Causes and Management of Lower Gastro-Intestinal Bleeding

1 Department of Gastroenterology and Endoscopy, Dr Samir Abbas Hospital, Jeddah, Saudi Arabia. 2 Department of Internal Medicine, Faculty of Medicine, AlAzhar University, Cairo, Egypt. 3 Imam Abdulrahman Bin Faisal University, Saudi Arabia. 4 Abqaiq General Hospital, Saudi Arabia. 5 King Saud University, Saudi Arabia. 6 Jouf University, Saudi Arabia. 7 King Khalid University, Saudi Arabia. 8 Qassim University, Saudi Arabia. 9 Batterjee Medical College, Saudi Arabia. 10 King Abdulaziz universityRabigh Branch. Saudi Arabia. 11 Tabuk University, Saudi Arabia.


INTRODUCTION
Bleeding beyond the ligament of Treitz, which is a thin band that links the ending of duodenum and the beginning of jejunum in the gastrointestinal tract (GIT) or called the suspensory muscle of duodenum, is considered as bleeding in the lower GIT, therefore the term lower gastrointestinal bleeding is a misnomer and should be called lower intestinal bleeding instead [1,2]. Gastrointestinal bleeding is also defined as any bleeding that takes place in the GIT from mouth to anus [3]. Bleeding above the ligament of Treitz, which is called upper gastrointestinal bleeding, is presented as either hematemesis or melena, hematemesis is the regurgitation of blood or blood mixed with stomach contents whereas melena is dark, black, and tarry faeces that has a strong distinctive odor caused by the activity of digestive enzyme and intestinal bacteria on hemoglobin. Bleeding below the ligament of Treitz, which is called lower gastrointestinal bleeding, is presented as hematochezia, which is the passing of bright red blood clots or burgundy stools through the rectum [4,5]. Lower GI bleeding is a common cause of emergency hospital admission, even though there is scarcity of data on presentations, interventions and outcomes. Many terms are used to describe lower gastrointestinal bleeding as rectal bleeding, and hematocheziahowever these terms do not indicate the perception or severity of bleeding, do not always localize the bleeding source, and are not special to bleeding from beyond the Treitz ligament [6].
The prevalence is approximately 36 per 100,000 population, half of patients suffer from upper GI bleeding, the frequency of hospitalization is higher in the elderly, with mortality rate of about 3.9% within 1 year, and it is thought that this rate may rise up to 13% by 5 years [4,[7][8][9]. In the UK the mean age of patients of lower GI bleeding at time of presentation is within the range of 63-77 years and they constitute about 3% of all surgical referrals to hospital [10,11]. GI bleeding is selflimiting and self-resolving in approximately 85% of patients spontaneously, however recurrence can occur with rates up to 19 % within one year and with continuing risks of rebleeding [9,12].
Critical hospitalization, diagnosis, as well as intervention are needed in the cases that do not resolve spontaneously, or presented with severe hematochezia which is seen as ongoing bleeding in the first 24 hours of hospitalization with a minimumfall in the hemoglobin of 2 g/dL and/or a need for transfusion of 2 units of packed red blood cells or more [13].

EPIDEMIOLOGY
Upper GI bleeding mainly occurs in the esophagus, stomach, or duodenum, whereas lower GI bleeding occurs in small bowel, colon, or anorectum. Many studies claimed that upper GI bleeding is more common than lower GI bleeding [14][15][16][17]. Where the incidence of upper GI bleeding is almost 67 per 100,000 population and the incidence of lower GI bleeding is approximately 36 per 100,000 population.
Lower GI bleeding is seen more frequently in men than women because of vascular diseases and diverticulosis which are more common in men than women [18]. The prevalence is higher in elderly patients and patients who are taking multiple medications. Another study claimed that prevalence of upper GI bleeding is decreasing due to the combined therapies eradicating Helicobacter Pylori and utilizing of proton pump inhibitors. The condition of lower GI bleeding is more likely to have a longer period of hospitalization and have higher risk of morbidity or recurrence [19]. Around 80% to 85% of lower GI bleedings initiate beyond the ileocaecal valve, only 0.7% to 9% initiating from the small intestine, and the rest initiates from the upper GIT [20]. Fortunately, the incidence of GI bleeding generally is decreasing.

CAUSES OF LOWER GI BLEEDING
Causes of lower GI bleeding can be summarized to diverticulosis (which is the protrusion of the colon wall at the site of penetrating vessels, and by time the mucosa lining the vessel can be injured and ruptured leading to bleeding), infectious colitis, ischemic colitis, angiodysplasia, inflammatory bowel disease, colon cancer, hemorrhoids, anal fissures, rectal varices, dieulafoy lesion, radiation-induced damage following cancer treatment, and post-surgical [5]. According to the UCLA-Center for Ulcer Research and Education (CURE) database, discussing frequencies of different etiologies, excluding upper GI sources, diverticulosis is still the most common cause of 30 % of lower GI bleeding cases that require hospitalization, the second most common cause is hemorrhoids, another causes frequencies is increasing greatly as ischemic colitis and post-polypectomy bleeding; this increase is due to the increasing use of anti-platelet/anticoagulant [21][22][23][24].
UCLA-CURE Hemostasis Research Group database had set frequencies for some causes of lower GI bleeding; 30% diverticulosis, 14% hemorrhoids, 12% ischemic, 9% irritable bowel disease, 8% post-polypectomy, 6% colon cancer, 6% rectal ulcer, 3% vascular ectasia, 3% radiation colitis, 6% other [23,24]. Another study conducted among 165 patients assessed for lower GI bleeding revealed that diverticulosis was the main cause in 56% of patients, followed by colonic ulcers in 10%, cancer in 7%, and vascular ectasias in 5% [25]. Diverticulosis counts for around 40% of lower GI bleedings and is presented in emergency as painless hematochezia and it always recur. The occurrence of diverticulosis is higher in older patients, mostly over 80 years, patients suffering of chronic constipation, and changed colonic motility. The left colon is frequently more affected as it is the source of diverticular bleedings.
Ischemic colitis happens in 20% of lower GI bleedings and is occurs more frequent in the older ages. It occurs as a result of decreased mesenteric flow to the colon due to reduced cardiac output, vasospasm, or atherosclerosis.
Non-occlusive and nonthrombotic diseases developments typically resolve with hydration and non-surgical intervention. Occlusive or thromboembolic processes can affect greater areas of the bowel and should be quickly evaluated and require intervention.
Almost one third of patients affected with presumed lower GI bleeding also get affected with upper GIbleedingespeciallyif the patient presents with symptoms of peptic ulcer or recent NSAID use.
Anorectal disorders, mainly hemorrhoids, are the most common cause of lower GI bleedings in patients under 50 years. Post-polypectomy bleeding is more frequent in patients aged over than 65 years with a polyp bigger than 1 cm, in this case bleeding is commonly self-limiting but can be delayed to one week after the process [20].
Occult, moderate, and massive bleeding are three categories of lower GI bleeding [21,22]. Occult bleeding in lower GI present in patients at any age. Lab tests show if patients had microcytic hypochromic anemia due to chronic blood loss. The differential diagnosis of those anemic patients should include inflammatory, neoplastic and congenital diagnosis. The patient classically appears in a good condition, and hemodynamically stable. Moderate bleeding in lower GI occur at any age and presents as hematochezia or melena, where the patient is typically hemodynamically stable. Many disease processes should be considered on the differential diagnostic list as neoplastic disease, inflammatory, infectious, benign anorectal, and congenital. Massive bleeding in lower GI happens in elderly patients over 65 years with multiple medications; this bleeding presents as hematochezia or bright red blood per rectum, where the patient is typically hemodynamically unstable, having a systolic blood pressure equal to or less than 90 mmHg, heart rate less than or equal 100/min, and reduced urine output. Lab tests reveal that hemoglobin equal to or less than 6 g/dl. Massive lower GI bleedings are commonly because of diverticulosis and angiodysplasias. Unfortunately, the mortality rate is high and may be up to 21% [20].

RISK FACTORS& HISTORY
The clinician should first ask the patient about his/her history to obtain any clues or risk factors that may aggravate the GI bleeding, as if the patient endured past episodes of bleeding, or if the patient had past history related to potential bleeding sources (like varices, portal hypertension, alcohol abuse, ulcers, H.pylori, diverticulosis, hemorrhoids, and inflammatory bowel disease), presence of comorbid conditions that affect management, contributory medications (as NSAIDs, anticoagulants, antiplatelet agents, bismuth, or iron), or symptoms related with bleeding (as painless vs. painful, trouble in swallowing, unintended weight loss, preceding emesis or vomiting, alter in bowel habits).
The clinician should also evaluate some physical signs as searching for signs of hemodynamic instability(as resting tachycardia associated with the loss of ≤15% total blood volume, orthostatic hypotension associated with the loss of around 15% total blood volume, supine hypotension associated with the loss of around 40% total blood volume), abdominal pain may increase notion about perforation or ischemia, and rectal examination is significant for evaluating anal fissures, hemorrhoids, anorectal mass, and stool exam [5].

DIAGNOSIS
Patients presented at the emergency department with lower GI bleeding should be evaluated immediately as the patient's case could deteriorate quickly [26]. Lab tests should be done to evaluate the case and to aid in finding the cause. Those tests as complete blood count (CBC), hemoglobin/hematocrit, lactate level, electrolyte evaluation, liver function tests, international normalized ratio (INR), prothrombin time, and activated partial thromboplastin time [5,20].
BLEED criteria are applied for diagnostic purposes: continuing Bleeding (Red bloody emesis), Low Systolic Blood Pressure less than 100 mmHg, Elevated Prothrombin time that is higher than 1.2 times normal, Erratic Mental Status (changed level of consciousness), and unstable Comorbid Disease (any other disease process that could increase risk of admission to intensive care unit (ICU) without the presence of a GI bleed). The presence of any of these symptoms is considered high risk to patients with higher risk of in-hospital complications.

MANAGEMENT OF GI BLEEDING
More than 80% of lower GI bleeding cases resolve on its own without any interventions, with a morbidity and mortality rate of 2% to 4% [7][8][9]. The first step for managing lower GI bleeding is to ask patient about history in order to get some clues as suggestions to acknowledge the source and know the etiology of the bleeding. Management of acute lower GI bleeding is summarized to setting an appropriate treatment followed by supportive and restorative therapy while examining the main cause and trying to resolve it.
Assessing the risks is essential in determining the management procedure suitable for each individual case, and there are specific calculators for measuring risks score. The AIMS65 score and the Rockall score calculate the mortality rate and risk score of upper GI bleeds, where the Oakland score is a risk calculator that helps calculating the probability of a safe discharge in lower GI bleedings [27].
In some cases, patients with hemodynamic instability, ongoing bleeding, or with a high risk of morbidity should be hospitalized in an intensive care unit (ICU) to enable more frequent observation and monitoring of vital signs and more emergency interventions. The majority of patients can go through examination and monitoring on a general medical floor. As we mentioned, the majority of patients with lower GI bleeding will require hospitalization, but some young, healthy patients with self-limiting and asymptomatic bleeding may be discharged safely and evaluated on an outpatient basis.
Colonoscopy is the main procedure to detect the source of lower GI bleeds in more than 75% of cases while also allowing a therapeutic effect. The period of colonoscopy remain divisive. Some studies recommend that this procedure should be done within the first 24 hours of admission. Treating bleeding of diverticulosis comprise the injection of epinephrine (adrenaline) 1:10000 in 1 mL to 2mL. If the patient does not fit for a colonoscopy, then a radiologic evaluation should be considered. CT angiography (CTA) is fairly noninvasive, quick and broadly available, however it has a low sensitivity (85%). Surgery may be needed when radiologic and endoscopic processes fail. [28,29] Treating patient is through assessing the overall health condition; as if the patient is hypoxic then supplemental oxygen should be provided. Important measure is avoiding non-invasive positive pressure ventilation because of expected aspiration. The patient may also need IV access then IV fluid restoration with normal saline or ringer lactate solution, also some cases need blood transfusions especially when hemoglobin drops under 7 g/dL or for coronary heart disease patients [30,31].

CONCLUSION
Patients with lower GI bleeding typically present to the emergency department, with different causes so it is best managed by professional team that includes a surgeon, gastroenterologist, radiologist, intensivist and the emergency department physician. Depending on the severity of symptoms, the medical procedures are determined, and also the clinicians determine whether the patient needs to be hospitalized in the ICU. Some patients require invasive processes as blood transfusions or even surgery. But after all lower GI bleeding is manageable disease and its mortality rates are dropping.

CONSENT
Not applicable.

ETHICAL APPROVAL
Not applicable.