How often does the left gonadal vein join directly to the left renal vein?

The left gonadal vein typically drains directly into the left renal vein almost all the time, which is reflected in the high percentage of 99%. This anatomical arrangement occurs because the left gonadal vein, which collects blood from the left ovary or testis, often takes a shorter and more direct route by emptying into the left renal vein rather than making a longer journey to the inferior vena cava, as is common with the right gonadal vein. This is an important anatomical distinction in understanding venous drainage in the human body, especially in the context of ultrasound and diagnostic imaging, and it underscores the importance of recognizing variations in venous anatomy during sonographic examinations related to phlebology.