USMLE Step 1 Problem Drill 17: Gastrointestinal System

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1 USMLE Step 1 Problem Drill 17: Gastrointestinal System Question No. 1 of A surgeon is planning to remove a patient s gallbladder endoscopically. During the procedure, the endoscope will traverse the abdominal layers in what order? Question #01 (A) Skin external oblique muscle internal oblique muscle transverse abdominis muscle superficial fascia transverse fascia extra-peritoneal tissue peritoneum (B) Skin superficial fascia external oblique muscle transverse abdominis muscle internal oblique muscle transverse fascia extra-peritoneal tissue peritoneum (C) Skin superficial fascia external oblique muscle internal oblique muscle transverse abdominis muscle transverse fascia extra-peritoneal tissue peritoneum (D) Skin superficial fascia transverse abdominis muscle external oblique muscle internal oblique muscle transverse abdominis muscle transverse fascia extra-peritoneal tissue peritoneum (E) None of the above Wrong order. Wrong order. C. Correct! Skin superficial fascia external oblique muscle internal oblique muscle transverse abdominis muscle transverse fascia extra-peritoneal tissue peritoneum, is the correct order of layers from external to internal when traversing the skin in the right upper quadrant of the abdomen. Wrong order. Answer C lists the correct order. Image Source: There are multiple layers of the abdominal wall which vary depending on location between the anterior and posterior midlines. A surgeon entering the abdomen in the right upper quadrant would traverse the following layers in this order: Skin Superficial Fascia External oblique muscle Internal oblique muscle Transverse abdominis muscle Transverse fascia Extra-peritoneal tissue Peritoneum RapidLearningCenter.com Rapid Learning Inc. All Rights Reserved

2 Question No. 2 of All of the following structures are located in the retroperitoneal space except for: Question #02 (A) 1 st portion of the duodenum (B) 4 th portion of the duodenum (C) Kidneys (D) Inferior vena cava (E) Ascending colon A. Correct! The 1 st portion of the duodenum is an intra-peritoneal structure. The 4 th portion of the duodenum is a retroperitoneal structure. The kidneys are retroperitoneal structures. The inferior vena cava is a retroperitoneal structure. The ascending colon is a retroperitoneal structure. Multiple organs and structures are located in the retroperitoneal space behind the abdominal cavity which include the: 2 nd, 3 rd, and 4 th parts of the duodenum Ascending and descending colon Rectum Kidneys and ureters Adrenal glands Head and body of pancreas Aorta IVC (A)1 st portion of the duodenum RapidLearningCenter.com Rapid Learning Inc. All Rights Reserved

3 Question No. 3 of An obstructing gallstone present at the level of the sphincter of Oddi would lead to dilatation of which of the following structures: Question #03 (A) Gallbladder (B) Cystic duct (C) Common hepatic duct (D) Pancreatic duct (E) All of the above The gallbladder would be secondarily dilated, but the remainder of the structures listed would be dilated as well. The cystic duct would be secondarily dilated, but the remainder of the structures listed would be dilated as well. The common hepatic duct would be secondarily dilated, but the remainder of the structures listed would be dilated as well. The pancreatic duct would be secondarily dilated, but the remainder of the structures listed would be dilated as well. E. Correct! The sphincter of Oddi is the last terminus before the biliary system drains into the duodenum, therefore, the pancreatic duct, common hepatic duct, cystic duct and gallbladder which are proximal to it would be dilated if it were obstructed. Image source: Important biliary structures are the: Gall bladder, which empties into the Cystic duct, which joins the common hepatic duct (arising from the left and right hepatic ducts) to form the Common bile duct, which joins the pancreatic duct distally at the Ampulla of Vater, and empties into the duodenum at the Sphincter of Oddi (E)All of the above RapidLearningCenter.com Rapid Learning Inc. All Rights Reserved

4 Question No. 4 of Which of the following GI ligaments separates the right greater and lesser sacs in the abdomen: Question #04 (A) Falciform ligament (B) Hepatoduodenal ligament (C) Gastrohepatic ligament (D) Gastrocolic ligament (E) Gastrosplenic ligament The falciform ligament connects the liver to the anterior abdominal wall. The hepatoduodenal ligament connects the liver with the duodenum and contains the portal triad. C. Correct! The gastrohepatic ligament connects the lesser curvature of the stomach to the liver and separates the right greater and lesser sacs. The gastrocolic ligament connects the greater curvature of the stomach to the transverse colon and is a component of the greater omentum. The gastrosplenic ligament connects the greater curvature of the stomach with the spleen and separates the left greater and lesser sacs. There are a number of significant ligaments within the abdomen of importance, the: Falciform ligament which connects the liver to the anterior abdominal wall and contains the ligamentum teres a derivative of the fetal umbilical vein. Hepatoduodenal ligament which connects the liver with the duodenum and contains the portal triad which is made up of the hepatic artery, portal vein and common bile duct. Gastrohepatic ligament which connects the lesser curvature of the stomach to the liver and separates the right greater and lesser sacs. Gastrocolic ligament which connects the greater curvature of the stomach to the transverse colon; is a component of the greater omentum and contains the gastroepiploic arteries. Gastrosplenic ligament which connects the greater curvature of the stomach with the spleen and contains the short gastric arteries, separating the left greater and lesser sacs. Splenorenal ligament connects the spleen with the posterior abdominal wall in front of the left kidney and contains the splenic artery and vein. (C)Gastrohepatic ligament RapidLearningCenter.com Rapid Learning Inc. All Rights Reserved

5 Question No. 5 of A healthy appearing full term newborn baby girl suddenly develops choking and respiratory distress when her mother first tries to feed her. The most likely diagnosis is: Question #05 (A) Zenker s diverticulum (B) Congenital pyloric stenosis (C) Hirschprung s disease (D) Tracheo-esophageal fistula (E) Congenital diaphragmatic hernia A Zenker s diverticulum is an abnormal outpouching of the esophagus that presents with halitosis, dysphagia, and signs of cervical esophageal obstruction in older patients. Congenital pyloric stenosis presents in newborns with projectile vomiting, but usually without associated choking and respiratory distress. Hirschprung s disease is a disorder of the colon that may present in the newborn with meconium ileus or in the older child as chronic constipation. D. Correct! A tracheo-esophageal fistula describes an abnormal connection between the lumens of the trachea and esophagus such that when the infant first tries to feed, milk ends up in the lungs either from a direct connection or secondary to aspiration in the case of a blind-ended upper esophagus, causing choking and acute respiratory distress. Congenital diaphragmatic hernia most commonly presents in the newborn with respiratory distress immediately at birth, well before the first feeding. Tracheo-esophageal fistula is a congenital abnormality that results in an abnormal connection between the lumens of the trachea and esophagus. Various types of connections occur with the most common being a connection of the trachea to the lower esophagus with a blind-ended upper esophagus. Polyhydramnios may be detected during pregnancy in this condition and babies born with TEF present with choking and vomiting at feeding which is associated with respiratory distress. (D)Tracheo-esophageal fistula RapidLearningCenter.com Rapid Learning Inc. All Rights Reserved

6 Question No. 6 of A 4 year old female is diagnosed with cystic fibrosis. You discuss with the parents that the following malabsorption syndrome is associated with CF: Question #06 (A) Celiac sprue (B) Tropical sprue (C) Whipple s disease (D) Pancreatic insufficiency (E) Disaccharide deficiency Celiac sprue is not associated with cystic fibrosis and is due to a wheat allergy. Tropical sprue is not associated with cystic fibrosis and is thought to be due to an infectious agent. Whipple s disease is associated with arthralgias, cardiac, and neurological symptoms, and is due to infection with Tropheryma whippelii. D. Correct! Patients with cystic fibrosis commonly have pancreatic insufficiency. Disaccharide deficiency is not associated with cystic fibrosis and is most commonly manifested as lactose intolerance. There are a variety of malabsorption syndromes with symptoms of diarrhea, steatorrhea, weight loss and malaise: Celiac sprue primarily a disease of the jejunum resulting from autoantibodies formed to gluten in wheat and other grain materials. Tropical sprue can affect the entire small bowel likely due to infection as it is responsive to antibiotic therapy. Whipple s disease due to infection with Tropheryma whippelii, most common in older men and may have associated arthralgias, cardiac, and neurological symptoms. Pancreatic insufficiency can be due to cystic fibrosis, chronic pancreatitis, and pancreatic cancer and leads to malabsorption of fat, protein, and vitamins A, D, E, K. Disaccharide deficiency the most common type being a lactase deficiency leading to lactose intolerance. (D)Pancreatic insufficiency RapidLearningCenter.com Rapid Learning Inc. All Rights Reserved

7 Question No. 7 of A 73 year old female patient presents to the emergency room with left lower quadrant pain and tenderness, fever, and some red blood in her stool. The most likely diagnosis is. Question #07 (A) Diverticulosis (B) Diverticulitis (C) Zenker s diverticulum (D) Meckel s diverticulum (E) Appendicitis Diverticulosis is asymptomatic. B. Correct! Symptoms and signs of diverticulitis include left lower quadrant pain, fever, possible bright red blood in stool, and leukocytosis. Zenker s diverticulum is an abnormal outpouching of the esophagus that presents with halitosis, dysphagia, and signs of cervical esophageal obstruction. Meckel s diverticulum is a diverticulum of the distal small bowel which presents with blood in stool, and possible intussusception, volvulus, and distal small bowel obstruction. Appendicitis symptoms generally evolve with mid-abdominal pain which progresses to the right lower quadrant at McBurney s point, with nausea, vomiting and fever. Diverticulitis occurs when diverticula become inflamed and infected, frequently due to obstruction at its origin. Symptoms and signs include left lower quadrant pain, fever, possible bright red blood in stool, and leukocytosis. Depending on the severity, complications may include a pericolonic abscess and/or perforation which can lead to peritonitis. CT scan and/or barium enema are useful in diagnosis. Diverticulitis is initially treated with antibiotics, but may require surgical intervention if there are complications. (B)Diverticulitis RapidLearningCenter.com Rapid Learning Inc. All Rights Reserved

8 Question No. 8 of All of the following conditions of the colon are associated with an increased incidence of colon cancer except for: Question #08 (A) Ulcerative colitis (B) Gardner s syndrome (C) Lynch syndrome (D) Hirschprung s disease (E) Peutz-Jeghers syndrome Ulcerative colitis has a high incidence of associated colon cancer. Gardner s syndrome has a high incidence of associated colon cancer. Lynch syndrome has a high incidence of associated colon cancer. D. Correct! Hirschprung s disease does not have an increased incidence of associated colon cancer. Peutz-Jeghers syndrome has an increased incidence of associated colon cancer. Colorectal cancer risk factors include increased age, a positive family history, and ulcerative colitis, history of colorectal villous adenoma, FAP, and HNPCC. Familial adenomatous polyposis (FAP) is an autosomal dominant condition in which patients have literally thousands of polyps throughout the colon. There are 2 types of FAP: 1) Gardner s syndrome is FAP associated with bone and soft tissue tumors, as well as retinal hyperplasia 2) Turcot s syndrome is FAP associated with brain tumors such as glioblastoma. Lynch syndrome is due to mutations of DNA leading to mismatched repair genes. The proximal colon is consistently involved and 80% of these patients go on to develop colorectal cancer. Peutz-Jeghers syndrome is a benign hamartomatous polyposis syndrome involving the colon and small bowel. Associated signs are hyperpigmentation of the mouth, lips, hands and genitalia. These patients are at increased risk for colorectal cancer as well as other malignancies of the stomach, pancreas, breast and ovary. (D)Hirschprung s disease RapidLearningCenter.com Rapid Learning Inc. All Rights Reserved

9 Question No. 9 of A patient with elevated serum levels of AST and ALT most likely has which of the following conditions? Question #09 (A) Common bile duct obstruction (B) Acute pancreatitis (C) Wilson s disease (D) Hepatocellular carcinoma (E) Hepatitis Common bile duct obstruction is associated with elevated serum levels of alkaline phosphatase. Acute pancreatitis is associated with elevated serum levels of amylase and lipase. Wilson s disease is associated with low serum levels of ceruloplasmin. Hepatocellular carcinoma is associated with elevated serum levels of alkaline phosphatase. E. Correct! Both alcoholic and infectious hepatitis are associated with elevated levels of serum AST and ALT. Aminotransferases (AST and ALT) levels are elevated in viral or alcoholic hepatitis, or possibly MI in the case of AST. (E)Hepatitis RapidLearningCenter.com Rapid Learning Inc. All Rights Reserved

10 Question No. 10 of Primary sclerosing cholangitis is associated with which of the following conditions: Question #10 (A) Bronze diabetes (B) Ulcerative colitis (C) Scleroderma (D) CREST syndrome (E) Ascending cholangitis Bronze diabetes is associated with hemochromatosis. B. Correct! Ulcerative colitis is associated with primary sclerosing cholangitis. Scleroderma is associated with primary biliary cirrhosis. CREST syndrome is associated with primary biliary cirrhosis. Ascending cholangitis is associated with secondary sclerosing cholangitis. Primary sclerosing cholangitis is a condition often associated with ulcerative colitis and can lead to secondary biliary cirrhosis. (B) Ulcerative colitis RapidLearningCenter.com Rapid Learning Inc. All Rights Reserved