Relationship of sternal foramina to vital structures of the chest: a computed tomographic study

Sternal foramina are a well-known variant anatomy of the sternum and carry the risk of life-threatening complications like pneumothorax or even pericardial/cardial punction during sternal biopsy or acupuncture. There have been numerous studies numerous studies examinimg prevalence of sternal foramina, but the study of the exact anatomical relationship to intrathoracic structures has received little attention. In a retrospective study of 15 patients with sternal foramina, the topographical anatomy in respect to vital chest organs was examined. In most patients, the directly adjacent structure was the lung (53.3%) or mediastinal fat (33.3%). Only in three patients, the heart was located directly adjacent to a sternal foramen (20%). Theoretically, if the needle is inserted deep enough it will at some point perforate the pericardium in all examined patients. There was no correlation between the patient habitus (i.e., thickness of the subcutaneous fat) and the distance to a vital organ. In this sample, pericardial punction would have not occured if the needle is not inserted deeper than 2.5 cm. Given the preliminary nature of the data, general conclusions of a safe threshold for needle depth should be made with caution. To minimize the risk of hazardous complications, especially with sternal biopsy, preprocedural screening or image guidance is advocated.