Retroperitoneal structures US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Retroperitoneal structures. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Retroperitoneal structures US Medical PG Question 1: A 72-year-old man presents to his primary care physician because he has been having flank and back pain for the last 8 months. He said that it started after he fell off a chair while doing yard work, but it has been getting progressively worse over time. He reports no other symptoms and denies any weight loss or tingling in his extremities. His medical history is significant for poorly controlled hypertension and a back surgery 10 years ago. He drinks socially and has smoked 1 pack per day since he was 20. His family history is significant for cancer, and he says that he is concerned that his father had similar symptoms before he was diagnosed with multiple myeloma. Physical exam reveals a painful, pulsatile enlargement in the patient's abdomen. Between which of the following locations has the highest risk of developing this patient's disorder?
- A. Superior mesenteric artery and renal arteries
- B. Diaphragm and renal arteries
- C. Renal arteries and common iliac arteries (Correct Answer)
- D. Superior mesenteric artery and common iliac arteries
- E. Diaphragm and superior mesenteric artery
Retroperitoneal structures Explanation: ***Renal arteries and common iliac arteries***
- The most common location for **abdominal aortic aneurysms (AAAs)** is the **infrarenal aorta**, specifically between the renal arteries and the common iliac arteries.
- This segment accounts for **~95% of all AAAs** due to decreased elastin content, hemodynamic stress, and reduced vasa vasorum.
- The patient's presentation with **flank/back pain**, a **pulsatile abdominal mass**, and risk factors like **hypertension** and **smoking** are highly suggestive of an infrarenal AAA [1].
*Superior mesenteric artery and renal arteries*
- This region defines the **suprarenal aorta**, which is less commonly affected by aneurysms than the infrarenal segment.
- Suprarenal aneurysms account for only **~5% of AAAs** and are typically more complex to manage.
*Diaphragm and renal arteries*
- This encompasses a significant portion of the **thoracoabdominal aorta**, including the suprarenal segment.
- While thoracoabdominal aneurysms can occur, they are much less common than infrarenal AAAs and often have different etiologies.
*Superior mesenteric artery and common iliac arteries*
- This range is anatomically imprecise and spans too broad a region, including both suprarenal and infrarenal segments.
- The **superior mesenteric artery** originates anteriorly from the aorta (typically at L1), well above the most common aneurysm site immediately distal to the renal arteries (L1-L2).
- The highest risk is specifically localized to the segment **below the renal arteries**, not this entire broad region.
*Diaphragm and superior mesenteric artery*
- This describes the **supraceliac and proximal suprarenal aorta**, an area significantly less prone to aneurysms compared to the infrarenal segment.
- Aneurysms in this more proximal segment are rare and often have different etiologies (e.g., connective tissue disorders).
Retroperitoneal structures US Medical PG Question 2: A 45-year-old male is brought to the emergency department by emergency medical services after sustaining a gunshot wound to the abdomen. He is unresponsive. His temperature is 99.0°F (37.2°C), blood pressure is 95/58 mmHg, pulse is 115/min, and respirations are 20/min. Physical examination reveals an entry wound in the left abdominal quadrant just inferior to the left lateral costal border. Abdominal CT shows the bullet trajectory through the left abdominal cavity. Which of the following structures has the bullet most likely penetrated?
- A. Transverse colon
- B. Ascending colon
- C. Descending colon (Correct Answer)
- D. Sigmoid colon
- E. Superior duodenum
Retroperitoneal structures Explanation: ***Descending colon***
- The **descending colon** is located in the left abdominal cavity, specifically in the left upper quadrant and extending into the left lower quadrant, making it highly susceptible to injury from a gunshot wound in the **left abdominal quadrant** just inferior to the left lateral costal border.
- Its position aligns directly with the described entry point and bullet trajectory.
*Transverse colon*
- The **transverse colon** lies more centrally in the upper abdomen, spanning from the right to the left upper quadrants.
- While possible to be hit by a left-sided entry wound, the trajectory described as "inferior to the left lateral costal border" makes the descending colon a more direct and likely target.
*Ascending colon*
- The **ascending colon** is located in the **right abdominal cavity**, specifically in the right upper and lower quadrants.
- A wound inferior to the left lateral costal border would be on the opposite side of the abdomen and thus unlikely to penetrate the ascending colon.
*Sigmoid colon*
- The **sigmoid colon** is located more inferiorly in the **left lower quadrant** and pelvis.
- While on the left side, the entry wound described as "inferior to the left lateral costal border" is generally higher than the typical location of the sigmoid colon.
*Superior duodenum*
- The **superior duodenum** is located in the **right upper quadrant** of the abdomen, anterior to the head of the pancreas.
- Its position on the right side makes it highly unlikely to be penetrated by a gunshot wound to the left abdominal quadrant.
Retroperitoneal structures US Medical PG Question 3: A 65-year-old man presents to his primary care provider after noticing increasing fatigue over the past several weeks. He now becomes short of breath after going up 1 flight of stairs. He was previously healthy and has not seen a doctor for several years. He denies any fever or changes to his bowel movements. On exam, his temperature is 98.8°F (37.1°C), blood pressure is 116/76 mmHg, pulse is 74/min, and respirations are 14/min. On basic labs, his hemoglobin is found to be 9.6 g/dL and MCV is 75 fL. Fecal blood testing is positive for occult blood. Imaging is notable for a mass in the cecum that is partially obstructing the lumen, as well as several small lesions in the liver. Which of the following structures is most at risk for involvement in this patient’s disease?
- A. Right gonadal vein
- B. Inferior mesenteric vein
- C. Inferior rectal vein
- D. Right renal vein
- E. Superior mesenteric vein (Correct Answer)
Retroperitoneal structures Explanation: ***Superior mesenteric vein***
- The patient has a **cecal mass** and **liver lesions** consistent with **colon cancer** with **liver metastasis**. Cancer cells from the cecum drain predominantly into the **superior mesenteric vein**, before traveling to the liver via the **portal vein system**.
- The **superior mesenteric vein (SMV)** drains blood from the cecum, ascending colon, and transverse colon. Metastatic cells from these regions would use this route to reach the liver.
*Right gonadal vein*
- The right gonadal vein drains into the **inferior vena cava (IVC)**, bypassing the portal system.
- Metastasis to the liver would be less direct via this route, and the **cecum** does not primarily drain into the gonadal veins.
*Inferior mesenteric vein*
- The **inferior mesenteric vein (IMV)** drains the descending colon, sigmoid colon, and rectum.
- While it eventually joins the **splenic vein** and then the **portal vein**, it is not the primary drainage for the cecum.
*Inferior rectal vein*
- The **inferior rectal vein** drains the lower rectum and anal canal, primarily into the **internal iliac veins** and then the **IVC**, bypassing the portal system.
- This route is not relevant for metastasis from a **cecal mass**.
*Right renal vein*
- The **right renal vein** drains blood from the right kidney into the **inferior vena cava (IVC)**.
- This vein is unrelated to the drainage of the gastrointestinal tract and would not be involved in metastasis from a **cecal mass**.
Retroperitoneal structures US Medical PG Question 4: A 43-year-old man is brought to the emergency department 30 minutes after falling from the roof of a construction site. He reports abdominal and right-sided flank pain. His temperature is 37.1°C (98.8°F), pulse is 114/min, and blood pressure is 100/68 mm Hg. Physical examination shows numerous ecchymoses over the trunk and flanks and a tender right abdomen without a palpable mass. Focused assessment with sonography for trauma (FAST) shows no intraperitoneal fluid collections. His hemoglobin concentration is 7.6 g/dL. The most likely cause of his presentation is injury to which of the following organs?
- A. Liver
- B. Kidney (Correct Answer)
- C. Stomach
- D. Small bowel
- E. Spleen
Retroperitoneal structures Explanation: ***Kidney***
- The patient's presentation with **flank pain**, **ecchymoses over the flank**, and **hypotension** following a fall from height is highly suggestive of **renal injury**. The absence of intraperitoneal fluid on FAST scan further supports an injury to a retroperitoneal organ like the kidney.
- The **significantly decreased hemoglobin (7.6 g/dL)** indicates substantial blood loss, which is consistent with the vascular nature of the kidney and potential for severe hemorrhage following trauma.
*Liver*
- While liver injury can cause **hypotension** and **abdominal pain** after trauma, the primary pain would typically be in the **right upper quadrant**, not specifically the flank.
- Liver injuries often result in **intraperitoneal fluid collections** (hemoperitoneum), which were explicitly absent on the FAST scan in this patient.
*Stomach*
- Stomach injuries typically result from penetrating trauma or severe blunt force, leading to **peritonitis** and potential **gastric content leakage**, which would cause diffuse abdominal pain and potentially peritonitis signs.
- It is an **intraperitoneal organ**, and injury might be seen on a FAST scan as free fluid, which is not present here.
*Small bowel*
- Small bowel injuries typically present with **diffuse abdominal pain**, **peritoneal signs**, and can lead to **sepsis** due to contamination.
- These injuries often cause **intraperitoneal fluid** or air, neither of which is reported.
*Spleen*
- Splenic injuries typically cause **left upper quadrant pain** and can lead to significant **intraperitoneal bleeding**, which would be detected by a FAST scan.
- The patient's symptoms are localized to the **right side** and flank, making splenic injury less likely.
Retroperitoneal structures US Medical PG Question 5: A CT scan of the abdomen reveals a mass in the pancreatic uncinate process. Which of the following structures is most likely to be compressed by this mass?
- A. Common bile duct
- B. Portal vein
- C. Splenic vein
- D. Superior mesenteric vein (Correct Answer)
Retroperitoneal structures Explanation: ***Superior mesenteric vein***
- The **uncinate process** of the pancreas hooks around the **superior mesenteric vessels**. Therefore, a mass in this region would most directly compress the **superior mesenteric vein (SMV)** and artery (SMA).
- Compression of the SMV can lead to **venous outflow obstruction** from the small intestine, potentially causing **bowel ischemia** or edema.
*Common bile duct*
- The **common bile duct** passes through the **head of the pancreas**, not typically the uncinate process.
- Compression of the common bile duct would more commonly be associated with masses in the **head of the pancreas**, leading to **jaundice**.
*Portal vein*
- The **portal vein** is formed by the union of the **splenic vein** and the **superior mesenteric vein**, generally posterior to the neck of the pancreas.
- While pancreatic masses can affect the portal vein, a mass specifically in the uncinate process would more directly impinge on the SMV before significantly affecting the main portal vein, which is superior and posterior to the uncinate process.
*Splenic vein*
- The **splenic vein** runs along the **posterior aspect of the body and tail of the pancreas**.
- A mass in the uncinate process, located at the inferior margin of the head, is relatively distant from the splenic vein.
Retroperitoneal structures US Medical PG Question 6: An investigator is studying the effects of an antihypertensive drug during pregnancy. Follow-up studies show that the drug can adversely affect differentiation of the ureteric bud into its direct derivatives in fetuses exposed during the first trimester. Which of the following structures is most likely to develop incorrectly in the affected fetus?
- A. Collecting ducts (Correct Answer)
- B. Proximal convoluted tubule
- C. Loop of Henle
- D. Bladder
- E. Distal convoluted tubule
Retroperitoneal structures Explanation: ***Collecting ducts***
- The **ureteric bud** is an outgrowth of the **mesonephric (Wolffian) duct** that directly gives rise to the **collecting ducts**, minor and major calyces, renal pelvis, and ureter.
- An adverse effect on the differentiation of the ureteric bud during the first trimester would directly impact the development of these structures, potentially leading to renal dysplasia or collecting system abnormalities.
- **Clinical correlation**: ACE inhibitors and ARBs are contraindicated in pregnancy due to their teratogenic effects on fetal renal development.
*Proximal convoluted tubule*
- The **proximal convoluted tubule** develops from the **metanephric mesenchyme**, not from the ureteric bud.
- This structure is part of the nephron proper, which forms when the metanephric mesenchyme is induced by the ureteric bud to differentiate.
*Loop of Henle*
- The **loop of Henle** also develops from the **metanephric mesenchyme**.
- While its formation depends on inductive signals from the ureteric bud, it is not a direct derivative of the ureteric bud itself.
*Bladder*
- The **bladder** develops from the **urogenital sinus**, which is derived from the ventral part of the **cloaca** after partitioning by the urorectal septum.
- Its development is distinct from the derivatives of the ureteric bud, though they are functionally connected.
*Distal convoluted tubule*
- The **distal convoluted tubule** develops from the **metanephric mesenchyme**.
- It is a component of the nephron and connects to the collecting duct but is not a direct derivative of the ureteric bud.
Retroperitoneal structures US Medical PG Question 7: A 65-year-old man presents to the emergency department with abdominal pain and a pulsatile abdominal mass. Further examination of the mass shows that it is an abdominal aortic aneurysm. A computed tomography scan with contrast reveals an incidental finding of a horseshoe kidney, and the surgeon is informed of this finding prior to operating on the aneurysm. Which of the following may complicate the surgical approach in this patient?
- A. Anomalous origins of multiple renal arteries (Correct Answer)
- B. Low glomerular filtration rate due to unilateral renal agenesis
- C. Proximity of the fused kidney to the celiac artery
- D. Abnormal relationship between the kidney and the superior mesenteric artery
- E. There are no additional complications
Retroperitoneal structures Explanation: ***Anomalous origins of multiple renal arteries***
- A horseshoe kidney often receives its blood supply from **multiple renal arteries** arising anomalously from the aorta, iliac arteries, or inferior mesenteric artery.
- These aberrant vessels can cross the surgical field and complicate **abdominal aortic aneurysm repair**, increasing the risk of injury and hemorrhage.
*Low glomerular filtration rate due to unilateral renal agenesis*
- This patient has a **horseshoe kidney**, which involves fused kidneys, not renal agenesis (absence of a kidney).
- While chronic kidney disease can be associated with horseshoe kidneys, **unilateral agenesis** is a distinct condition and not described in this scenario.
*Proximity of the fused kidney to the celiac artery*
- The fused portion of a horseshoe kidney (the **isthmus**) typically lies anterior to the great vessels at the L3-L5 vertebral level, below the origin of the celiac artery.
- Therefore, its proximity to the **celiac artery** is generally not the primary surgical concern during abdominal aortic aneurysm repair.
*Abnormal relationship between the kidney and the superior mesenteric artery*
- The superior mesenteric artery typically originates from the aorta above the level of the horseshoe kidney's isthmus.
- While other anomalies can exist, an **abnormal relationship** between the kidney and the superior mesenteric artery is not a classic or primary complication of horseshoe kidney during AAA repair.
*There are no additional complications*
- The presence of a horseshoe kidney significantly increases the complexity of **abdominal aortic aneurysm** surgery.
- The potential for **vascular anomalies** and altered anatomical relationships makes this statement incorrect, as there are definite additional surgical considerations.
Retroperitoneal structures US Medical PG Question 8: A 55-year-old man comes to the physician because of a 3-week history of intermittent burning epigastric pain. His pain improves with antacid use and eating but returns approximately 2 hours following meals. He has a history of chronic osteoarthritis and takes ibuprofen daily. Upper endoscopy shows a deep ulcer located on the posterior wall of the duodenal bulb. This ulcer is most likely to erode into which of the following structures?
- A. Splenic vein
- B. Descending aorta
- C. Pancreatic duct
- D. Gastroduodenal artery (Correct Answer)
- E. Transverse colon
Retroperitoneal structures Explanation: ***Gastroduodenal artery***
- A deep ulcer on the **posterior wall of the duodenal bulb** is anatomically very close to the **gastroduodenal artery**.
- Erosion into this artery can lead to **life-threatening upper gastrointestinal bleeding**, a severe complication of peptic ulcer disease.
*Splenic vein*
- The **splenic vein** is located more posteriorly and superiorly, primarily in relation to the pancreas and spleen, making it less likely to be eroded by a duodenal bulb ulcer.
- While erosion into major vessels can occur, the gastroduodenal artery is in a much more direct and immediate proximity to the posterior duodenal bulb.
*Descending aorta*
- The **descending aorta** is a retroperitoneal structure located much more posteriorly and medially, far from the duodenal bulb.
- Erosion into the aorta is an extremely rare and catastrophic event, not typically associated with duodenal ulcers.
*Pancreatic duct*
- The **pancreatic duct** (Wirsung's duct) is located within the pancreas, which lies posterior to the duodenum. While a *deep* ulcer could hypothetically penetrate the pancreas, the primary structure at risk for hemorrhage from a posterior duodenal bulb ulcer is the gastroduodenal artery.
- Erosion into the pancreatic duct would likely cause **pancreatitis** or **fistula formation**, rather than acute hemorrhage.
*Transverse colon*
- The **transverse colon** is located inferior to the duodenum, separated by the greater omentum.
- Ulcers would typically erode anteriorly or directly posteriorly, not inferiorly into the transverse colon, which would involve fistula formation rather than arterial erosion.
Retroperitoneal structures US Medical PG Question 9: What is the most common site of congenital diaphragmatic hernia?
- A. Central tendon
- B. Posterolateral (Correct Answer)
- C. Crural
- D. Anterolateral
- E. Esophageal hiatus
Retroperitoneal structures Explanation: ***Posterolateral***
- The **posterolateral** region, specifically the foramen of Bochdalek, is the most common site for congenital diaphragmatic hernia (CDH).
- This type of hernia accounts for approximately 80-90% of all CDH cases and usually occurs on the **left side**.
*Central tendon*
- Hernias through the **central tendon** are extremely rare and are distinct from the more common forms of CDH.
- Defects in the central tendon are often associated with **pericardial defects** rather than typical diaphragmatic hernias which allow abdominal contents into the thoracic cavity.
*Crural*
- Hernias involving the **crura** of the diaphragm are typically **hiatal hernias** (e.g., sliding or paraesophageal), which are different in origin and presentation from CDH.
- These are usually acquired and involve the stomach moving into the mediastinum, rather than a congenital defect leading to abdominal viscera migrating into the chest.
*Anterolateral*
- While congenital diaphragmatic hernias can occur **anterolaterally** through the foramen of Morgagni, these are much less common than posterolateral hernias.
- Morgagni hernias account for a small percentage of CDH cases (around 2-5%) and are typically located on the right side, often containing omentum or colon.
*Esophageal hiatus*
- The **esophageal hiatus** is the normal opening in the diaphragm through which the esophagus passes.
- While hiatal hernias can occur at this site, these are typically **acquired hernias** in adults, not congenital diaphragmatic hernias.
- Congenital CDH refers to developmental defects in the diaphragm itself, not enlargement of normal openings.
Retroperitoneal structures US Medical PG Question 10: Structure preventing vertical descent of spleen
- A. Ligamentum teres
- B. Ligamentum flavum
- C. Hepatogastric ligament
- D. Phrenocolic ligament (Correct Answer)
- E. Lienorenal ligament
Retroperitoneal structures Explanation: ***Phrenocolic ligament***
- The **phrenocolic ligament** is a fold of peritoneum that extends from the left colic (splenic) flexure of the colon to the diaphragm.
- It forms a shelf or sling underneath the spleen, providing crucial support and preventing its **vertical descent**.
*Ligamentum teres*
- The **ligamentum teres hepatis** is the remnant of the obliterated umbilical vein, found in the free margin of the falciform ligament.
- It connects the umbilicus to the liver and plays no role in supporting the spleen.
*Ligamentum flavum*
- The **ligamentum flavum** is a series of elastic ligaments connecting the laminae of adjacent vertebrae in the spinal column.
- It is a component of the vertebral column and has no anatomical or functional relationship with the spleen.
*Hepatogastric ligament*
- The **hepatogastric ligament** is part of the lesser omentum, extending from the liver to the lesser curvature of the stomach.
- Its primary function is to contain the **gastric arteries** and connect these organs, not to support the spleen.
*Lienorenal ligament*
- The **lienorenal ligament** (splenorenal ligament) connects the hilum of the spleen to the anterior surface of the left kidney.
- While it provides **lateral support** to the spleen, it does not prevent **vertical descent** as effectively as the phrenocolic ligament.
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