Postmortem Examination of Fetuses and Infants

Facilities and Equipment

The standard autopsy suite used for postmortem examinations of adults should be adequate for pediatric autopsies. Access to a photography setup and a specimen x-ray machine must be available. The entire body of the fetus or small infant can be placed on an elevated dissection stand to bring the work area up to chest level. Good lighting is essential; a portable operating room spot to illuminate the field works well. In addition to a standard kilogram scale and linear measuring device, a gram-milligram scale, a flexible ruler, and a tape measure are necessary. Instruments of appropriate scale for the size of the body include round-tip and pointed small scissors, scalpel, forceps, and probes. Fine probes for very small structures (<1 mm) can be crafted by blunting the ends of small-caliber pins. A magnifying glass or low-power loupes (e.g., 2.5×) are necessary, and a dissecting microscope may be useful in some cases.

Postmortem Examination

The following section details a protocol that is useful in a postmortem examination of a fetus or infant. Although generally applicable, the protocol may have to be tailored for certain cases with unusual anomalies. The various measurements and observations are used to document either normal anatomy or various pathologic conditions (listed in templates in Appendix A and described in standard texts), and will not be presented here. Further information regarding how to perform an autopsy of a fetus or infant can be found in standard texts or numerous articles on the topic.

A proper postmortem examination is always documented with photographs. Photographs of the external features are routine: pictures of the front and back of the entire body and close-ups of the face and side of the head, as well as any other unusual aspects (such as hand or foot abnormalities), should be taken before the autopsy commences. Photographs provide an accurate record not only for future conferences, but also for the occasional case in which review of the gross and histologic findings prompts a reevaluation of the external features. Similarly, photographs should be made of any major abnormality encountered in the evisceration and dissection.

Whole-body radiographs (anteroposterior and lateral) are routine in stillborn fetuses and in neonates who have not been examined radiographically during life. In many instances skeletal abnormalities identified in radiographs provide the first clue to a malformation complex or syndrome, and in some cases radiographs provide data supporting a particular diagnosis (e.g., Fig. 7-4 ). Although the literature is replete with articles describing various radiographic abnormalities in fetuses and infants, consulting colleagues in radiology can be extremely helpful in correctly identifying the lesions.

Many fetuses and neonates present a dysmorphic appearance that heralds a syndrome. In addition to pictures, the abnormal features may be documented through measurements of certain structures that can be compared with reference standards. For this reason these autopsies require additional linear measurements using a tape measure, as described later. In many cases consultation with a geneticist is useful.

Maceration (organ and tissue softening due to decomposition) is a confounding problem in fetuses that have been retained in utero following fetal demise. Abiotic decomposition (autolysis) refers to a sterile process due to intrinsic degradation; biotic decomposition is tissue breakdown due to overgrowth by microorganisms. The degree of autolysis is variable depending on intrauterine conditions. Nevertheless, sequential gross and microscopic changes help one estimate the time of death ( Table 5-1 ). Following delivery, the autolytic process can progress at room temperature but is slowed considerably by refrigeration of the body. Thus, in cases of perinatal death, the delivery room staff can assist the pathologist by putting the body in the refrigerator as soon after delivery as possible. Despite deformation due to maceration, many malformations may be discerned on careful gross inspection. Linear measurements and weights may be artifacted, however, and histologic results are usually suboptimal.

External Examination

Some indication of the degree of autolysis should be given to frame the context of the postmortem examination. We use a rough index that may be helpful to the clinician: mild (skin sloughing only), moderate (skin sloughing and organ softening), and marked (skin sloughing, organ softening, and joint laxity) maceration. The external examination of the fetus or infant includes measurements of: circumferences of head (frontooccipital “hatline”), chest (at nipples), and abdomen (at umbilicus); lengths of crown-rump (uncurved back to ischial tuberosities), crown-heel (legs mildly stretched straight), and foot length (to tip of longest toe); and weight of the body. Abnormal body parts should also be measured. The positions of penetrating tubes and wires are recorded. The distribution and quality of hair over the head and rest of the body are noted. The fontanel dimensions are measured. Abnormalities of the shape of the head related to molding, trauma, soft tissue edema, hemorrhage, or autolysis are noted; the basis for these changes may be investigated later. The facial features are examined and abnormalities recorded. The distances between inner and outer canthi are measured. These and other common facial measurements are shown in Figure 5-1 . If the palpebral fissures can be opened, the color of the sclera and iris, sizes of the pupils, and interpupillary distance are recorded. The color of the conjunctiva is noted. By late intrauterine development, the crest of the external ear should be superior to the level of the lateral canthus. In all fetuses, a line from the occipital notch to the lateral canthus should pass just above the tragus. The configuration of the ear is examined and plasticity (indicating amount of cartilage) evaluated as an index to developmental stage ( Fig. 5-2 ). Patency of each external auditory canal should be ascertained. The position and shape of the nose are noted; patency of the choanae should be determined by probing. The configuration of the philtrum and mouth are observed, and the philtrum length and mouth width are measured (see Fig. 5-1 ). Examination of the oral cavity consists of digital palpation of the palate and direct observation of the gingiva.

The position of the trachea and thyroid within the neck is palpated. The lateral and posterior aspects of the neck should be examined for edema or excess skin. Symmetry or abnormal shape of the thorax is noted. The internipple distance is recorded and the presence of any mammary tissue determined. The amount of subcutaneous tissue over the chest and abdomen is noted. The shape of the abdomen and integrity of the anterior abdominal wall are noted. The liver and spleen are palpated to determine approximate size; abnormal masses are noted. Lymphadenopathy or hematoma at a catheter access site may be palpable in the inguinal areas. The genitalia are inspected. The contents of the bladder may be gently expressed (Credé method) to document urethral patency. In boys, the position of the meatus is determined and scrotal contents assessed. In girls, the position of the meatus and configuration and relative size of the labia and clitoris are observed. The perineal area is inspected and the anal opening probed to document patency. The back of the body is examined for midline defects or discoloration of the skin.

The extremities must be examined for muscle bulk, as well as symmetry and configuration. The mobility of the joints should be evaluated, and the amount and distribution of the skin and subcutaneous tissues around joints noted. The position of the hands and feet, as well as the fingers, must be noted. The appearance of each digit must be considered, including the number of phalanges and their form, as well as the shape and length of the nails; the hand length and foot length should be recorded. The palmar and plantar markings should be observed.