Endovascular treatment of anterior nutcracker syndrome and pelvic varices in a patient with an anterior and a posterior renal vein

Abstract

There are few data on endovascular treatment of anterior nutcracker syndrome and pelvic varices in patients with anterior and posterior renal veins. Our objective is to report a case, identify occurrences and compare diagnosis and treatments. A 42-year-old woman presented with flank and pelvic pain and hematuria. She had anterior nutcracker syndrome and pelvic varices with an anterior and a posterior renal vein. A successful complete endovascular approach was done with stent implantation in the anterior renal vein and left gonadal vein embolisation. After 12-month follow-up, the patient remained asymptomatic with good results on CT. Only two case reports of patients with nutcracker syndrome with anterior and posterior renal veins were identified. In both, a self-expanding stent was implanted in the anterior renal vein. In conclusion, endovascular treatment represents a safe and successful option in patients with nutcracker syndrome and pelvic varices with an anterior and a posterior renal vein.

Background

Nutcracker syndrome is a well-characterised pathological condition, but no consensus has been reached on indications and treatment techniques. The most commonly reported symptoms are flank and/or pelvic pain and hematuria. Pelvic congestion and varicocele may also occur in women and men, respectively, resulting from reflux in the gonadal vein, which, in this condition, becomes the main collateral pathway for left renal vein (LRV) drainage. When symptoms are severe, surgical intervention may be necessary. In this setting, a widely accepted modality is endovascular treatment with placement of a self-expanding stent, which may be combined with left gonadal vein embolisation. This technique is not without complications, with reports of stent migration even into cardiac cavities.^1–5

The nutcracker phenomenon is often anterior and results from LRV compression between the aorta and the superior mesenteric artery. More rarely, the nutcracker phenomenon may be posterior, resulting from LRV compression between the aorta and the spine or even in a circumaortic renal vein. Given the rarity of this condition, it is difficult to define the role of endovascular treatment, because there is no evidence of the evolution of these patients in the long term.^6–9

We report a case of anterior nutcracker syndrome in a patient with an anterior and a posterior renal vein successfully treated with endovascular stent implantation in the renal vein anterior to the aorta and left gonadal vein embolisation. The patient showed complete clinical improvement and remains asymptomatic for 12 months since the procedure.

Search strategy

A literature search was designed and conducted using the following electronic databases: MEDLINE (via PubMed), Web of Sciences, and Latin American and Caribbean Health Sciences Literature (LILACS). On LILACS Database, we deleted from the search results all records already indexed in the English-language literature. The following search terms were used: circumaortic renal collar, circumaortic renal vein, nutcracker syndrome and endovascular treatment.

Eligibility criteria

Studies were eligible if they reported data on specific outcomes, such as clinical presentation, diagnosis and treatment of nutcracker syndrome accompanying circumaortic LRV. We included studies of different designs (case report, case–control and case series studies), sizes, lengths of follow-up and in different languages.

Statistical analysis

We used descriptive statistics to analyse the data. No pairwise comparisons were made, mainly because the sample size was very small and several clinical results were reported after the interventions.

Results

The search strategy yielded only two case reports of endovascular treatment of nutcracker syndrome in patients with anterior and posterior renal veins: Cohen et al in 2009 and Policha et al in 2016. In both cases, a self-expanding stent was implanted in the anterior renal vein.^{10 11}

Case presentation

A 42-year-old woman was admitted to the emergency department for flank and pelvic pain and hematuria. The patient reported long-lasting pelvic pain and dyspareunia, with numerous visits to the gynaecologist, but without an accurate diagnosis of the aetiology of pain. There was no episode of hematuria or proteinuria before admission. Renal function tests were normal. Contrast-enhanced CT of the abdomen and pelvis showed a circumaortic LRV, with the presence of anterior and posterior nutcracker syndrome (figure 1A, B), dilation of the left gonadal vein and pelvic varices. Endovascular treatment was proposed for this patient, and surgical planning was based on CT scan reconstruction.

Figure 1.

CT scan showing compression of the anterior renal vein (A) and posterior renal vein (B).

The procedure was performed in a hybrid operating room. The right basilic vein was accessed. LRV phlebography confirmed the presence of an anterior and a posterior vein with significant compression in both of them (figure 2) and reflux into the left gonadal vein (figure 3). The renocaval pressure gradient was 5 mm Hg (reference value: ≤ 1 mm Hg). Embolisation of the gonadal vein was performed with six MicroVention coils of smaller diameters (from 8 mm) in the distal part and larger diameters (up to 14 mm) in the proximal part.

Figure 2.

Phlebography showing the presence of anterior and posterior nutcracker syndrome and reflux in the gonadal vein.

Figure 3.

Phlebography showing the pelvic varicose veins from the reflux in the gonadal vein.

After embolisation, renal vein diameters were measured with a Volcano intravascular ultrasound (IVUS) and a 12×40 mm Venovo stent was implanted in the renal vein portion anterior to the aorta (figure 4).

Figure 4.

Control phlebography showing correct positioning of the Venovo stent in the renal vein portion anterior to the aorta and coil embolisation of the gonadal vein.

Outcome and follow-up

Postdilation was done with a 10×40 mm Conquest balloon. Control phlebography and IVUS showed good results, and the renocaval pressure gradient decreased to 1 mm Hg. The patient progressed without complaints and received dual antiplatelet therapy (acetylsalicylic acid 100 mg and clopidogrel 75 mg) for 1 month, followed by monotherapy with acetylsalicylic acid (100 mg) for 6 months.

The patient has been followed up for 12 months and has presented no other complications. Control CT angiography showed stent patency (figure 5), complete obliteration of the gonadal vein and absence of dilated pelvic veins.

Figure 5.

Control CT scan showing stent patency and absence of compressions.

Discussion

Development of the fetal LRV occurs between the 4th and 8th gestational weeks. Abnormal development may occur during this process, leading to variations in the renal venous system. Failure of posterior arch regression may result in a retroaortic or circumaortic LRV. The mean incidence of circumaortic renal veins found in cadavers is up to 7%.^{12 13}

In adults, contrast-enhanced CT is the method of choice for identifying renal vein variations, with most cases being found incidentally. Knowledge of these variations is extremely important before an open abdominal surgery, because injury to a retroaortic renal vein has high-bleeding potential.¹⁴

Retrograde phlebography is useful for the diagnosis of nutcracker syndrome, and both the use of IVUS and measurement of the renocaval pressure gradient are the gold standard. Anterior and posterior nutcracker syndrome causes venous hypertension, leading to the development of a collateral network that may cause pelvic varices and venous congestion syndrome in women. This venous hypertension may be the cause of hematuria, flank and pelvic pain, and dyspareunia.¹⁵

When symptoms are severe and imaging studies identify significant extrinsic LRV compression, surgical intervention should be considered. Children and adolescents younger than 18 years should be treated conservatively because of a high likelihood of symptom remission in most of these patients, as up to 75% of them will have complete resolution of symptoms within 2 years.¹⁶ Likewise, asymptomatic patients with an incidental finding of compression should be treated conservatively, since the natural history of nutcracker syndrome in these patients is not well defined.

Open surgery was first described by Pastershank in 1974. Operative procedures include transposition of the LRV into the inferior vena cava 3–5 cm below its previous origin, renal autotransplantation and LRV bypass, among others. Excellent results have been reported with the use of open surgery in the medium and long term.¹⁷ Reed et al,¹⁸ over a mean follow-up of 39 months in 11 patients undergoing LRV transposition, reported that symptoms of flank pain and hematuria improved in 80% and 100% of cases, respectively. Two cases of preoperatively occluded LRV rethrombosed; one underwent thrombolysis with stenting and the other underwent reimplantation of the gonadal vein into the inferior vena cava.¹⁸ Although open surgery provides good results, it is an invasive treatment with risks of significant bleeding and injury to the ureter or other adjacent structures.

Endovascular stent placement as a treatment for nutcracker syndrome was first described by Neste et al.¹⁹ Since then, very encouraging results have been reported in large studies.^{1 2 17} Wang et al² retrospectively evaluated 30 patients who underwent endovascular stenting from 2004 to 2010. The authors concluded that endovascular treatment with stent placement is safe, effective and a minimally invasive technique with high long-term patency rates. However, their sample consisted of only Asian male patients with a mean age of 18 years (range, 13–32 years); therefore, the results cannot be extrapolated to an older female population, which is most commonly treated in Western countries.²

Chen et al,¹ in a retrospective study of 61 patients, evaluated the efficacy and safety of endovascular stenting procedures performed from 1998 to 2009. Mean patient age was 26 years, and 75% were men. Mean follow-up was 66 months. The stents used were 1 Palmaz stent, 15 Wallstents and 45 SmartControl stents measuring,^{10 12 14} or 16×40 mm. Symptoms of hematuria, proteinuria and flank pain improved in 15 patients within 1 week, in other 24 patients within 1 month and in other 20 patients within 6 months. Symptoms remained unchanged in two patients and recurred in one.¹

There are not many large studies on the topic in the Western world. Hartung et al¹⁷ published a study in which five patients treated with endovascular stenting between 2002 and 2004 were evaluated. All patients received Wallstents ranging from 16 to 20 mm in diameter and from 40 to 60 mm in length. At 1-month follow-up, all patients reported symptom improvement and all stents were patent on Doppler ultrasonography. Pelvic pain recurred in a patient who was later diagnosed with endometriosis. In two other patients, symptoms recurred owing to stent dislodgement in the renal vein. These patients were followed up more closely and progressed asymptomatically. A 40 mm long stent was used in these two cases; therefore, the authors recommended the use of longer stents to minimise complications.¹⁷

There are several reports of stent migration in the literature, and this is still one of the most feared complications.^20–22 Wang et al² used a single-sized stent (14×60 mm) in all their patients, resulting in a varying degree of oversizing of 3%–40%.² As a general rule, it is recommended to oversize the stent by 20%. It is important also to deploy the stent in the first branch of the renal vein to minimise the risk of stent migration, and, as a general rule, this should be performed before balloon angioplasty.²³ Postoperatively, there are no specific guidelines on the use of anticoagulants or antiplatelet therapy to increase stent patency. Our patient received dual antiplatelet therapy (acetylsalicylic acid 100 mg and clopidogrel 75 mg) for 30 days and then monotherapy (acetylsalicylic acid 100 mg).

Finally, treatment of pelvic congestion or varicocele may be necessary and performed concomitantly with the treatment of nutcracker syndrome. Embolisation of the left gonadal vein may be performed to alleviate pelvic pain. Because the embolisation removes the pathway for drainage of the kidney with a compressed renal vein, stent implantation is imperative in these cases. Currently, embolisation with concomitant stent placement is recommended, obviating the need for reintervention in these patients.^{15 16}

In sum, only two cases of endovascular treatment of nutcracker syndrome in patients with a circumaortic renal vein were found in the literature. Cohen et al,¹¹ in 2009, performed angioplasty of the renal vein anterior to the aorta with placement of a 12×40 mm self-expanding stent (Memotherm) with good results, without embolisation of the gonadal veins. Policha et al,¹⁰ in 2016, performed angioplasty of the renal vein anterior to the aorta with placement of a 14×60 mm self-expanding stent (Wallstent). Because symptoms remained unchanged 3 months later, embolisation was performed with coils (one 7 mm coil and one 9 mm coil) and injection of 1% sodium tetradecyl sulfate; the patient reported significant improvement in symptoms 7 months after the procedure.¹⁰ In the case reported here, we used a new self-expanding stent designed for the venous system (Venovo). This stent has good physical characteristics of radial force, stent deployment precision and resistance to fracture, which are important in cases of extrinsic venous compression. As reported in the two previous cases, in the present case we also opted for stent implantation in the renal vein portion anterior to the aorta, since external compression between the superior mesenteric artery and the aorta is certainly lower than that between the aorta and the spine.⁹ In our case, the sclerosing agent used was 3% polidocanol, which is widely used in Brazil for sclerotherapy and, therefore, is our preferred sclerosing agent based on our previous experience.

Conclusion

In patients with an anterior and a posterior renal vein and nutcracker syndrome, endovascular treatment with gonadal vein embolisation and stent implantation in the anterior renal vein, a priori, does not have significant differences in relation to the endovascular approach for the regular anterior nutcracker syndrome from a technical point of view. We can affirm that, in a medium-term follow-up, the treatment of this case does not seem to be inferior in terms of safety and efficacy to that of regular anterior nutcracker syndrome.

Learning points.

• More rarely, the nutcracker phenomenon may be posterior, resulting from left renal vein (LRV) compression between the aorta and the spine or even in a circumaortic renal vein.

• Open surgery is still the first option, and procedures include transposition of the LRV into the inferior vena cava, renal autotransplantation and LRV bypass, among others.

• Treatment of pelvic congestion or varicocele with embolisation may be necessary and performed concomitantly with the endovascular treatment of nutcracker syndrome.