Ectasia (/ɛkˈteɪʒə/), also called ectasis (/ˈɛktəsɪs/), is dilation or distention of a tubular structure, either normal or pathophysiologic but usually the latter (except in atelectasis, where absence of ectasis is the problem). Ectasia (/ɛkˈteɪʒə/), also called ectasis (/ˈɛktəsɪs/), is dilation or distention of a tubular structure, either normal or pathophysiologic but usually the latter (except in atelectasis, where absence of ectasis is the problem).