Introduction

Extracorporeal shockwave lithotripsy (ESWL) is a very common and safe procedure for kidney stones. Renal hematoma is an infrequent and feared complication. The probability of developing a hematoma increases significantly with age, coagulation disorders, hypertension and obesity.¹

We report a case of a 45-year-old man who developed a scrotal hematoma 4 days following ESWL. This finding led us to investigate the kidney, detecting a hematoma that resolved spontaneously after 8 weeks of observation.

Clinical Case

This is a 45-year-old patient with no medical history, with a 16 mm and 1,500 HU stone located in the left renal pelvis. He received 3,000 shocks with growing intensity using a Sonolith-I-move lithotripter. He was medicated with 50 mg of tramadol before the procedure. No symptoms were present, and he was discharged 2 hours after the procedure.

Figure 1. Scrotal hematoma.

Figure 2. Renal hematoma.

Four days later, he was consulted for hematoma at the left inguinoscrotal zone (fig. 1); no scrotal or lumbar pain was noted. The blood test showed hemoglobin of 14.3 g/L and normal renal function. The renal ultrasonography showed 2 residual stones at the renal pelvis of 4 and 3 mm. No renal or scrotal hematoma was visualized. Two days later, abdominal computerized tomography (CT) showed a 32 mm renal hematoma and two 4 mm stones at renal pelvis (fig. 2). With these results, an ambulatory management of the patient was decided. He continued progressing asymptomatically, with no change in lab results. The hematoma reabsorbed completely after 2 months.

Discussion

Renal hematomas are rare after ESWL. The reported incidence ranges between 0.32% and 13% depending on the method used to assess this complication.^1,2 Management is usually conservative, with complete spontaneous reabsorption after some weeks. On the other hand, scrotal hematoma after ESWL is very rare. To our knowledge, only 4 cases were reported.^3–6 Fortunately, all cases progressed without requiring treatment, with a complete remission after several weeks. In our case, the patient had the same evolution, without requiring hospitalization or any treatment.

The most probable explanation for this finding is that blood tracked down from the retroperitoneum, as reported in other case.⁶ Nevertheless, in our case there was no retroperitoneal blood in the CT–only the perirenal hematoma. It is possible that a small quantity of blood drained the way down to the scrotum without leaving signs in the CT.

Although ESWL technology has evolved significantly over the past 2 decades, there is still debate regarding the physical basis and clinical benefits of technical modifications such as the tight focal width and high peak pressure fields often used in many contemporary lithotripters. The cigar-shaped focal region of a lithotripter exceeds the average stone size along the propagation direction of the incident shock waves. Therefore, a significant volume of the kidney including the perirenal tissue will be exposed to high-energy and high-pressure shock waves. Moreover, the patient’s motion (due to respiration or pain-induced movements) will exacerbate the risk of tissue injury because a significant portion of the shock waves may completely miss the target stone and hit the tissue solely.⁷

In conclusion, we present a rare clinical presentation of an infrequent complication of ESWL. We suggest that the appearance of a scrotal hematoma after a shock wave procedure should make it necessary to investigate the possible presence of a renal hematoma.