Doctors treating Michael Schumacher have revealed they carried out a two-hour operation to remove blood from a clot in the skull of the Formula One star.<br /><br />The procedure took place on Monday night after consultations with the 44-year-old’s family, who remain at his bedside.<br /><br />The medical team at the University Hospital in Grenoble said the decision to operate was taken after a scan showed changes in the patient’s situation.<br /><br />While doctors said they were pleased with the development they refused to give any prognosis, stressing there is still a long way to go and adding the former champion is still critical.<br /><br />Schumacher remains in a medically induced coma after sustaining injuries while skiing off piste on Sunday.<br /><br />The doctors stressed they want to be transparent on the treatment of the driver who won seven Formula One titles but added they will not be giving regular medical updates.