Chapter 5 Abdominal Emergencies in Cancer and Immunocompromised Patients

Acute abdominal pathologies in oncology and immunocompromised patients can be challenging to diagnose. In addition to acute diseases that occur in otherwise healthy populations, these patients are susceptible to a host of tumor-specific, organ-specific, and treatment-related processes that can range from inconsequential to life threatening. Imaging strategies can include radiographs, ultrasound, computed tomography, or magnetic resonance, depending on the presentation, with the objective to identify the underlying etiology and, importantly, reversible pathologies for which treatment could substantially improve quality of life. Immune checkpoint inhibitors, anti–vascular endothelial growth factor (VEGF) and non-VEGF molecular targeted therapies, and conformal radiation treatment can present with unique complications not commonly seen with classic cytotoxic chemotherapy, including arterial thromboembolic events, tumor-bowel fistulae, and segmental colitis associated with diverticulosis (SCAD). Radiologists should avoid using misleading statements when reporting imaging examinations of the abdomen and pelvis in oncology patients, including “tumor thrombus,” and should avoid using restaging criteria terms such as “partial response” or “progressive disease” when tumor burden has not also been restaged elsewhere in the body.