Formation of extended defects during 4H-SiC{0001} epitaxial growth has been investigated by grazing incidence synchrotron reflection X-ray topography and KOH-defect selective etching analysis. Details of the defect topography contrast features are collated with the KOH etched features. Conversion of threading screw dislocations (TSDs) into a defect on the basal plane as well as a carrot defect is tracked by performing topography before and after epitaxial growth. We found simultaneous nucleation of a TSD and a defect on the basal plane during epitaxial growth. The polytype inclusions are confirmed to be transparent in the topography condition. Formation of threading dislocation clusters during epitaxial growth is also investigated. (c) 2007 Elsevier B.V. All rights reserved.