The image shows a transverse view of the left lobe of the liver with the portal triads clearly visible. The "parallel channel" or "double barrel" sign is observed—where dilated intrahepatic bile ducts run alongside the portal veins, creating a characteristic sonographic pattern of paired anechoic (black) tubular structures.

This sonographic feature is diagnostic for dilated intrahepatic bile ducts and is typically seen in obstructive jaundice or biliary obstruction from conditions such as:

Choledocholithiasis (stone in the common bile duct)

Stricture or mass compressing the bile ducts

Cholangiocarcinoma

The intrahepatic bile ducts normally are too small to visualize clearly unless dilated. Their dilation gives the liver a "too many tubes" appearance, where bile ducts become as prominent as the portal veins.

Comparison of answer choices:

A. Normal intrahepatic ducts are not usually seen this clearly or prominently on ultrasound.

B. Dilated intrahepatic — Correct. The parallel channel sign supports this diagnosis.

C. Dilated common bile duct would be visualized extrahepatically, typically anterior to the portal vein near the head of the pancreas.

D. Dilated common hepatic duct is also extrahepatic and seen in the porta hepatis, not within the liver parenchyma.

The image demonstrates a characteristic "central dot sign" — a hallmark finding of Caroli disease. This is best appreciated on ultrasound as a cystic dilation of the intrahepatic bile ducts with a central echogenic dot or linear structure (which corresponds to the portal vein and fibrous tissue within the dilated duct). The arrow in the image points to one such dilated duct.

Caroli disease is a rare congenital disorder characterized by segmental, saccular dilation of intrahepatic bile ducts. It is often associated with congenital hepatic fibrosis and may predispose to cholangitis, stone formation, and even cholangiocarcinoma.

Key ultrasound features of Caroli disease:

Cystic or saccular dilations of the intrahepatic bile ducts

The "central dot sign" — echogenic focus in the center of the dilated ducts (representing portal vein radicle or fibrous tissue)

May show associated hepatosplenomegaly or signs of portal hypertension

Differentiation from other options:

A. Sclerosing cholangitis: Typically causes diffuse or segmental biliary ductal wall thickening and stricturing; does not present with cystic dilations.

B. Alagille syndrome: A multisystem disorder often characterized by a paucity of intrahepatic bile ducts, not dilation.

D. Biliary atresia: Presents in infancy with obliteration of extrahepatic bile ducts, echogenic "triangular cord" sign, and absence of a visible gallbladder. It does not cause ductal dilation.

The ultrasound image reveals a well-defined, anechoic (black), thin-walled fluid collection located in the subcutaneous or parenchymal plane of the breast. This is most consistent with a seroma, particularly in the context of recent breast surgery.

A seroma is a common postsurgical finding, representing a sterile collection of serous fluid that accumulates in the surgical bed. It typically appears:

Anechoic (or hypoechoic if older)

Well circumscribed

Without internal septations or debris

Lacking hyperemia or surrounding inflammatory changes

This contrasts with:

A. Carcinoma — typically presents as an irregular, hypoechoic mass with angular margins, internal vascularity, and shadowing.

B. Blood clot (hematoma) — often appears heterogeneous, with internal echoes and variable echotexture depending on the age of the clot.

C. Abscess — appears as a complex fluid collection with thick walls, internal debris, septations, and surrounding hyperemia (often with clinical signs of infection).

D. Seroma — Correct. The described anechoic, clean-walled fluid collection is classic for a postoperative seroma.

In percutaneous procedures such as biopsies or drainages, maintaining a sterile field is critical to avoid introducing infection. While the transducer is covered by a sterile cover, the gel placed inside this cover (between the probe and the cover) must also be sterile, as it contacts the sterile field. The transducer itself and machine controls are not sterile but are handled appropriately to avoid field contamination.

According to the AIUM Guidelines:

"Sterile coupling gel must be used inside the sterile probe cover during all invasive or percutaneous procedures." (AIUM Guidelines for Cleaning and Preparing Ultrasound Transducers, 2021).

Urinomas are collections of urine in the retroperitoneum that result from trauma, surgery, or obstruction causing urine leakage. Trauma is a frequent cause of urinoma formation due to disruption of the urinary tract.

According to Rumack’s Diagnostic Ultrasound:

“Urinomas may develop as a complication of trauma, surgery, or obstructive uropathy with urinary extravasation into the retroperitoneum.”

The celiac trunk arises from the abdominal aorta and immediately divides into three primary branches:

Left gastric artery

Common hepatic artery

Splenic artery

The proper hepatic and gastroduodenal arteries are secondary branches of the common hepatic artery.

According to Moore’s Clinically Oriented Anatomy:

“The celiac trunk trifurcates into the left gastric, common hepatic, and splenic arteries.”

The renal arteries originate from the abdominal aorta just inferior to the superior mesenteric artery (SMA). The SMA arises anteriorly from the abdominal aorta at the level of L1, and just below it, the renal arteries branch laterally. The splenic vein, portal vein, and hepatic artery are located more superiorly in relation to the renal arteries.

According to Moore's Clinically Oriented Anatomy:

"The superior mesenteric artery arises from the anterior surface of the abdominal aorta just above the renal arteries." (Moore KL et al., Clinically Oriented Anatomy, 8th ed.)