Special Autopsy Techniques

POSTOPERATIVE AUTOPSIES Few autopsies present more difficulties because the pathologist is rarely familiar with all operative techniques that may have been used, the complications that were encountered, including anesthesia-related and drug-induced mishaps, and the postoperative events that may completely obscure the immediate surgical results. Possible medicolegal implications must be considered also (16). The following general guidelines should be observed.

1. In any team, the most experienced autopsy pathologist should do postoperative cases. At least one assistant should be available.

2. The surgeon or one surgical assistant who participated in the operation should attend the autopsy. If this cannot be arranged, a telephone conversation, prior to the autopsy, between pathologist and surgeon is essential. Frequently, the main questions of the surgeon are not at all obvious from the written notes.

3. More important than in most other situations, the case history, the surgical report, and the results of roentgeno-graphic and laboratory studies should be studied prior to the autopsy.

4. The autopsy technique should be changed as required by the specific situation. Incisions should not be carried through operative wounds. Instead, wounds should be viewed from their outer and inner aspects and then opened to find possible suture abscesses. To determine whether a dehiscence developed before or after death, the sutured region should be widely excised and fixed for preparation of properly oriented histologic sections for evaluation of vital tissue reactions. For the exclusion of air embolism, see Part II. Chest roentgenograms or other appropriate tests for pneumothorax should be performed also. Fistulas should be filled with a stained contrast medium so that their course can be demonstrated by roentgenograms and dissection. Drains should not be removed before their precise location has been established, always from an incision distant to the drain. At repeated and appropriate intervals, smears should be prepared and material removed for microbiologic examination (see Chapter 9). This may be of considerable help in determining the source of an infection. Some authors prefer en block removal for dissection after abdominal surgery (17). We would recommend this only under exceptional circumstances and only if great care is taken to avoid trauma to the operative sites during the excision of the organ block.

5. Instructive views of all decisive phases of the autopsy should be documented by photographs.

6. Protocols of postoperative autopsies should be dictated during the actual inspection and dissection of organs and tissues. At a later time, surgically significant findings often cannot be recalled and described accurately. For the measurements of volumes, lengths and weights, the metric system should be used (mL, cm, g).

7. During the autopsy, the pathologist should describe the findings but not interpret or comment on them. Hasty conclusions are often proved wrong by subsequent histologic studies or additional clinical information.

IMMEDIATE AUTOPSIES FOR SPECIAL LABORATORY PROCEDURES SUCH AS ELECTRON MICROSCOPY, CYTOCHEMISTRY, AND TISSUE CULTURE For the preservation of cytological detail or growth in tissue culture, autopsies often prove unsuited unless the postmortem interval is very short. For microbiologic studies and many other laboratory techniques, immediate autopsies also are indicated. Whenever possible, the prosector should be assisted by technicians who process the freshly removed samples and do the necessary paper work.

The first phase of the autopsy begins immediately after death has been pronounced and appropriate permissions have been obtained. Through a modified "Y" incision, organs and tissues are sampled for rapid processing. If there is no time to bring the body to the morgue, samples often can be removed with surgical instruments through mini-incisions. Depending on the purpose of the study, the specimens are immediately snap-frozen (e.g., for subsequent biochemical analysis), prepared and fixed for electron and light microscopic study, and transferred to tissue culture media (see Chapter 10) or other solutions as indicated by the intended procedures. Blood samples also can be collected during this phase of the autopsy. If a patient died from a hematologic disorder, procurement of good bone marrow preparations may be the most important autopsy technique. This can be achieved by injecting, shortly after death, 10 mL B-5 fixative into the sternum. The method is described further in Chapter 8.

For the examination of the central nervous system by electron microscopy, the intracranial vasculature is rinsed through an internal carotid artery with a solution of isotonic sodium chloride, followed by in situ fixation with a buffered solution of glutaraldehyde. The perfusion work in the neck can be done while another prosector procures tissue from other sites. In neonates, Zamboni's solution can be injected percutaneously into the lateral ventricles and drained through an intrathecal spinal needle (18).

Once samples for electron microscopy have been collected, and in some instances revived in a tissue-culture medium (see Chapter 10), methods of fixation and specimen preparation for transmission or scanning electron microscopy do not differ from those used with biopsy material. Energy-dispersive X-ray microanalysis can then be used to identify metals and other elements (see Chapter 14). For immunohistochemisty and other special studies described in Chapter 14, samples should be collected with the same speed that often is needed for tissue culture and electron microscopy.

The second phase of the "immediate autopsy" is the routine dissection procedure, which can be delayed as necessary. An alternative to the "immediate autopsy" is described in the next paragraphs.

NEEDLE AUTOPSIES Needle biopsies in the immediate postmortem interval may be used to obtain tissue samples when more invasive procedures, as described under "immediate autopsies," are not possible. This may be the case in tropical countries (19), if proper infection precautions cannot be taken (20), or if all efforts to obtain permission for a regular autopsy fail (21) but the next of kin agree to multiple sampling by needle. Obviously, needle autopsies are inferior to conventional autopsies but they may be an acceptable alternative in selected cases (22,23). Wide-core needles give the best results, either biopsy needles from the hospital supply or special autopsy needles (with a projecting trocar), which should be 10-15 cm in length with a bore of 2-3 mm. A large syringe should be used to provide appropriate suction. Liver, heart, lung, and kidneys usually can be biopsied successfully with this technique (22). Specimens from large tumors also may be easy to obtain.

A variant of these methods can be used to prefix tissues prior to a routine autopsy. For example, if electron microscopic study of pulmonary tissue is intended, stained glutaraldehyde can be injected through the chest wall into the lungs during the immediate postmortem period. The staining permits identification of the fixed tissue at the time of autopsy.

ENDOSCOPIC AUTOPSIES The indications may be the same as those for needle autopsies, described in the previous paragraphs. Neoplasms and traumatic lesions with or without intraperitoneal or thoracic hemorrhages can be readily identified with these techniques (23-25).

RESTRICTION OF SKIN INCISIONS Autopsy permission may be restricted to the re-opening of a surgical incision or it may specify that only an abdominal incision may be made. Many and often remote organs and tissues can be removed or at least sampled through these incisions, provided next of kin consent to such extended procedures.

LESIONS OF FACE, ARMS, OR HANDS The face is essentially "off limits" for the autopsy pathologist. Small specimens of facial skin tumors occasionally can be taken, particularly if the tumor is large enough to cover the defect. Lesions of facial soft tissues or bones may be removed only with special permission; removal of minute samples may be hardly noticeable but after excision of large specimens, reconstruction usually is difficult (26).

Accidental damage such as cuts into facial tissues during an autopsy may be very traumatic to the next of kin. If such a mishap does occur, delicate suturing, cream and powder may render the damage nearly invisible. A plastic surgeon and a sympathetic mortician may provide much needed help in such a situation.

Tissues of the arms and hands should be removed only with special permission. If bones, joints or soft tissues of the hands are to be removed, the incision should be placed at the volar surfaces. A prosthesis may be needed to restore the contours (see Chapter 8).

DEATH MASKS In very rare instances, a pathologist may be asked to prepare or aid in the preparation of a death mask (27). First, oil or petroleum jelly is applied to the face, and hair is protected with gauze. The nostrils are closed with gauze or other material. Next, a cardboard with an oval opening for the face is placed over the head to provide a frame that determines how far back the death mask should reach—for example, whether the ears will be included. Plaster of Paris or plastic molding material (also used in dentistry for moldings needed for the preparation of dentures) is placed over the face and allowed to harden. The facial mold is then greased and used to create the actual mask.

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