1. To define acute, overt and occult GI bleeding.
2. To learn about different imaging modalities that can be utilised in the work-up of GI bleeding.
3. To define the role of the interventional radiologist in the management of the GI bleeding.
Sometimes, things may become more difficult and easier at the same time. On one hand advances in imaging allow for very precise and also fast diagnoses in a continuous increasing number of cases. Consequently, even the bleeding of the GI-tract comes even more into radiological play. On the other hand, radiologists have to be more and more aware of clinical entities, pathological patterns, and interdisciplinary networks to quickly and precisely provide our clinical partners with the information they need. Besides that, more and more cases can be managed by minimal-invasive interventional procedures, i.e., by
1. To learn about the common causes of the acute upper and lower GI bleeding.
2. To understand the rationale for different investigative pathways depending on the likely site of bleeding.
3. To appreciate how best to optimise imaging protocols to identify the site and cause of bleeding, and assist with treatment planning.
Acute gastrointestinal (GI) bleeding is a common medical problem associated with high morbidity and mortality. The clinical presentation of acute GI bleeding varies with the location of the bleeding site, the cause, the amount of blood loss, and the presence of comorbidities. Anatomically, the ligament of Treitz is the border between upper (mouth to Treitz) and lower (Treitz to anus) GI bleeding. However, it is not always possible to differentiate between upper and lower GI bleeding clinically, despite the fact that clinical presentation is different, as is the etiology. In decreasing order, erosions and ulcer, variceal bleeding, Mallory-Weiss tears, vascular lesions, and neoplasms are responsible for upper GI bleeding. In contrast, lower GI bleeding occurs in the elder population, with diverticular disease, angiodysplasia, neoplasms, colitis and benign anorectal lesions being the major etiologies. The main diagnostic objective is the identification of the etiology and site of bleeding. Endoscopy is the initial diagnostic step in upper GI bleeding, but limited in lower GI bleeding due to difficulties in colonic cleansing in an emergency situation. Accordingly, CT is the imaging method of choice [technique: no positive oral contrast, high dose /iodine content/flow of contrast material (e.g.,100-150 ml, 350 mg/ml, 4-6 ml/sec), plain, arterial and parenchymal phases, dual-energy CT with iodine maps if available, multiplanar reformation, high anatomic resolution]. We search for high-attenuation (> 80HU) luminal or wall lesions not seen on unenhanced CT data. Detection rates vary, and an amount of bleeding > 0.35-0.5 ml/min is required. As bleeding might be intermittent, CT should be performed when active bleeding is present.
1. To learn about the differences between obscure, occult and overt GI bleeding, and the most common causes of each.
2. To understand when imaging is indicated which tests to perform, and the most important diagnoses to look for.
3. To appreciate the interaction between endoscopic and radiologic investigations in managing patients with obscure GI bleeding.
The term obscure gastrointestinal bleeding (OGIB) was traditionally used to include patients with gastrointestinal bleeding who underwent normal upper and lower endoscopic examinations in addition to a small bowel series that did not reveal a source of bleeding. This definition was a sign of the difficulties experienced in small bowel exploration in the past. Given to recent advances in small bowel investigative methods, including endoscopic (video capsule endoscopy, deep enteroscopy) and radiological (CT and MR enterography, CT angiography) techniques, the cause of bleeding is no longer obscure and can now be reached in majority of the patients. For this reason, the term OGIB has been reclassified as “small bowel bleeding”, which corresponds to ~5-10% of all patients presenting with gastrointestinal bleeding. “OGIB” is now reserved for patients in whom a source of bleeding cannot be identified anywhere in the gastrointestinal tract after a comprehensive investigation. Small bowel bleeding can be overt, if patient presents with melena or hematochezia, or occult for patients presenting with iron-deficiency anaemia. Causes of small bowel bleeding are varied and the likelihood to be due to a vascular, inflammatory or mass lesion is related to the patient’s age. Algorithms for investigation of suspected small bowel bleeding include endoscopic and radiological methods, frequently with a complementary role, indicating that an adequate interaction is required among the elements of a multidisciplinary team.
1. To learn about the role of interventional radiology in the management of acute and chronic GI bleeding.
2. To learn about the variety of techniques available to the interventional radiologist to evaluate obscure GI bleeding and control acute GI bleeding.
3. To understand when interventional radiology is clearly indicated, when it should be considered, and when it should be avoided if possible.
Acute significant gastrointestinal bleeding is generally defined as a bleeding requiring transfusion of at least 4 units of blood within 24 hours or showing signs of hemodynamic instability (hypotension, tachycardia, signs of hypovolemic shock). Most cases are resolved endoscopically, pharmacologically, or by correction of coagulation parameters. Due to its minimally invasive nature, the endovascular solution is currently in most cases, after the previous methods fail, considered the method of choice. The most often used access to undergo embolisation is percutaneous access via common femoral or brachial artery. After reaching the appropriate visceral artery with a diagnostic 4 or 5F catheter, and verification of the source of bleeding, microcatheres are introduced coaxially. The most commonly used embolic materials are microcoils , PVA microspheres and gelatin foam. In the case of more massive bleeding, using of tissue glue (Histoacryl, etc.) may be considered . Upper gastrointestinal tract is characterised by a rich network of collateral supply with lower risk of ischemia. In the risk of rebleeding via collaterals, it is necessary to perform embolisation proximally and distally from the site of bleeding (so-called sandwich method). In the lower gastrointestinal tract, and in particular in the colon, due to the higher portion of terminal branches, ischemia risk is higher and embolisation should be as selective as possible.