Local complications of arterial puncture include hematoma, pseudoaneurysm and formation of arteriovenous fistula (AVF). The latter could cause ischemia of the particular extremity or can be hemodynamically significant especially in patients suffering from congestive heart failure. We report a case of femoro-femoral AVF after thin needle arterial puncture for blood drawing. The development of this iatrogenic AVF led to pulmonary edema. The patient stabilized completely after surgical closure of the AVF. The AVF was diagnosed by duplex Doppler ultrasonography and this method was also used for estimation of blood flow through the AVF. We discuss the role of ultrasound AVF diagnostics and the method of flow calculation.