Hémorragies digestives basses aiguës : intérêt de l’imagerie

Gastrointestinal bleeding of undetermined origin: What diagnostic strategy to propose?

Gastrointestinal bleeding of undetermined origin (GBUO) is defined as gastrointestinal bleeding without an identified cause or location despite an endoscopic assessment including an esogastroduodenal endoscopy (EOGD) and a total colonoscopy. A distinction is made between exteriorized GBUO and non-exteriorized occult GBUO. The causes in the majority of cases (vascular, inflammatory and tumoral) are located in the small intestine. The diagnostic strategy aiming to locate the origin of the GBUO is a real challenge. Innovation in endoscopic and imaging techniques has enabled minimally invasive exploration of the small intestine. In Europe, there is a strong consensus to recommend a video-capsule endoscopy (VCE) as the first-intention study. If there is reason to suspect intestinal obstruction, VCE is contraindicated and a CT-enteroscopy is then performed as first intention. Enteroscopy is performed as a second-line treatment, either for therapeutic purposes after a positive VCE or CT-enteroclysis, or for diagnostic purposes after a negative VCE. Finally, intraoperative enteroscopy (IOE) coupled with surgical exploration should be reserved either for therapeutic purposes in the event of impossibility or failure of preoperative enteroscopy, or for diagnostic purposes in the event of recurrent GBUO after failure of all other studies and explorations of the small intestine.

How to manage lower gastrointestinal bleeding in 2022?

Lower gastrointestinal bleeding (LGIB), originating mainly in the colon, rectum and anus, occurs most often in older patients (7th decade) with co-morbidity, half of whom have coagulation abnormalities due to anti-coagulant or anti-aggregant therapy. In three cases out of four, bleeding regresses spontaneously but can recur in up to one third of patients. The main causes are diverticular disease, vascular disorders (hemorrhoids, angiodysplasia) and colitis. Ten to 15% of patients present in hypovolemic shock. The main problem is to determine the precise location and etiology of bleeding. First-line steps include correction of hemodynamics, correction of coagulation disorders and transfusion, as necessary. Rectal digital examination allows differentiation between melena and hematochezia. In patients with severe LGIB, upper endoscopy can eliminate upper gastro-intestinal bleeding (UGIB). Computerized tomography (CT) angiography can pinpoint the source. If contrast material extravasates, the therapeutic strategy depends on the cause of bleeding and the general status of the patient: therapeutic colonoscopy, arterial embolization and/or surgery. In the absence of severity criteria (Oakland score≤10), ambulatory colonoscopy should be performed within 14 days. Discontinuation of anticoagulant and/or antiplatet therapy should be discussed case by case according to the original indications.

The management of lower gastrointestinal bleeding

Lower gastrointestinal (LGI) bleeding is generally less severe than upper gastrointestinal (UGI) bleeding with spontaneous cessation of bleeding in 80% of cases and a mortality of 2-4%. However, unlike UGI bleeding, there is no consensual agreement about management. Once the patient has been stabilized, the main objective and greatest difficulty is to identify the location of bleeding in order to provide specific appropriate treatment. While upper endoscopy and colonoscopy remain the essential first-line examinations, the development and availability of angiography have made this an important imaging modality for cases of active bleeding; they allow diagnostic localization of bleeding and guide subsequent therapy, whether therapeutic embolization, interventional colonoscopy or, if other techniques fail or are unavailable, surgery directed at the precise site of bleeding. Furthermore, newly developed endoscopic techniques, particularly video capsule enteroscopy, now allow minimally invasive exploration of the small intestine; if this is positive, it will guide subsequent assisted enteroscopy or surgery. Other small bowel imaging techniques include enteroclysis by CT or magnetic resonance imaging. At the present time, exploratory surgery is no longer a first-line approach. In view of the lesser gravity of LGI bleeding, it is most reasonable to simply stabilize the patient initially for subsequent transfer to a specialized center, if minimally invasive techniques are not available at the local hospital. In all cases, the complexity and diversity of LGI bleeding require a multidisciplinary collaboration involving the gastroenterologist, radiologist, intensivist and surgeon to optimize diagnosis and treatment of the patient.