<prompt> The commonest cause of UL mucopurulent rhinorrhoea in a child is -Foreign bodyAdenoids which are blocking the airwaysDeviated nasal septumInadequately treated acute frontal sinusitis  <response>: A unilateral nasal discharge is nearly always due to a foreign body and if the discharge has an unpleasant smell, it is pathognomonic. Logan Turner 10the p. 63If a child presents with unilateral, foul smelling nasal discharge, the foreign body must be excluded. Dhingra 5the p. 176 