On the other hand, if clinical suspicion of IE or its complications is high (eg, prosthetic valve or new atrioventricular block), then a negative TTE will not definitely rule out IE or its potential complications, and TEE should be performed first. Investigation in adults has shown TEE to be significantly more sensitive than TTE for the detection of veg- etations and abscesses.47 In the setting of a prosthetic valve, transthoracic images are greatly hampered by the structural components of the prosthesis and are inadequate for assess- ment of the perivalvular area where those infections often Although cost-effectiveness calculations suggest that TEE should be the first examination in adults with suspected IE (Table 4), particularly in the setting of staphylococcal bac- many patients are not candidates for immediate TEE because of having eaten within the preceding 6 hours or because the patients are in institutions that cannot provide 24-hour TEE services. When TEE is not clinically possible or must be delayed, early TTE should be performed without delay. Although TTE will not definitively exclude vegeta- tions or abscesses, it will allow identification of very-high- risk patients, establish the diagnosis in many, and guide early treatment decisions. Although interesting results suggest that there may be a high negative predictive value of TTE in some further work is needed to better define the subgroup of patients with bloodstream infection caused by S aureus who need only TTE to evaluate for IE. Many findings identified by TEE also can be detected on TTE. Concurrent TTE images can serve as a baseline for rapid and noninvasive comparison of vegetation size, valvular insufficiency, or change in abscess cavities during the course of the patient s treatment should clinical dete- rioration occur. 