Horseshoe kidney with a retrocaval ureter: A case report from teaching hospital in Ethiopia

Abstract

Introduction

The combination of a horseshoe kidney with a retrocaval ureter in one patient is extremely rare.

Presentation of case

A 12-year-old adolescent presented with the compliant of absent testis in the right scrotum since birth with incidental radiologic finding of horseshoe kidney with retrocaval ureter.

Clinical findings and investigations

Physical examination was unremarkable except for a left non-palpable testis. A complete blood count, renal function test, urine analysis, ultrasound of the abdomen and pelvis, and computed tomography urography were performed.

Intervention and outcome

Right ureteral uncrossing with ureterourererostomy and right orchidectomy was done. The patient is doing well during postoperative follow-up.

Relevance and impact

Modern imaging techniques can accurately define the anatomical details, facilitating appropriate preoperative planning.

Highlights

• •The combination of a horseshoe kidney with a retrocaval ureter in one patient is extremely rare.
• •Patients with retrocaval ureter commonly present during the third or fourth decade of life
• •Treatment is indicated if there is significant obstruction, infection, urolithiasis, or increasing hydronephrosis
• •Modern imaging enables accurate preoperative planning.

1. Introduction

1.1. Background and rationale

The combination of a horseshoe kidney and a retrocaval ureter is an extremely rare condition. Horseshoe kidney results from the fusion of metanephric buds between weeks 4 and 8 of embryogenesis, which blocks their cephalic migration and normal rotation [1]. The retrocaval ureter is a developmental anomaly where the ureter passes behind an abnormal inferior vena cava. Symptoms are typically due to ureteric obstruction, either extrinsic from the abnormal inferior vena cava or intrinsic from ureteric hypoplasia [2].

This case report aims to describe the imaging findings and management of this rare congenital anomaly.

1.2. Guidelines: SCARE 2023 paper

This case report has been reported in line with the SCARE Criteria [3].

1.3. Patient information: demographics and presentation

A 12 year old adolescent presented with the compliant of absent testis in the right scrotum since birth.

1.4. Past medical and surgical history

He had no known history of TB, Hypertension; or Diabetes Mellitus. He had no surgical interventions done in the past.

1.5. Drug and allergy history

No history of long-term drug intake and no known allergies until date.

1.6. Family history

He had no history of similar illness in the family.

1.7. Clinical findings

On Physical examination, the right scrotum was empty and the testis was not palpable. The rest of the examination was unremarkable.

1.8. Diagnostic assessment and interpretation

The laboratory investigations, including complete blood count, creatinine, urinalysis, and renal function tests, were all within normal limits. Ultrasound imaging of the abdomen and pelvis revealed a right intra-abdominal atrophic testis, a horseshoe kidney, a right retrocaval ureter, and right-sided hydroureteronephrosis with tapering of the proximal ureter. The right kidney's cortical thickness was notably thinner than the contralateral side.

The CT urography confirmed a horseshoe kidney with right-sided hydroureteronephrosis secondary to a retrocaval ureter (Fig. 1). The 3D CT scan revealed that only a portion of the right proximal ureter was opacified with contrast, while the entire length of the left ureter appeared normal and fully contrast-filled (Fig. 2). The right kidney's cortical thickness was notably thinner, measuring 7.5 mm at its thinnest point, compared to the normal kidney's cortical thickness of 1.37 mm. Unfortunately, a renal scan could not be performed due to unavailability.

Fig. 1.

CT urography showing horseshoe kidney with retrocaval ureter. There is right hydroureteronephrosis (A & B) with tapering at the proximal ureter (E). The right mid and distal parts of the ureter are not seen (F).

Fig. 2.

3D uroscan image reconstruction showing horseshoe kidney with right proximal ureteric obstruction.

1.9. Intervention

After a thorough history and relevant investigations, a diagnosis of horseshoe kidney with right hydroureteronephrosis with retrocaval ureter was made. Given the lack of functional renal studies, and the imaging findings of proximal ureteric obstruction leading to moderate hydroureteronephrosis and cortical thinning, we decided to proceed with surgical intervention.

The patient was planned for ureteroureterostomy and right orchidopexy or orchidectomy. The abdomen was entered through a midline laparotomy incision. The intraoperative findings were atrophic right testis, non-rotation of the intestines, horseshoe kidney, right hydronephrosis and dilated proximal ureter with retrocaval ureter. Division of the retrocaval segment, relocation of the ureter anterior to the inferior vena cava and ureteroureteral spatulated end-to-end anastomosis was performed (Fig. 3). Right orchidectomy was also done.

Fig. 3.

Intraoperative images showing: A & B, dilated pelvis (P) and proximal ureter (U) with the proximal ureter curving medially and then passing behind the IVC. C, uncrossed ureter brought anterior to the IVC. D, spatulated ends anastomosed with double j stent in place. E, the ureter passing anterior to isthmus.

The surgical intervention was uncomplicated, with minimal blood loss. The patient's drains were removed on the second postoperative day. The postoperative period was unremarkable, and the patient achieved a successful recovery.

The indwelling ureteral catheter was removed six weeks following the surgical intervention.

1.10. Outcome

The patient has been regularly followed up in the outpatient clinic and has remained asymptomatic. His renal function tests are normal.

2. Discussion

Horseshoe kidney, the most common congenital renal fusion disorder, exhibits a male predominance of approximately 2:1. In around 5 % of cases, the fusion occurs at the lower poles, resulting in an isthmus typically situated anterior to the major vascular structures at the level of the third to fifth lumbar vertebrae [4]. Horseshoe kidney arises from the abnormal fusion of the metanephric blastema during weeks 4 to 8 of embryonic development, which impedes their cephalic migration and typical rotation. Consequently, the renal pelves and ureters are characteristically positioned in an anterior orientation [1]. Up to two-thirds of patients with horseshoe kidney have associated genitourinary anomalies, such as duplications, cryptorchidism, and urethral abnormalities. Ureteropelvic junction obstruction is also frequently observed in this patient population [5]. Our patient had a right undescended testis associated with the horseshoe kidney and retrocaval ureter.

Retrocaval ureter is a rare congenital abnormality where the ureter passes behind the inferior vena cava. This condition is caused by the persistence of the posterior cardinal vein during embryonic development [6]. Retrocaval ureters have been categorized based on radiographic characteristics or the vertebral level at which the ureter passes posterior to the inferior vena cava. These classifications typically distinguish retrocaval ureters into two groups. Type I retrocaval ureter exhibits significant medial deviation of the ureter with an “S” or reversed “J” configuration, which often results in severe hydronephrosis. Conversely, Type II retrocaval ureter has a more subtle medial deviation with a sickle-shaped curve and is associated with milder hydronephrosis [7]. Our patient had type 2 retrocaval ureter. Patients commonly present during the third or fourth decade of life due to the gradual onset of hydronephrosis. Diagnosis in the pediatric population is uncommon [8].

The combination of a horseshoe kidney with a retrocaval ureter in one patient is extremely rare. Cukier et al. first reported the presence of retrocaval ureter along with horseshoe kidney. Since then, few additional cases have been reported in the literature [5]. While a horseshoe kidney is readily identifiable when present, the coexisting right-sided retrocaval ureter can be difficult to diagnose. In fact, only 2 out of 10 reported cases had the retrocaval ureter detected through preoperative CT imaging, with the remainder discovering it during exploratory surgery for the horseshoe kidney [4]. Notably, in our patient's case, both anomalies were identified prior to the operation.

Treatment of retrocaval ureter is indicated only if there is significant obstruction, infection, urolithiasis, or increasing hydronephrosis [2]. Asymptomatic patients require long-term follow-up with periodic ultrasound and diuretic renogram to ensure early diagnosis and prevent further renal impairment. The technique usually used is ureteral uncrossing with restoration of continuity of the excretory pathway by direct plasty and end-to-end uretero-ureteral anastomosis in type 2 and resection-anastomosis of the retrocaval segment in type 1 [6]. Good surgical outcomes are noted with minimal dissection of the ureter and minimal handling [9].

In our case, since there was significant right hydroureteronephrosis with cortical atrophy, we opted for simultaneous ureteroureteral anastomosis along with abdominal exploration for the right intraabdominal testis.

3. Conclusion

Horseshoe kidney occurring alongside retrocaval ureter is an uncommon condition. However, modern imaging technologies can now clearly delineate the anatomical details, enabling proper preoperative planning.

Author contribution

Yirgalem Teklebirhan Gebreziher - Writing – review & editing. Writing-original draft, visualization, conceptualization

Yoseph Equar Assefa – writing – review & editing, Conceptualization

Zeamanuel Berihu Teshome – Investigation, conceptualization.

Consent

Written informed consent was obtained from the patient's mother for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this Journal on request.

Ethical approval

This type of study does not require any ethical approval by our institution. Mekelle university, college of health sciences.

Guarantor

Yirgalem Teklebirhan Gebreziher.

Funding

This case report hasn't been funded by any person or any institutions.

Conflict of interest statement

There are no any conflicts of interest with this article.