Organization, Use of Estimates and Basis of Presentation - Narrative (Details)	3 Months Ended
	Jul. 31, 2017 USD ($) subsidiary	Jul. 31, 2016 USD ($)	Apr. 30, 2017 USD ($)	Apr. 30, 2016 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating subsidiaries | subsidiary	2
Net loss	$ (674,157)	$ (2,546,449)
Net cash used in operating activities	1,948,000	2,439,000
Positive working capital	0
Cash and cash equivalents	430,000	4,463,000	$ 3,295,000	$ 2,585,000
Investment in new lab equipment	910,000,000
Capitalized, non-recurring costs	100,000
Reduction in net loss	3,600,000
Reduction in use of cash in operations	$ 3,600,000
Revenue growth percent	38.00%
Unrecognized tax benefits	$ 121,000		$ 121,000
Provision for income taxes	$ 4,000	$ 14,000