Abdominal Ultrasonography

Abdominal Ultrasonography

Abdominal Ultrasonography

On this page

USG Basics & Artifacts - Pixel Puzzles

  • Physics: Piezoelectric effect (PZT). ↑Frequency = ↑Resolution, ↓Penetration. Impedance mismatch → reflection.
  • Modes: B-mode (2D), M-mode (motion), Doppler (Color/Spectral for flow).
  • Echogenicity: Anechoic (fluid, black) 📌 All Fluid Black, Hypoechoic (dark), Hyperechoic (calcification/bone, white).
  • Common Artifacts:
    • Acoustic Shadowing: Post. to stones/bone.
    • Acoustic Enhancement: Post. to cysts/fluid.
    • Reverberation: Parallel lines (comet tail).
    • Mirror Image: Mirror across reflector (diaphragm).
    • Twinkle: Color Doppler, stones. Mirror Image Artifact in Abdominal Ultrasound

⭐ Posterior acoustic enhancement helps differentiate cystic vs. solid lesions.

Liver & Biliary USG - Bile Buddies 📌

  • Liver Findings:
    • Normal: Homogeneous, < 15.5 cm. Portal Vein < 13 mm.
    • Fatty Liver (Steatosis): ↑Echogenicity (liver > R. kidney), vascular blurring.
    • Cirrhosis: Coarse texture, nodular surface, caudate hypertrophy, ascites.
    • Focal Lesions:
      • Cyst: Anechoic, posterior acoustic enhancement.
      • Hemangioma: Uniformly hyperechoic (most common benign).
      • HCC: Variable echogenicity, halo, Doppler flow.
  • Gallbladder & Biliary Tree Findings:
    • Normal GB & CBD: GB wall < 3 mm. CBD < 7 mm (↑ 1mm/decade >60y; up to 10mm post-cholecystectomy).
    • Cholelithiasis: Mobile hyperechoic foci + posterior acoustic shadowing.
    • Acute Cholecystitis: GB wall > 3 mm, pericholecystic fluid, +ve Sonographic Murphy's sign.
    • Chronic Cholecystitis: Thick wall, WES sign (Wall-Echo-Shadow).
    • Biliary Dilatation: Intrahepatic (parallel channel/"too many tubes"), Extrahepatic.

      ⭐ Sonographic Murphy's sign (focal tenderness over GB with transducer pressure) is highly specific for acute cholecystitis.

Gallbladder ultrasound with gallstones and shadowing

Pancreas & Spleen Scan - Belly Besties

  • Pancreas:
    • Normal: Homogeneous, echogenicity ≥ liver. Pancreatic duct < 3mm. Splenic vein posterior.
    • Acute Pancreatitis: Enlarged, hypoechoic, peripancreatic fluid.
    • Chronic Pancreatitis: Atrophic, calcifications, ductal dilatation.
    • Masses: Adenocarcinoma (hypoechoic, often in head).
  • Spleen:
    • Normal: Homogeneous, echotexture like liver. Length < 12-13 cm.
    • Splenomegaly: > 13 cm (causes: portal HTN, infections).
    • Focal Lesions: Cysts (anechoic), infarcts (wedge-shaped, hypoechoic).

⭐ Accessory spleen (splenunculus): common variant near hilum/pancreatic tail; don't mistake for pathology.

Renal & Retroperitoneal USG - Kidney Chronicles

Ultrasound of hydronephrosis with Doppler box

  • Normal Kidney: Length 9-13 cm. Cortex typically hypoechoic or isoechoic to liver/spleen. Medullary pyramids more hypoechoic. Central sinus fat is hyperechoic.
  • Hydronephrosis: Dilation of pelvicalyceal system. Graded I-IV. Identify level & cause (e.g., stone, stricture, mass).
  • Renal Calculi: Hyperechoic foci with posterior acoustic shadowing. 📌 Twinkling artifact on color Doppler is a key sign.
  • Renal Cysts: Simple cysts: anechoic, thin smooth walls, posterior acoustic enhancement. Complex cysts: septations, wall thickening, calcifications, internal echoes.
  • Renal Cell Carcinoma (RCC): Typically solid, variable echogenicity (often isoechoic/hyperechoic), may show internal vascularity on Doppler.
  • Retroperitoneum: Scan for collections (hematoma, abscess), lymphadenopathy. Evaluate major vessels like aorta & IVC.

⭐ Angiomyolipomas (AMLs) are common benign renal tumors, typically markedly hyperechoic due to high fat content.

FAST & GI Tract Hints - Gut Feelings & Trauma Triage

  • FAST: Rapid trauma scan for free fluid (hemoperitoneum, pericardial effusion).
    • 4 Key Views: Morrison's, perisplenic, pelvic, subxiphoid.
    • eFAST: Adds lung views (pneumothorax).
  • GI Tract US:
    • Appendicitis: Diameter >6mm, non-compressible, target sign.
    • Intussusception: Target/doughnut sign. 📌 "Sausage Loves Doughnuts".
    • Pyloric Stenosis: Muscle >3mm thick, canal >15mm long. RUQ Ultrasound: Morrison's Pouch

⭐ Key US criteria for hypertrophic pyloric stenosis: pyloric muscle thickness >3mm and length >15mm.

High‑Yield Points - ⚡ Biggest Takeaways

  • First-line imaging for acute abdomen, especially cholecystitis, appendicitis (children/pregnant), and hydronephrosis.
  • Gallstones: hyperechoic foci with posterior acoustic shadowing; cholecystitis: wall thickening >3mm, sonographic Murphy's.
  • Liver: cirrhosis (coarse echotexture), fatty liver (↑echogenicity), focal lesions.
  • Kidneys: hydronephrosis, stones (echogenic + shadowing), cysts.
  • FAST scan detects free fluid/hemoperitoneum in trauma.
  • Appendicitis: non-compressible tube >6mm, target sign.
  • AAA: abdominal aorta >3cm.

Practice Questions: Abdominal Ultrasonography

Test your understanding with these related questions

Which of the following structures is LEAST suitable for ultrasound visualization?

1 of 5

Flashcards: Abdominal Ultrasonography

1/9

Target sign on USG Abdomen is suggestive of _____.

TAP TO REVEAL ANSWER

Target sign on USG Abdomen is suggestive of _____.

intussusception

browseSpaceflip

Enjoying this lesson?

Get full access to all lessons, practice questions, and more.

Start Your Free Trial