Retrocaval Ureter in a 7-Year-Old Girl Causing Symptomatic Unilateral Hydronephrosis- A Rare Case Report

INTRODUCTION

Retrocaval ureter, also called circumcaval ureter, is a rare developmental anomaly where the proximal ureter passes behind the inferior vena cava (IVC) before following its normal path to the bladder. The exact prevalence of retrocaval ureter remains unknown, partly because it is often asymptomatic. However, it is estimated to occur in 0.13% of the population, roughly 1 in 1,000 births.^[1,2] Although it is a congenital condition, patients are usually young men (M: F = 4:1) in their third or fourth decade of life.^[3] Retrocaval ureter most commonly appears on the right side and may be linked to other congenital anomalies, especially when found on the left side. The associated conditions include urogenital and cardiovascular anomalies, which make up 21%, with duplicated IVC being the most common.^[3]

This anomaly causes a part of the ureter to become trapped between the IVC and the third or fourth lumbar vertebra, with or without ureteric obstruction. When external compression occurs, it can lead to dilation of the proximal ureter and collapse of the distal part. Most patients with retrocaval ureters are asymptomatic and are often diagnosed incidentally during imaging studies or surgery.^[1,4]

The predominant symptom, which may recur intermittently, is right flank pain caused by hydroureteronephrosis that develops progressively over the years.^[1] However, patients might also experience haematuria, urinary tract infections, or nephrolithiasis.^[2,5] The diagnosis of retrocaval ureter is primarily made through contrast-enhanced imaging studies, including intravenous urogram (IVU), retrograde pyelogram, and, more reliably, computerised tomographic (CT) urography.^[1]

An asymptomatic retrocaval ureter can be managed with active surveillance, including follow-up imaging and kidney function tests.^[3] However, symptomatic cases require surgical intervention, which involves ureteral division, excision of any abnormal retrocaval segment, precaval transposition, and reanastomosis. Given the rarity of this anomaly, especially in a young girl presenting at an early age, this case is presented here along with a review of the literature.

CASE REPORT

A 7-year-old girl was referred to the urology clinic with a 6-month history of right flank pain. The pain was intermittent, of moderate intensity, and associated with nausea and one episode of vomiting. She had no haematuria, passage of stones in her urine, recurrent fevers, or lower urinary tract symptoms. She had been treated with various medications for urinary tract infections. There was no known comorbidity or significant prior surgical, medical, or family history. Upon examination, she appeared generally healthy and was afebrile, with no signs of pallor, pedal oedema, or lymphadenopathy. No tenderness was noted, and her kidneys were not ballotable on abdominal exam. Her full blood count, renal function tests, and urinalysis were all within normal ranges. An initial abdominal ultrasound showed right hydronephrosis. A diagnosis of right retrocaval ureter was confirmed by CT urography, which showed moderate right hydronephrosis, proximal ureter dilation, and a “J”-shaped deformity with a tapered end at the level of the L3 vertebral body on coronal view [Figure 1].

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Figure 1: CT urography (a) Reformatted—blue and green arrow identify the proximal and distal segments of the J-shaped ureter, (b) white arrow reveals the same segments as in 1a- blue arrow, (c) white arrow reveals the same segments as in 1a- green arrow.

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The left ureter and kidney showed no abnormalities. She subsequently underwent open surgical correction via an extraperitoneal flank approach. Intraoperative findings included a dilated renal pelvis and ureter, with a J-shape above the compressed segment, and a collapsed ureter running posteromedially to the IVC [Figure 2a]. The ureter was freed along its course, transected near the renal pelvis, the distal collapsed segment spatulated, both ends moved anterior to the IVC, and a pyeloureteric anastomosis was performed over a double J (DJ) stent [Figures 2b-e]. The postoperative period was uneventful, and she was discharged home comfortably on postoperative day 5. At the 2nd and 6th week after surgery, the patient was no longer in pain and has been doing very well.

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Figure 2: Intraoperative observations: (a) The blue arrow shows the dilated proximal ureter and renal pelvis with the point of constriction below; the green arrow indicates the collapsed distal ureteral segment. (b) The blue arrow highlights the renal parenchyma, while the green arrow points to the freed IVC running over the ureter. (c) The blue and green arrow identify both ends of the transected retrocaval ureteral segment. (d) The blue arrow shows the double J(DJ) stent within the ureteral anastomosis. The white oval structure is the upper end of the double-J (DJ) stent placed into the ureter before ureteral anastomosis to mitigate the effect of oedema and improve drainage. (e) The blue and green arrow mark the IVC and the newly positioned precaval ureter, respectively, after re-anastomosis. IVC: Inferior vena cava

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DISCUSSION

Retrocaval ureter, as commonly recognised by urologists, remains a rare congenital anomaly resulting from abnormal development of the IVC. Therefore, it is better described as the preureteral vena cava. The surgical treatment has excellent clinical and functional outcomes. However, diagnosis can be challenging due to its rarity, subtle and non-specific clinical features, and dependence on imaging studies. It was first documented in the literature by Hochstetler in 1893.^[6] This embryological abnormality occurs during the first and second months of gestation and arises from the persistence of the right subcardinal vein (the renal segment of the IVC) instead of the right posterior cardinal vein, which normally lies lateral to the ureter.^[1] According to Bateson and Atkinson, retrocaval ureter can be classified into two anatomical types based on the segment of the upper urinary tract located behind the vena cava.^[7] Type 1, known as the Low Loop Type, accounts for about 90% of cases and features a ureter that courses behind the IVC at the L3/L4 vertebral level, forming a “fishhook” deformity on imaging. Patients frequently present with upper urinary tract dilation caused by significant displacement of the ureter toward the midline and obstruction.^[2,7] Type 2, known as the High Loop Type, accounts for about 10% of cases and describes a ureter that curves around the IVC at the level of the renal pelvis, forming a smooth, sickle-shaped bend. It is generally non-obstructive and associated with less prominent hydronephrosis because the ureteral segment is positioned more proximally in a transverse orientation.^[1,7] Our patient was diagnosed with a Type 2 retrocaval ureter.

The circumcaval ureter is often seen in otherwise healthy young adults aged 20 to 40 years, with a male-to-female ratio of 4:1, and it mainly affects the right ureter. The presentation in our patient is unusual because she is a female and also a child, showing symptoms early in life. Very few reports exist of girls under age 10 with retrocaval ureter who have undergone surgery.^[3,8] The clinical signs of circumcaval ureter vary greatly, depending on the degree of ureteral compression and the resulting hydronephrosis. Usually, if there is no hydronephrosis, the person remains asymptomatic, and diagnosis often occurs later in life, although flank pain is the main symptom when present.^[1] It is important to distinguish this condition from other causes of midureteric obstruction, such as congenital ureteral valves, stenosis, diverticulum, or external compression from cysts, lymph nodes, tumours, or retroperitoneal fibrosis. Other congenital anomalies are found in about 20% of retrocaval ureter cases, mainly affecting the urogenital system (e.g., horseshoe kidney, renal malrotation, pelviureteric junction obstruction, vesicoureteral reflux) and the cardiovascular system (e.g., duplicated IVC, nutcracker syndrome, aberrant renal artery).^[1,3] Rare associations include Goldenhar syndrome, situs inversus, and oesophageal atresia.^[2] A thorough assessment is recommended to rule these out. In our patient, no associated anomalies were identified.

Diagnosis depends on imaging. While ultrasound detects hydronephrosis and is used for screening and monitoring, CT urography remains the gold standard, revealing the pathognomonic “fishhook” or “J” sign, exact obstruction level, and related abnormalities.^[1] MR urography serves as an alternative. Management of retrocaval ureter varies based on symptoms and severity. Asymptomatic patients or those with mild dilation often require conservative management with periodic ultrasound and renal function tests.^[1,2] Surgery is recommended for symptomatic cases with moderate to severe hydronephrosis, progression, hypertension, or decreasing renal function.^[4] The goal is to relieve compression by repositioning the ureter anterior to the IVC. Approaches include open, laparoscopic, or robotic surgery; minimally invasive methods are preferred to reduce pain, blood loss, scarring, and enable quicker recovery.^[9] Standard treatment involves ureteral dissection, transection of the retrocaval segment, removal of any atretic segment, spatulation, anterior repositioning, and stented pyeloureteric or ureteroureteric anastomosis. Abandoned techniques, such as IVC resection or Zhang support procedures, were associated with high complication rates.^[10] Nephrectomy is rarely done for non-functioning kidneys. Regular imaging follow-up is essential to assess surgical outcomes and detect potential complications. Early diagnosis and surgery are vital in preventing irreversible renal damage.

CONCLUSION

Retrocaval ureter is rare in children, especially females. Maintaining a high index of suspicion, using CT urography for diagnosis, and performing early surgical intervention help preserve renal function and lead to excellent outcomes. This case emphasises retrocaval ureter as an important differential diagnosis in paediatric patients with unexplained, persistent unilateral flank pain or hydronephrosis.