Deobstruction

[…] in case, that they who had thus diverted and obstructed these Water-courses, were not able to repair them again; then to distrain all such to give assistance therein, as by such reducing them to their former Chanels, and deobstruction of those stops, should receive benefit and safeguard.

1861, James Yearsley, On Throat Deafness and the Pathological Connexions of the Throat, Nose, and Ear, London: John Churchill, 9th edition, Cases, p. 81, The proper treatment of such a case was immediately apparent; namely, the deobstruction of the nasal and Eustachian passages.