The value of color flow Doppler ultrasonography of the superior thyroid artery in the surgical management of Graves disease.

HYPOTHESIS The factors affecting blood flow within the hypervascular thyroid gland and the effect of vascularization on the preparation for thyroidectomy as treatment for Graves disease can be documented. DESIGN Blood flow through the superior thyroid arteries of patients with Graves disease, maintained in a euthyroid status, was measured by color flow Doppler ultrasonography. The microvessel density was assessed immunohistochemically using the level of expression of factor VIII in tissue sections. Both the thyroid gland's weight and blood loss volume were measured during the operation. SETTING Tertiary care teaching hospital. PATIENTS Fifty-two patients with Graves disease undergoing thyroidectomy. RESULTS The blood flow rate was significantly correlated with thyroid weight (P<.01), thyroid microvessel density (P<.001), and histopathologic microscopic pattern (P<.001). The relation between these factors could be expressed as follows: Blood flow (mL/min) = [[0.0158 + 0.00136] x (weight (g) x microvessel density)](1/2) (R2 = 0.64, P<.001). Diffuse microfollicular hyperplastic thyroid tissue had a significantly higher blood flow and vascular density than tissue having an inactive colloid pattern (P<.01). Ten patients having a blood loss exceeding 200 mL during thyroidectomy showed a higher preoperative blood flow rate and microvessel density (P<.01). Of 8 patients whose blood flow was more than 0.15 L/min, 6 (75%) had blood loss in excess of 200 mL during surgery. CONCLUSIONS The blood flow of the superior thyroid artery is positively related to intrathyroid microvessel density, glandular weight, and histopathologic microscopic pattern. Preoperative color flow Doppler ultrasonography may help in identifying patients with Graves disease who are liable to bleed intraoperatively during thyroidectomy.