BMBL Section VII - D Table 2, Table 3, Table 4, and Table 5
Table 2.
Standard precautions* for autopsies of patients with suspected prion disease
*Not to be confused with "Standard Universal
Precautions"
1. Attendance should be limited to at least one experienced pathologist and minimal staff. One of the staff avoids direct contact with the deceased but assists with handling of instruments and specimen containers.
2. Standard autopsy attire is mandatory.a. A disposable, waterproof gown is worn in place of a cloth gown.b. Cut-resistant gloves are worn underneath two pairs of surgical gloves or chain mail gloves are worn between two pairs of surgical gloves.c. Aerosols are mainly created during opening of the skull with a Stryker saw. Appropriate respiratory protection should be worn (i.e., PAPR).
3. To reduce contamination of the autopsy suite:a. The autopsy table is covered with an absorbent sheet that has a waterproof backing.b. Contaminated instruments are placed on an absorbent pad.c. The brain is removed while the head is in a plastic bag to reduce aerosolization and splatter.d. The brain can be placed into a container with a plastic bag liner for weighing.e. The brain is placed onto a cutting board and appropriate samples are dissected for snap freezing (see Table 4).f. The brain or organs to be fixed are immediately placed into a container with 10% neutral buffered formalin.g. In most cases of suspected prion disease, the autopsy can be limited to examination of the brain only. In cases requiring a full autopsy, consideration should be given to examining and sampling of thoracic and abdominal organs in situ.
Table 3. Autopsy suite decontamination procedures
1. Instruments (open box locks and jaws) and saw blades are placed into a large stainless steel dish, soaked for 1 h in 2N sodium hydroxide or 2 h in 1N sodium hydroxide, and then rinsed well in water before autoclaving at 134C (gravity displacement steam autoclaving for 1 h; porous load steam autoclaving for one 18-minute cycle at 30 lbs psi or six 3-minute cycles at 30 lbs psi).
2. The Stryker saw is cleaned by repeated wetting with 2N sodium hydroxide solution over a 1 h period. Appropriate washing to remove residual NaOH is required.
3. The absorbent table cover and instrument pads, disposable clothing, etc. are double bagged in appropriate infectious waste bags for incineration.
4. Any suspected areas of contamination of the autopsy table or room are decontaminated by repeated wetting over 1 h with 2N sodium hydroxide
Table 4. Brain cutting procedures
1. After adequate formaldehyde fixation (at least 10-14 days), the brain is examined and cut on a table covered with an absorbent pad with an impermeable backing.
2. Samples for histology are placed in cassettes labeled with "CJD precautions." For laboratories that do not have embedding and staining equipment or microtome dedicated to infectious diseases including CJD, blocks of formalin-fixed tissue can be placed in 96% absolute formic acid for 30 minutes, followed by fresh 10% neutral buffered formalin solution for at least 48 h.(51) The tissue block is then embedded in paraffin as usual. Standard neurohistological or immunohistochemical techniques are not obviously affected by formic acid treatment; however, in our experience, tissue sections are brittle and crack during sectioning.
3. All instruments and surfaces coming in contact with the tissue are decontaminated as described in Table 3.
4. Tissue remnants, cutting debris, and contaminated formaldehyde solution should be discarded within a plastic container as infectious hospital waste for eventual incineration.
Table 5. Tissue preparation
1. Histology technicians wear gloves, apron, laboratory coat, and face protection.
2. Adequate fixation of small tissue samples (e.g. biopsies) from a patient with suspected prion disease is followed by post-fixation in 96% absolute formic acid for 30 minutes, followed by 48 hours in fresh 10% formalin.
3. Liquid waste is collected in a 4L waste bottle containing 600 ml 6N sodium hydroxide.
4. Gloves, embedding molds, and all handling materials are disposed of as biohazardous waste.
5. Tissue cassettes are processed manually to prevent contamination of tissue processors.
6. Tissues are embedded in a disposable embedding mold. If used, forceps are decontaminated.
7. In preparing sections, gloves are worn, section waste is collected and disposed of in a biohazard waste receptacle. The knife stage is wiped with 1-2N NaOH, and the knife used is discarded immediately in a "biohazard sharps" receptacle. Slides are labeled with "CJD Precautions." The sectioned bloc is sealed with paraffin.
8. Routine staining:a. Slides are processed by hand.b. Reagents are prepared in 100 ml disposable specimen cups.c. After placing the coverslip on, slides are decontaminated by soaking them for 1 h in 2N NaOH.d. Slides are labeled as "Infectious-CJD."
9. Other suggestions:a. Disposable specimen cups or slide mailers may be used for reagents.b. Slides for immunocytochemistry may be processed in disposable petri dishes.c. Equipment is decontaminated as described above.
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