Retrocaval ureter: a narrative review

Abstract

Background and Objective

Retrocaval ureter is a rare congenital anomaly resulting from the abnormal development of the inferior vena cava (IVC), where the ureter passes posteriorly and loops around the IVC. This review aims to provide a comprehensive overview of the etiology, classification, clinical presentation, diagnostic approaches, and management strategies for retrocaval ureter.

Methods

We performed a narrative, non-systematic literature review using PubMed, Google Scholar, Embase, and Web of Science for articles related to retrocaval ureter to perform a narrative review of the current literature on retrocaval ureter, including clinical case series, reviews, and surgical outcome studies. Emphasis was placed on diagnostic imaging, surgical techniques, and outcomes.

Key Content and Findings

Retrocaval ureter has an estimated incidence of 1 in 1,000 births and is more frequently diagnosed in males. It is classified into two anatomical types, with Type 1 being more common and often associated with significant hydronephrosis. Advances in imaging, including computed tomography (CT) urography and magnetic resonance (MR) urography, have improved diagnostic accuracy. The management of retrocaval ureter varies depending on the severity of symptoms, but surgical correction, primarily through minimally invasive techniques like laparoscopic or robotic ureteroureterostomy, is the treatment of choice in symptomatic patients. Minimally invasive surgery offers reduced recovery time and excellent outcomes.

Conclusions

Retrocaval ureter is a rare but significant condition that can lead to ureteral obstruction and hydronephrosis. Early diagnosis through modern imaging and prompt surgical intervention in symptomatic cases can prevent long-term renal damage. Minimally invasive techniques have emerged as the gold standard for surgical management, offering favorable outcomes with minimal complications.

Introduction

Retrocaval ureter, also known as circumcaval ureter, is a rare congenital anomaly caused by the abnormal development of the inferior vena cava (IVC). In this condition, instead of crossing in front of the IVC, the ureter wraps around it at the level of the third or fourth lumbar vertebra (Figure 1) (1-3).

Figure 1.

Retrocaval ureter.

The exact prevalence of retrocaval ureter is not well-defined, although it is estimated to occur in approximately 1 in 1,000 births (4,5). The condition is more common in males, with a male-to-female ratio of 3:1, and is typically diagnosed between the ages of 20 and 40. However, due to its often asymptomatic nature, the true frequency of this anomaly may be underestimated. With the advancement of imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI), incidental diagnosis of retrocaval ureter has become increasingly common (2,6,7).

In most cases, affected individuals are young and otherwise healthy, with associated anomalies present in approximately 20% of cases. Most of the associated anomalies are genitourinary (agenesis, hypoplasia or contralateral renal ectopia, horseshoe kidney, renal malrotations, pyeloureteral stenosis, ureterocele, polycystic kidney disease, hypospadias) or cardiovascular (double vena cava, aberrant renal artery, nutcracker syndrome, aortic coarctation, pulmonary stenosis) (7). Other anomalies described are of the musculoskeletal system, situs inversus, gastrointestinal, Turner syndrome, Goldenhar syndrome, myelomeningocele and tumors (8-10).

The cause of this malformation lies in an embryologic anomaly of the venous system rather than the upper urinary tract. Embryologically, this anomaly is characterized by a pre-ureteral IVC, where the right subcardinal vein persists as the main component of the infrarenal IVC, instead of the right supracardinal vein (Figure 2) (3,11-13).

Figure 2.

Embryology. (A) Normal development of the inferior vena cava. (B) Abnormal development of the inferior vena cava, leading to a retrocaval right ureter.

Retrocaval ureter can be asymptomatic or cause ureteral obstruction, sometimes necessitating surgical intervention. This review aims to discuss the various therapeutic options available, highlighting the role of minimally invasive uretero-ureterostomy. We present this article in accordance with the Narrative Review reporting checklist (available at https://tau.amegroups.com/article/view/10.21037/tau-24-580/rc).

Methods

We performed a narrative, non-systematic review of the literature by searching PubMed, Google Scholar, Embase, and Web of Science for articles related to retrocaval ureter without a limit on dates of publication. Articles related to retrocaval ureter were first screened by title and abstract, and eligible studies were then reviewed in full and summarized (Table 1).

Table 1. The search strategy summary.

Items	Specification
Date of search	September 7, 2024 and July 21, 2025 (for revision)
Databases and other sources searched	PubMed, Google Scholar, Embase, Web of Science
Search terms used	(retrocaval ureter) And (circumcaval ureter)
Timeframe	From 1935 to 2025
Inclusion and exclusion criteria	Inclusion: English and Spanish language studies were included. Peer-reviewed published articles were prioritized
	Exclusion: duplicate, irrelevant subject matter
Selection process	The literature search and screening were conducted by S.P.B.. Relevant articles were identified by reviewing titles and abstracts, and the full texts were assessed for eligibility. The other co-authors contributed to reviewing the included studies and refining the content. L.G.A. provided overall supervision

Classification

The retrocaval ureter presents different anatomical types, depending on the position of the ureter crossing around the vena cava.

Radiological exploration allows for determining the malformation’s morphology, as defined by Bateson and Atkinson (3,7,14). Two types of retrocaval ureters are described (Figure 3):

Figure 3.

Radiological classification of retrocaval ureter: (A) type 1, (B) type 2.

• ❖ Type 1, the most common form, corresponds to a very pronounced “S” or “hook” course at the level of L3 due to a pronounced curve or “kinking”; radiologically, there is an inverted “J” image on urography. It is associated with moderate to severe hydronephrosis in 50% of patients due to an obstructive disorder;

• ❖ Type 2, accounting for 10% of cases, is described as a progressive coiling with a much softer curve. In this case, it is the initial portion of the ureter that has a retrocaval position. It is associated with moderate hydronephrosis or no dilatation at all.

Clinical presentation

When symptomatic, retrocaval ureter typically presents in the third or fourth decade of life, often due to complications from ureteral obstruction. Although the condition is congenital, most symptomatic cases are diagnosed in adulthood due to the progressive nature of hydronephrosis. The most frequent symptom is lumbar pain, but patients may also present with urinary tract infections, hematuria, or urolithiasis. Symptoms may recur intermittently (13,15).

Some cases remain asymptomatic, with or without associated hydronephrosis. In these instances, the diagnosis is often incidental, discovered during imaging studies for unrelated conditions or during evaluations for other congenital anomalies (7).

Diagnostic approach

The diagnosis of retrocaval ureter is made primarily through imaging studies. Morphological studies such as intravenous urography (IVU), retrograde ureteropyelography, CT, or MRI help determine the level of the anomaly, the extent of dilatation, and local anatomical conditions. Renal scintigraphy and diuretic renography are used to assess renal function and the degree of ureteral obstruction (2,12).

IVU

Historically, IVU has been the most informative test for assessing retrocaval ureters (Figure 4), but it has largely been replaced by newer imaging modalities such as MR urography and contrast-enhanced CT with delayed image reconstruction (uro-CT). IVU can still be useful in detecting radiopaque stones, renal anomalies, and abnormalities of the upper urinary tract on the affected or contralateral side (2,3,14,16).

Figure 4.

Intravenous urography. (A) Right retrocaval ureter type 1 with proximal ureterohydronephrosis. (B) Right retrocaval ureter type 2 with mild proximal ureterohydronephrosis.

Retrograde ureteropyelography

This intraoperative test allows for a complete anatomical study of the ureteral course. Typically, the segment below the superior ureter is normal, but the ureter adopts a medial position at L4, then laterally at L3, creating an “inverted J” appearance (2,3).

Renal ultrasound

Non-invasive imaging test without radiation, useful for monitoring patients with retrocaval ureter. It should be used in the initial evaluation. It assesses for increased hydronephrosis (Figure 5), parenchymal thinning, and urolithiasis. However, ultrasound alone may not provide adequate anatomical detail, and further imaging, such as MRI or CT, is typically required to confirm the diagnosis (3,17-20).

Figure 5.

Ultrasound of patients with right retrocaval ureter. (A) Hydronephrosis; (B) dilatation of the proximal right ureter.

CT

Currently, uro-CT is considered the preferred diagnostic test for retrocaval ureter. However, its use in pediatric patients is controversial due to radiation exposure (2,3,12,17,21-25).

MRI

MRI is favored by some authors over CT due to the high-quality images obtained without the need for iodinated contrast or ionizing radiation, which is especially important in pediatric patients. Drawbacks include limited availability, higher costs, and longer study durations (3,6,22).

Nuclear medicine

Nuclear medicine tests provide functional information regarding the kidneys and the excretory process. Diuretic renography with ^99mTc-MAG3 is used to diagnose urinary tract obstruction, measuring the drainage time from the pelvis and differential renal function (Figure 6) (3,21).

Figure 6.

Diuretic renogram with ^99mTc-MAG3 showing a right obstructive pattern with preserved renal function.

Renal scintigraphy with ^99mTc-DMSA is an alternative for evaluating differential renal function but does not assess for obstruction.

Treatment

Conservative management and active surveillance

Active surveillance is recommended for asymptomatic patients without signs of obstruction. If dilatation is present, a diuretic renogram should be performed to assess for obstruction and renal function. Surgical treatment may be considered if an obstructive pattern is identified or renal function deteriorates (12).

Surgical treatment

Various surgical techniques can be employed, including both open and minimally invasive surgery. The principle of reconstructive surgery for retrocaval ureter is to restore normal anatomical positioning by relocating the ureter and the IVC. This can be achieved through ureteral resection and anastomosis or, historically, IVC resection and reanastomosis (a technique now largely abandoned) (3).

Nephrectomy

Indicated for symptomatic patients with a non-functioning kidney (≤10% function on scintigraphy) to prevent complications, primarily infections (10,16,26).

Ureteral reconstructive surgery

Indicated for symptomatic patients or those with demonstrated obstruction and deteriorating renal function. Both the dilated renal pelvis section with transposition and reanastomosis (pyelopyelostomy) and the ureteropyeloplasty or ureteroureterostomy have been the most popular procedures for treating patients with retrocaval ureter (Figure 7) (3). There is ongoing debate regarding whether it is necessary to dissect and remove the retrocaval ureter segment. Dissection is not mandatory as long as there is sufficient ureteral length for reconstruction. In fact, some authors consider this maneuver risky and advise against it, as inadvertent avulsion of a lumbar vein could necessitate immediate conversion to open surgery. Resection of the retrocaval segment is not always required. The ureter can be sectioned, transposed, and reanastomosed if it appears macroscopically normal, with proper coloration, peristalsis, and a suitable caliber. However, in cases where the retrocaval ureter segment presents dysplastic, stenotic, kinked features, or abnormal peristalsis, or is redundant, excision is recommended (4,27-29).

Figure 7.

Uretero-ureterostomy with ureteral transposition.

Open surgery has been the standard treatment for many years, with both lumbotomy and abdominal approaches described (1,3,9,13,30-34). The outcomes appear to be equivalent across all approaches; however, the morbidity associated with large incisions has led to the adoption of minimally invasive techniques, which offer benefits such as shorter hospital stays, quicker recovery, and less postoperative pain.

Minimally invasive surgery can be performed via transperitoneal or retroperitoneal laparoscopy, or even robotic surgery. These techniques are equally effective for treating retrocaval ureter, and the indications and relative contraindications are similar to those for pyeloureteral stenosis.

• ❖ Transperitoneal laparoscopic surgery: offers excellent exposure and a broader operative field, facilitating intracorporeal suturing (Figure 8, Video 1). The first laparoscopic repair of retrocaval ureter was described by Baba in 1994 (35), following the principles of a dismembered pyeloplasty (3,4,10,27,28,31,34,36-40).

• ❖ Retroperitoneoscopy: first described by Salomon in 1999 (41), retroperitoneoscopy offers direct access to the ureter and IVC, avoiding the need to mobilize and retract intraperitoneal organs, thereby reducing the risk of complications. However, the smaller surgical field can make intracorporeal suturing more challenging (22,42-45).

• ❖ Robotic surgery: first performed by Gundeti in 2006 (46), robotic uretero-ureterostomy via a transperitoneal approach has since been reported in several case series (23,29,33,47-51).

• ❖ Single-port umbilical surgery: only two cases of retrocaval ureter repair using single-port umbilical surgery have been reported. Both cases utilized a 2–3 mm assist port for intracorporeal suturing (52,53).

Figure 8.

Right retrocaval ureter. Transperitoneal laparoscopic approach. IVC, inferior vena cava.

Video 1.

Download video file ^{(2.7MB, mp4)}

Right retrocaval ureter. Transperitoneal laparoscopic approach. Following careful dissection of the ureter from the inferior vena cava, a shoeshiner maneuver is performed to verify complete circumferential mobilization and ensure that no residual adhesions remain between the ureter and the vascular wall.

Venous reconstructive surgery

Initially proposed by Goodwin in 1957 (54), this technique involves IVC resection and reanastomosis following anterior ureteral transposition. Due to significant intraoperative risks and potential complications, this technique has been abandoned (7).

IVC support

Zhang’s “IVC support” technique involves dissection of the retrocaval ureter from surrounding tissues, correction of the tortuous ureteral path, and placement of a support structure on either side of the ureter (Figure 9) (16). This technique has not shown favorable results and has also been largely abandoned (1,3,7).

Figure 9.

Inferior vena cava support.

Complications

Potential complications of laparoscopic uretero-ureterostomy for retrocaval ureter include (3):

Intraoperative

Hollow or solid organ injury (such as bowel or liver) during trocar insertion or instrument manipulation, bleeding during dissection, ureteral ischemia due to extensive dissection or excessive handling, ureteral perforation during double-J stent placement, and incorrect placement of the double-J stent.

Postoperative

Urinary leakage, anastomotic stricture, residual obstruction due to preservation of the retrocaval segment, and adhesions.

Discussion

The management of retrocaval ureter, a rare congenital anomaly, continues to evolve, particularly with the adoption of minimally invasive techniques. Despite the technical advancements, there remains a lack of consensus regarding the optimal surgical approach, particularly in cases where the retrocaval ureter segment is involved. Studies consistently highlight the benefits of minimally invasive surgery, such as reduced hospital stays, quicker recovery, and less postoperative pain, compared to open surgery (34). However, there is still debate over whether it is necessary to dissect and remove the retrocaval segment. The argument against this approach is based on the risk of injury to adjacent vascular structures, notably the lumbar veins, which could result in the need for immediate conversion to open surgery. Some authors even caution against extensive dissection due to potential complications like ureteral ischemia or inadvertent lumbar vein avulsion. The decision to remove the segment should therefore be based on intraoperative findings, such as ureteral dysplasia or abnormal peristalsis, which could necessitate excision for a better long-term outcome (4,27-29).

Limitations

Several limitations in the current literature on retrocaval ureter management need to be acknowledged. Firstly, most studies are retrospective case series with small sample sizes, limiting the generalizability of the findings. Prospective randomized studies comparing open and minimally invasive approaches are scarce, and long-term follow-up data are often lacking. Furthermore, while minimally invasive surgery is gaining widespread acceptance, access to laparoscopic or robotic platforms and surgical expertise may be limited in certain centers. Finally, the role of active surveillance for asymptomatic patients remains under-explored, with many studies focusing on surgical outcomes rather than long-term management strategies for patients with mild hydronephrosis or non-obstructive cases.

Conclusions

Retrocaval ureter is a rare congenital anomaly caused by abnormal development of the IVC. It is often associated with proximal ureterohydronephrosis. Imaging studies allow for the diagnosis of retrocaval ureter and evaluation of its impact on renal function. While CT is currently considered the imaging modality of choice in adults, its use in pediatric patients is more controversial due to ionizing radiation. MRI is equally effective for diagnosing retrocaval ureter without radiation exposure.

Surgical treatment is indicated for symptomatic patients or those with significant obstruction and can be performed using minimally invasive techniques. Ureteral reconstructive surgery, particularly via minimally invasive approaches, yields the best outcomes for retrocaval ureter.

Supplementary

The article’s supplementary files as

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. Informed consent for publication of images and video was obtained from the patients’ parents.