GI ANATOMY LAB 4: CLINICAL CASES Midgut & Hindgut Case 1: A 23-year-old man was admitted to the hospital with severe abdominal pain and a mildly elevated temperature. He complained that he originally experienced generalized abdominal pain. Later he said he felt most pain in the pit of his stomach (epigastrium) and that pain was more intense around his umbilicus. Further examination revealed right lower quadrant pain and rebound tenderness. What is the likely diagnosis? Case 2: A 38-year-old man presented at the emergency department with fatigue and abdominal swelling. For several months, he had noticed that his abdomen had been growing larger and that his skin was turning yellow. He denied any medical problems but admitted to drinking alcohol almost every day. On examination, his skin clearly had a yellow hue indicative of icterus (jaundice). His palms had some redness. His abdomen was markedly distended and tense and a fluid wave was present. On the surface of the abdomen were found prominent vascular markings. What is the likely diagnosis? Case 3: A 49-year-old man complained of tenderness and pain on the right side of his anus, which he said was aggravated by defecation and sitting. Because of his history of hemorrhoids, he suspected that he might be having a recurrence of this problem. On physical examination of his anal canal and rectum, prolapsed internal hemorrhoids came into view when the patient was asked to strain as if to defecate. Digital examination of the anal canal and rectum revealed some swelling in the patient’s right ischioanal fossa. What is the diagnosis? The answers to the cases begin on the next page. Clinical Case Answers Case 1: A 23-year-old man was admitted to the hospital with severe abdominal pain and a mildly elevated temperature. He complained that he originally experienced generalized abdominal pain. Later he said he felt most pain in the pit of his stomach (epigastrium) and that pain was more intense around his umbilicus. Further examination revealed right lower quadrant pain and rebound tenderness. What is the likely diagnosis? Answer: Appendicitis Explanation: The history and physical findings suggest acute appendicitis. Acute inflammation of the appendix is a common cause of acute abdominal pain (acute abdomen). Digital pressure over McBurney’s point usually registers the maximum abdominal tenderness. Appendicitis is usually caused by obstruction of the lumen of the appendix. Two common causes of lumen obstruction are fecaliths and lymphoid follicle hyperplasia. Fecaliths form when calcium salts and fecal debris become layered around a nidus of inspissated fecal material located within the appendix. Lymphoid hyperplasia is associated with a variety of inflammatory and infectious disorders including Crohn disease, gastroenteritis, amebiasis, respiratory infections, measles, and mononucleosis. When its secretions cannot escape, the appendix swells and stretches the visceral peritoneum. The pain of acute appendicitis usually commences as a vague pain in the periumbilical region because afferent pain fibers enter the spinal cord at the T10 level. Later, severe pain develops in the lower right quadrant; this pain is caused by irritation of the parietal peritoneum on the posterior abdominal wall. Pain can be elicited by extending the thigh at the hip joint. Source: Moore KL, Dalley AF. Clinically Oriented Anatomy, 4th ed. Baltimore: Lippincott Williams & Wilkins, 1999, Case 2.13. Case 2: A 38-year-old man presented at the emergency department with fatigue and abdominal swelling. For several months, he had noticed that his abdomen had been growing larger and that his skin was turning yellow. He denied any medical problems but admitted to drinking alcohol almost every day. On examination, his skin clearly had a yellow hue indicative of icterus (jaundice). His palms had some redness. His abdomen was markedly distended and tense and a fluid wave was present. On the surface of the abdomen were found prominent vascular markings. What is the likely diagnosis? Answer: Cirrhosis of the liver Explanation: This patient abuses alcohol and has manifestations of end-stage liver disease (cirrhosis). Cirrhosis results in severe fibrotic scarring of the liver, which decreases blood flow through the organ. Hypertension in the portal venous system is the result, with collateral venous flow, especially in organs having venous drainage by the portal and vena caval systems, such as the abdominal surface, and the esophagus. The spleen is frequently enlarged, and the ascites, fluid within the peritoneal cavity, is due to liver insufficiency. Death may ensue due to bleeding from esophageal varices or bacterial peritonitis of the ascitic fluid. Marked hepatic insufficiency is another complication. The liver receives a dual blood supply; approximately 30 percent of the blood entering the organ is from the hepatic artery, and 70 percent is from the portal vein. The proper hepatic artery is a branch of the common hepatic artery, one of the three major branches of the celiac artery. As it approaches the liver, it divides into right and heft hepatic branches that enter the liver and divide into lobar, segmental, and smaller branches. Eventually blood reaches the arterioles in the portal areas at the periphery of the hepatic lobules and, after providing oxygen and nutrients to the parenchyma, drain into the hepatic sinusoids. The majority of blood entering the liver is venous blood rich in nutrients and molecules absorbed by the gastrointestinal organs. The portal venous system arises from the capillary beds within the abdominal organs supplied by the celiac artery, SMA, and IMA and blood will flow to and through the liver for metabolism of its contained molecules. Veins from these organs, for the most part, accompany arteries of the same name. The portal vein itself is formed by the union of the splenic vein and SMV posterior to the neck of the pancreas. This short, wide vein ascends within the hepatoduodenal ligament, posterior to the bile duct and hepatic artery, and enters the liver through the porta hepatis. Typically, the SMV drains its blood into the splenic vein. Portacaval (systemic) venous anastomoses occur at sites where blood may ultimately drain into the portal system and/or the vena caval system. If venous flow through the portal system is prevented by liver disease, for example, the absence of valves within the portal system veins allows reverse flow. This dilates the smaller veins and blood is drained by veins emptying into the vena cavae. This occurs at several sites and may produce clinical signs or symptoms. Source: Toy EC, Ross LM, Clearly LJ, Papsakelariou C. Case Files: Gross Anatomy. New York: Lange Medical Books/McGraw-Hill. 2005. Case 3: A 49-year-old man complained of tenderness and pain on the right side of his anus, which he said was aggravated by defecation and sitting. Because of his history of hemorrhoids, he suspected that he might be having a recurrence of this problem. On physical examination of his anal canal and rectum, prolapsed internal hemorrhoids came into view when the patient was asked to strain as if to defecate. Digital examination of the anal canal and rectum revealed some swelling in the patient’s right ischioanal fossa. What is the diagnosis? Answer: Ischioanal abscess Explanation: Internal hemorrhoids are mucosal prolapses containing the normally varicose-appearing veins of the internal rectal venous plexus draining blood from the anal canal. The hemorrhoids occur because of a breakdown of the muscularis mucosae. These veins are usually tributaries of the superior rectal vein. This vein is a tributary of the inferior mesenteric vein and belongs to the portal system of veins. The tributaries of the superior rectal vein arise in the internal rectal plexus that lies in the anal columns. They normally appear varicose (dilated and tortuous), even in newborns. Internal hemorrhoids are covered by mucous membrane. At first, they are contained in the anal canal, but as they enlarge they may protrude through the anal canal on straining during defecation. Bleeding from internal hemorrhoids is common. External hemorrhoids are thromboses (blood clots) in the tributaries of the inferior rectal vein arising from the external rectal plexus, which drains the inferior part of the anal canal. External hemorrhoids are covered by anal skin and are painful, but they usually resolve within hours, often by rupturing. Local anesthetics or sitting in a warm bath often brings relief. Perianal abscesses often result from injury to the anal mucosa by hardened fecal material. Inflammation of the anal sinuses may result, producing a condition called cryptitis. The infection may spread through a small crack or lesion in the anal mucosa and pass through the anal wall into the ischioanaI fossa, producing an ischioanal abscess. The ischioanal fossa is a wedge-shaped space lateral to the anus and levator ani. The main component of the ishioanal fossae is fat. The branches of the nerves and vessels (pudendal nerve, internal pudendal vessels, and the nerve to the obturator internus) enter the ischioanaI fossa through the lesser sciatic foramen. The pudendal nerve and internal pudendal vessels pass in the pudendal canal lying in the lateral wall of the ischioanal fossa. The inferior rectal nerve leaves the pudendal canal and runs anteromedially and superficially across the ischioanal fossa. It passes to the external anal sphincter and supplies it. It is vulnerable during surgery in the ischioanal fossa. Damage to the inferior rectal nerve results in impaired action of this voluntary anal sphincter. Source: Moore KL, Dalley AF. Clinically Oriented Anatomy, 4th ed. Baltimore: Lippincott Williams & Wilkins, 1999, Case 3.16. .