Pediatric Abdominal Imaging — MCQs
Most common intra-abdominal solid tumor in children:
A 6-month-old child woke up at night, crying with severe colicky abdominal pain, and later passed red currant jelly stools. What is the most likely diagnosis?
Investigation of choice to diagnose hypertrophic pyloric stenosis in infants is
How do you differentiate between mechanical obstruction and paralytic ileus?
A 28-year-old male patient presents with colicky abdominal pain along with vomiting. X-ray abdomen shows:
Investigation of choice for the diagnosis of congenital hypertrophic pyloric stenosis is:
The "triangular cord sign" on ultrasonography is indicative of which condition in a neonate?
What is the investigation of choice for hydrocephalus in infants?
A neonate presented on day one of life with bilious vomiting. What is the first investigation to be done?
The lung-head ratio is useful in the diagnosis of which of the following conditions?
Pediatric Abdominal Imaging Indian Medical PG Practice Questions and MCQs
Question 1: Most common intra-abdominal solid tumor in children:
- A. Neuroblastoma
- B. Hodgkin lymphoma
- C. Rhabdomyosarcoma
- D. Wilms' tumor (Correct Answer)
Explanation: ***Wilms' tumor*** - **Wilms' tumor**, also known as **nephroblastoma**, is the **most common primary renal tumor** in children. - It is also recognized as the **most frequently diagnosed intra-abdominal solid tumor** in pediatric patients, typically presenting as an asymptomatic abdominal mass. *Neuroblastoma* - **Neuroblastoma** is the **most common extracranial solid tumor** in childhood and the most common cancer in infancy. - While frequently intra-abdominal (arising from the **adrenal gland** or **sympathetic ganglia**), its overall incidence is slightly lower than Wilms' tumor when considering all intra-abdominal solid tumors, particularly renal ones. *Hodgkin lymphoma* - **Hodgkin lymphoma** is a cancer of the lymphatic system, which is a part of the body's immune system. - While it can occur in children and sometimes involve intra-abdominal lymph nodes, it is primarily a **lymphoid malignancy** and is not typically classified as an intra-abdominal **solid organ tumor** in the same manner as Wilms' tumor or neuroblastoma. *Rhabdomyosarcoma* - **Rhabdomyosarcoma** is a malignant tumor of **skeletal muscle origin**, which can occur in various sites, including the head and neck, genitourinary tract, and extremities. - While it can be found in the abdomen (e.g., in the bladder or retroperitoneum), it is far **less common** than Wilms' tumor as an intra-abdominal solid tumor in children.
Question 2: A 6-month-old child woke up at night, crying with severe colicky abdominal pain, and later passed red currant jelly stools. What is the most likely diagnosis?
- A. Malrotation
- B. Meckel's diverticulum
- C. Intestinal obstruction
- D. Intussusception (Correct Answer)
Explanation: ***Intussusception*** - The classic presentation of **intussusception** includes sudden onset of **severe colicky abdominal pain** (intermittent crying spells), drawing legs to the chest, and passing **red currant jelly stools** (blood and mucus). - The pain occurs in intermittent episodes with periods of relative calm in between. Red currant jelly stools typically appear later in the disease course (often after 12-24 hours). - This is a **pediatric emergency** with peak incidence at **6-18 months** of age. *Malrotation* - Malrotation typically presents with **bilious vomiting** due to midgut volvulus and duodenal obstruction, particularly in the neonatal period. - While it can cause abdominal pain, the hallmark is persistent bilious vomiting rather than the intermittent colicky pain with red currant jelly stools seen in intussusception. *Meckel's diverticulum* - Meckel's diverticulum typically causes **painless rectal bleeding** (due to **heterotopic gastric mucosa** causing ulceration). - When it causes pain, it's usually due to **diverticulitis** or obstruction from an inverted diverticulum, but these do not produce the classic red currant jelly stools of intussusception. *Intestinal obstruction* - While intussusception is a specific type of intestinal obstruction, this option is too general. Other forms of intestinal obstruction (e.g., from adhesions, hernias) in an infant would typically present with **bilious vomiting**, abdominal distension, and may not produce red currant jelly stools. - The combination of intermittent colicky pain and red currant jelly stools is pathognomonic for intussusception.
Question 3: Investigation of choice to diagnose hypertrophic pyloric stenosis in infants is
- A. Gastroscopy
- B. CT scan abdomen
- C. Ultrasound abdomen (Correct Answer)
- D. Contrast radiology
Explanation: ***Ultrasound abdomen*** - **Abdominal ultrasound** is the diagnostic procedure of choice due to its **non-invasive nature**, **lack of radiation exposure**, and high accuracy in visualizing the pylorus. - It allows for direct measurement of the **pyloric muscle wall thickness** (typically >3-4 mm) and **pyloric channel length** (typically >14-17 mm), which are characteristic findings of hypertrophic pyloric stenosis. *Gastroscopy* - While gastroscopy can visualize the gastric outlet, it is an **invasive procedure** and not the primary diagnostic tool due to the risk associated with endoscopy in infants. - It is often reserved for cases where the diagnosis is unclear or other upper gastrointestinal pathologies are suspected. *CT scan abdomen* - **CT scans** expose infants to **ionizing radiation**, making it an unsuitable primary diagnostic investigation, especially when a highly accurate non-irradiating alternative exists. - Although it can show pyloric thickening, its disadvantages outweigh its benefits for this diagnosis. *Contrast radiology* - **Barium studies** are less sensitive and specific than ultrasound for diagnosing pyloric stenosis, especially for distinguishing muscle thickening from spasm. - This method also involves **radiation exposure** and poses a risk of aspiration, making it a secondary choice.
Question 4: How do you differentiate between mechanical obstruction and paralytic ileus?
- A. Presence of multiple air-fluid levels in the bowel (Correct Answer)
- B. Presence of abdominal distension
- C. Absence of rectal gas shadow in imaging studies
- D. Elevation of hemidiaphragm on imaging
Explanation: ***Presence of multiple air-fluid levels in the bowel*** - The presence of multiple **air-fluid levels** on upright abdominal X-rays or CT scans is a hallmark of **mechanical bowel obstruction**, indicating a blockage preventing the normal progression of gas and fluid. - In a paralytic ileus, bowel loops are generally **gas-filled but without distinct air-fluid levels**, as there is no physical blockage impeding fluid movement. *Absence of rectal gas shadow in imaging studies* - An **absent rectal gas shadow** can be seen in both severe **mechanical obstruction** and **paralytic ileus**, particularly if the obstruction or ileus is significant and prolonged, making it a less specific differentiating feature. - While it suggests an empty distal bowel, it does not reliably distinguish between the two conditions without additional findings. *Presence of abdominal distension* - **Abdominal distension** is a common finding in both **mechanical obstruction** (due to trapped gas and fluid proximal to the blockage) and **paralytic ileus** (due to generalized bowel dilation). - Therefore, its presence alone does not help differentiate between these two conditions. *Elevation of hemidiaphragm on imaging* - An **elevated hemidiaphragm** can occur in various abdominal conditions, including large collections of fluid or gas pushing up the diaphragm, or conditions affecting diaphragmatic motion itself (e.g., phrenic nerve palsy). - It is not a specific finding to differentiate between **mechanical obstruction** and **paralytic ileus**.
Question 5: A 28-year-old male patient presents with colicky abdominal pain along with vomiting. X-ray abdomen shows:
- A. Pseudo-obstruction
- B. Cancer colon
- C. Small bowel obstruction (Correct Answer)
- D. Paralytic ileus
Explanation: ***Small bowel obstruction*** - The X-ray image shows multiple **dilated loops of small bowel** with **air-fluid levels** and prominent **valvulae conniventes** (herringbone pattern), which are classic signs of small bowel obstruction. - The clinical presentation of **colicky abdominal pain** and **vomiting** is highly consistent with a small bowel obstruction. *Pseudo-obstruction* - Pseudo-obstruction, or Ogilvie's syndrome, primarily affects the **large bowel**, leading to colonic dilation without a mechanical obstruction. - While it can cause abdominal pain and vomiting, the X-ray findings would typically show marked dilation of the colon rather than predominantly small bowel loops. *Cancer colon* - Colon cancer, if it causes obstruction, typically presents as a **large bowel obstruction**, with colonic dilation proximal to the tumor. - While severe cases could lead to cecal dilation and subsequent small bowel obstruction, the primary radiographic findings would focus on the colon. *Paralytic ileus* - Paralytic ileus, or adynamic ileus, involves generalized bowel dilation (both small and large bowel) due to **impaired peristalsis**, without mechanical obstruction. - Although it causes abdominal pain and vomiting, it usually presents with more continuous, less colicky pain, and the X-ray often shows gas in the colon, which is typically absent or minimal in a complete small bowel obstruction.
Question 6: Investigation of choice for the diagnosis of congenital hypertrophic pyloric stenosis is:
- A. USG (Correct Answer)
- B. Barium meal
- C. Barium meal follow through
- D. CT scan with contrast
Explanation: ***USG*** - **Ultrasound** is the preferred initial imaging modality due to its non-invasiveness, lack of radiation, and high accuracy in visualizing the thickened pyloric muscle. - The classic ultrasound findings include a **pyloric muscle thickness** of ≥ 4 mm and a **pyloric channel length** of ≥ 14 mm. *Barium meal* - While a barium meal can show findings like the "string sign" or "shoulder sign," it involves **radiation exposure** and is generally considered a second-line investigation. - Its diagnostic accuracy is good, but it is less convenient and riskier than ultrasound for this condition. *Barium meal follow through* - This procedure tracks barium through the entire gastrointestinal tract, which is **excessive and unnecessary** for diagnosing pyloric stenosis, which is a localized obstruction. - It also involves significant **radiation exposure** and a prolonged examination time. *CT scan with contrast* - A **CT scan** involves significant **radiation exposure** and is not typically used for diagnosing congenital hypertrophic pyloric stenosis. - It is also less sensitive than ultrasound for visualizing the specific soft tissue changes in the pyloric muscle.
Question 7: The "triangular cord sign" on ultrasonography is indicative of which condition in a neonate?
- A. Galactosemia
- B. Biliary atresia (Correct Answer)
- C. Hepatitis
- D. None of the above
Explanation: **Explanation:** The **triangular cord sign** is a highly specific ultrasonographic finding for **Biliary Atresia (BA)**. It represents a cone-shaped or triangular fibrotic mass of the cranial part of the extrahepatic biliary tree. On ultrasound, it appears as an echogenic (hyperechoic) area located anterior to the bifurcation of the portal vein. A thickness of **>4 mm** is generally considered diagnostic. **Why Biliary Atresia is correct:** In BA, there is progressive fibro-obliterative destruction of the extrahepatic biliary system. The "triangular cord" is the sonographic visualization of this fibrous remnant at the porta hepatis. When combined with an absent or small, irregular gallbladder (ghost gallbladder sign), it is a pathognomonic finding. **Why other options are incorrect:** * **Galactosemia:** This is a metabolic disorder. While it can cause neonatal jaundice and hepatomegaly, it does not involve anatomical obliteration of the bile ducts; diagnosis is via enzyme assays and urine reducing sugars. * **Hepatitis (Neonatal):** This is the primary differential for BA. On ultrasound, neonatal hepatitis typically shows a patent biliary tree and a normal-sized gallbladder. It lacks the specific fibrous cord seen in BA. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Diagnosis:** Intraoperative Cholangiogram (IOCG). * **Best Initial Screening:** Ultrasound (looking for the triangular cord sign). * **Functional Imaging:** HIDA scan (shows uptake by the liver but **no excretion** into the bowel even after 24 hours). * **Surgical Management:** Kasai Procedure (Hepatoportoenterostomy), ideally performed before 60 days of life. * **Liver Biopsy:** Shows bile duct proliferation and portal fibrosis.
Question 8: What is the investigation of choice for hydrocephalus in infants?
- A. Cranial USG (Correct Answer)
- B. CT Scan
- C. MRI
- D. X-ray skull
Explanation: **Explanation:** **1. Why Cranial USG is the Correct Answer:** In infants, the **anterior fontanelle** remains open (typically until 12–18 months), providing an ideal "acoustic window" for ultrasound waves. Cranial Ultrasound (USG) is the **investigation of choice (screening and initial)** for hydrocephalus because it is non-invasive, bedside (portable), cost-effective, and involves **no ionizing radiation**. It accurately visualizes ventricular size, detects intraventricular hemorrhage (a common cause of hydrocephalus in preterms), and allows for serial monitoring of ventricular dilatation. **2. Why Other Options are Incorrect:** * **CT Scan:** While excellent for bone and acute hemorrhage, it involves significant radiation exposure. In infants, the developing brain is highly sensitive to radiation. It is reserved for emergencies or when USG is inconclusive. * **MRI:** This is the **gold standard** for detailed anatomical evaluation (e.g., identifying the specific site of obstruction like aqueductal stenosis). However, it is not the *initial* investigation of choice because it often requires sedation in infants, is expensive, and is not readily available at the bedside. * **X-ray Skull:** This has a very limited role. While it may show "copper beaten appearance" or suture diastasis in chronic raised intracranial pressure, it cannot visualize the brain parenchyma or ventricular system. **Clinical Pearls for NEET-PG:** * **Acoustic Window:** The Anterior Fontanelle is the primary window; the Mastoid fontanelle is used to visualize the posterior fossa. * **Best Initial Test for IVH:** Cranial USG is also the investigation of choice for Intraventricular Hemorrhage (IVH) in premature neonates. * **Hydrocephalus Sign:** On physical exam, look for the **"Setting Sun Sign"** (downward gaze) and Macewen’s sign (cracked pot sound on percussion).
Question 9: A neonate presented on day one of life with bilious vomiting. What is the first investigation to be done?
- A. Chest skiagram
- B. Babygram (Correct Answer)
- C. Ultrasound
- D. Manometry
Explanation: **Explanation:** The clinical presentation of **bilious vomiting** in a neonate on the first day of life is a surgical emergency until proven otherwise. It indicates an intestinal obstruction distal to the Ampulla of Vater. **Why Babygram is the correct answer:** A **Babygram** (a single-view X-ray including both the chest and abdomen) is the initial screening investigation of choice. It is rapid, non-invasive, and provides immediate clues to the level of obstruction. Characteristic gas patterns on a babygram can diagnose conditions like: * **Double Bubble Sign:** Duodenal atresia. * **Triple Bubble Sign:** Jejunal atresia. * **Gasless Abdomen:** Suggestive of esophageal atresia without fistula or high-level obstruction. * **Pneumoperitoneum:** Indicating perforation. **Analysis of Incorrect Options:** * **Chest Skiagram (A):** While useful for respiratory distress or esophageal atresia, it does not provide sufficient information about the abdominal gas patterns necessary to evaluate bilious vomiting. * **Ultrasound (C):** Though excellent for diagnosing Pyloric Stenosis (which presents with *non-bilious* vomiting) or identifying the "whirlpool sign" in midgut volvulus, it is usually performed after the initial X-ray. * **Manometry (D):** This is used for functional disorders like Hirschsprung disease in older infants; it has no role in the acute emergency management of a neonate with bilious vomiting. **Clinical Pearls for NEET-PG:** * **Gold Standard for Malrotation/Volvulus:** Upper GI Contrast Study (showing "corkscrew" appearance). * **Most common cause of neonatal bowel obstruction:** Duodenal atresia (associated with Down Syndrome). * **Management Rule:** Any neonate with bilious vomiting requires an immediate X-ray to rule out life-threatening **Midgut Volvulus**.
Question 10: The lung-head ratio is useful in the diagnosis of which of the following conditions?
- A. Congenital diaphragmatic hernia (Correct Answer)
- B. Sequestration
- C. Ileal atresia
- D. Esophageal atresia
Explanation: **Explanation:** The **Lung-to-Head Ratio (LHR)** is a critical prenatal ultrasonographic parameter used primarily to assess the severity of pulmonary hypoplasia in fetuses with **Congenital Diaphragmatic Hernia (CDH)**. In CDH, abdominal viscera herniate into the thoracic cavity, compressing the developing lungs. The LHR is calculated by measuring the area of the contralateral (healthy) lung at the level of the four-chamber view of the heart and dividing it by the fetal head circumference. A lower LHR indicates more severe pulmonary hypoplasia and correlates with a poorer prognosis and higher need for postnatal ECMO (Extracorporeal Membrane Oxygenation). **Analysis of Incorrect Options:** * **Sequestration:** While this is a bronchopulmonary malformation, it is characterized by non-functional lung tissue with an anomalous systemic blood supply. Diagnosis is usually based on identifying the feeding systemic artery via Doppler, not LHR. * **Ileal Atresia:** This is a distal bowel obstruction. Antenatal ultrasound typically shows dilated bowel loops and polyhydramnios, but it does not involve lung measurement. * **Esophageal Atresia:** This is suggested prenatally by a "small or absent stomach bubble" and polyhydramnios. It does not directly impact lung volume in a way that requires LHR measurement. **High-Yield Clinical Pearls for NEET-PG:** * **Most common type of CDH:** Bochdalek hernia (Posterolateral, more common on the **Left** side). * **Morgagni Hernia:** Anterior/Retrosternal, usually occurs on the right side. * **Observed/Expected LHR (o/e LHR):** A more modern refinement of LHR that accounts for gestational age to better predict survival. * **Scaphoid abdomen:** A classic physical exam finding in newborns with CDH.
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