Instrument Assembly, Packaging, Sterilization, and Storage

Why This Lesson Matters

Assembling, packaging, sterilizing, and storing surgical instrument sets are the core tasks that define a Sterile Processing Technician's daily work. Every step in this chain directly affects patient safety. A missed instrument, an improperly wrapped set, an unrecognized sterilization failure, or a shelf-life violation can contribute to a surgical-site infection. This lesson walks through each phase so you can perform them safely and confidently during your clinical practicum.

Instrument Assembly from Count Sheets

A count sheet (also called a tray list or set list) is the official written record of every instrument that belongs in a specific set. Before assembly, inspect each instrument for cleanliness, function, and integrity — hinges should move freely, box locks should not be sprung, cutting edges should be intact, and tips should be aligned. Never assemble a visibly soiled or damaged instrument.

Place instruments in the tray so that steam or low-temperature sterilant can contact all surfaces. For steam, open all hinged instruments (hemostats, scissors, needle holders) and disassemble any multi-part items per the manufacturer's instructions for use (IFU). Heavy instruments go on the bottom; lighter, more delicate items go on top or in protective holders. String or rubber-band groupings that trap moisture are not acceptable.

Add an internal chemical indicator (CI) — usually a Type 5 integrating or Type 6 emulating strip — to the geometric center of each set before closing the tray. This indicator is the one that matters most to the end user: it tells the person opening the set whether the load conditions inside the package were met.

Packaging: Double-Wrap and Peel-Pouch Techniques

The packaging system must maintain sterility from the point of release until the point of use. Two common methods are:

• Double-wrap (sequential wrap): Two sheets of CSR (non-woven) wrap are applied one after the other using the square-fold or envelope-fold technique. Each fold creates a pleat that unfolds during aseptic presentation without contaminating contents.
• Peel pouch: A paper-plastic or Tyvek-plastic pouch sized so that the instrument fills no more than about three-quarters of the pouch. Heat-seal the open end with a validated sealer set to the manufacturer's specified temperature and dwell time. Check every seal — it must be continuous, with no channels or incomplete bonds.

After packaging, apply an external chemical indicator (CI Type 1 process indicator tape or a printed indicator on the pouch) to confirm the package was exposed to the sterilization process. Document the load number, date, sterilizer number, and your initials on each package label.

Loading and Running Sterilizer Cycles

Always consult the sterilizer manufacturer's IFU and AAMI ST79 (for steam) or the applicable standard for low-temperature modalities when loading a chamber. Key loading principles:

• Steam: Load items so steam can circulate freely. Basins and bowls are placed on edge. Peel pouches are placed on edge, paper-to-plastic, not flat-stacked. Never overload the chamber.
• Low-temperature sterilization (e.g., hydrogen peroxide gas plasma, ethylene oxide): Follow the facility-specific and manufacturer's IFU exactly; packaging material compatibility is critical because not all wraps and pouches are approved for every modality.

Record all required cycle parameters in the sterilizer log immediately after the cycle: date, cycle number, sterilizer identification, operator ID, load contents, exposure temperature, exposure time, and pressure (for steam). Most modern sterilizers print a cycle tape — attach it to the log.

Monitoring: Chemical, Physical, and Biological Indicators

Sterility assurance depends on three types of monitoring used together:

1. Physical monitors — the sterilizer's own gauges, printouts, and digital readouts. Review these first. If parameters were not met, the load must not be released regardless of indicator results.

2. Chemical indicators (CIs) — change color or form when specific sterilization conditions are met. Review external CIs before shelving and internal CIs are reviewed by the end user at the point of use.

3. Biological indicators (BIs) — the most challenging test. A BI contains a standardized population of highly resistant bacterial spores. After incubation per the manufacturer's instructions, a positive (growth) result means sterilization cannot be confirmed.

A failed BI is a critical event. Stop using the sterilizer immediately. Notify the preceptor and supervisor. Initiate the facility's recall procedure: identify all loads processed since the last negative BI, quarantine or retrieve those items, and notify the appropriate clinical areas. Document every step. Never release a failed load without authorization from a supervisor — doing so is the single most serious error in sterile processing.

Sterile Storage and Distribution

Sterile goods must be stored in a clean, dry, temperature- and humidity-controlled environment on closed or covered shelving, away from foot traffic and plumbing. Use event-related shelf life as the standard: a package is considered sterile until the packaging is compromised, not based on a fixed calendar date — though many facilities add a practical maximum date per policy.

Always use FIFO (First In, First Out): place newly released items behind or beneath existing stock so older sets are used first. Before shelving any package, inspect it for integrity — tears, moisture, broken seals, or a CI that did not change correctly.

When building case carts from OR scheduling sheets, pull each item listed, verify external indicator status, check packaging integrity, and organize the cart so items are accessible in the order they will be needed. For sterile-supply returns, inspect packaging integrity before deciding to restock or reprocess. When in doubt, reprocess.

Safety Summary

Every decision you make — from verifying a count sheet to incubating a BI — exists to protect the patient who will be on the operating table. Work carefully, document accurately, ask your preceptor when you are unsure, and never take shortcuts on indicator verification or load release.