Image guided drainage of fluid collections

A collection forms when fluid collects in a potential space. Fluid can be a transudate or an exudate determined by the biochemical composition. Collections can occur anywhere in the body. Patients may present with symptoms depending on the site of collection and its contents, e.g. shortness of breath, swelling, pain or discomfort. Treatment is determined by the severity of symptoms. The natural sequela of collections vary. They can resolve or an inflammatory process can ensue. The inflammatory response can result in focal inflammation with formation of suppurative exudate or abscess formation. Clinical manifestations of an abscess include general malaise, swinging pyrexia and SIRS (Systemic Inflammatory Response Syndrome). Initial treatment is with systemic intravenous antibiotics guided by organism sensitivity. However, many will not resolve until drained either radiologically or surgically. IR drainage is a minimally invasive alternative to surgery in many cases, provided the collection is visible by imaging and there is a safe access route to the abscess. Abscess drainage by IR is generally called percutaneous abscess drainage (PAD) and is one of the most significant advances in patient care in the post-operative patient. Repeat abdominal surgery to drain a post-operative abscess is associated with an increased mortality and significant morbidity. Ultrasound or CT imaging are generally used to guide drainage. In certain circumstances intra-cavitary US can be utilised to gain access to sites, which may be inaccessible by the percutaneous route, such as endovaginal, endorectal. Ultrasound has an advantage over CT during placement because the position of the needle/catheter can be monitored in real-time. This is compared to CT where a stop and shoot technique is used, as the needle is advanced, repeat CT images are performed to check that the catheter is in the correct place. A sample is sent for laboratory analysis to determine the contents of the fluid depending on the clinical indication, which can include microbiology, biochemistry, cytology or histopathology.