Ultrasound Practice Questions

Q: Doppler ultrasound in pregnancy is useful to detect all of the following, except?

Abdominal masses. **Explanation** The core principle of **Doppler Ultrasound** is the measurement of the shift in frequency of sound waves reflected from moving objects, primarily **red blood cells**. Therefore, Doppler is used to evaluate **blood flow (hemodynamics)** and vascular structures. * **Why "Abdominal Masses" is the correct answer:** Abdominal masses (such as a fetal neuroblastoma or ovarian cyst) are structural/anatomical abnormalities. These are primarily diagnosed using **B-mode (2D) Gray-scale Ultrasound**, which provides high-resolution images of morphology and tissue density. While Doppler might be used to check the vascularity *within* a known mass, it is not the primary tool for its detection. * **Why the other options are incorrect:** * **Cardiovascular Malformations:** Color Doppler is essential for visualizing turbulent flow across septal defects (VSD/ASD) and assessing valvular regurgitation or stenosis in the fetal heart. * **Vasa Previa:** This is a life-threatening condition where fetal vessels run across the internal os. Color Doppler is the gold standard for identifying these vessels and distinguishing them from a funic presentation (umbilical cord). * **IUGR:** Doppler assessment of the **Umbilical Artery**, **Middle Cerebral Artery (MCA)**, and **Ductus Venosus** is the clinical standard for monitoring fetal well-being and placental insufficiency in growth-restricted fetuses. **High-Yield Clinical Pearls for NEET-PG:** * **Umbilical Artery Doppler:** Look for "Absent or Reversed End Diastolic Flow" (AREDF), which indicates severe placental resistance and fetal distress. * **MCA Doppler:** Used to detect fetal anemia (Peak Systolic Velocity) and the "Brain Sparing Effect" in IUGR. * **Uterine Artery Doppler:** Presence of a "diastolic notch" at 20-24 weeks is a predictive marker for Pre-eclampsia.

Q: Color Doppler study can evaluate the following EXCEPT?

Intravascular pressure. **Explanation:** Color Doppler ultrasound is a non-invasive imaging technique based on the **Doppler Effect**, which detects the shift in frequency of sound waves reflected off moving red blood cells. **Why Option D is the Correct Answer:** Color Doppler **cannot directly measure intravascular pressure**. While Doppler can measure the velocity of blood flow, pressure is a hemodynamic parameter that usually requires invasive catheterization (manometry) or indirect calculation using the Bernoulli equation (commonly used in Echocardiography, but not a direct measurement of the Doppler signal itself). **Analysis of Incorrect Options:** * **A. Direction of blood flow:** This is the primary function of Color Doppler. By convention, flow toward the transducer is encoded in **Red**, and flow away from the transducer is encoded in **Blue** (BART: Blue Away, Red Toward). * **B. Velocity of blood flow:** Doppler measures the frequency shift, which is directly proportional to the velocity of the moving blood cells. Spectral Doppler provides precise quantitative velocity measurements. * **C. Impedance index:** Also known as the **Resistive Index (RI)** or Pulsatility Index (PI). These are calculated ratios derived from velocity waveforms (Systolic vs. Diastolic velocities) to assess the resistance to blood flow in a vessel. **High-Yield Clinical Pearls for NEET-PG:** * **Power Doppler:** More sensitive than Color Doppler for detecting slow flow (e.g., in torsion or inflammation) but does **not** show direction or velocity. * **Duplex Scanning:** Refers to the simultaneous use of B-mode (grayscale) imaging and Doppler ultrasound. * **Aliasing Artifact:** Occurs when the blood velocity exceeds the Nyquist limit (1/2 of the Pulse Repetition Frequency), causing the color to "wrap around" and appear as the opposite direction.

Q: What is the recommended frequency range for transvaginal ultrasound for obstetric purposes?

5 - 7.5 MHz. **Explanation:** The choice of ultrasound frequency involves a fundamental trade-off between **resolution** and **penetration**. Higher frequencies provide superior image resolution but have poor depth penetration, while lower frequencies penetrate deeper at the cost of image clarity. * **Option B (5 – 7.5 MHz) is Correct:** Transvaginal ultrasound (TVS) utilizes a probe placed in close proximity to the pelvic organs (uterus and ovaries). Because the distance to the target tissue is minimal, high penetration is not required. Therefore, a higher frequency range of **5 – 7.5 MHz** is used to achieve the high-resolution images necessary for early pregnancy detection, such as identifying a gestational sac or fetal cardiac activity. **Analysis of Incorrect Options:** * **Option A (3 – 5 MHz):** This is the standard frequency for **Transabdominal Ultrasound (TAS)**. It is lower because the sound waves must penetrate through the abdominal wall and a full bladder to reach the pelvic organs. * **Option C (7.5 – 20 MHz):** These very high frequencies are reserved for **superficial structures** with minimal depth, such as the thyroid, breast, testes, or musculoskeletal imaging. * **Option D (> 20 MHz):** These frequencies are used in specialized applications like **Intravascular Ultrasound (IVUS)** or high-resolution ophthalmic imaging. **High-Yield Clinical Pearls for NEET-PG:** * **Early Pregnancy:** TVS can detect a gestational sac as early as **4.5 to 5 weeks**, whereas TAS typically requires **5.5 to 6 weeks**. * **Discriminatory Zone:** The β-hCG level at which a gestational sac should be visible is **1,500–2,000 mIU/mL** for TVS and **>6,500 mIU/mL** for TAS. * **Yolk Sac:** The first structure to appear within the gestational sac; its presence confirms an intrauterine pregnancy.

Q: What is the primary use of a probe in a medical context?

Transesophageal echocardiography. **Explanation:** The term **"probe"** in radiology and cardiology most commonly refers to an **ultrasound transducer**. In **Transesophageal Echocardiography (TEE)**, a specialized probe containing an ultrasound transducer at its tip is passed into the esophagus. Because the esophagus lies directly behind the heart, this "probe" allows for high-resolution imaging of cardiac structures (especially the left atrium and valves) without interference from the lungs or chest wall. **Analysis of Options:** * **A. Enteroclysis:** This procedure involves the small bowel. It typically uses a **Bilbao-Dotter or Sellink tube** to infuse contrast directly into the duodenum/jejunum, not a "probe." * **C. Esophageal temperature monitoring:** This uses a **thermistor probe or sensor**. While it is a probe, it is a physiological monitoring tool rather than a primary diagnostic radiological/cardiological "probe" procedure in the context of standard medical imaging exams. * **D. ERCP:** This procedure utilizes a **side-viewing duodenoscope**. While catheters and cannulas are used to inject contrast into the biliary tree, the primary instrument is an endoscope, not a "probe." **NEET-PG High-Yield Pearls:** * **TEE Gold Standard:** It is the investigation of choice for detecting **left atrial appendages (LAA) thrombi** and **infective endocarditis vegetations**. * **Frequency:** TEE probes use higher frequencies (5–7 MHz) than transthoracic probes (2–5 MHz), providing better resolution but less depth. * **Contraindication:** The main contraindication for TEE is esophageal pathology (e.g., stricture, varices, or perforation).

Q: Which of the following statements about transvaginal ultrasound is incorrect?

The bladder should be full.. **Explanation:** In gynecological imaging, the state of the urinary bladder is a critical factor for image quality. For **Transabdominal Ultrasound (TAS)**, a **full bladder** is required because it acts as an acoustic window, pushing the gas-filled bowel loops out of the pelvis and providing a clear view of the uterus and ovaries. However, for **Transvaginal Ultrasound (TVS)**, the **bladder should be empty**. A full bladder during TVS is counterproductive as it pushes the pelvic organs away from the high-frequency vaginal probe, thereby decreasing the resolution and causing patient discomfort during probe manipulation. **Analysis of Options:** * **Option A (Correct):** This statement is **incorrect**. As established, TVS requires an empty bladder to bring the pelvic organs into the focal zone of the transducer. * **Option B:** This is a **correct** statement. Emptying the bladder improves the proximity of the probe to the target organs (uterus/adnexa). * **Option C:** This is a **correct** statement. Since TVS is an invasive procedure involving the insertion of a probe into the vaginal canal, obtaining informed consent (and often having a female chaperone present) is a mandatory medico-legal and ethical requirement. **High-Yield Clinical Pearls for NEET-PG:** * **TVS vs. TAS:** TVS uses higher frequency probes (5–9 MHz) compared to TAS (3–5 MHz), offering superior spatial resolution but less depth of penetration. * **Early Pregnancy:** TVS can detect a gestational sac as early as **4.5 to 5 weeks**, which is about 1 week earlier than TAS. * **Discriminatory Zone:** The β-hCG level at which a gestational sac should be visible on TVS is typically **1,500–2,000 mIU/mL**. * **Contraindication:** TVS is generally avoided in patients with an intact hymen (virgins) or if there is active heavy vaginal bleeding/premature rupture of membranes (relative).

Q: What is the characteristic radiological feature of pneumothorax on ultrasound?

Stratosphere sign. In ultrasound imaging of the lung, the diagnosis of pneumothorax relies on the absence of normal pleural movement. **Correct Answer: D. Stratosphere sign** In a normal lung, the visceral and parietal pleura slide against each other, creating a dynamic "shimmering" effect. In M-mode, this appears as the **Sea-shore sign** (motionless tissues above the pleura look like waves, while moving lung below looks like sand). In a **pneumothorax**, air separates the pleural layers, preventing the ultrasound beam from reaching the moving lung. This results in a series of static, horizontal parallel lines across the entire screen, resembling a barcode or the layers of the atmosphere. Hence, it is called the **Stratosphere sign** (or Barcode sign). **Explanation of Incorrect Options:** * **A. Lung sliding sign:** This is a normal finding. Its presence effectively rules out a pneumothorax at that specific location. * **B. Sea shore sign:** This is the normal M-mode appearance of a healthy, sliding lung. * **C. B lines:** Also known as "comet-tail artifacts," these are vertical hyperechoic lines originating from the pleural line. They indicate fluid in the interstitium. Their presence **rules out** pneumothorax because they require contact between the two pleural layers to form. **High-Yield Clinical Pearls for NEET-PG:** 1. **Lung Point Sign:** This is the most specific ultrasound sign for pneumothorax (100% specificity). It represents the physical transition point where the collapsed lung intermittently contacts the chest wall. 2. **E-FAST:** Ultrasound is more sensitive than a supine Chest X-ray for detecting a traumatic pneumothorax. 3. **Rule of Thumb:** If you see **Lung Sliding** or **B-lines**, you can 100% exclude a pneumothorax at that point.

Q: What is the investigation of choice for minimal ascites?

Ultrasound (USG). **Explanation:** **Ultrasound (USG)** is the investigation of choice for minimal ascites because of its high sensitivity and non-invasive nature. It can detect as little as **5–10 mL** of peritoneal fluid, typically first appearing in the **Pouch of Douglas** (in females) or the **rectovesical pouch** (in males). USG is preferred over other modalities due to its bedside availability, lack of ionizing radiation, and ability to guide diagnostic paracentesis. **Analysis of Options:** * **X-ray (A):** This is the least sensitive method. Ascites only becomes visible on a plain radiograph (as "ground-glass" opacification or bulging flanks) when the volume exceeds **500–1000 mL**. * **CT Scan (C):** While CT is highly sensitive and can detect small amounts of fluid (approx. 30 mL), it is not the *first-line* investigation due to high cost, radiation exposure, and the need for transport to a radiology suite. It is usually reserved for characterizing the cause of ascites (e.g., malignancy). * **MRI (D):** MRI is excellent for soft tissue characterization but is unnecessary, expensive, and time-consuming for the simple detection of fluid. **Clinical Pearls for NEET-PG:** * **Earliest site of fluid collection:** In a supine patient, fluid first collects in **Morison’s Pouch** (hepatorenal space). * **Physical Exam:** "Shifting dullness" requires at least **500 mL** of fluid, while "Fluid thrill" requires **1500–2000 mL**. * **FAST Scan:** Focused Assessment with Sonography for Trauma is used in emergencies to detect hemoperitoneum (blood in the peritoneal cavity).

Q: Placental grading on ultrasound is based on which of the following criteria?

Chorionic plate undulations. **Explanation:** Placental grading, commonly known as the **Grannum Classification**, is used to assess the maturity of the placenta via ultrasound. This system evaluates the physiological changes and calcification patterns that occur as a pregnancy progresses. **Why the correct answer is right:** The Grannum classification is based on three specific anatomical components of the placenta: 1. **Chorionic Plate:** Evaluated for the presence and depth of **undulations** (indentations). 2. **Placental Substance:** Evaluated for the presence of echogenic densities (calcifications). 3. **Basal Layer:** Evaluated for the presence of basal calcifications (comma-like densities). As the placenta matures (Grade 0 to Grade III), the chorionic plate becomes increasingly interrupted by deep indentations that eventually reach the basal layer. **Why the incorrect options are wrong:** * **A & B (Location and Dimension):** While these are critical parameters in an obstetric ultrasound (e.g., to rule out Placenta Previa or Placental Megaly), they do not determine the "grade" or maturity of the placenta. * **C (Amniotic fluid ratio):** Amniotic fluid volume (AFI) is a component of the Biophysical Profile (BPP) and reflects fetal well-being and renal function, but it is not a criterion for placental grading. **High-Yield Facts for NEET-PG:** * **Grade 0:** Smooth chorionic plate; homogenous substance (Typical of early pregnancy). * **Grade I:** Subtle undulations; scattered calcifications. * **Grade II:** Deep undulations; comma-shaped densities in the substance. * **Grade III:** Indentations reach the basal plate, dividing the placenta into **cotyledons**; significant calcification with "fallout" areas (Typical after 37-38 weeks). * **Clinical Significance:** Presence of a Grade III placenta before 34 weeks may indicate **placental insufficiency**, often associated with Preeclampsia or IUGR.

Question 1

Doppler ultrasound in pregnancy is useful to detect all of the following, except?

Accepted Answer

Abdominal masses

Answer

Cardiovascular malformation

Answer

Placental vascular anomalies like Vasa Previa

Answer

Intrauterine Growth Restriction (IUGR)

Question 2

Color Doppler study can evaluate the following EXCEPT?

Accepted Answer

Intravascular pressure

Answer

Direction of blood flow

Answer

Velocity of blood flow

Answer

Impedance index

Question 3

What is the recommended frequency range for transvaginal ultrasound for obstetric purposes?

Accepted Answer

5 - 7.5 MHz

Answer

3 - 5 MHz

Answer

7.5 - 20 MHz

Answer

> 20 MHz

Question 4

What is the primary use of a probe in a medical context?

Accepted Answer

Transesophageal echocardiography

Answer

Enteroclysis

Answer

Esophageal temperature monitoring

Answer

Endoscopic retrograde cholangiopancreatography (ERCP) probe

Question 5

Which of the following statements about transvaginal ultrasound is incorrect?

Accepted Answer

The bladder should be full.

Answer

The bladder should be empty.

Answer

Informed consent is mandatory.

Answer

None of the above.

Question 6

What is the characteristic radiological feature of pneumothorax on ultrasound?

Accepted Answer

Stratosphere sign

Answer

Lung sliding sign

Answer

Sea shore sign

Answer

B lines

Question 7

What is the investigation of choice for minimal ascites?

Accepted Answer

Ultrasound (USG)

Answer

X-ray

Answer

CT scan

Answer

MRI scan

Question 8

Match the following ultrasound probe types with their typical frequency ranges (in MHz): 
1. Linear probe
2. Endoscopic probe
3. Curvilinear probe
4. Endocavitatory probe

A. 7-10 MHz
B. 3-5 MHz
C. 10-12 MHz
D. 20 MHz

Accepted Answer

1-D, 2-C, 3-A, 4-B

Answer

1-A, 2-D, 3-C, 4-B

Answer

1-C, 2-A, 3-B, 4-D

Answer

1-C, 2-B, 3-D, 4-A

Question 9

Comet tail artifact in USG is typically seen in which of the following conditions?

Accepted Answer

Adenomyomatosis

Answer

Cholesterosis

Answer

Porcelain gallbladder

Answer

Acute cholecystitis

Question 10

Placental grading on ultrasound is based on which of the following criteria?

Accepted Answer

Chorionic plate undulations

Answer

Placental location

Answer

Placental dimension

Answer

Amniotic fluid and placental ratio

Ultrasound — MCQs

Ultrasound — MCQs

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