After their surgery is over, Addie asks Derek if he got all of the baby's tumor and he nearly bites her head off at what seems like a rather reasonable question. She explains that she's asking just so she knows what to tell the mom, and Derek condescendingly replies that he'll go ahead and talk to the mom himself. She asks him about the preschool but instead of answering he announces that he's going to stay late to work on his clinical trial idea. It's very obviously just something he realizes will let him avoid his wife and she calls him on it, but then passive aggressively says that maybe he'll find her more interesting when the baby arrives. He mocks her for thinking that the baby will improve things between the two of them and she finally demands to know if he even wanted the baby, and if he loves her. He claims he did want the baby but can't lift his gaze from the floor to look her in the eye as he claims to love her. She knows a bad lie when she hears one. He uses the great cop-out line that he "can't do this," and storms out, and we see that Charles has had a front-row view of the whole argument from the other side of the window.
Callie is still flipping through her magazine but looks up long enough to yell at her charges that they have three minutes left before this poor, unsuspecting patient's organs start dying. The girls bicker some more until Cristina finishes up something or other and they can put him back on bypass. Then Meredith notices that he's got a leak somewhere, and can't believe Cristina when she says she will find it by feel. Meredith -- proving that she's spent too long relying on her mom to bail her out of tough situations -- whines to Callie who finally admits that Mere's suggested method is safer, so that's what they should do. Cristina reluctantly takes her hands out of the guy's chest and Mere starts to fiddle slowly with her instruments, which gives Cristina a split second to shove her hands back inside and, while Meredith shrieks, to find the leak and take care of it.