Observing vessel stumps axially: A novel exoscope for end-to-end microvascular anastomosis.

Although many free tissue transfers have been performed, free flap loss can still occur because of vascular compromise. To facilitate microsurgery, we invented the axial-view microscope (aMS), a new type of microscope that can axially visualize vessel stumps. The aMS was combined with an optical microscope, the so-called bird's-eye-view microscope (bMS). Using our aMS, we observed the cross-sections of the following 12 arteries during vascular anastomosis: three deep inferior epigastric arteries, three suprathyroid arteries, two thoracodorsal arteries, two jejunal arteries, one lateral circumflex femoral artery, and one facial artery. For each artery, we measured the vessel height-to-width (H-W) ratio to determine the roundness of the vessel stump. Based on the aMS and bMS, the average H-W ratios were 0.877 ± 0.187 and 0.445 ± 0.172, respectively. The H-W ratio obtained using the aMS was significantly higher than that of the bMS (P < 0.001). Providing the surgeon with a bidirectional view of the vessel stump reduced blind spots at the anastomotic site. In this report, we describe our new microscope and associated clinical cases.