To me this is inexplicable. Or at least it leads me to one conclusion. The McCann's claim that a (probably/possibly paedophile) abductor stole Madeleine from her bed, and possibly drugged her and the twins in order to facilitate the abduction. Kate claims that there was a suspicious stain on Madeleine's pajama top from the evening before, which lead her to think that maybe the abductor came into the apartment the previous evening and drugged Madeleine but did not have time to take her. So the abductor came back the following evening.
Now, if you are to give any credence to this version of events, you must ask yourself, why on earth did Kate and Gerry, who are both doctors, on the discovery that Madeleine was missing, insist that the twins were taken to hospital? To check what drugs had been used, if any. And to check that they had not been molested by the abductor? This is inexplicable to me. Also inexplicable is leaving the twins in the apartment if she thought an abductor had just been in.