title: Doppler waveform indices of the Middle Cerebral Artery of normal fetuses in the first half of pregnancy in the Thai population.
abstract: OBJECTIVE
  To establish the reference ranges of middle cerebral artery (MCA) Doppler indices including pulsatility index (PI), resistance index (RI) and peak systolic velocity (PSV) of the Thai fetuses at gestational age of 11-20 weeks.
  
  
  METHODS
  A descriptive cross-sectional study was conducted at Department of Obstetrics and Gynecology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. Normal singleton pregnancies between 11 and 20 weeks of gestation were recruited into the study for measurements of MCA Doppler indices between November 2005 and August 2006. The trans-abdominal ultrasound, Aloka Model Prosound 5000 (Tokyo) was used. The MCA Doppler data were analyzed for median, 5th, and 95th percentile for each gestational week. The best-fit mathematical model was derived.
  
  
  RESULTS
  A total of 300 measurements, with average of 30 +/- 7.35 per gestational week (mean +/- SD) and range 23-45 per gestational week, were obtained from 149 patients. Regression analysis yielded the best-fitted equation of quadratic function as follows: PI = 8.421 - 0.705(GA) + 0.018(GA(2)) (r (2) = 0.452), RI = 1.54 - 0.073(GA) + 0.002(GA(2)) (r (2) = 0.309), PSV = -63.456 + 9.425(GA) - 0.262(GA(2)) (r (2) = 0.504).
  
  
  CONCLUSIONS
  A nomogram for MCA Doppler indices, including PI, RI and PSV ratio for each gestational age during 11-20 weeks was constructed. This may be a useful aid in the early detection of abnormalities in fetal cerebral blood flow, especially in fetal anemia secondary to hemoglobin Bart's disease.
authors.affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine, Chulalongkorn University, Pathumwan, Bangkok, Thailand. jittima_r@hotmail.com
authors.forename: Jittima
authors.initials: J
authors.lastname: Rujiwetpongstorn
authors.forename: Vorapong
authors.initials: V
authors.lastname: Phupong
mesh_terms: D003430:Cross-Sectional Studies; D005260:Female; D005315:Fetal Diseases / Q000000981:diagnostic imaging; D005311:Fetal Hypoxia / Q000000981:diagnostic imaging; D005333:Fetus / Q000033:anatomy & histology*; D005865:Gestational Age; D006801:Humans; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging* / Q000196:embryology*; D011247:Pregnancy; D012016:Reference Values; D013785:Thailand / Q000453:epidemiology; D016216:Ultrasonography, Prenatal / Q000592:standards* / Q000706:statistics & numerical data; D017085:alpha-Thalassemia / Q000000981:diagnostic imaging