BACKGROUND: An elevated peak systolic velocity in the middle cerebral artery, assessed by Doppler ultrasonography, is commonly associated with fetal anemia. Other fetal abnormalities associated with a high middle cerebral artery velocity have rarely been reported. CASE: A fetus with increasing ascites was found to have an elevated middle cerebral artery peak systolic velocity. Following paracentesis, the peak systolic velocity normalized. Peak systolic velocity continued to correlate with the level of ascites, falling to normal ranges when large-volume amniocentesis and paracentesis were performed. At birth, the infant was found to have a normal hematocrit. CONCLUSION: An elevated middle cerebral artery peak systolic velocity may result from massive fetal ascites without anemia. We hypothesize that the massive ascites led to increased afterload of the heart, with relatively preserved preload, leading to an increased systolic blood pressure and an elevated middle cerebral artery peak systolic velocity.
