Anatomical variations and clinical significance US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Anatomical variations and clinical significance. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Anatomical variations and clinical significance US Medical PG Question 1: A 39-year-old male is rushed to the emergency department after he developed a sudden-onset severe headache with ensuing nausea, vomiting, vision changes, and loss of consciousness. Past medical history is unattainable. He reports that the headache is worse than any he has experienced before. Noncontrast CT of the head is significant for an intracranial hemorrhage. Follow-up cerebral angiography is performed and shows a ruptured anterior communicating artery aneurysm. Which of the following has the strongest association with this patient's current presentation?
- A. Abdominal CT suggestive of renal cell carcinoma
- B. Kidney ultrasound showing numerous bilateral renal cysts (Correct Answer)
- C. Brain MRI showing a butterfly glioma with a central necrotic core
- D. History of renal transplantation at 8 years of age
- E. History of multiple hemangioblastomas of the retina and spine as well as pheochromocytoma
Anatomical variations and clinical significance Explanation: ***Kidney ultrasound showing numerous bilateral renal cysts***
- This finding is highly suggestive of **Autosomal Dominant Polycystic Kidney Disease (ADPKD)**, which is strongly associated with an increased risk of **intracranial aneurysms**.
- Ruptured intracranial aneurysms, like the one described in the patient, are a major cause of morbidity and mortality in individuals with ADPKD.
*Abdominal CT suggestive of renal cell carcinoma*
- While renal cell carcinoma can be associated with certain genetic syndromes (e.g., von Hippel-Lindau disease), it does not have a direct strong association with **intracranial aneurysms** causing a sudden-onset severe headache in the manner described.
- The primary presentation here is a ruptured cerebral aneurysm, making other associations less likely.
*Brain MRI showing a butterfly glioma with a central necrotic core*
- A **butterfly glioma with a central necrotic core** is characteristic of **glioblastoma multiforme**, a primary brain tumor.
- While brain tumors can cause headaches, they typically lead to a more gradual onset of symptoms and do not directly predispose to the formation and rupture of **intracranial aneurysms**.
*History of renal transplantation at 8 years of age*
- A history of renal transplantation suggests prior **end-stage renal disease**, which can have various underlying causes.
- While some causes of kidney disease (like ADPKD) are linked to aneurysms, transplantation itself is not a direct risk factor for aneurysm rupture; rather, it's the *underlying cause* of kidney disease that might be relevant.
*History of multiple hemangioblastomas of the retina and spine as well as pheochromocytoma*
- This constellation of symptoms is indicative of **von Hippel-Lindau disease**, which is associated with various tumors, including **hemangioblastomas** of the central nervous system.
- While von Hippel-Lindau disease is linked to CNS lesions, it is **not primarily associated with an increased risk of intracranial saccular aneurysms** leading to subarachnoid hemorrhage.
Anatomical variations and clinical significance US Medical PG Question 2: A 27-year-old man is brought to the emergency department after a motorcycle accident 30 minutes ago. He was found at the scene of the accident with a major injury to the anterior chest by a metallic object that was not removed during transport to the hospital. The medical history could not be obtained. His blood pressure is 80/50 mm Hg, pulse is 130/min, and respiratory rate is 40/min. Evaluation upon arrival to the emergency department reveals a sharp metal object penetrating through the anterior chest to the right of the sternum at the 4th intercostal space. The patient is taken to the operating room immediately, where it is shown the heart has sustained a major injury. Which of the following arteries supplies the part of the heart most likely injured in this patient?
- A. Right marginal artery (Correct Answer)
- B. Left anterior descending artery
- C. Left coronary artery
- D. Posterior descending artery
- E. Left circumflex coronary artery
Anatomical variations and clinical significance Explanation: ***Right marginal artery***
- The right marginal artery typically arises from the **right coronary artery** and supplies the **right ventricle**.
- Given the injury location to the **right of the sternum** and the 4th intercostal space, the right ventricle is the most superficial and anterior chamber and thus the most likely to be injured.
*Left anterior descending artery*
- The left anterior descending artery supplies the **anterior** two-thirds of the **interventricular septum** and the anterior wall of the **left ventricle**.
- While located anteriorly, it is generally to the left of the sternum and would be protected by the more anterior right ventricle from an injury to the right of the sternum.
*Left coronary artery*
- The left coronary artery is a **short main stem** that quickly branches into the left anterior descending and left circumflex arteries.
- It is located more superiorly and to the left, making it less likely to be directly injured by a penetrating trauma to the **right of the sternum** at the 4th intercostal space.
*Posterior descending artery*
- The posterior descending artery supplies the **posterior** wall of both ventricles and the posterior one-third of the **interventricular septum**.
- This vessel is located on the posterior aspect of the heart, making it extremely unlikely to be injured by an anterior penetrating trauma.
*Left circumflex coronary artery*
- The left circumflex coronary artery supplies the **lateral and posterior walls of the left ventricle** and the left atrium.
- Its location on the posterior-lateral aspect of the heart makes it much less vulnerable to a penetrating injury coming from the **anterior chest**.
Anatomical variations and clinical significance US Medical PG Question 3: A 6-year-old girl is brought to the physician by her parents because of concern that she is the shortest in her class. She has always been short for her age, but she is upset now that her classmates have begun teasing her for her height. She has no history of serious illness and takes no medications. She is 109 cm (3 ft 7 in) tall (10th percentile) and weighs 20 kg (45 lb) (50th percentile). Her blood pressure is 140/80 mm Hg. Vital signs are otherwise within normal limits. Physical examination shows a low-set hairline and a high-arched palate. Breast development is Tanner stage 1 and the nipples are widely spaced. Extremities are well perfused with strong peripheral pulses. Her hands are moderately edematous. This patient is at increased risk of developing which of the following complications?
- A. Precocious puberty
- B. Acute lymphoblastic leukemia
- C. Ectopia lentis
- D. Renal cell carcinoma
- E. Aortic insufficiency (Correct Answer)
Anatomical variations and clinical significance Explanation: ***Aortic insufficiency***
- The patient's features, including **short stature**, **low-set hairline**, **widely spaced nipples**, **high-arched palate**, and **hand edema**, are classic for **Turner syndrome (45,XO)**.
- Individuals with Turner syndrome are at significantly increased risk of **cardiovascular anomalies**, particularly **bicuspid aortic valve** and **coarctation of the aorta**, which can both lead to **aortic insufficiency** and hypertension.
*Precocious puberty*
- **Precocious puberty** involves the premature onset of puberty, which is not suggested by the patient's **Tanner stage 1 breast development**, indicating **absent breast development**.
- Girls with Turner syndrome typically experience **delayed or absent puberty** due to gonadal dysgenesis and **ovarian failure**.
*Acute lymphoblastic leukemia*
- While chromosomal abnormalities can increase cancer risk, there is no strong, direct association between **Turner syndrome** and an increased risk of **acute lymphoblastic leukemia (ALL)** specifically.
- The presenting symptoms do not point towards hematological malignancy, which would involve signs like **fatigue**, **bruising**, or **recurrent infections**.
*Ectopia lentis*
- **Ectopia lentis**, or displaced lens, is a hallmark feature of conditions like **Marfan syndrome** and **homocystinuria**, not typically associated with Turner syndrome.
- There are no other features of connective tissue disorders presented in the patient's clinical picture.
*Renal cell carcinoma*
- While individuals with Turner syndrome can have a higher incidence of **renal anomalies**, such as **horseshoe kidney** or **duplex collecting systems**, there is no specific increased risk of **renal cell carcinoma** directly linked to the syndrome.
- The high blood pressure in this patient is more attributable to **cardiovascular defects** like coarctation of the aorta.
Anatomical variations and clinical significance US Medical PG Question 4: A 14-year-old boy is brought to the emergency department because of acute left-sided chest pain and dyspnea following a motor vehicle accident. His pulse is 122/min and blood pressure is 85/45 mm Hg. Physical examination shows distended neck veins and tracheal displacement to the right side. The left chest is hyperresonant to percussion and there are decreased breath sounds. This patient would most benefit from needle insertion at which of the following anatomical sites?
- A. 5th left intercostal space along the midclavicular line
- B. 8th left intercostal space along the posterior axillary line
- C. 2nd left intercostal space along the midclavicular line (Correct Answer)
- D. Subxiphoid space in the left sternocostal margin
- E. 5th left intercostal space along the midaxillary line
Anatomical variations and clinical significance Explanation: ***2nd left intercostal space along the midclavicular line***
- The patient's symptoms (chest pain, dyspnea, hypotension, distended neck veins, tracheal deviation, hyperresonance, and decreased breath sounds on the left) are classic signs of a **tension pneumothorax**.
- Immediate treatment for **tension pneumothorax** involves needle decompression at the **2nd intercostal space** in the midclavicular line to relieve pressure and restore hemodynamic stability.
*5th left intercostal space along the midclavicular line*
- This location is typically used for **chest tube insertion** in a more controlled setting, not for emergent needle decompression of a tension pneumothorax.
- While it's a safe location for pleural access, it is not the **first-line site** for immediate life-saving decompression.
*8th left intercostal space along the posterior axillary line*
- This site is too low and posterior for effective needle decompression of a tension pneumothorax, which requires rapid access to the **apex of the lung**.
- It is more commonly used for **thoracentesis** to drain fluid from the pleural cavity.
*Subxiphoid space in the left sternocostal margin*
- This location is primarily used for **pericardiocentesis** to drain fluid from the pericardial sac in cases of cardiac tamponade.
- It is not appropriate for addressing a **pneumothorax**, which involves air in the pleural space.
*5th left intercostal space along the midaxillary line*
- This site is a common alternative for **chest tube insertion** but is not the preferred or most immediate site for needle decompression of a tension pneumothorax.
- While it offers pleural access, the **2nd intercostal space** anteriorly is chosen for expediency and safety in an emergency.
Anatomical variations and clinical significance US Medical PG Question 5: A female infant is born with a mutation in PKD1 on chromosome 16. An abdominal ultrasound performed shortly after birth would most likely reveal which of the following?
- A. Microscopic cysts
- B. Normal kidneys (Correct Answer)
- C. Adrenal atrophy
- D. Horseshoe kidney
- E. Bilateral kidney enlargement
Anatomical variations and clinical significance Explanation: ***Normal kidneys***
- Autosomal dominant polycystic kidney disease (ADPKD), caused by a mutation in **PKD1 or PKD2**, typically presents with **cysts that develop later in life**, usually in adulthood.
- At birth, the kidneys of an infant with the ADPKD mutation are usually **structurally normal** and do not yet show macroscopic cyst formation on ultrasound.
*Microscopic cysts*
- While the genetic mutation is present, significant **macroscopic cyst formation** detectable by standard abdominal ultrasound does not typically occur at birth in ADPKD.
- The cysts develop and enlarge over decades, leading to symptoms later in adulthood.
*Adrenal atrophy*
- **Adrenal atrophy** is not a feature of polycystic kidney disease and is caused by other conditions like autoimmune diseases or prolonged corticosteroid use.
- The adrenal glands are distinct from the kidneys and are not directly affected by PKD1 mutations.
*Horseshoe kidney*
- **Horseshoe kidney** is a congenital anomaly where the kidneys are fused, usually at the lower poles, and is not associated with PKD1 mutations.
- This condition is a **developmental fusion defect** during embryogenesis.
*Bilateral kidney enlargement*
- Bilateral kidney enlargement due to multiple cysts is characteristic of **ADPKD in adulthood**, not at birth.
- Though ADPKD is a genetic condition, the **phenotypic expression (cyst growth)** progresses over time.
Anatomical variations and clinical significance US Medical PG Question 6: A 35-year-old Caucasian female with a history of rheumatoid arthritis presents to your clinic with pleuritic chest pain that improves while leaning forward. Which of the following additional findings would you expect to observe in this patient?
- A. Exaggerated amplitude of pulse on inspiration (Correct Answer)
- B. Pulsatile abdominal mass
- C. Increase in jugular venous pressure on inspiration
- D. S3 heart sound
- E. Continuous machine-like murmur
Anatomical variations and clinical significance Explanation: ***Exaggerated amplitude of pulse on inspiration***
- The clinical presentation of **pleuritic chest pain that improves while leaning forward** is highly suggestive of **acute pericarditis**.
- **Pulsus paradoxus** (an exaggerated drop in systolic blood pressure >10 mmHg during inspiration, manifesting as decreased pulse amplitude) can occur when pericarditis is complicated by **pericardial effusion**.
- While not present in all cases of acute pericarditis, pulsus paradoxus is the most relevant finding among the options listed and suggests developing **cardiac tamponade physiology**.
- Rheumatoid arthritis can cause serositis including pericarditis with effusion.
*Pulsatile abdominal mass*
- A **pulsatile abdominal mass** is characteristic of an **abdominal aortic aneurysm (AAA)**, which is unrelated to pericarditis.
- AAA typically presents with abdominal or back pain, not pleuritic chest pain.
*Increase in jugular venous pressure on inspiration*
- An **increase in JVP on inspiration** is known as **Kussmaul's sign**, which is characteristic of **constrictive pericarditis** or **right ventricular failure**.
- In acute pericarditis, this sign is not typically present unless chronic constriction has developed.
*S3 heart sound*
- An **S3 heart sound** is heard during early diastole and indicates **rapid ventricular filling**, typically associated with **heart failure** or **volume overload**.
- S3 is not a feature of acute pericarditis, which primarily involves pericardial inflammation.
*Continuous machine-like murmur*
- A **continuous machine-like murmur** is the classic finding for **patent ductus arteriosus (PDA)**, a congenital heart defect.
- This has no association with pericarditis or rheumatoid arthritis.
Anatomical variations and clinical significance US Medical PG Question 7: A researcher is investigating the blood supply of the adrenal gland. While performing an autopsy on a patient who died from unrelated causes, he identifies a vessel that supplies oxygenated blood to the inferior aspect of the right adrenal gland. Which of the following vessels most likely gave rise to the vessel in question?
- A. Inferior phrenic artery
- B. Abdominal aorta
- C. Renal artery (Correct Answer)
- D. Superior mesenteric artery
- E. Common iliac artery
Anatomical variations and clinical significance Explanation: ***Renal artery***
- The **inferior suprarenal artery**, which supplies the inferior part of the adrenal gland, typically arises from the **renal artery**.
- The adrenal glands receive a rich blood supply from three main arterial sources: superior, middle, and inferior suprarenal arteries.
*Inferior phrenic artery*
- The **superior suprarenal arteries** typically arise from the **inferior phrenic arteries** and supply the superior aspect of the adrenal glands.
- While critical for adrenal blood supply, they do not typically contribute to the inferior aspect directly.
*Abdominal aorta*
- The **middle suprarenal artery** usually arises directly from the **abdominal aorta**.
- This vessel supplies the central part of the adrenal gland, but not primarily the inferior aspect.
*Superior mesenteric artery*
- The **superior mesenteric artery** primarily supplies structures of the midgut (e.g., small intestine, ascending colon) and does not typically give rise to vessels supplying the adrenal glands.
- It is located inferior to the origin of the renal arteries and the adrenal glands.
*Common iliac artery*
- The **common iliac arteries** supply the lower limbs and pelvic organs, originating from the abdominal aorta bifurcation.
- These arteries are located much too far inferior to supply the adrenal glands, which are retroperitoneal structures in the upper abdomen.
Anatomical variations and clinical significance US Medical PG Question 8: A 24-year-old woman comes to the emergency department because of abdominal pain, fever, nausea, and vomiting for 12 hours. Her abdominal pain was initially dull and diffuse but has progressed to a sharp pain on the lower right side. Two years ago she had to undergo right salpingo-oophorectomy after an ectopic pregnancy. Her temperature is 38.7°C (101.7°F). Physical examination shows severe right lower quadrant tenderness with rebound tenderness; bowel sounds are decreased. Laboratory studies show leukocytosis with left shift. An abdominal CT scan shows a distended, edematous appendix. The patient is taken to the operating room for an appendectomy. During the surgery, the adhesions from the patient's previous surgery make it difficult for the resident physician to identify the appendix. Her attending mentions that she should use a certain structure for guidance to locate the appendix. The attending is most likely referring to which of the following structures?
- A. Epiploic appendages
- B. Right ureter
- C. Deep inguinal ring
- D. Ileocolic artery
- E. Teniae coli (Correct Answer)
Anatomical variations and clinical significance Explanation: ***Teniae coli***
- The **teniae coli** are three distinct longitudinal bands of smooth muscle that run along the length of the cecum and colon, converging at the base of the **appendix**.
- Following these bands inferiorly from the ascending colon or cecum during surgery is a reliable method to locate the **vermiform appendix**, especially in the presence of adhesions.
*Epiploic appendages*
- These are small, fat-filled sacs that protrude from the surface of the **large intestine** but are not directly used as a reliable landmark for locating the appendix.
- While present in the vicinity, they do not consistently lead to the base of the appendix like the teniae coli.
*Right ureter*
- The **right ureter** is located retroperitoneally, deep to the cecum and appendix, and is not a direct anatomical landmark used for identifying the appendix during an appendectomy.
- Identifying the ureter is important to avoid injury, but not for localizing the appendix.
*Deep inguinal ring*
- The **deep inguinal ring** is an opening in the transversalis fascia, involved in the formation of the inguinal canal, and is located far anterior and inferior to the region of the appendix.
- It has no anatomical relationship that would guide a surgeon to locate the appendix.
*Ileocolic artery*
- The **ileocolic artery** branches from the superior mesenteric artery and supplies the terminal ileum, cecum, and appendix. While it provides blood supply to the appendix, it is not a direct or consistent surface landmark for locating the appendix itself, especially in complex cases with adhesions.
- Locating the artery would be more complex and less reliable for initial identification compared to the teniae coli.
Anatomical variations and clinical significance US Medical PG Question 9: 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
Anatomical variations and clinical significance 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.
Anatomical variations and clinical significance US Medical PG Question 10: An 11-year-old girl is brought to the office by her mother due to complaint of intermittent and severe periumbilical pain for 1 day. She does not have any significant past medical history. She provides a history of a recent school trip to the suburbs. On physical examination, there is a mild tenderness around the umbilicus without any distension or discharge. There is no rebound tenderness. Bowel sounds are normal. An abdominal imaging shows enlarged mesenteric lymph nodes, and she is diagnosed with mesenteric lymphadenitis. However, incidentally, a mass of tissue was seen joining the inferior pole of both kidneys as shown in the image. Which of the following best describes this renal anomaly?
- A. Fused kidneys ascend beyond superior mesenteric artery.
- B. Rapid progression to acute renal failure
- C. Kidneys are usually non-functional.
- D. Increased risk of developing renal vein thrombosis
- E. Association with ureteropelvic junction obstruction (UPJO) (Correct Answer)
Anatomical variations and clinical significance Explanation: ***Association with ureteropelvic junction obstruction (UPJO)***
- **Horseshoe kidney** is characterized by the fusion of the lower poles (most common) or upper poles of the kidneys, forming a U-shape. This anomaly is associated with an increased incidence of **ureteropelvic junction obstruction (UPJO)** due to the abnormal course of the ureters over the isthmus.
- The abnormal ascent of the fused kidneys can also lead to an increased incidence of other anomalies such as **vesicoureteral reflux**, **renal calculi**, and recurrent urinary tract infections.
*Fused kidneys ascend beyond superior mesenteric artery.*
- The **horseshoe kidney** typically **fails to ascend** completely during development because its isthmus (the fused part) can get trapped under the **inferior mesenteric artery**.
- Therefore, fused kidneys in horseshoe kidney are often found in a **lower position** than normal, not ascended beyond the superior mesenteric artery.
*Rapid progression to acute renal failure*
- While horseshoe kidney can be associated with an increased risk of complications (like UPJO, stones, infections), it does not inherently lead to **rapid progression to acute renal failure**.
- Many individuals with a horseshoe kidney have **normal renal function** without significant clinical manifestations.
*Kidneys are usually non-functional.*
- The presence of a horseshoe kidney **does not typically mean the kidneys are non-functional**.
- In most cases, both renal units of a horseshoe kidney are **functional**, although they may be at increased risk for complications that could impact function over time.
*Increased risk of developing renal vein thrombosis*
- There is **no established increased risk** of developing **renal vein thrombosis** specifically associated with horseshoe kidney.
- The primary vascular anomalies associated with horseshoe kidney relate to the arterial supply and variations in the number and origin of renal arteries, not typically venous thrombosis.
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