A Case of Transient Unilateral Right Leg Edema Caused by a Markedly Distended Bladder

External compression of a vein is a relatively rare but important cause of unilateral leg edema. Here, we present a case of unilateral right leg edema caused by external compression of the right iliac vein due to a markedly distended urinary bladder, secondary to a neurogenic bladder. The patient initially had bilateral leg edema associated with chronic heart failure. However, the right-leg edema worsened and remained painful for several days. Lower extremity ultrasonography and computed tomography revealed an enlarged bladder. Based on these findings, venous angiography and intravascular ultrasound were performed. External compression is a significant cause of leg edema. It is important to consider the possibility of intra-abdominal/pelvic processes that may lead to external compression of the venous system in patients with unilateral and even bilateral lower extremity swelling.