Risk factors for delayed hemorrhage after colonoscopic postpolypectomy: Polyp size and operative modality

Introduction

The incidence of colorectal polyps is high in colonoscopy screening, accounting for 25% of lesions, mostly benign.1 Colorectal cancer is the third most common tumor worldwide and the fourth cause of morbidity from tumors.2 The early detection and removal of polyps lead to a marked reduction in the incidence of colorectal cancer.3, 4 Complications following polypectomy have significantly reduced with the advancement of the submucosal injection technique,5-7 but the potential for iatrogenic injury during polypectomy still exists.5 The primary complications are hemorrhage and perforation,8 and hemorrhage includes immediate and delayed postoperative bleeding. The incidence rate of the delayed type is 0.4–1.1%,9, 10 with evidently more blood loss compared with the immediate type and delayed management, endangering life. Hence, the prudence of clinicians should never be undermined.11 Therefore, the identification of risk factors for delayed postpolypectomy hemorrhage is essential for the reduction of risks of complications and bleeding. A spectrum of studies exists regarding postoperative hemorrhage, but with contradictory results. The relatively unequivocal awareness is the close correlation of polyp size with hemorrhage. More controversy of perceptions lies in the correlation with other factors, including polyp location, pathology, operative modality, concurrent diseases, and preoperative anticoagulation medications. Bowel preparation and surgeon experience are less referred.

The causal factors for bleeding include concurrent lesions, bowel preparation, location and size of polyps, operative modality, and operation clinicians. This study analyzed the risk factors from the aforementioned multiple perspectives for delayed postpolypectomy hemorrhage.

Methods

This study was a retrospective cohort study analyzing patients who underwent colonoscopic polypectomy at the Department of Gastroenterology and Hepatology, Shanghai Tenth People's Hospital of Tongji University, China, between January and December 2015. Delayed hemorrhage was defined as more than one occurrence of overt bleeding per anus, including melena or hematochezia, 6 h after operation. Each delayed hemorrhage had undergone a therapeutic colonoscopy. The inclusion criteria were patients who underwent colonoscopic polypectomy at the age of 18–80 years, excluding patients with familial adenomatous polyps, polyps combined with inflammatory bowel disease, or a history of colorectal surgery. At least 1-week cessation of anticoagulation medicines, such as aspirin, Plavix, and warfarin, was instructed for all patients, and not even one patient took the specific medicine at the interval of 1 week before operation. Bowel preparation was recorded by two doctors with more than 5 years of specific practice according to Ottawa Bowel Preparation Scale.12 Patient's information, including age, gender, concurrent diseases, bowel preparation, location, size and number of polyps, operative modality, pathology, and operation practitioner, was collected. Polyp size was assessed by an endoscopist and classified into four grades: <1 cm, 1–2 cm, 2–3 cm, and ≥3 cm. Polyp location was classified as rectum, left semicolon distal to the splenic flexure, and right semicolon proximal to the splenic flexure. Operative modalities comprised biopsy forceps polypectomy, argon plasma coagulation (APC), endoscopic mucosal resection (EMR), and endoscopic submucosal dissection (ESD). Pathologically, polyps were divided into three types: hyperplastic and inflammatory polyps, adenomatous polyps (tubular adenoma, villous adenoma, and villous tubular adenoma), and serrated adenoma. Surgeons were classified into three grades based on practice experience: 5–10 years, 10–15 years, and more than 15 years. This retrospective study had been approved by the ethnic committee of Shanghai Tenth People's Hospital of Tongji University. All data were anonymized and deidentified.

Results

Discussion

This study analyzed correlation factors for postpolypectomy hemorrhage. Delayed postpolypectomy hemorrhage occurred within the interval of 6 h to 4 days, at a mean time of 1.85 ± 1.05 days, which was similar to the findings of Kim Hee.13, 14 Therefore, more caution was needed against delayed hemorrhage 1–3 days after operation. Other studies reported the incidence of delayed hemorrhage within postoperative 6 h to 17 days.15 Therefore, postoperative surveillance for hemorrhage should be prolonged to avoid serious outcomes.

Referring to prior literature, the present study also displayed polyp size as a conspicuous risk factor. Min and colleagues discovered that the incidence rate was 2.6-fold higher for polyps larger than 1 cm than for smaller polyps.16 Another study reported that every 1-mm increase in polyp size increased the incidence rate by 11.6%.17 Previous studies did not analyze the polyp size of various ranges but assessed the mean size. In contrast, the present study achieved a more meaningful conclusion by the classification of polyp size. Nonetheless, the limited number of >3-cm polyps could give rise to bias.

In terms of operative modality, Zhang et al. found that EMR or endoscopic piecemeal mucosal resection was more susceptible to hemorrhage compared with APC or biopsy forceps polypectomy, but without statistical significance.15 The present study demonstrated a 9.128-fold incidence rate of hemorrhage in EMR and 31.257-fold susceptibility to hemorrhage in ESD with statistical significance. The difference could be caused by the exclusion of ESD from the comparisons in Zhang's study.

Regarding pathology, Watabe et al. believed that no difference in postoperative hemorrhage existed between adenoma and adenocarcinoma, with the conclusion derived from 37 cases.18 In contrast, Zhang and colleagues found a close correlation between pathology and postoperative hemorrhage (4.3- and 3.3-fold), respectively, in juvenile polyposis and Peutz-Jeghers syndrome compared with inflammatory/hyperplastic polyps.15 In the present study, no significant increase is found in hemorrhage in adenomatous polyps.

Some studies suggested a correlation between polyp location and postpolypectomy hemorrhage. The right semicolon was more susceptible to postoperative hemorrhage compared with the left semicolon.19, 20 The present study detected no conspicuous correlation between them, which could be related to higher incidences of polyps in the left semicolon of Chinese populations but nearly equal incidence in the left and right semicolon of Western populations.21 In the present study, 17.9% of polyps were located in the rectum, 51.9% in the left semicolon, and 30.2% in the right semicolon.

This study had certain limitations. First, it was a single-center retrospective analysis, and data of only 1 year is not comprehensive. Second, the number of polyps ≥3 cm in size was inadequate, and hence, the results could interfere with the precision of the conclusion. Meanwhile, the assessment of bowel preparation was literally subjective, leading to potential bias on evaluation and hence a statistical error.

In summary, this study demonstrated the risk factors for postpolypectomy hemorrhage, including polyp size and operative modality. For polyps >1 cm in size, the operative modality of ESD resulted in a higher incidence of hemorrhage. More clinical prudence should be taken in this regard.