Determination of Gestational Age and Sex by Histology of Fetal Gonads
A Baldwin, A Szpaderska, H Brown, C Ersahin. Loyola University Medical Center, Maywood, IL
Background: The histology of fetal lungs and kidneys has long been used to assess fetal gestational age at autopsy. There are five phases of lung development during gestation and four periods of nephrogenesis that can be used to date the gestational age to within weeks. Up until the 6th week of gestation, the fetal gonads are indifferent. Thereafter, the gonads differentiate into ovaries or testes with distinct, temporally-related histologic changes throughout gestation. However, fine week-to-week details of these changes have not been well documented. It is proposed that the histology of fetal gonads from the autopsy will be equally effective or contributory in determining gestational age, as compared to lung and kidney, and will also allow for sex determination.
Design: Prepared slides of lung, kidney and gonadal tissue from fetal autopsies were reviewed, ranging from gestational age of eight to thirty-nine weeks. A total of 150 cases were obtained from years 1995 to 2008 at our institution. Lungs, kidneys and gonadal tissue were examined blindly and then compared to given gestational age (calculated from last menstrual period). Sex of the fetus was determined from the examined gonadal tissue and then compared to cytogenetics studies performed at the time of autopsy.
Results: The analysis of 150 fetal autopsies demonstrated that gonad development has distinct morphological features during gestation that allow examiners to determine a gestational age with 99% agreement with clinical gestational age, determined from last menstrual period. Sex determination by gonadal histology correlated with cytogenetic studies with 100% agreement.
Conclusions: Discrete patterns of gonadal development during gestation can be divided into separate stages and subtle differences can be used to date a pregnancy to within weeks. These findings are a valuable resource for pathologists, to be able to correctly determine the age of the fetus and correlate with clinical pathological findings. It was found that fetal gonads are equally useful for gestational dating, as compared to the lungs and kidneys, and can be used for sex determination as well.
Monday, March 9, 2009 8:00 AM
Platform Session: Section H1, Monday Morning