The American College of Gastroenterology defines acute lower gastrointestinal bleeding (LGIB) as a bleeding episode from the gastrointestinal tract originating distal to the ligament of Treitz that may lead to unstable vital signs, anemia, or requirement of a blood transfusion.1 Acute LGIB most commonly presents as hematochezia and often necessitates hospital admission, immediate workup, and treatment. In this section, we will be focusing on the initial evaluation of acute hematochezia associated with inflammatory bowel disease (IBD), the major etiology of LGIB in the young adult population.
It is essential to obtain a thorough history and physical examination in patients presenting with acute LGIB. Clinicians should inquire about the duration and nature of bleeding, stool color, and frequency. Patients may present with symptoms of fever, shortness of breath, dyspnea, palpitations, orthostatic symptoms, abdominal pain, weight loss, urgency/tenesmus, or change in bowel habits. One should also note any past history of abdominal surgeries, prior bleeding episodes, radiation exposure, inflammatory bowel disorders, previous peptic ulcer disease, recent trauma, or liver disease. Exposure of medications (NSAIDS, Aspirin, or anticoagulants) that may cause or exacerbate LGIB should be enquired. Initial patient monitoring with basic vital signs assessment, and fetal monitoring should be ensured if indicated. Large bore intravenous access and initial laboratory workup should be obtained. Laboratory workup should include a complete blood count, coagulation panel, type and screen, electrocardiogram, and basic metabolic panel. Resuscitative measures such as fluid resuscitation with crystalloids or blood transfusion (hemoglobin <7 g/dL) should be initiated. If the patient does not respond to initial interventions, admission to an intensive care unit should be considered. After initial evaluation and resuscitative maneuvers, determining the source of bleeding becomes imperative. Diagnosis and management of this clinical scenario should involve a multidisciplinary team consisting of the obstetrician (usually the primary care physician), maternal fetal medicine specialist, surgeon, and gastroenterologist. The first step in working up the source of LGIB is to rule out an upper gastrointestinal source as up to 11% of patients with hematochezia have a proximal source of bleeding.2 The latter may require placement of a nasogastric tube and if its aspirate is negative for blood, the patient should undergo a colonoscopy. If the latter is negative, small bowel studies (enteroscopy, capsule video assisted endoscopy, small bowel radiography) may be required. If the source is not identified by conventional studies, an arteriography (+/−nuclear scan) with potential surgical consultation may be indicated. The overall yield to identify correctly the source of bleeding of a colonoscopy is 69% to 80%,3 and of arteriography is 40% to 78%.4,5 Arteriography is a useful tool to localize the site of bleeding presuming that the minimum rate of bleeding of 1 to 1.5 mL/min is met. The rate of bleeding for optimal results using a nuclear scan is 0.1 to 0.4 mL/min. The detection yield for the latter is 26% to 72%.6 If surgical intervention is required for saving life, it should be pursued irrespective of the gestational age. Continuous fetal monitoring during any procedure should be performed if pregnancy is viable.
COMMON ETIOLOGIES OF LOWER GASTROINTESTINAL BLEEDING
In the general population, the three most common pathologies responsible for LGIB encompass diverticular disease, colonic vascular ectasia, and inflammatory bowel disease. IBD affects a large number of women during childbearing age. Consequently, it is the most common cause of LGIB during pregnancy (together with hemorrhoids). The exact incidence of IBD during pregnancy remains unknown. ...