Background and AimDelayed colonic postpolypectomy bleeding is the commonest serious complication after polypectomy. This study aimed to utilize massive sampling data of polypectomy to analyze risk factors for delayed postpolypectomy bleeding.Patients and MethodsThe endoscopic data of 5600 patients with 15553 polyps removed (2005 to 2013) were analyzed retrospectively through univariate analysis and multiple logistic regression analysis to evaluate the risk factors for delayed bleeding.ResultsDelayed postpolypectomy bleeding occurred in 99 polyps (0.6%). The rates of bleeding for different polypectomy methods including hot biopsy forcep, biopsy forcep, Argon Plasma Coagulation (APC), Endoscopy piecemeal mucosal resection (EPMR), Endoscopic Mucosal Resection (EMR), and snare polypectomy were 0.1%, 0.0%, 0.0%, 6.9%, 0.9% and 1.0%, respectively. The risk factors for delayed bleeding were the size of polyps over 10 mm (odds ratio [OR] = 4.6, 95% CI, 2.9–7.2), pathology of colonic polyps (inflammatory/hyperplastic, OR = 1; adenomatous, OR = 1.4, 95% CI, 0.7–2.6; serrated, OR = 1.5, 95% CI, 0.2–11.9; juvenile, OR = 4.3, 95% CI, 1.8–11.0; Peutz-Jegher, OR = 3.3, 95% CI, 1.0–10.7), and immediate postpolypectomy bleeding (OR = 2.9, 95% CI, 1.4–5.9). In addition, although polypectomy method was not a risk factor, compared with hot biopsy forcep, snare polypectomy, EMR, and EPMR had increased risks of delayed bleeding, with ORs of 3.2 (0.4–23.3), 2.8 (0.4–21.7) and 5.1 (0.5–47.7), respectively.ConclusionPolyp size over 10 mm, pathology of colonic polyps (especially juvenile, Peutz-Jegher), and immediate postpolypectomy bleeding were significant risk factors for delayed postpolypectomy bleeding.

Tissue biopsy is often not very accurate for the diagnosis of gastric epithelial neoplasia (GEN), and the results differ notably from endoscopic resection (ER) in terms of the pathological diagnosis. The aims of this study were to evaluate the diagnostic performances of biopsy, magnifying endoscopy with narrow-band imaging (ME-NBI), and biopsy plus ME-NBI for GEN.This study retrospectively analyzed 101 cases diagnosed as GEN using ER samples. The discrepancies between biopsy and ER, as well as between biopsy plus ME-NBI and ER in the diagnosis of GEN were evaluated. Factors that contributed to such discrepancies were analyzed. The sensitivity and specificity of biopsy and ME-NBI for the diagnosis of high-grade neoplasia (HGN) were determined.The discrepancy in the pathological diagnosis between biopsy and ER was 39.6% for GEN and 54.2% for HGN. The discrepancy between biopsy combined with ME-NBI and ER was 15.9% for GEN and 10.2% for HGN. Factors that undermined the diagnostic accuracy of biopsy included the lesion size (≤10 mm, odds ratio [OR] 1; 10–20 mm, OR 0.2, 95% confidence interval [CI] 0.1–0.7; >20 mm, OR 0.5, 95% CI 0.1–2.1, P = 0.03) and the number of biopsy fragments (OR 0.6, 95% CI 0.5–0.8, P = 0.001). The sensitivity and specificity for HGN were 45.8% (33.7%–58.3%) and 100% (87.5%–100%) for biopsy, and 88.1% (77.5%–94.1%) and 92.9% (81.0%–97.5%) for ME-NBI, respectively.In conclusion, biopsy-based diagnoses for GEN should be interpreted with caution. Biopsy combined with ME-NBI can contribute to the diagnosis of GEN, which improves diagnostic consistency with pathological result of ER specimens.

Generally, many high-strength alloy materials used in aerospace, power and chemical industries have strength differential effect in tension and compression (SD effects). Usually, in mechanical calculations of sheet metal forming, Treasca yield criterion and Mises yield criterion are applied. Because the yield criterions don’t take SD effects into consideration, the calculation result may have errors for certain materials. However, generalized twin shear stress yield criterion, which takes into account the influence of the intermediate principal stress, is more suitable for most metal materials than Mohr-Coulomb strength theory. Therefore, this article has made plastic analysis on thin film stress issues of metal sheet forming with generalized twin shear stress yield criterion. We have obtained a unified plastic solution to the internal and external stretching issue of thin material with rounded holes and different tension and compression ratio. Providing a new result with wider applicability is very significant.