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NBME 22 Answers

nbme22/Block 2/Question#1

A 29-year-old woman is brought to the emergency ...

Avulsion of hepatic veins from the inferior vena cava

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apparently this is a common sequelae of abdominal trauma.

(from link below) Twenty-two of the 25 deaths were caused by blood loss. Two patterns of hepatic venous injury appeared to predominate: avulsion of the trunk of the right hepatic vein from the inferior vena cava and avulsion of the upper branch of the right hepatic vein.


 +2  upvote downvote
submitted by monoloco(56),

Anyone else figure out how a surgeon gets his hand inside the patient deep enough to avulse the hepatic veins from the IVC during a LAPAROTOMY? Baffles me.

mesoform  I think this one was pretty easy if you just know the regional anatomy. That was the only answer choice that could remotely have that presentation, so I think it was just testing your knowledge of the structures listed relative to the description. +1  
kimcharito  aorta is also behind of liver... +1  

 +2  upvote downvote
submitted by alexb(14),

It's also just the only option that's "behind" the liver.

Guessed on this one but if you look into pg 354-355 FA 19, you'l notice the structure of the IVC compared to the liver 1:IVC is retroperitoneal 2: if transected, (similar to an abdominal aorta) blood accumulates behind the peritoneum and causes severe hypovolemia 3: all other answers are either too far, or within the peritoneum

This is another question testing the concept of spatial anatomy. If the surgeon is lifting the liver and then the bleed went from a small amount to a sudden massive hemorrhage, clearly this is implying the bleed is occuring behind the liver.

What structure is behind the liver? IVC

What connects to the IVC from the liver? Hepatic veins

Also the idea that the patient has been bleeding for 6 hours because thats how long it took until the exploratory laparomaty was prefromed means the bleed is most likely from a low pressure system... venous system.

I think besides knowing basic anatomy (I suck BIG time on anatomy), we could more or less easily rule out most of the options. She is in pain, but she is awake and with stable vital signs (even after 6 hours) so I think arterial damage would definitely lead to a more rapid deterioration. That leaves us with the portal vein and the hepatic veins. The portal vein (if knowing zero anatomy) brings much more blood to the liver than the hepatic artery (if I'm not mistaken), and so that leaves you with only the hepatic veins.

I think it's more of a general type question. When a surgeon tris to slide his hand behind the liver; it gives traction to the liver and thus can stretch the hepatic veins and thus excess traction can even avulse the hepatic veins from UVC. That makes sense.