Property and Equipment - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	Jul. 31, 2019	Apr. 30, 2019
Property, Plant and Equipment [Abstract]
Furniture and fixtures	$ 178	$ 142
Computer equipment and software	1,117	1,104
Laboratory equipment	3,455	3,358
Assets in progress	619	16
Total property and equipment	5,369	4,620
Less: Accumulated depreciation	(2,256)	(2,074)
Property and equipment, net	$ 3,113	$ 2,546

Assets in Progress, Gross

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Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated amortization of capitalized costs for computer software, including but not limited to, acquired and internally developed computer software.

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Amount before accumulated depreciation of equipment commonly used in offices and stores that have no permanent connection to the structure of a building or utilities. Examples include, but are not limited to, desks, chairs, tables, and bookcases.

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Amount before accumulated depreciation of tangible personal property used to produce goods and services, including, but is not limited to, tools, dies and molds, computer and office equipment.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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