatation, or evidence of an etiology, e.g., stricture, stone, obstructing mass).
• The panel did not identify any studies assessing the accuracy of abdominal US or CT for the diagnosis of acute cholangitis and relied on indirect evidence from acute cholecystitis.
• Because acute cholecystitis and acute cholangitis are uncommon in children, evidence in children was not systematically reviewed; however, it would be reasonable to mirror the imaging pathway for adults in children.

• The diagnosis of acute cholangitis should include clinical signs (jaundice, fever, chills, and RUQ abdominal pain), laboratory findings (indicators of inflammation and biliary stasis), and imaging findings (biliary dilatation, or evidence of an etiology, e.g., stricture, stone, obstructing mass).
• CT with intravenous contrast is preferable and usually appropriate when CT is obtained for subsequent imaging.
• The panel did not identify any studies assessing the accuracy of abdominal US or CT for the diagnosis of acute cholangitis and relied on indirect evidence from acute cholecystitis.
• Because acute cholecystitis and acute cholangitis are uncommon in children, evidence in children was not systematically reviewed; however, it would be reasonable to mirror the imaging pathway for adults in children.

• If both abdominal US and CT are inconclusive but acute cholangitis is suspected, MRI/MRCP is a reasonable option.
• The diagnosis of acute cholangitis should include clinical signs (jaundice, fever, chills, and right upper quadrant abdominal pain), laboratory findings (indicators of inflammation and biliary stasis), and imaging findings (biliary dilatation, or evidence of an etiology, e.g., stricture, stone, obstructing mass).
• Because acute cholecystitis and acute cholangitis are uncommon in children, we did not systematically review the evidence for children; however, it would be reasonable to mirror the imaging pathway for adults in children.

• The diagnosis of acute cholangitis should include clinical signs (jaundice, fever, chills, and RUQ abdominal pain), laboratory findings (indicators of inflammation and biliary stasis), and imaging findings (biliary dilatation, or evidence of an etiology, e.g., stricture, stone, obstructing mass).

Remarks:

• IV contrast is usually appropriate whenever a CT is obtained and can be helpful to characterize and detect subtle bowel wall abnormalities and complications of diverticulitis; however, CT without IV contrast may be appropriate.

Remarks:

• When CT is obtained, the use of intravenous contrast may improve visualization of the abscess wall.
• Because of CT’s accuracy, immediate additional imaging studies beyond CT are usually not necessary.

Remarks:

• At least one study suggests MRI as a reasonable option for initial imaging of suspected acute intra-abdominal abscess in children.
• US is generally available but is also operator-dependent and can yield equivocal results. MRI is not always readily available, and sedation may be required for young children. CT is generally readily available but involves radiation exposure and may require use of IV contrast or sedation.

• US is generally available but is also operator-dependent and can yield equivocal results. MRI is not always readily available, and sedation may be required for young children. CT is generally readily available but involves radiation exposure and may require use of IV contrast or sedation.

Remarks:

• Direct evidence on obtaining blood cultures in patients with intra-abdominal infections is lacking.
• Concern for antibiotic-resistant organisms includes high rates of regional resistance to commonly used agents administered as empiric treatment for intra-abdominal infections, patient history of any colonization or infection with organisms not susceptible to commonly used empiric regimens within the previous 90 days, antibiotic treatment within the previous 90 days, elderly or immunocompromised patients or patients with other significant comorbidities, and/or healthcare-associated infection.

Remarks:

• Direct evidence on obtaining blood cultures in patients with intra-abdominal infections is lacking.
• Clinicians should use their best judgment considering the benefits and risks of performing blood cultures. In select cases (e.g., concern for antibiotic-resistant organisms, concern for ascending cholangitis, complex intra-abdominal abscess), blood cultures may be helpful to assist with clinical decision-making and further management. Concern for antibiotic- resistant organisms includes high rates of regional resistance to commonly used agents administered as empiric treatment for intra-abdominal infections, patient history of any colonization or infection with organisms not susceptible to commonly used empiric regimens within the previous 90 days, antibiotic treatment within the previous 90 days, elderly or immunocompromised patients or patients with other significant comorbidities, and/or healthcare-associated infection.

• When obtaining intra-abdominal cultures, fluid inoculation is the preferred method of collection.

• Immunocompromised patients are at increased risk for antibiotic-resistant organisms and intra-abdominal cultures are generally warranted.
• At the time of surgery, if complicated disease is suspected/recognized, intra-abdominal cultures may be advised.