Hypergammaglobulinemia and elevated acute-phase reactants (eg, erythrocyte sedimentation rate and C-reactive protein) are present in a large proportion of patients. Hematuria may occur and be accompanied by red blood cell casts, proteinuria, and renal insufficiency in patients who develop immune complex glomerulonephritis, but this is less common in children than adults. In patients with immune complexes, there may also be hypocomple- mentemia. Rheumatoid factor is present in a substantial pro- portion of IE patients whose duration of illness is >6 weeks. Other supportive and useful tests include the ECG, which can indicate the presence of complicating rhythm disorders such as ventricular ectopy and conduction disorders such as com- plete heart block. The presence of either of these findings, and in particular heart block, may signal a serious or even life-threatening IE complication. Echocardiography The standard diagnostic method for identifying the intracar- diac manifestations of IE is 2-dimensional echocardiography although neither sensitivity nor specificity is 100%. Unlike the situation in adults, transthoracic echocardiography (TTE) is usually sufficient for children (especially if they weigh <60 kg) to fully understand cardiovascular findings in definite or presumptive IE. However, transesophageal echocardiog- raphy (TEE) is superior to TTE in diagnosing paravalvular leakage or dehiscence; left ventricular outflow tract compli- cations, including root abscesses; involvement of the sinuses of Valsalva; and prosthetic valve endocarditis, even in chil- TEE is reasonable to consider for infants and children in whom TTE views may be limited. This includes those who have had chest wall disruptions from previous surgery or from trauma, who have had placement of intracardiac prosthetic material, or who have congenital or acquired anomalies of the thoracic cage. 