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Untreated preoperative anemia and acute perioperative blood loss may add to surgical risk. To understand the prevalence of anemia in surgical patients (with a primary focus on preoperative anemia), and the impact that preexisting anemia has on transfusion rates as well as on clinical and functional outcomes, a systematic review was performed of articles published between January 1966 and February 2003. The estimates of anemia prevalence in the literature ranged widely, from 5% in geriatric women with hip fracture to 75.8% in patients with Dukes stage D colon cancer. Diagnosis of anemia was most strongly associated with an increased risk of receiving an allogeneic transfusion. In general, patients who donated autologous blood preoperatively received less allogeneic blood than those who did not donate. There was some suggestion that lower hemoglobin levels are associated with decreased survival rates, although this was not found universally. Too few studies were found that evaluated the impact of anemia on other outcomes, such as functional status and costs and resource utilization, to draw reliable conclusions. Several other factors also limited the interpretation of the data, including the lack of a uniform definition for anemia and a dearth of studies expressly designed to quantify the prevalence and impact of anemia. Establishing a uniform definition and specifically evaluating the effect of anemia on outcomes are important considerations for future study.

Since first being described as such by Galen of Pergamum (130-200 ad), the thymus has remained an "organ of mystery" throughout the 2000-year history of medicine. The thymus reaches its maximum weight in puberty and subsequently undergoes involution, and thus is hardly an eye-catching structure on imaging studies performed in healthy adults. However, once there has been involvement of the thymus by a disease process, the gland demonstrates a variety of clinical and radiologic manifestations that require comprehensive understanding of each entity. Furthermore, it is important for radiologists to be familiar with the current World Health Organization histologic classification scheme for thymic epithelial tumors and to understand its clinical-pathologic, radiologic, and prognostic features.

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