Welcome to the online lecture series on lower gastrointestinal bleeding (LGIB) designed specifically for medical students on their surgery clerkships. In this comprehensive series, we will explore the various aspects of LGIB, including its introduction, pathophysiology, common causes, evaluation, and management.

Part 1: Introduction and Pathophysiology
In the first part of the series, we will provide an introduction to LGIB and delve into its pathophysiology. We will discuss the anatomical structures involved in LGIB, including the jejunum, ileum, colon, and rectum. Understanding the pathophysiological mechanisms underlying LGIB will help you grasp the clinical presentation and diagnostic challenges associated with this condition.

Part 2: Common Causes
Moving on to the second part, we will focus on the common causes of LGIB. We will explore the primary culprits behind lower gastrointestinal bleeding, such as diverticular hemorrhage and vascular malformations. Additionally, we will discuss less common causes, including malignancy, polyps, hemorrhoids, anal fissures, ischemic colitis, Meckel diverticulum (more commonly seen in pediatrics), infectious colitis, and inflammatory bowel disease (IBD). Gaining knowledge about these causes will enable you to approach the diagnosis and management of LGIB more effectively.

Part 3: Evaluation, Workup, and Management
In the final part of the series, we will focus on the evaluation, workup, and management of LGIB. We will guide you through the essential steps in evaluating patients with LGIB, including the initial approach and resuscitation. You will learn about various diagnostic modalities, such as nasogastric and gastric lavage, endoscopy (for visualization of the stomach, duodenum, and colon), radiographic imaging (such as tagged red cell scan and angiography), and capsule endoscopy or push enteroscopy. We will also discuss the importance of localizing the bleeding source and highlight the challenges in differentiating upper and lower GI bleeding.

Furthermore, we will delve into the management strategies for LGIB, including the cessation of immediate hemorrhage and the prevention of future episodes. You will learn about both medical and surgical options for managing LGIB, such as exploratory laparotomy, angiographic embolization, and surgical resection. We will emphasize the significance of resuscitation, control of hemorrhage, and reversal of coagulopathy in the management of LGIB.

Throughout the series, we will provide real-life case examples, interactive quizzes, and additional resources to enhance your understanding of LGIB. By the end of this lecture series, you will have a comprehensive knowledge of LGIB, enabling you to confidently approach and manage patients with this condition.