Reference values of the pulsatility index for pregnant women between 11 and 13 weeks of gestation.

The pulsatility index velocity (DV PIV) has become a popular ultrasonographic measurement during the first trimester of pregnancy. The value of the DV PIV has been the topic of ongoing discussion in the literature, and its reference value in the normal population has not yet been established. Therefore, we aimed to determine a reference value for the DV PIV. We retrospectively evaluated our records of first-trimester ultrasonography performed between 2016 and 2017. Our inclusion criteria were as follows: singleton pregnancy; crown-rump length (CRL) between 45 and 84 mm; absence of structural abnormalities on the ultrasound examination; and absence of chromosomal abnormalities. Records of 820 patients were evaluated. According to the inclusion criteria, records of 458 patients were included in this study. All ultrasound examinations were performed by a single operator with the Voluson E8 (5- to 8-MHz 3 D transducer; General Electric Healthcare, Little Chalfont, UK) via the transabdominal route. Gestational weeks were designated according to CRL measurements at the beginning of the examination. Nuchal translucency (NT), nasal bone visualization (NB), tricuspid valve regurgitation (TR), "a"-wave pattern, DV PIV, S-wave (peak systolic velocity), D-wave (peak diastolic velocity), a-wave (atrial contraction in late diastole), and time-averaged maximum velocity (TAMXV) measurements were performed. To evaluate the DV Doppler images, a mid-sagittal view of the fetal profile was obtained. Color Doppler and pulse Doppler gate were used in the distal portion of the umbilical sinus, and at least three typical DV waveforms were detected. The SPSS 21.0 statistical program (IBM, Armonk, NY) was used to analyze variables. The mean age, body mass index, CRL, gestational age, and NT values were 30.3 years (range, 18-45), 23.9 kg/m (range, 15.5-46.6), 59.5 mm (range, 45-79), 12.3 weeks (range, 11.2-13.6), and 1.58 mm (range, 0.73-2.62), respectively. The median gravidity and parity were 2 (1-8) and 0 (0-4), respectively. The "a"-wave pattern was identified in all cases, but TR was not detected in any of the cases. Measurements of DV PIV with a Gaussian distribution were suitable according to the Shapiro-Wilk test ( = .252). The mean DV PIV was 0.98, and the fifth and 95th percentiles were 0.73 and 1.22 (±2 SD), respectively. A statistical analysis of our cohort revealed that DV PIV values less than 0.73 and more than 1.22 were beyond the normal range. The mean S-wave, D-wave, a-wave, and TAMXV values were 31.18, 25.64, 8.68, and 22.72 cm/s, respectively. The value of DV PIV measurements is debated in the literature. Using our cohort, we defined the means and ranges of DV PIV. Determining the normal ranges of DV PIV could be helpful to anticipate congenital or chromosomal abnormalities. Further studies are needed to demonstrate the clinical importance of DV PIV, especially for patients with abnormal DV PIV measurements.