E1609. Retroperitoneal Infections: From Anatomic Basis to Making the Diagnosis
  1. Muhammad Awiwi; The University of Texas Health Science Center
  2. Khaled Elsayes; The University of Texas MD Anderson Cancer Center
Retroperitoneal infections are frequently encountered in daily practice and infection types vary according to the involved organ and/or retroperitoneal compartment. Reteroperitoneal fasciae not only define anatomic spaces, but they can contain the spread of the disease. On the other hand, infectious processes contained within different retroperitoneal compartments have typical spread pathways. This educational exhibit reviews the anatomy of retroperitoneal compartments, potential infections involving each compartment, and typical routes for spread of pyogenic processes.

Educational Goals / Teaching Points
To review the anatomy of the retroperitoneum. To review the imaging appearances of several retroperitoeneal infections (e.g. pancreatic abcesses, duodonal perforation, duodenal diverticulitis, colon perforation into the retroperitoneum, different types of pyelonephritis, adrenal infections, puerperal septic thrombophlebitis, mycotic aortic aneurysm, retroperitoneal abscesses related to Pott’s disease or osteomyelitis/spondylodiscitis, and hematogenously disseminated infections such as hydatid/echinococcal cyst, tuberculosis, histoplasmosis, coccidiomycosis, cat scratch disease, and disseminated Mucor). To demonstrate potential pathways for spread of retroperitoneal pyogenic processes.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The exhibit first illustrates the normal anatomy of the retroperitoneum and its compartments with the help of several CT images and a few illustrations. Next, we will review imaging appearances of infectious processes involving retroperitoneal organs. Finally, we describe potential routs of pyogenic disease spread (e.g. spread through interfascial planes, the great escape, spread form the anterior pararenal space into the mesocolon and/or small bowel mesentery, spreading pathways from the retroperitoneum to the anterior abdominal wall, spreading pathways allowing upper abdominal infections to spread to the pelvis and lower extremities, pathways of spread of adjacent musculoskeletal infections into the the retroperitoneum).

Clear understanding of retroperitoneal anatomy allows the radiologist to formulate a list of differential diagnoses based on the involved anatomic compartment. In addition, knowledge of anatomic compartments allows the radiologist to understand and predict potential pathways of pyogenic disease spread.