The horseshoe kidney (HSK) is the predominant congenital anomaly of the upper urinary system, occurring in around 1 in 500 individuals in the general population. It encompasses three anatomical abnormalities: ectopia, malrotation, and vascular alterations. HSK is distinguished by the merging of the kidney at either the upper or more frequently the lower pole, resulting in an isthmus that connects the two sides and forms a recognizable U-shaped arrangement [1].
In adults, HSK is usually asymptomatic and is mostly detected during radiological diagnostics such as ultrasound (US), intravenous pyelography (IVP), and computed tomography. The ectopic positioning results in compression of the HSK against the lumbar vertebrae, enhancing the possibility of severe injuries following the case of abdominal trauma, as a consequence of ribs protection lackage [2]. Renal trauma is present in nearly 1–5% of all injuries, with the kidney being the most frequently affected urinary system organ. Blunt kidney trauma has a 9 times higher incidence than penetrating trauma [3]. Blunt force injury constitutes 19% among all kidney injuries in individuals with preexisting renal disease [4].
According to the European Association of Urology, the most commonly used classification system for renal trauma is that of the American Association for the Surgery of Trauma (Table 1).
Table 1
Renal injury grading scale
| Grade | Type of injury | Description of injury |
| 1 | Haematoma and/or Countusion | Subcapsular non-expanding haematoma or parenchymal contusion without parenchymal laceration. |
| 2 | Haematoma | Non-expanding perirenal haematoma confined to Gerota fascia. |
| Laceration | Renal parenchymal laceration < 1 cm depth without urinary extravasation |
| 3 | Laceration | Renal parenchymal laceration > 1 cm depth without collecting system rupture or urinary extravasation. Any injury in the presence of a kidney vascular injury or active bleeding contained within Gerota fascia. |
| 4 | Laceration | Parenchymal laceration extending into urinary collecting system with urinary extravasation. Renal pelvis laceration and/or complete ureteropelvic disruption. |
| Vascular | Segmental renal vein or artery injury. Active bleeding beyond Gerota fascia into the retroperitoneum or peritoneum. Segmental or complete kidney infarction(s) due to vessel thrombosis without active bleeding |
| 5 | Laceration | Shattered kidney with loss of identifiable parenchymal renal anatomy. |
| Vascular | Main renal artery or vein laceration or avulsion of renal hilum. Devascularised kidney with active bleeding. |
It has been validated and can accurately predict the morbidity and the necessity for intervention, and it is still considered the most valuable. Nevertheless, a substantial number of Grade 1–4 injuries are treated conservatively nowadays. The debate has focused on revising the classification of high-grade injuries, specifically identifying the injuries that are most probable to benefit from early angiographic embolization, repair, or nephrectomy [5]. In our case, according to this classification system, this injury was considered grade IV.
Maintenance of haemodynamic stability is the main factor considered in the treatment of all renal injuries. Non-operative management has emerged as the preferred approach for the majority of cases. Grade 4 injuries are primarily treated conservatively, although there is a higher probability of additional intervention needed [5].
Legg (1998) first reported a successful super-selective embolization of a ruptured horseshoe kidney [6]. Until today, there have been reported nine cases of blunt force injury to a horseshoe kidney, with five of them treated nonoperatively [4, 7]. The most common location of the injury among the eight reported patients was the lower pole (78%). This majority may be because the lower pole lies and fuses in the midline of the body, which is apt to be crushed to the lumbar spine during blunt force assault and is vulnerable to a shearing force [4, 7]. Present case adds up as the location of injury was the lower pole of horseshoe kidney.