To diagnose renal obstruction, a resistive index (RI) greater than which value is significant?

A resistive index (RI) greater than 0.70 is significant in diagnosing renal obstruction. The resistive index is a Doppler ultrasound measurement that assesses the resistance to blood flow in the renal arteries. A higher RI typically indicates increased resistance, which can be associated with conditions such as renal obstruction or renal artery stenosis.

Values above 0.70 suggest that there is likely a significant obstruction affecting blood flow to the kidneys. In cases of obstruction, the increased resistance in the renal vascular bed often leads to compromised perfusion, which is reflected in the elevated RI.

Understanding the clinical relevance of the resistive index is crucial for appropriately interpreting ultrasound findings. An RI above this threshold prompts further investigation and potential intervention to address the underlying cause of the obstruction, thereby improving patient outcomes.