The change of curve and clinical effect of hepatic and portal vein flow forms in the pregnancy progress

Objective: Pregnancy involves profound physiological adaptations, including significant hemodynamic changes. This study aimed to evaluate alterations in hepatic and portal vein flow patterns throughout gestation using Doppler ultrasonography and to define reference values that may help avoid misinterpretation and unnecessary interventions. Method: A total of 215 healthy pregnant women between 10 and 40 weeks of gestation, all with singleton pregnancies and no underlying conditions, were included. A control group of 22 healthy, non-pregnant women of reproductive age was also assessed. Doppler measurements were obtained from the middle hepatic vein and central portal vein using subcostal or intercostal approaches. Parameters recorded included hepatic vein waveform morphology, portal vein diameter, velocity, and calculated flow rate. Results: All control subjects exhibited triphasic hepatic vein flow. As gestation progressed, hepatic vein flow patterns in pregnant women shifted significantly from triphasic to biphasic and monophasic waveforms (p < 0.001). In late pregnancy, monophasic flow was observed in 72.6% of subjects, compared to 5.6% in early pregnancy. Portal vein flow velocity was significantly higher in all trimesters compared to the control group (p < 0.001), peaking between 15 and 25 weeks, then declining. Portal vein diameter increased steadily across gestation, showing a strong positive correlation with gestational age (R² = 0.346, p < 0.001). A statistically significant negative correlation was observed between portal vein velocity and gestational week (R² = 0.416, p < 0.001). Portal vein flow rate also rose throughout pregnancy but did not differ significantly between trimesters (p > 0.05). Conclusion: Hepatic and portal vein Doppler flow patterns undergo significant, progressive alterations during pregnancy. Recognizing these physiological changes—and referencing established normal values—is essential to avoid misdiagnosis of pathological conditions and to guide accurate clinical assessment.