Variations in Visceral Anatomy — MCQs

10 questions

Anorectal anomalies are commonly associated with which of the following congenital anomalies?

Which of the following is NOT a recognized cause of renal agenesis?

A newborn male is noted to have difficulty feeding and "turns blue and chokes when drinking formula." The prenatal records reveal that the amniotic fluid appeared normal on ultrasound. A pediatric feeding tube is passed orally to 20 cm without difficulty, with gastric secretions aspirated. Which of the following is the most likely diagnosis?

Sequestered lung is supplied most commonly by which artery?

The chest radiograph shown below is from a 25-year-old male patient presenting with hypertension. The image demonstrates bilateral inferior rib notching. What is the most likely diagnosis?

Which artery dilatation causes compression of the 3rd part of the duodenum?

Which one of the following life-threatening congenital anomalies in the newborn presents with polyhydramnios, aspiration pneumonia, excessive salivation and difficulty in passing a nasogastric tube?

Unilateral renal agenesis is associated with:

Which malformation is associated with mutations in the HOX gene?

Q10

Identify the condition shown in the plain abdominal radiograph.

Variations in Visceral Anatomy Indian Medical PG Practice Questions and MCQs

Question 1: Anorectal anomalies are commonly associated with which of the following congenital anomalies?

A. Cardiac anomalies (Correct Answer)
B. Duodenal atresia
C. CNS malformations
D. Abdominal wall defects

Explanation: ***Cardiac anomalies*** - **Cardiac anomalies** occur in approximately 30-50% of patients with **anorectal malformations**, making them the most commonly associated congenital anomaly. - These can range from simple septal defects to complex **congenital heart diseases**, often requiring surgical intervention. *Duodenal atresia* - **Duodenal atresia** is a common gastrointestinal anomaly but is less frequently associated with **anorectal malformations** compared to cardiac anomalies. - It typically presents with **bilious vomiting** and a "double bubble" sign on X-ray, which is not directly linked to the embryological development of the anorectum. *CNS malformations* - **CNS malformations**, such as **spinal dysraphism** (e.g., tethered cord, myelomeningocele), are certainly associated with **anorectal malformations**, particularly in the context of **VACTERL association**. - While significant, their incidence is generally lower than that of **cardiac anomalies** in this group. *Abdominal wall defects* - **Abdominal wall defects** like **omphalocele** or **gastroschisis** are distinct congenital anomalies with different embryological origins than **anorectal malformations**. - They are not considered a primary or most common associated anomaly with **anorectal malformations**.

Question 2: Which of the following is NOT a recognized cause of renal agenesis?

A. Failure of fusion of ureteric bud with metanephros
B. Defective development of nephric tissue
C. Failure of ascent of primitive cells (Correct Answer)
D. None of the above

Explanation: Failure of ascent of primitive cells - **Renal agenesis** involves the complete absence of a kidney(s), primarily due to early developmental failures. - While issues with cell migration are important in **kidney development**, the *failure of ascent of primitive cells* is not a direct or recognized primary cause of renal agenesis itself; rather, it relates more to aspects of kidney migration or positional anomalies, not complete absence of the organ. *Defective development of nephric tissue* - If the **nephric tissue** (metanephric mesenchyme) fails to develop properly, it cannot interact with the ureteric bud to form a kidney. - This lack of proper development is a direct cause of **renal agenesis**. *Failure of fusion of ureteric bud with metanephros* - The **ureteric bud** induces the differentiation of the metanephros into the various components of the kidney. - If this crucial **fusion and interaction** do not occur, the kidney will not form, leading to renal agenesis.

Question 3: A newborn male is noted to have difficulty feeding and "turns blue and chokes when drinking formula." The prenatal records reveal that the amniotic fluid appeared normal on ultrasound. A pediatric feeding tube is passed orally to 20 cm without difficulty, with gastric secretions aspirated. Which of the following is the most likely diagnosis?

A. Floppy epiglottis
B. Tracheoesophageal fistula (Correct Answer)
C. Zenker diverticulum
D. Congenital heart disease

Explanation: ***Tracheoesophageal fistula*** - The combination of **feeding difficulties**, **cyanosis** ("turns blue"), and **choking** in a newborn, along with the ability to pass a feeding tube to 20 cm, strongly suggests a tracheoesophageal fistula (TEF), specifically a type where the **proximal esophagus ends in a blind pouch and the distal esophagus connects to the trachea**. - The **normal amniotic fluid** on prenatal ultrasound suggests that the fetus was able to swallow amniotic fluid, ruling out esophageal atresia without a fistula as the primary cause of polyhydramnios. Passage of the feeding tube to 20 cm and aspiration of gastric secretions indicates that the stomach is connected to the esophagus, but the reflux of gastric contents during feeding leads to aspiration into the trachea via the fistula. *Floppy epiglottis* - **Laryngomalacia**, or "floppy epiglottis," typically causes **stridor** (a high-pitched inspiratory sound), especially when crying or feeding, which is not the primary symptom described here. - While it can cause some feeding difficulties, **severe cyanosis and recurrent choking** during feeding are more characteristic of aspiration due to a different anatomical defect like TEF. *Zenker diverticulum* - A **Zenker diverticulum is a pharyngoesophageal pouch** that typically causes dysphagia, regurgitation of undigested food, and halitosis, primarily in **older adults**. - It is an acquired condition and **extremely rare in newborns**, making it an unlikely diagnosis for these symptoms in an infant. *Congenital heart disease* - While congenital heart disease can cause **cyanosis and feeding difficulties** due to increased metabolic demand or heart failure, it would not typically present with the specific description of **choking during feeding and successful passing of a feeding tube to the stomach with aspirated gastric secretions**. - The symptoms in this case point more directly to a **problem with the swallowing mechanism or the connection between the esophagus and the trachea**.

Question 4: Sequestered lung is supplied most commonly by which artery?

A. Descending aorta (Correct Answer)
B. Subclavian artery
C. Intercostal arteries
D. Bronchial arteries

Explanation: ***Descending aorta*** - **Bronchopulmonary sequestration** is an abnormal lung tissue that does not communicate with the tracheobronchial tree and receives its blood supply from a **systemic artery**. - The most common source of this systemic arterial supply, particularly for intralobar sequestrations, is the **descending thoracic aorta**. *Subclavian artery* - The subclavian artery mainly supplies the **upper limbs**, neck, and parts of the chest wall. - While it can give off branches that contribute to the thoracic blood supply, it is **not the primary or most common source** for sequestered lung. *Intercostal arteries* - Intercostal arteries primarily supply the **intercostal spaces**, chest wall, and pleura. - Although they are systemic arteries, they are **less common** than the descending aorta as the main blood supply to sequestered lung segments. *Bronchial arteries* - Bronchial arteries are typically branches of the descending aorta that supply the **normal respiratory system** (bronchi, visceral pleura, etc.) [1]. - Sequestrated lung tissue is distinct from normal lung tissue and thus is **not usually supplied by the standard bronchial arterial system**.

Question 5: The chest radiograph shown below is from a 25-year-old male patient presenting with hypertension. The image demonstrates bilateral inferior rib notching. What is the most likely diagnosis?

A. Tetralogy of Fallot
B. Ebstein's Anomaly
C. TAPVC
D. Coarctation of Aorta (Correct Answer)

Explanation: ***Coarctation of Aorta*** - The chest radiograph shows findings consistent with **rib notching**, which is a classic sign of coarctation of the aorta due to increased collateral circulation through intercostal arteries. - The history of **hypertension** in a male patient, especially if presenting at a younger age or with differential blood pressures between upper and lower extremities, strongly suggests coarctation of the aorta. *Tetralogy of Fallot* - Characterized by a **boot-shaped heart** due to right ventricular hypertrophy and pulmonary outflow obstruction. - Would typically present with **cyanosis** and decreased pulmonary vascular markings, not rib notching or isolated hypertension. *Ebstein's Anomaly* - Involves apical displacement of the **tricuspid valve**, leading to atrialization of the right ventricle and severe tricuspid regurgitation. - Chest X-rays often show **severe cardiomegaly** (huge heart due to right atrial enlargement) and decreased pulmonary vascularity, which are not depicted here. *TAPVC* - Total anomalous pulmonary venous connection (TAPVC) involves all pulmonary veins draining into the systemic circulation. - The classic chest X-ray finding for supracardiac TAPVC is a **"snowman" or "figure of 8" sign** due to dilated anomalous vessels and superior vena cava, which is absent in this image.

Question 6: Which artery dilatation causes compression of the 3rd part of the duodenum?

A. Superior mesenteric artery (Correct Answer)
B. Gastroduodenal artery
C. Inferior mesenteric artery
D. Celiac artery

Explanation: Superior mesenteric artery - The superior mesenteric artery (SMA) originates from the aorta and passes anterior to the third part of the duodenum [1]. - Dilatation or an unusually acute angle between the SMA and aorta (the aortomesenteric angle) can compress the duodenum, leading to superior mesenteric artery syndrome. Gastroduodenal artery - The gastroduodenal artery typically runs posterior to the first part of the duodenum; its dilatation would not affect the third part. - It primarily supplies the pylorus, proximal duodenum, and head of the pancreas. Inferior mesenteric artery - The inferior mesenteric artery supplies the hindgut, including the distal colon and rectum, and is located far from the duodenum. - Its position makes it anatomically unlikely to cause direct compression of the duodenum. Celiac artery - The celiac artery branches superior to the duodenum and supplies the foregut organs such as the stomach, liver, and spleen. - It does not directly cross or lie in close proximity to the third part of the duodenum in a way that would cause compression if dilated [1].

Question 7: Which one of the following life-threatening congenital anomalies in the newborn presents with polyhydramnios, aspiration pneumonia, excessive salivation and difficulty in passing a nasogastric tube?

A. Choanal atresia
B. Gastroschisis
C. Diaphragmatic hernia
D. Tracheo-esophageal fistula (Correct Answer)

Explanation: ***Tracheo-esophageal fistula*** - This condition presents with **polyhydramnios** due to the fetus being unable to swallow amniotic fluid, **excessive salivation** from accumulated secretions in the blind-ending esophageal pouch, and difficulty passing a **nasogastric tube** because of the esophageal obstruction. - **Aspiration pneumonia** is a common complication as saliva and gastric contents can be aspirated into the lungs through the fistula. *Choanal atresia* - Characterized by **blocked nasal passages**, leading to **cyclical cyanosis** relieved by crying, but not typically associated with polyhydramnios or excessive salivation in this manner. - While it can cause respiratory distress, it does not involve esophageal obstruction or directly cause aspiration pneumonia from swallowed fluids. *Gastroschisis* - This is an **abdominal wall defect** where intestines protrude outside the body, unrelated to swallowing difficulties, polyhydramnios caused by inability to swallow, or excessive salivation. - It does not involve difficulty in passing a nasogastric tube or directly cause aspiration pneumonia. *Diaphragmatic hernia* - Involves **abdominal contents herniating into the chest cavity**, leading to **pulmonary hypoplasia** and respiratory distress. - It does not explain polyhydramnios due to impaired swallowing, excessive salivation, or the characteristic inability to pass a nasogastric tube.

Question 8: Unilateral renal agenesis is associated with:

A. Hiatus Hernia
B. Single umbilical artery (Correct Answer)
C. Hypogonadism
D. Polycystic disease of pancreas

Explanation: ***Single umbilical artery*** - **Unilateral renal agenesis** is often associated with other congenital anomalies, including the presence of a **single umbilical artery** (2-vessel cord instead of the normal 3-vessel cord). - Both conditions can be part of **VACTERL association** (Vertebral, Anorectal, Cardiac, Tracheo-Esophageal, Renal, and Limb anomalies). - The **single umbilical artery** is a marker for increased risk of **urogenital and cardiovascular malformations**, which fits with renal agenesis. - Found in approximately **7-10% of cases with renal anomalies**. *Hiatus Hernia* - A **hiatal hernia** is a condition where part of the stomach pushes up through the diaphragm. - Not a recognized or common association with **unilateral renal agenesis**. - While it can be congenital, it arises from different developmental pathways than renal agenesis. *Hypogonadism* - **Hypogonadism** involves reduced function of the gonads and is not directly associated with **renal agenesis**. - Renal agenesis results from problems with the **metanephric blastema** and **ureteric bud** development, not the reproductive axis. *Polycystic disease of pancreas* - **Polycystic disease of the pancreas** is an extremely rare condition and does not have a well-established association with **unilateral renal agenesis**. - This should not be confused with **polycystic kidney disease**, which is a completely different entity.

Question 9: Which malformation is associated with mutations in the HOX gene?

A. Polysyndactyly (Correct Answer)
B. Holoprosencephaly
C. Mayer Rokitansky syndrome
D. Gorlin syndrome

Explanation: ***Polysyndactyly*** - The **HOX gene** plays a critical role in limb development and is associated with the malformation of **polysyndactyly**, which is characterized by extra fingers or toes [1]. - This condition is due to the disruption of the normal **patterning** during limb formation, directly involving the action of HOX genes [1]. *Gorlin syndrome* - Gorlin syndrome is primarily caused by mutations in the **PTCH1 gene**, linked to **basal cell carcinoma** and other abnormalities. - It does not involve HOX gene mutations, hence is **not** related to limb malformations. *Holoprosencephaly* - Holoprosencephaly is a developmental condition often linked to **chromosomal anomalies** and abnormal embryonic development, **not specifically** HOX gene mutations. - It refers to the incomplete separation of the forebrain, distinct from the **limb malformations** associated with HOX genes. *Mayer Rokitansky syndrome* - Mayer-Rokitansky syndrome involves **agenesis** or **hypoplasia** of the uterus and upper two-thirds of the vagina, which is due to other genetic factors. - This condition is not related to the functions of the **HOX genes** in limb or skeletal development. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1186.

Question 10: Identify the condition shown in the plain abdominal radiograph.

A. Pancreatic calcification (Correct Answer)
B. Mesenteric calcification
C. Horseshoe kidney
D. Jejunal fecolith

Explanation: ***Pancreatic calcification*** - The radiograph displays **multiple, punctate, and amorphous calcifications** clustered in the upper abdomen, characteristic of **chronic pancreatitis**. - These calcifications represent **calcium deposits within the pancreatic ducts and parenchyma**, a hallmark sign of chronic inflammation and damage to the pancreas. *Mesenteric calcification* - **Mesenteric calcifications** are typically more scattered and linear, often following the distribution of blood vessels or lymph nodes within the mesentery, which is not seen here. - They are generally less dense and less granular than the calcifications observed in the image. *Horseshoe kidney* - A **horseshoe kidney** is a congenital anomaly where the kidneys are fused at their lower poles, forming a U-shape, and is typically located lower in the abdomen, often overlying the spine. - This condition presents with the characteristic **renal outlines** and not diffuse calcifications as shown. *Jejunal fecolith* - A **jejunal fecolith** would appear as a singular or a few discrete, dense, and typically rounded or oval radio-opacities within the lumen of the jejunum. - The diffuse, scattered pattern of calcifications displayed in the image is inconsistent with a fecolith, which is usually composed of inspissated fecal material.

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