This 27 week fetus has an right upper quadrant cyst detected on a routine scan:

Findings

The cystic structure is non vascular and located in the region of the hilum of the liver. Right upper quadrant cyst may represent:

• Hepatic cysts (very uncommon)
• Mesenteric cysts (lower in the abdomen)
• Adrenal or Kidney, cysts (more posterior)
• Duplicated loop of bowel (usually more echogenic and lower in the abdomen)
• Duodenal atresia (but with a distended stomach and polyhydramnios)
• Gallbladder duplication
• Choledochal cyst.

Of these, a choledochal cyst is the most likely due to the position and the intimate connection to the gallbladder.