vanishing twin

I have a question on this. Vanishing twin is when a twin disappears in the uterus during pregnancy. Why would you not use o31.1? I thought the intrauterine death (o31.2) is after completion of 20th week? Then the papyraceous is the flattened remains of one of the fetuses (o31.0). Thanks in advance for your help.

Thank you,
Neither of these codes states anything specific regarding gestational age. If O31.2 was only referring to a pregnancy over 20 weeks, it would not list a code for the first trimester. You would think if a fetus was aborted, there would be some sort of bleeding. I guess, in my opinion, if it was a intrauterine death the body may absorb that fetus, ie; vanishing fetus.

I guess you could use either code depending on the situation.