Malrotation of an iliac ectopic kidney with pyelo-ureteral duplication: An incidental three-in-one congenital anomaly

Abstract

Renal ectopia is a rare congenital anomaly that mostly occurs in the pelvic area. An ectopic kidney is usually associated with other anomalies such as a malrotation. We report the case of a 15-year-old male who consulted after a blunt abdominal trauma. A left iliac renal ectopia was incidentally discovered. This ectopic kidney was associated with a malrotation, and a pyelo-ureteral duplication. Iliac renal ectopia should be dissociated from other abdominal renal ectopias, and its association with other renal malformations should be further investigated.

Introduction

Renal ectopia is a rare birth anomaly with an incidence of 1 in 3000 [1]. Renal ectopia can occur in different parts of the body, such as in the abdomen, in the pelvis, in the iliac, or in the thorax [2]. Renal ectopia can be associated with other renal or extrarenal abnormalities [3].

We report the case of a 15-year-old male who consulted for a blunt abdominal trauma. An iliac renal ectopia on the left side was incidentally discovered. This ectopic kidney was associated with malrotation, and a pyelo-ureteral duplication.

Case report

This is a 15-year-old male with no particular medical history who was seen after a road traffic accident. The patient presented with abdominal pain in the right hypochondrium. He had no fever or vomiting. His blood pressure was 120/70. The physical examination revealed no tenderness or palpable mass.

No injuries to the liver, spleen, or other organs were detected by the abdominal CT scan with contrast that was performed. Moreover, the CT scan did not detect any contrast extravasation, pneumoperitonrum, or peritoneal effusion.

However, the CT scan revealed a left ectopic kidney located in front of the iliac vessels. This kidney was smaller than the contralateral one with irregular shape and a cleft in the middle (Fig. 1B)

Fig. 1.

Abdominal CT scan with contrast in coronal view. (A) Right kidney in normal position and emptiness of the left renal compartment. (B) Left kidney in ectopic position in front of the left iliac vessels. The left kidney is deformed with a cleft (red arrow) at its middle part.

The CT-scan also revealed a malrotation with a forward-facing renal hilum (Fig. 2). The excretory phase of the CT scan showed 2 nondilated ureters (excretory cavities) (Fig. 3A). The upper ureter fused with the lower ureter at the pyelon level, forming a common distal ureteral orifice joining the bladder trigone (Fig. 3B). There was 1 single renal artery that originated from the aorta, and that was located 1 cm away from the iliac bifurcation. The left renal vein was located behind the right common iliac artery, and it drained into the inferior vena cava (Fig. 4). There was no traumatic injury to the kidneys. The kidney on the right side was without anomalies and in a normal position (Fig. 1A).

Fig. 2.

Abdominal CT scan in 3D reconstruction, anterior view, showing malrotation of an ectopic kidney with an anterior hilum (white arrow).

Fig. 3.

Abdominal CT scan with injection in the late phase, focus on the left kidney. (A) show the 2 pyelons (red arrows). (B) shows the 2 ureters forming a single terminal ureter.

Fig. 4.

Abdominal CT scan with contrast, focus on the left kidney and iliac vessels, showing the left renal vein (white arrow) passing behind the right common iliac artery (red arrow).

Conservative management was performed with some antalgic. The follow-up was uneventful.

Discussion

Renal ectopia is a birth anomaly that occurs during embryogenesis when the kidneys fail to ascend, and is more frequently localized in the pelvic area [4]. In addition, iliac ectopias are often diagnosed either as pelvic or abdominal ectopias although they are between those 2 areas located in the front of the iliac vessels [5]. The iliac ectopia should be considered as a separate entity by radiologists during imaging examinations. Renal ectopias are most often asymptomatic, and are discovered incidentally [6]. In our patient, the incidental finding occurred after an abdominal trauma. Even if there was no traumatic injury to the kidney, it is important to note that ectopic kidneys are more exposed to trauma because they are not protected by the ribs of the posterior thoracic wall [7]. Patients with ectopic kidneys are also prone to complications such as vesicoureteral reflux, urinary tract infections, kidney stones, all of which could be an opportunity to discover an ectopia [1]. Renal ectopias are most often located on the left side, which was the case for our patient [8].

Pyelo-ureteral duplications are congenital anomalies with an incidence of approximately 0.7%, and are most often discovered incidentally [9,10]. Pyelo-ureteral duplication can be incomplete or complete [11]. In the incomplete form, also called bifid ureter, the 2 ureters join and form a single distal ureter that drain into the bladder. This can cause a dilation of the 2 pyelons if there is an obstruction beyond the fusion of the 2 ureters. Our patient presented with an incomplete type.

In the complete type, both ureters are independent and are connected separately to the bladder, and a ureteral obstruction only causes dilation of the homologous pyelon.

Renal ectopia is often associated with various renal vascular abnormalities [5]. In our patient, there was a single artery that originated in the aorta, 1 cm above the iliac bifurcation. This low origin of the renal artery can help in the differential diagnosis between congenital renal ectopia and renal ptosis, where the renal artery has a normal origin [12].

In our patient, the renal vein was located behind the right common iliac artery. This positioning is related to the iliac posturing of the kidney. This disposition is seemingly not as compressive as would be the case of a retro-aortic renal vein which can cause compression of the renal vein located between the aorta and the spine [13]. Renal artery duplicity is also reported as another vascular abnormality that may be associated with renal ectopia [14].

Double excretory cavities are often associated with abnormalities of the size and the form of the renal parenchyma [11]. In our patient, the ectopic kidney was smaller than the contralateral one, and it presented with a cleft in the middle. Renal malrotation is the anomaly that is most often associated with renal ectopia because they both occurs at the same time during embryogenesis [12,15].

In our patient, because of the absence of urinary symptoms, a simple urological consultation was recommended because of the potential risk of infection or a lithiasis event. A surgical treatment is not indicated, unless complications arise [8].

Author's contribution

IN wrote the manuscript with input of AN, ML, and KND. IN, NBM, and CTD edit the illustrations. NSN is following up the patient. SB and ADD supervised the work. All the authors have read and approved the final version of the manuscript.

Patient consent

The patient's father has signed an informed consent form