GI

GI US Medical PG Question 1: A 3-year-old recent immigrant is diagnosed with primary tuberculosis. Her body produces T cells that do not have IL-12 receptors on their surface, and she is noted to have impaired development of Th1 T-helper cells. Which of the following cytokines would benefit this patient?

• A. IL-4
• B. IL-22
• C. TGF-beta
• D. IL-17
• E. Interferon-gamma (Correct Answer)

GI Explanation: ***Interferon-gamma*** - This patient has an impaired **Th1 response**, which is crucial for controlling intracellular infections like **tuberculosis** by activating macrophages. - **Interferon-gamma** is the primary cytokine produced by **Th1 cells** that activates macrophages, leading to enhanced phagocytosis and killing of intracellular pathogens. *IL-4* - **IL-4** is a key cytokine produced by **Th2 cells**, which primarily drive **humoral immunity** and allergic responses, not cellular immunity against intracellular bacteria. - Its administration would promote a **Th2 response**, which is not beneficial for combating **tuberculosis** and might even suppress the desirable Th1 response. *IL-22* - **IL-22** is mainly involved in **epithelial cell proliferation**, host defense at mucosal surfaces, and tissue repair. - While it has a role in host defense against certain pathogens, it is not the primary cytokine required to compensate for a deficient **Th1 response** in **tuberculosis**. *TGF-beta* - **TGF-beta** is a pleiotropic cytokine with roles in cell growth, differentiation, and immune regulation, often acting as an **immunosuppressant** or driving **Treg differentiation**. - It would not directly compensate for a lack of **Th1 cell function** needed to activate macrophages against **tuberculosis**. *IL-17* - **IL-17** is the signature cytokine of **Th17 cells**, which are important for host defense against **extracellular bacteria** and fungi, primarily by recruiting neutrophils. - While it plays a role in some immune responses, it is not the crucial cytokine to boost in a patient with impaired **Th1 development** against **intracellular M. tuberculosis**.

GI US Medical PG Question 2: A 66-year-old man is brought to the emergency department after a motor vehicle accident. The patient was a restrained passenger in a car that was struck on the passenger side while crossing an intersection. In the emergency department, he is alert and complaining of abdominal pain. He has a history of hyperlipidemia, gastroesophageal reflux disease, chronic kidney disease, and perforated appendicitis for which he received an interval appendectomy four years ago. His home medications include rosuvastatin and lansoprazole. His temperature is 99.2°F (37.3°C), blood pressure is 120/87 mmHg, pulse is 96/min, and respirations are 20/min. He has full breath sounds bilaterally. He is tender to palpation over the left 9th rib and the epigastrium. He is moving all four extremities. His FAST exam reveals fluid in Morrison's pouch. This patient is most likely to have which of the following additional signs or symptoms?

• A. Pain radiating to the back
• B. Gross hematuria
• C. Muffled heart sounds
• D. Free air on chest radiograph
• E. Shoulder pain (Correct Answer)

GI Explanation: ***Shoulder pain*** - The presence of **fluid in Morrison's pouch** (hepatorenal recess) on FAST exam indicates **intra-abdominal bleeding**, likely from a liver or spleen injury. - **Diaphragmatic irritation** due to intra-abdominal hemorrhage often manifests as referred **shoulder pain** (Kehr's sign), especially on the left side with splenic injury or right side with liver injury. *Pain radiating to the back* - While pancreatic injury can cause pain radiating to the back, the primary finding of **fluid in Morrison's pouch** points towards hemoperitoneum, less specifically to pancreatic trauma. - Significant pancreatic injury would likely involve more severe abdominal tenderness and potentially elevated **amylase/lipase**, which are not mentioned here. *Gross hematuria* - **Gross hematuria** would suggest a **renal or urologic injury**, but the patient's primary finding is intra-abdominal fluid in Morrison's pouch, which is more indicative of solid organ injury like the liver or spleen. - Though concurrent injuries are possible in trauma, hepatorenal fluid points specifically to **hemoperitoneum**, not necessarily kidney damage. *Muffled heart sounds* - **Muffled heart sounds** are a component of **Beck's triad** (along with hypotension and jugular venous distension), indicative of **cardiac tamponade** due to fluid around the heart. - There is no clinical information in the stem suggestive of cardiac injury or tamponade; the fluid is specifically mentioned in the abdomen. *Free air on chest radiograph* - **Free air on chest radiograph** (pneumoperitoneum) indicates a **perforated hollow viscus**, such as the bowel or stomach. - The FAST exam finding of fluid in Morrison's pouch is characteristic of **hemoperitoneum** from a solid organ injury, not free air from a perforation.

GI US Medical PG Question 3: A 57-year-old man presents with 2 days of severe, generalized, abdominal pain that is worse after meals. He is also nauseated and reports occasional diarrhea mixed with blood. Apart from essential hypertension, his medical history is unremarkable. His vital signs include a temperature of 36.9°C (98.4°F), blood pressure of 145/92 mm Hg, and an irregularly irregular pulse of 105/min. Physical examination is only notable for mild periumbilical tenderness. Which of the following is the most likely diagnosis?

• A. Diverticular disease
• B. Acute pancreatitis
• C. Gastroenteritis
• D. Crohn's disease
• E. Acute mesenteric ischemia (Correct Answer)

GI Explanation: ***Acute mesenteric ischemia*** - The patient's presentation with **severe, generalized abdominal pain worse after meals**, along with **bloody diarrhea** and **irregularly irregular pulse** (suggesting **atrial fibrillation**), is highly indicative of acute mesenteric ischemia. - Atrial fibrillation can lead to **emboli** that occlude mesenteric arteries, causing rapid onset of **ischemic bowel injury** with disproportionate pain and often minimal findings on physical exam. *Diverticular disease* - While diverticulitis can cause abdominal pain, it is typically localized to the **left lower quadrant** and often associated with fever and leukocytosis, which are absent here. - **Diverticular bleeding** usually presents as painless rectal bleeding, not severe, diffuse abdominal pain with ischemic features. *Acute pancreatitis* - Characterized by severe **epigastric pain radiating to the back**, often associated with nausea and vomiting, but not typically with bloody diarrhea. - Elevated **lipase** and **amylase** levels are diagnostic markers, and an irregularly irregular pulse is not a direct symptom. *Gastroenteritis* - Often causes diffuse abdominal pain, nausea, vomiting, and diarrhea, but the pain is rarely as severe or disproportionate to physical findings as described. - **Bloody diarrhea** can occur, but the rapid onset of severe pain, particularly in the context of possible **embolic source** (atrial fibrillation), makes ischemia more likely. *Crohn's disease* - A chronic inflammatory bowel disease presenting with **abdominal pain**, **diarrhea** (often bloody), and weight loss, developing over weeks to months. - The acute, severe onset of symptoms in this patient does not fit the typical chronic presentation of Crohn's disease.

GI US Medical PG Question 4: An unconscious middle-aged man is brought to the emergency department. He is actively bleeding from the rectum. He has no past medical history. At the hospital, his pulse is 110/min, the blood pressure is 90/60 mm Hg, the respirations are 26/min, and the oxygen saturation is 96% at room air. His extremities are cold. Resuscitation is started with IV fluids and cross-matched blood arranged. His vitals are stabilized after resuscitation and blood transfusion. His hemoglobin is 7.6 g/dL, hematocrit is 30%, BUN is 33 mg/dL, and PT/aPTT is within normal limits. A nasogastric tube is inserted, which drains bile without blood. Rectal examination and proctoscopy reveal massive active bleeding, without any obvious hemorrhoids or fissure. The physician estimates the rate of bleeding at 2-3 mL/min. What is the most appropriate next step in diagnosis?

• A. Exploratory laparotomy with segmental bowel resection
• B. Radiolabeled RBC scan
• C. Colonoscopy
• D. Mesenteric angiography (Correct Answer)
• E. EGD

GI Explanation: ***Mesenteric angiography*** - Mesenteric angiography is indicated for **active lower GI bleeding** when the bleeding rate is high (2-3 mL/min) and colonoscopy is challenging due to massive bleeding. It can localize the source of bleeding and allow for therapeutic embolization. - The patient's presentation with **massive rectal bleeding**, signs of hypovolemia, and the exclusion of upper GI bleeding (bile without blood in NG tube) points to a lower GI source. *Exploratory laparotomy with segmental bowel resection* - This is an **invasive surgical procedure** typically reserved for cases where other less invasive diagnostic and therapeutic methods have failed, or in cases of uncontrolled life-threatening hemorrhage. - Doing an exploratory laparotomy without clear localization of the bleeding site carries significant risks and may lead to unnecessary bowel resections. *Radiolabeled RBC scan* - A radiolabeled RBC scan is a highly sensitive diagnostic tool for **detecting intermittent or slow GI bleeding**, but it requires a very low rate of bleeding (as low as 0.1 mL/min). - Given the patient's **active and massive bleeding** (2-3 mL/min), a more rapid and precise localization method like angiography is preferred. *Colonoscopy* - While colonoscopy is the primary diagnostic tool for lower GI bleeding, it is often **challenging to perform effectively in the presence of massive active bleeding**, as the view can be obscured by blood. - The patient's hemodynamic instability has been corrected, but the high bleeding rate makes a diagnostic colonoscopy difficult. *EGD* - EGD (Esophagogastroduodenoscopy) is used to diagnose **upper GI bleeding**, which has been effectively ruled out by the nasogastric tube draining bile without blood. - This procedure would not be helpful for localizing a lower GI bleeding source.

GI US Medical PG Question 5: A 51-year-old man with a recent diagnosis of peptic ulcer disease currently treated with an oral proton pump inhibitor twice daily presents to the urgent care center complaining of acute abdominal pain which began suddenly less than 2 hours ago. On physical exam, you find his abdomen to be mildly distended, diffusely tender to palpation, and positive for rebound tenderness. Given the following options, what is the next best step in patient management?

• A. Serum gastrin level
• B. Urgent CT abdomen and pelvis (Correct Answer)
• C. H. pylori testing
• D. Abdominal radiographs
• E. Upper endoscopy

GI Explanation: ***Urgent CT abdomen and pelvis*** - The sudden onset of severe abdominal pain, diffuse tenderness, and **rebound tenderness** in a patient with a history of peptic ulcer disease (PUD) suggests a **perforated ulcer**, which is a surgical emergency. - A CT scan is the **most sensitive imaging modality** for detecting **free air** (pneumoperitoneum) and can confirm the diagnosis with >95% sensitivity, helping to localize the perforation and identify complications such as abscess formation. - CT also helps evaluate alternative diagnoses in the acute abdomen and provides detailed anatomic information for surgical planning. *Serum gastrin level* - This test is primarily used in the diagnosis of **Zollinger-Ellison syndrome**, a rare condition characterized by gastrinomas leading to severe, refractory PUD. - It is not indicated in an acute emergency setting with signs of perforation, as it would delay critical diagnostic imaging and management. *H. pylori testing* - **_H. pylori_ infection** is a common cause of PUD, but testing for it is part of routine initial management or follow-up for chronic disease. - Testing would not address the immediate life-threatening complication of suspected perforation and would delay definitive diagnosis. *Abdominal radiographs* - An upright chest X-ray or abdominal radiograph can detect **free air under the diaphragm** in cases of perforation and is a reasonable initial imaging test. - However, plain radiographs have lower sensitivity (75-80%) compared to CT scan and may miss smaller perforations or provide insufficient information about the location and extent of injury. - In modern practice with readily available CT, cross-sectional imaging is preferred for its superior diagnostic accuracy in evaluating the acute abdomen. *Upper endoscopy* - **Upper endoscopy** is a valuable diagnostic and therapeutic tool for stable PUD but is **absolutely contraindicated** in cases of suspected or confirmed hollow viscus perforation. - Introducing an endoscope with air insufflation could worsen the perforation and lead to further contamination of the peritoneal cavity, increasing morbidity and mortality.

GI Flashcard 1 of 5

Question: _____ syndrome presents with a grossly black liver, but is otherwise not clinically significant

Answer: Dubin-Johnson

GI Flashcard 2 of 5

Question: _____ gastric ulcers are usually large and irregular with heaped up margins

Answer: Malignant

GI Flashcard 3 of 5

Question: _____ gastritis arises due to imbalance between mucosal defenses and acidic environment

Answer: Acute

GI Flashcard 4 of 5

Question: _____ gastritis occurs due to acidic damage to the stomach mucosa

Answer: Acute

GI Flashcard 5 of 5

Question: Budd-Chiari syndrome results in congestion and necrosis of the _____ zone of the liver

Answer: centrilobular