Faculty Bibliography

OBJECTIVE: The purpose of this study was to validate prospectively a previous retrospectively established nomogram for the prediction of gestational age using transcerebellar diameter, especially in the third trimester. STUDY DESIGN: In a previous study, we retrospectively constructed a cross-sectional nomogram using transcerebellar diameter measurements in 24,026 well-dated singleton fetuses. In the present study, this nomogram was validated prospectively on the basis of patients who were seen between August 2002 and May 2003 and who were carrying non-anomalous and non-malformed singleton gestations between 14 and 42 weeks (n = 2597 gestations). The actual gestational age was then subtracted from the predicted gestational age, and the concordance between actual and predicted gestational ages was assessed based on the Pearson correlation (r). RESULTS: Concordance between the actual and predicted gestational age was high (r = 0.92; P < .0001). This agreement was superior in the second trimester (r = 0.93; P < .0001) than in the third trimester (r = 0.81; P < .001). Between 17 and 21 weeks, and between 22 and 28 weeks of gestation, the predicted gestational age ranged between 0 and 4 days, and between 0 and 2 days, respectively, of actual gestational age. Between 29 and 36 weeks of gestation, predicted gestational age was within 5 days of actual gestational age; at 37 weeks of gestation, the predicted gestational age was discrepant by 9 days. CONCLUSION: This prospective study demonstrates that transcerebellar diameter measurement is an accurate predictor of gestational age, even in the third trimester of pregnancy.

OBJECTIVE: This study was undertaken to construct an institution-specific transverse cerebellar (transcerebellar) diameter nomogram with special emphasis in the third trimester and to compare its ability to predict gestational age with previously published nomograms. STUDY DESIGN: A cross-sectional nomogram was constructed using transcerebellar diameter measurements in 24,026 well-dated singleton fetuses by using linear regression models. Third-trimester measurements from 2,010 fetuses were included. The performance of previously established transcerebellar diameter nomograms for predicting gestational age was assessed in our population to determine comparability between nomograms. RESULTS: Interobserver and intraobserver variabilities in the second and third trimesters were 3.1% to 3.7% and 3.4% to 3.8%, respectively. Between 14 and 27 weeks' gestation, there were no clinically important differences between our nomogram and those previously published in terms of the predicted gestational age. However, predicted gestational age in the third trimester was considerably different by using our nomogram by 1 to 2 weeks from 28 to 30 weeks and by 4 to 6 weeks after 32 weeks. CONCLUSION: Transcerebellar measurements had a similar relationship with gestational age across previously published nomograms before 28 weeks. However, clinically significant differences in predicting gestational age appear later, especially after 32 weeks. These findings suggest that this new nomogram may be particularly useful for accurate dating of pregnancies in the third trimester.

BACKGROUND: Thrombotic thrombocytopenic purpura is a rare but serious medical complication, but is relatively common among patients with human immunodeficiency virus (HIV) infection. It is characterized by the pentad of thrombocytopenia, microangiopathic hemolytic anemia, neurological symptoms, fever, and renal abnormalities. However, the pentad is often incomplete, especially in HIV-positive patients. CASE: An HIV-positive patient complained of easy bruising, hematuria, fever, myalgias, and headache during the second trimester of pregnancy. Laboratory testing revealed hemolytic anemia and severe thrombocytopenia. Bone marrow biopsy was consistent with thrombocytopenic purpura. The patient recovered after plasmapheresis. At 36 weeks' gestation, she was delivered for preeclampsia and fetal growth restriction. CONCLUSION: Absence of the classic pentad seen in thrombocytopenic purpura among pregnant HIV-positive patients may make the diagnosis of thrombocytopenic purpura challenging. Frequent monitoring of patients with thrombotic thrombocytopenic purpura for signs and symptoms of preeclampsia and fetal growth assessment is suggested.