Administrative Office
St. Joseph's Hospital Site, L301-10
50 Charlton Avenue East
HAMILTON, Ontario, CANADA L8N 4A6
PHONE: (905) 521-6141
FAX: (905) 521-6142
http://www.fhs.mcmaster.ca/hrlmp/
Issue No. 61
QUARTERLY NEWSLETTER
February 2002
Embryofetal Pathology Diagnostic Service
Embryofetal pathology is a sub-specialized area of anatomic pathology and encompasses two main areas. The first area
includes the examination of unexpected pregnancy losses of either spontaneous abortions or stillbirths. The intrauterine death
is usually an unexpected event and represents the majority of perinatal deaths. Since the perinatal death rate is approximately
9.7/1,000 births in the United States and Canada, this represents a significant amount number of losses. The second area is the
examination of fetuses from pregnancies discontinued for prenatally determined abnormalities (ultrasound, amniocentesis). At
McMaster, there are over 120 cases examined per year from both of these areas. The role of the pathologist is two fold. The
first is to determine wherever possible the cause of the in utero demise or spontaneous abortion. The second, especially in the
embryofetal cases, is to correlate the pathological findings with the radiologic (ultrasound), and chromosomal abnormalities.
The vast majority of examined cases are presented at multidisciplinary rounds which include staff from obstetrics, neonatology,
radiology and genetics. Ultimately the discussions are used to provide information that can be utilized for the counseling of
parents about whether the causes of the anomalies or demise are syndromic, inherited, sporadic, maternally caused, infectious
or due to placental abnormalities. This allows for appropriate follow-up and treatment for subsequent pregnancies.
Prior to starting any examination, all fetuses are x-rayed in the AP and lateral planes. This is particularly important in cases of
skeletal dysplasia. As a routine, photographs are taken prior to starting the examination. The general approach to the fetus
should include a careful external examination, paying particular attention to facial features, hands and feet which often show
external abnormalities linked to many chromosomal and inherited disorders. Internal examination concentrates on the in situ
examination of the viscera which is also essential. Documenting any abnormally positioned or deformed organs is done by
photography. The heart is especially important to examine. Since the fetuses are usually quite small, the heart is often
examined using a dissecting scope.
Specific important ancillary tests in these examinations include cultures for organisms, tissue for cytogenetics and electron
microscopy. In cases of spontaneous abortion when the fetus has recently died, gastric contents and lung tissue are sent for
culture. These are often positive in cases of ascending infection and show less contamination than placental swabs. If
Streptococcal infection is truly suspected, a swab taken from the subamniotic plate of the placenta can be helpful. If the fetus is
extensively macerated from prolonged retention time in utero after death, bacterial cultures are not usually helpful. However, if
there is an indication for viral studies, the placenta may be a source of tissue that is still viable and useful for culturing. Liver
from the fetus is usually sent if viral causes are suspected such as in hydrops (parvovirus B19). In all cases where
developmental anomalies are noted, tissue for fibroblast culture for cytogenetics (karyotype) is essential for a complete
examination.
The approach to the late stillbirth (third trimester) is similar, however, other issues need to be considered and may not be
related to prenatal diagnoses. Approximately 50% of the deaths cannot be explained adequately. The concept of the
maternal/fetal placental "unit" is particularly important in these cases. The placenta is essential in preterm life. The placenta
needs to be examined not only grossly but microscopically as well. In addition to determining a cause of death, the pathologist
attempts to obtain information that may be useful in counseling the patient for future pregnancies. The approach to these cases
requires a clinical review of the maternal age, obstetrical history (past history of stillbirths or pathological details if examined),
last menstrual period, EDC, blood group, serology, ultrasound results (dysmorphism, growth retardation, umbilical vessel flow
studies, amniotic fluid volume, fetal monitoring records, severe variable decelerations, biophysical profile, non-reactive nonstress test, delivery (spontaneous vs. intervention), amniocentesis, cordocentesis, CVS result, triple marker screening results
etc.).
External examination is essential. Documenting the extent of maceration is important to allow estimation of time of death to
delivery interval. Measurements are essential to document growth, they include: weights, crown-rump length, crown-heel length,
head circumference, chest circumference, abdominal girth, foot length. It is essential to compare to standards to identified
growth restriction. As with congenital anomaly cases, systematic external and internal examinations for anomalies is standard.
Electron microscopy, cytogenetic analysis, molecular studies, biochemical studies, viral/bacterial study are sent as indicated by
the examination and history.
Examination of the placenta is imperative when examining either the stillborn or in the case of a perinatal death. An autopsy is
incomplete without the placenta.
Terminology:
Previable Fetal Death: Delivery of dead fetus between 11 and 19 weeks gestational age
Stillbirth: Delivery of infant with no signs of life between 20 weeks gestation and term (Stillbirths/1000Total Births). These cases
need to have a death certificate for government statistics.
Intrauterine Fetal Death: Delivery of an infant with no sign of life between 28 weeks and term.
Perinatal Death: Stillbirths (fetal death with weight more than 500 grams (National) or 1,000 grams (International) at birth plus
first week deaths (early neonatal deaths).
Prematurity (Pre-term): Delivery occurring before 37 weeks gestation.
Abortion: Expulsion of the fetus prior to the stage of viability and lacks evidence of life.
Gestational Age: Age calculated from the first day of the last menstrual period.
Fertilization or Conceptual Age (Developmental Age): Is the age from the day of conception (estimated to be 14 days following
the onset of the last normal menstrual period).
Term Infant: Born between 37 and 42 weeks.
Embryonic age: Less than 10 weeks menstrual (gestational) age or less than 8 weeks developmental age (fertilization age).
Trimesters: First trimester: last menstrual period to 14 weeks gestational age; Second Trimester: from 14 to 26 weeks
gestational age; Third Trimester: between 26 and 40 weeks gestational age.
REFERENCES
1. Kaiser,L, et al. Correlation of prenatal clinical findings with those observed in fetal autopsies: pathological approach.
Prenat. Daign 2000 Dec; 20(12):970-5.
2. Bove,KE, et al. Practice guidelines for autopsy pathology. The perinatal and pediatric autopsy. Arch Pathol Lab Med,
1997; 121:368-376.
3. Pitkin, RM. Fetal death: diagnosis and management. Am J. Obstet. Gynecol. 1980; 161:254.
Dr. J. Bourgeois
Hamilton Regional Laboratory Medicine Program
Anatomic Pathology Section
McMaster University Medical Centre Site