We extend the Sudakov formalism from vacuum to opaque media by supplementing the splitting functions with an adittional term given by the medium-induced gluon radiation spectrum. We then solve DGLAP evolution equations to obtain the medium-modified fragmentation functions. In this way, both the additional energy loss and the modification of the QCD evolution by the medium are included in a consistent manner.
The medium-modified splitting functions allow us to implement a simple medium modification of the Pythia parton shower code. Some results will be presented.