The student's dilemma, liver edition: incorporating the sonographer's language into clinical anatomy education

Anatomy students are often confused by multiple names ascribed to the same structure by different clinical disciplines. Increasingly, sonography is being incorporated into clinical anatomical education, but ultrasound textbooks often use names unfamiliar to the anatomist. Confusion is worsened when ultrasound names ascribed to the same structure actually refer to different structures. Consider the sonographic main lobar fissure (MLF). The sonographic MLF is a hyper-echoic landmark used by sonographers of the right upper quadrant. Found in approximately 70% of people, there is little consensus on what the sonographic MLF is anatomically. This structure appears to be related to the main portal fissure (aka principal plane of the liver or principal hepatic fissure), initially described by anatomists and surgeons as in intrahepatic division along the middle hepatic vein which in essence divides the territories of the left and right hepatic arteries and biliary systems. By exploring the relationship between the main portal fissure and the sonographic MLF in cadaveric livers ex vivo, the data suggest the sonographic MLF is actually an extrahepatic structure that parallels the rim of the main portal fissure. The authors recommend that this structure be renamed the "sonographic cystic pedicle," which includes the cystic duct and ensheathing fat and blood vessels. In the context of the redefined underlying anatomy, the absence of the sonographic cystic pedicle due to anatomic variation may serve an important clinical role in predicting complications from difficult laparoscopic cholecystectomies and is deserving of future study.