Inventory Control: Methods and Systems for Labs and Clinics

Inventory control is the set of controls that tell a laboratory or clinic what stock it holds, in what condition, and when to reorder. The WHO laboratory quality management handbook describes the goal as letting a laboratory “closely monitor the condition of all supplies and reagents, know what quantities are available and be alerted when there is a need to reorder” (WHO, Laboratory Quality Management System handbook, 2011, section 4-3; checked 2026-11-03). This guide is general information for lab and clinic staff, not medical advice.

Short answer

Inventory control combines six things: a named owner, an analysis of what is needed, a minimum stock level, a receiving and storage routine, records for every item, and regular physical counts to check the records. The method (paper log, card system or computerised system) matters less than whether all of these are in place across every storage area.

What inventory control is, and how it differs from inventory management

The WHO handbook uses the terms “inventory control programme” and “inventory management programme” within the same section (4-3), so they are not sharply separated there. In practice, readers use inventory management for the wider supply lifecycle and inventory control for the checks inside it: who is responsible, what is recorded, how stock is received and rotated, and how the count is verified. For the lifecycle view, see inventory management in healthcare; for records, expiry and recall readiness, see medical supply inventory management.

Inventory control methods

Several named methods are used to control stock. The table maps each to what it controls and to the CASRAI page that covers it.

Method	What it controls	Where to read more
Perpetual inventory	Running balance updated at each receipt and use, reconciled to counts	Perpetual inventory system
Cycle counting	Verifying records through repeated partial counts	Cycle counting
Just-in-time	Holding little stock and relying on delivery timing	Just-in-time inventory
Consignment and vendor-managed	Who owns and replenishes the stock	Consignment vs vendor-managed inventory
Lot and expiry tracking	Which batch is on the shelf and when it must be used	Medical inventory tracking

Expiry-first rotation

The WHO handbook tells staff to store a new shipment behind the existing stock so that “older materials get used first (i.e. items with the first expiry dates are the first used)” (section 4-6). The rule is driven by expiry date, not by purchase order date, which is the distinction that matters for reagents and consumables.

Inventory control systems

The handbook lists standardised forms, card systems and log books as ways to keep the record (section 4-5), with the logbook kept in the storage area. It also describes a simple computerised system (section 4-7).

What WHO says a computerised system adds

• Tracks the exact number of supplies and reagents on hand, updated daily.
• Can alert when lot numbers are near their expiration date.
• Generates statistics that help when planning purchases.
• Helps manage distribution of reagents to satellite laboratories.

The drawbacks the handbook names are that an on-site computer is needed and may be expensive, and that staff must be trained. See also laboratory inventory management software.

A control checklist for a lab or clinic store

This checklist restates the implementation steps and storage rules in WHO handbook sections 4-3 to 4-7. It summarises that source and is not a regulatory requirement.

1. Assign responsibility. WHO: “without this, nothing may get done.” Name a person for the programme and for monitoring.
2. Analyse needs. List the tests or tasks performed and the supplies each needs, collecting the fields listed below.
3. Set a minimum stock for the period between orders, taking delivery time and storage space into account.
4. Quantify use. The handbook says laboratories most frequently use the consumption-based method, and that wastage and discarded expired or spoiled items should be estimated to get actual usage.
5. Inspect on receipt. Check the goods are in good condition and match the order; sign, date and note the expiry date; update the logbook.
6. Store correctly. Follow the manufacturer’s storage instructions; keep the storeroom clean, organised and locked; label shelves and record which shelves hold which items; label reagents with the date opened.
7. Cover every storage area and every reagent and supply.
8. Count weekly. WHO recommends weekly physical counts of reagents and supplies to check the system, with records kept up to date.

What to record for each item

Field	Status in WHO section 4-5
Date received	Recorded
Lot numbers for supplies, reagents and kits	Recorded
Pass or fail acceptance criteria	Recorded
Date put into service, or date and method of disposition if unusable	Recorded
Receiver name and signature, expiration date, quantity received, minimum stock, current balance	Recommended
Shelf location, destination	Optional

Needs-analysis data

For each item the handbook lists: a complete description; the package count (for example a kit of 12 or 100 tests, or pipette tips at 100 or 1000 per box); approximate monthly use; priority; time to receive a delivery; and storage space and conditions, such as refrigeration.

Device identifiers as an extra record

For medical devices that carry a Unique Device Identifier, FDA describes the UDI as a unique numeric or alphanumeric code made of a Device Identifier (a mandatory, fixed part identifying the labeler and the specific version or model) and a Production Identifier (a conditional, variable part that can include lot or batch, serial number, expiration date and manufacturing date) (FDA, UDI Basics; checked 2026-11-03). FDA describes the system as identifying devices from manufacturing through distribution to patient use; that page does not describe UDI as an inventory-control requirement. Where a label carries these fields, they are one source for the lot and expiry entries above; see medical inventory tracking.

Common misunderstandings

• “More stock is safer.” The handbook states that balancing availability against expiry dates is a challenge, and that it is too costly and wasteful to overstock.
• “The system balance is the truth.” WHO asks for weekly physical counts specifically to check the system.
• “Use the oldest delivery first.” The WHO rule is first expiry first, which can differ from first received.
• “Software replaces the routine.” The computerised features WHO lists still depend on someone assigned to monitor and on staff training.

FAQ

What is the difference between inventory control and inventory management?

Management covers the whole supply lifecycle; control is the set of checks inside it (ownership, records, receiving, rotation and counts). The WHO handbook uses the two terms together in one section.

How often should stock be counted?

WHO recommends weekly physical counts of reagents and supplies to check the system. Your own quality system or accreditation body may set a different requirement.

Which inventory control system suits a small laboratory?

The handbook presents forms, card systems and log books as standard options and a simple computerised system as an alternative, with named advantages (daily counts, expiry alerts, purchasing statistics) and drawbacks (on-site computer, cost, training). It does not rank them.

Sources

• World Health Organization, Laboratory Quality Management System: handbook, 2011, ISBN 978 92 4 154827 4, section 4 (Purchasing and inventory), copy at stacks.cdc.gov; module 4-3 to 4-7 at extranet.who.int. Checked 2026-11-03.
• U.S. Food and Drug Administration, UDI Basics. Checked 2026-11-03.