When do patients with acute lower gastrointestinal bleeding have colonoscopy?

This article is only for medical professionals to read for reference.
Master the endoscopic management of acute lower gastrointestinal bleeding.

Lower gastrointestinal bleeding usually refers to intestinal bleeding beyond the Trietz ligament, including small intestinal bleeding and colorectal bleeding.

Lower gastrointestinal bleeding is common clinically, accounting for 20% to 30% of all gastrointestinal bleeding.

However, the current research on lower gastrointestinal bleeding is not as deep as that of upper gastrointestinal bleeding, and there are few relevant guidelines and consensus.

The diagnosis of gastrointestinal bleeding relies on gastrointestinal endoscopy, which has certain requirements for the patient's vital signs and bowel preparation.

Therefore, when is the appropriate time to perform colonoscopy for patients with acute lower gastrointestinal bleeding, and how to stop bleeding after the bleeding point is discovered, is a problem of great concern to gastroenterologists.

This year's American Digestive Disease Week (DDW) was held online on May 21-23, bringing together experts and scholars in the field of gastroenterology from around the world to discuss the research results and clinical standards of digestive system diseases.

From 5:30-7:00 in the morning on May 23, 2021, Beijing time, the American Society of Gastrointestinal Endoscopy (ASGE) gave a lecture on lower gastrointestinal emergencies at the DDW conference.

Professor Lisa L.
Strate, director of the Department of Gastroenterology, University of Washington Harborview Medical Center, shared the experience of endoscopic management of acute lower gastrointestinal bleeding in this DDW seminar.

01When should colonoscopy be done for patients with acute lower gastrointestinal bleeding? For patients with acute lower gastrointestinal bleeding, the biggest advantage of emergency colonoscopy lies in the early identification of bleeding points and simultaneous endoscopic hemostasis, which reduces the rate of rebleeding and mortality; at the same time, the risk of patients can be analyzed by clarifying the severity of bleeding.
At the same time, patients with a lower risk of rebleeding after treatment can be triaged as soon as possible, reducing the length of hospitalization and saving medical expenses.

However, the bowel preparation for emergency colonoscopy is often insufficient, which has a greater impact on the visual field.
The sedatives given during colonoscopy may also cause adverse consequences; moreover, many medical units lack professional endoscopists.

The first clinical evidence that emergency colonoscopy can improve the prognosis of severe diverticulum bleeding comes from a case-control study published in the New England Journal of Medicine in 2000, comparing patients who underwent emergency colonoscopy with those who did not.
, The rebleeding rate (0 vs 88%), the proportion of surgical intervention (0 vs 35%), and the average length of stay (2 days vs.
5 days) all have significant benefits.

However, in the past 20 years, many studies on emergency enteroscopy of lower gastrointestinal bleeding have failed to reach a consistent conclusion.

A 2018 meta-analysis included 21 studies.
The results of the analysis showed that emergency colonoscopy increased the detection rate of bleeding points, but compared with elective colonoscopy, the patient’s hospital stay, rebleeding rate and mortality rate were not Statistical difference.

In 2020, a Japanese multi-center randomized controlled trial (15 centers, 159 patients) compared emergency colonoscopy (average 13.
9 hours) and elective colonoscopy (average 41.
4 hours) between the two groups for recent bleeding signs (stigmata of recent hemorrhage) , SRH) there was no significant difference (21.
5% vs.
21.
3%), and there was no statistical difference in the rebleeding rate within 30 days (15.
3% vs.
6.
7%).

In addition, the results of a high-quality meta-analysis involving 4 randomized controlled trials in 2020 also showed that compared with elective colonoscopy, emergency colonoscopy failed to improve the rebleeding rate, mortality, SRH, etc.
of patients with lower gastrointestinal bleeding.
The prognosis puts forward higher requirements on medical resources.

Therefore, Professor Strate introduced a brief treatment principle in conjunction with the "Guidelines for Diagnosis and Management of Lower Gastrointestinal Bleeding" issued by the British Gastroenterology Society (BCG).
For shock index (ratio of heart rate to systolic blood pressure, SI)> 1 In patients with unstable bleeding, CT angiography (CTA) should be performed first to quickly identify the bleeding site.

For patients with stable bleeding (SI≤1), colonoscopy should be arranged under feasible conditions, but it is not required to be completed within 24 hours.

02How should colonoscopy and treatment be done? The first main purpose of colonoscopy is to clarify bleeding points.
Emergency colonoscopy (OR=8.
5), under-scope flushing (OR=5.
8), transparent caps (OR=3.
4), and professional endoscopists (OR=3.
0) ) Are all helpful to improve the detection of bleeding points.

The judgment of SRH is also conducive to predicting the risk of rebleeding.
Taking the SRH of the colonic diverticulum as an example, the rebleeding rate of patients with active bleeding observed under the microscope is 84%, and the rebleeding rate of exposed blood vessels without bleeding is 60%.
The rebleeding rate of clots is only 43%.

The second purpose of colonoscopy is to stop bleeding.

Professor Strate summarized several commonly used endoscopic methods of hemostasis and the success rate of hemostasis for diverticulum hemorrhage, including heat coagulation (88%), submucosal injection of norepinephrine (85%), band ligation (92%) and hemostatic clip ( 87%).

For diverticulum hemorrhage, Professor Strate recommends the use of mechanical hemostasis (ligation or hemostasis clip), especially for bleeding points on the deep surface of the diverticulum, where there is no muscle layer protection on the back wall, and thermal coagulation can easily cause perforation.

03 Radiological examination and treatment of unstable bleeding In addition, Professor Strate also introduced the treatment of patients with unstable bleeding (SI≤1).

The commonly used imaging method is abdominal CT vascular reconstruction (CTA).

CTA examination helps to find inflammatory changes such as colonic space-occupying lesions and intestinal wall thickening and edema, and can indicate possible bleeding sites.

The use of radionuclide to label red blood cells is also one of the means to determine the location of gastrointestinal bleeding.

Studies have shown that CTA is more accurate in locating bleeding points (53% vs 30%) than radionuclide inspection, with a sensitivity of 85% and a specificity of 92%.

At the same time, because of its short time-consuming, it is more suitable for patients with unstable bleeding.
In contrast, radionuclide examination requires about 90 minutes of preparation time.

Due to the intermittent nature of lower gastrointestinal bleeding, it is easier to find active bleeding by doing angiography as soon as possible after the bleeding point is found by CTA.

Studies have shown that if an angiography is done within 90 minutes after CTA, the chance of finding signs of contrast agent spillage will increase by 8.
6 times.

The positive findings of angiography are more conducive to guide accurate vascular embolization.

In summary, patients with acute lower gastrointestinal bleeding do not need to complete emergency colonoscopy within 24 hours.
Adequate bowel preparation, transparent cap and flushing are beneficial to the detection of bleeding points; for common diverticulum bleeding, Mechanical hemostasis (vascular clip, band ligation) is a more effective and safe treatment method.

CTA and angiography are suitable for patients with unstable bleeding with SI≤1.

Expert profile Wang Xiaoze, post-doctorate in the Department of Gastroenterology, West China Hospital, Sichuan University, Doctor of Medicine.

He is good at digestive system and peripheral vascular interventional therapy.
He is engaged in basic and clinical research on the pathogenesis of portal hypertension and interventional therapy in liver cirrhosis.
He won the first prize of Sichuan Science Progress Award.
He has published many SCI papers and participated in editing 2 books/monographs.

References: 1.
Colorectal Group of Chinese Medical Association Digestive Endoscopy, Colorectal Group of Digestive Physician Branch of Chinese Medical Doctor Association, National Center for Clinical Medicine of Digestive Diseases.
Guidelines for Diagnosis and Treatment of Lower Gastrointestinal Bleeding (2020)[J] China Medical Journal.
2020, 55(10): 1068-1076.
2.
Oakland K, Chadwick G, East JE, Guy R, Humphries A, Jairath V, McPherson S, Metzner M, Morris AJ, Murphy MF, Tham T, Uberoi R, Veitch AM, Wheeler J, Regan C, Hoare J.
Diagnosis and management of acute lower gastrointestinal bleeding: guidelines from the British Society of Gastroenterology.
Gut.
2019 May;68(5):776-789.
doi:10.
1136/gutjnl -2018-317807.
3.
Jensen DM, Machicado GA, Jutabha R, Kovacs TO.
Urgent colonoscopy for the diagnosis and treatment of severe diverticular hemorrhage.
N Engl J Med.
2000 Jan 13;342(2):78-82.
doi:10.
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