We saw the obstetrician today, and he explained basically what we already knew: that Joaquín is significantly smaller than his brother, and that he's retaining liquid in his stomach (technically it's something called fetal ascites; ἀσκίτης is greek for "retaining liquid in his stomach", so now you know). The first isn't too bad, especially as it's clearly not twin-to-twin transfusion syndrome, but the second is pretty bad because it usually indicates either a malformation of the heart, or a genetic alteration. The doc was very good about telling us all this, and did a lot to take the edge off our panic. What we've got to do over the next few days is have a (broader, deeper) scan for infectious deseases (which is the third cause of fetal ascites, which isn't very likely right now because if it were this, it's pretty certain Pedro would have it too), a double (just in case) fetal ecocardiogram, and a second sonogram from an independant doctor. I was particularly impressed by the obstetrician himself requesting this last item. The schedule is: part of the blood tests were taken today, right after the obstetrician; tomorrow morning we have the parvo virus test, and the ecocardiogram in the afternoon. The sonogram unfortunately will have to wait until wednesday because the specialist we were recommended is a very busy person (being the alleged best guy in town), but some of the blood tests won't be ready till then so it's not that bad.