Various approaches for CT-guided percutaneous biopsy of deep pelvic lesions: anatomic and technical considerations.

Access route planning for computed tomography-guided biopsy of deep pelvic masses remains challenging because vital structures often obstruct the projected needle path. The classical approach through the lower anterior abdominal wall allows access to lesions located anterior, superior, or lateral to the urinary bladder. However, this approach has limitations: Deep masses are difficult to reach because of intervening structures, the bowel or bladder may be unavoidably traversed, and peritoneal transgression is often painful. A transgluteal approach is useful for biopsy of presacral and perirectal lesions and lesions located posterolateral to the bladder. An anterolateral approach through the iliopsoas muscle allows safe extraperitoneal access to external and internal iliac nodes, masses located along the lateral pelvic sidewall, and adnexal lesions. A transosseous (transsacral or transiliac) approach can occasionally be used for otherwise inaccessible lesions. Use of a curved needle, change in patient position, or injection of saline solution to displace intervening structures may also be helpful. Familiarity with normal cross-sectional pelvic anatomy facilitates planning of a safe access route and helps avoid injury to adjacent structures. A thorough understanding of the advantages and disadvantages of each approach allows the clinician to choose the most appropriate approach in a given situation.