Non-traumatic causes of fluid in the retropharyngeal space

There are multiple reasons for imaging the soft tissues of the neck in the emergency setting, in particular when symptoms are vague or if there is worry for complications from a certain clinical diagnosis. When fluid is seen in the retropharyngeal space, it is important to pay attention to history and look at key structures in the neck. This article will discuss anatomy of the retropharyngeal space, followed by four causes of fluid within the space that the radiologist is likely to encounter in the emergency setting: tonsillitis/pharyngitis, acute calcific tendinitis of the longus colli muscles, internal jugular vein thrombosis, and post-radiation changes. It is important to recognize these entities because each has different clinical implications and management.