Background: This study aimed to compare CD31, smooth muscle myosin (SMM), and transgelin antibodies for their efficiency in detecting venous invasion (VI) and the nature of free tumor deposits (TDs) in gastric, pancreatic, and colorectal adenocarcinomas. Materials and Methods: Eleven Whipple, 5 gastrectomy, and 3 colectomy specimens and 1 low anterior resection specimen were reviewed and examined, revealing 254 probable foci. Foci were reviewed and divided into 3 types: Type A, the "orphan artery" pattern; Type F, free TDs in the periorgan adipose and connective tissue without an unaccompanied artery; and Type X, a focus that could be detected only with the immunohistochemical procedures mentioned. Results: No foci were positive for CD31. Transgelin staining was more sensitive than SMM staining in all focus types, Type A only and Type F only (P < 0.001, P = 0.001, and P = 0.10, respectively). In free TDs (Type F), 35.7% of the samples were negative for all four stains, and 64.2% of the samples were positive for SMM and transgelin. We did not make the distinction between a metastatic lymph node and VI in positive foci. Conclusion: We conclude that hematoxylin and eosin (H and E) staining is inadequate and that smooth muscle markers, such as transgelin and/or SMM, are more effective than endothelial markers, such as CD31, in revealing VI and lymph node/large extramural invasion.