Given the task definition and input, reply with output. In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.

Context: Surgeon-performed ultrasonography is increasingly becoming part of the initial evaluation of patients after blunt or penetrating trauma. Currently, most institutions obtain a subxyphoid or subcostal view of the heart and pericardial space, and a three-view ultrasonogram of the abdomen to detect blood in the pericardial sac or in three dependent abdominal areas.', 'A left parastemal standard transverse transthoracic view is described in addition to the aforementioned views. This facilitates the visualization of the pericardial sac when a subxyphoid or subcostal view cannot be obtained because of anatomical reasons (narrow subxyphoid space) or local factors (pain, fractures, subcutaneous emphysema, or chest wall contusion).', 'The transthoracic view can be useful in patients where the subxyphoid view is difficult to obtain through the conventional approach. In most patients an excellent view of the pericardial sac and ventricles can be obtained and, therefore, expedites the diagnosis and treatment of patients with hemopericardium.\Question: Is transthoracic ultrasonography an alternative to subxyphoid ultrasonography for the diagnosis of hemopericardium in penetrating precordial trauma?
Surgeon-performed ultrasonography has become the diagnostic test of choice for patients suspected of having hemopericardium and cardiac tamponade. Transthoracic ultrasonography is an excellent alternative for those patients where a subxyphoid or subcostal view to visualize the pericardial sac and heart cannot be obtained owing to local or anatomical factors.