Ultraschall Med 2013; 34 - WS_SL22_05
DOI: 10.1055/s-0033-1354941

Biparietal diameter in fetuses with spina bifida in first, second and third trimester

K Karl 1, KS Heling 2, R Chaoui 2
  • 1Ludwig-Maximilians-University, Department of Obstetrics and Gynecology, Munich, Germany
  • 2Center for Prenatal Diagnosis and Human Genetics, Berlin, Germany

Purpose: The measurement of the Biparietal Diameter (BPD) is an intrinsic part of antenatal ultrasound from 10 weeks on until delivery. The aim of the study was to investigate changes in BPD size in fetuses with open spina bifida through all three trimesters.

Material and methods: Retrospective data analysis of 84 fetuses with open spina bifida between 11 weeks and 37 weeks of gestation was achieved and the BPD was compared with reference ranges. Z- Score was calculated to eliminate gestational age dependency and facilitate comparision of data.

Results: The BPD values in fetuses at 11 – 15 weeks (n = 26) and 15 – 20 weeks (n = 16) were below the 10th centile. In mid trimester (20 – 25 weeks, n = 20) the BPD was significantly smaller (below the 5th centile) and increasing in size again in fetuses > 25 weeks of gestation (n = 22), often due to the associated ventriculomegaly.

Conclusion: In fetuses with spina bifida, the BPD is small in the first and second trimesters of gestation. Especially before 15 weeks where additional signs as lemon and banana signs are lacking, a small BPD can be an easy screening tool to improve the early detection rate of this fetal anomaly.