Micro- and macroscopic hematuria caused by renal vein entrapment: systematic review of the literature

Nutcracker syndrome in pediatrics: initial findings and long-term follow-up results

BACKGROUND

Nutcracker syndrome (NCS) describes a set of symptoms and signs resulting from compression of the left renal vein (LRV). There is a lack of knowledge about its natural course, diagnosis, and management, especially in children. Herein, we present our single-center experience with a large number of patients who have long-term follow-up results.

METHODS

All patients with NCS diagnosed between January 2011 and March 2021 were included and their data were obtained retrospectively.

RESULTS

A total of 123 NCS patients (85 females) were included. The median age at the time of diagnosis was 12 (IQR 10-14) years, and BMI percentiles were below 5% in 38% of the cases. At the time of diagnosis, two-thirds of the patients were asymptomatic. The most common laboratory finding was nephritic proteinuria (98%), followed by microscopic hematuria (16%). Signs of LRV compression were significantly more evident in upright position Doppler ultrasonography (DUS) examination. All patients have been followed conservatively; hematuria and/or proteinuria resolved in 43 of the 108 patients (40%) within 35.8 ± 25.8 months of follow-up. Control DUS was performed in 52 patients after a mean period of 39.1 ± 21.3 months. The median peak velocity and diameter ratios of the LRV in the upright position were found to be decreased significantly when compared to the initial assessment (p < 0.05). Normal DUS findings were noted in 13 patients at the final evaluation.

CONCLUSIONS

In unexplained proteinuria and/or hematuria, NCS should be considered, especially in asthenic adolescents. Our results support conservative management in children as the first-line treatment approach.

Diagnostic Clues in Pediatric Nutcracker Syndrome: From Two Clinical Cases to Current Literature Analysis

Nutcracker syndrome (NCS) is a rare pediatric disease caused by left kidney vein compression. Besides the "Triade's symptoms", including hematuria, proteinuria, and flank pain, a wide spectrum of clinical manifestations has been reported. As the significant hemodynamic changes secondary to the dilatation of the left renal vein, serious consequences such as renal vein thrombosis and severe anemia might occur in these children. NCS diagnosis includes a variety of invasive and non-invasive imaging tools, but cutoff values need to be further validated. A conservative treatment represents the most common therapeutic approach for these patients, but operative options are available in selected cases. To complicate matters, a standard diagnostic and treatment algorithm is currently lacking and scientific pediatric evidence in this field is still poor and limited. In this perspective, early recognition of NCS is crucial but challenging for pediatricians. Therefore, a better knowledge of the disease is recommended. Starting from two different clinical presentations of NCS, we aimed to provide a comprehensive overview of the disease in children.

Nutcracker syndrome in children: Appearance, diagnostics, and treatment - A systematic review

BACKGROUND

The nutcracker syndrome (NCS) is defined by compression of the left renal vein (LVR) and may present with a wide variety of symptoms. Due to its rarity in pediatric patients, incidence, diagnostics and performed therapy regimen are widely undefined. To this date, there are only case reports and small collectives of pediatric patients described but comprehensive research is lacking.

METHODS

A systematic literature research on pediatric NCS was carried out on Medline and Scopus databases according to PRISMA principles using predefined search terms and inclusion criteria. The PROSPERO registered review (CRD42021237415) identified patients' characteristics regarding age, sex, clinical symptoms, applied diagnostic methods and treatment options.

RESULTS

In total 47 articles were included. Overall, 423 children (218 boys and 205 girls) with diagnosed NCS were included in the analysis. Mean age was 12.0 (boys 12.9, girls 12.0) years. Hematuria was most common presentation (55.5%), followed by proteinuria (49.9%). Classical flank pain was only detected in 19.1% of patients. Sonographic evaluation was the most commonly used diagnostic tool (99%). Invasive diagnostic studies were performed in 97 children. 86.8% patients were treated conservatively and 94.9% showed complete resolution (42.8%) or at least improvement (52.2%) of symptoms. Type of operative treatment comprised of open surgery with transposition of LRV, endovascular stenting and laparoscopy.

CONCLUSIONS

Overall, data quality regarding NCS in children is poor. However, conservative approach in pediatric patients is recommended and should be regarded first treatment option. Diagnostic and treatment should follow a defined algorithm when NCS is suspected. Sufficient observation and follow-up must be assured in all patients to get significant results in this heterogenous syndrome.

LEVEL OF EVIDENCE

V-IV.

Association between body mass index and varicocele among 211 989 Chinese reproductive-age males

Objectives

To explore the relationship between body mass index and varicocele, the range of body mass index that leads to increased odds of varicocele, and the association between body mass index with the position and grade of varicocele.

Methods

We conducted a cross‐sectional study of 211 989 Chinese males aged 18–65 years participated in the National Free Pre‐conception Check‐up Projects from January 2013 to December 2018. Univariate and multivariate logistic regression models were constructed to assess the association between body mass index and varicocele.

Results

Overweight and obese males had 13.1% (odds ratio 0.869, 95% confidence interval 0.838–0.902) and 32.3% (odds ratio 0.677, 95% confidence interval 0.632–0.725) lower odds of varicocele than those with normal body mass index, respectively. The association between them was non‐linear, and males with body mass index of 17.74 to 23.09 kg/m² had an increased odds of varicocele. The overweight and obese males had lower odds of left and bilateral varicocele, but the right varicocele odds was increased by 63.3% in obese males.

Conclusion

Body mass index was associated with the odds of varicocele among reproductive‐age males, but the odds varied by position. The effects of weight management and varicocele on fertility should be taken into account in fertility guidance.

The association between body mass index and varicocele: A meta-analysis

Objective:

Recently, several studies have found that obesity had a protective effect against varicocele, but no meta-analysis has confirmed this finding. Therefore, we conducted this meta-analysis to investigate the association between body mass index (BMI) and varicocele.

Material and Methods:

We searched for studies in PubMed, Science Direct and the Cochrane Library from inception until February 2018. The association between BMI and varicocele was assessed by pooling the odds ratios (ORs).

Results:

Eleven eligible studies with a total study population of 1.376.658 participants were included in our analysis. According to BMI, the subjects were defined as belonging to the obese, overweight and underweight groups. Our results showed that the obese group had a lower risk of varicocele when compared with the normal weight group (odds ratio [OR] 0.46, 95% confidence intervals [CIs] 0.37-0.58). Additionally, an overweight BMI had a protective effect against varicocele (OR 0.70, 95% CIs, 0.56-0.86). However, underweight patients had a more than 30% higher risk of varicocele (OR 1.31, 95% CI, 1.04-1.64). Furthermore, there was no publication bias in any of the analyses.

Conclusions:

Our study demonstrates that BMI is negatively associated with the presence of varicocele.

Image-guided study of swine anatomy as a tool for urologic surgery research and training

PURPOSE

To describe the anatomy of the swine urinary system using computed tomography and to discuss the role of this animal as an experimental model for urological procedures.

METHODS

Three male Landrace pigs underwent computed tomography and the anatomy of the urinary system and renal circulation was analyzed and described.

RESULTS

In all animals, 2 kidneys, 2 ureters and one bladder were identified. Each kidney presented a single renal artery vascularization, with a mean diameter on the right of 4.45 and 5.31 mm on the left (p < 0.0001) and single renal vein drainage, with a mean diameter on the right of 5.78 and 5.82 mm on the left (p = 0.0336). The average renal length was 9.85 cm on the right and 10.30 cm on the left (p < 0.0001). The average renal volume was 113.70 cm3 on the right and 109.70 cm3 on the left (p < 0.0001). The average length of the ureter was 19.78 cm on the right and 22.08 cm on the left (p < 0.0001). The average bladder volume was 423.70 cm3.

CONCLUSIONS

The data obtained show similarities with human anatomy, suggesting the viability of the swine model for planning preclinical trials, basic research, refinement in experimental surgery and surgical training for urological procedures.

A Case of Posterior Nutcracker Syndrome Revealed in the Aerospace Environment

BACKGROUND: Nutcracker syndrome is caused by a rare anatomic variant where the left renal vein is trapped between the aorta and the superior mesenteric artery. Posterior nutcracker syndrome is an even rarer entity, characterized by the retro-aortic positioning of the renal vein, causing compression between the aorta and spinal vertebrae. Symptoms include microscopic or frank hematuria, flank pain, varicocele, pelvic congestion syndrome, and abdominal pain. A search of the literature did not reveal prior cases of nutcracker syndrome that became symptomatic and diagnosed secondary to the unique stressors of high gravitational force (G force) in the aviation environment.CASE REPORT: A 25-yr-old man training as an F-16 flight test engineer presented with left scrotal/testicular pain, varicocele, and intermittent gross hematuria. After an extensive workup, he was diagnosed with posterior nutcracker syndrome and underwent a left varicocele ligation with spermatic cord denervation. He was eventually able to be returned to flying duties with limitation to non-high performance aircraft.DISCUSSION: This case is particularly unique as its diagnosis was dependent on exposure to high G force conditions that may have otherwise remained asymptomatic without this environmental stressor. Education on the diagnosis of nutcracker syndrome as a differential in the setting of hematuria and pain is an important lesson learned. This case also illustrates the necessity of considering the effects of the stressful environment of high G force on even overall healthy individuals. Fortunately, due to the collaboration of medical-surgical expertise and familiarity with the requirements for operational readiness, this patient was able to resume his aviation career, albeit in a different capacity compatible with his condition.Chung CY, Lytle ME, Clemente Fuentes RW. A case of posterior nutcracker syndrome revealed in the aerospace environment. Aerosp Med Hum Perform. 2021; 92(1):5456.

Approach to Persistent Microscopic Hematuria in Children

Persistent isolated microscopic hematuria is relatively common in pediatric practice, affecting around 0.25% of children. Isolated microscopic hematuria can be caused by a myriad of potentially benign or serious causes, including urologic issues; kidney stones; glomerular diseases, including disorders of the glomerular basement membrane; hematologic abnormalities; and others. The challenge for the pediatrician or pediatric nephrologist is to distinguish children with potentially progressive forms of kidney disease versus other causes while minimizing cost and inconvenience for the child and family. This manuscript will review the multiple potential causes of microscopic hematuria and provide a framework for the initial evaluation and monitoring of such patients.

ACR Appropriateness Criteria® Hematuria-Child

Hematuria is the presence of red blood cells in the urine, either visible to the eye (macroscopic hematuria) or as viewed under the microscope (microscopic hematuria). The clinical evaluation of children and adolescents with any form of hematuria begins with a meticulous history and thorough evaluation of the urine. The need for imaging evaluation depends on the clinical scenario in which hematuria presents, including the suspected etiology. Ultrasound and CT are the most common imaging methods used to assess hematuria in children, although other imaging modalities may be appropriate in certain instances. This review focuses on the following clinical variations of childhood hematuria: isolated hematuria (nonpainful, nontraumatic, and microscopic versus macroscopic), painful hematuria (ie, suspected nephrolithiasis or urolithiasis), and renal trauma with hematuria (microscopic versus macroscopic). The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

[Nephrotic syndrome and microhematuria in a patient with nutcracker syndrome: Report of a case and review of the literature]

We report about a 43-year-old woman with polyvalent drug addiction (i.e. alcohol, nicotine, methadone maintenance program with parallel consumption of heroin) who presented to the emergency department with peripheral edema, generalized weakness, and arthralgia. Laboratory findings revealed, among others, proteinuria, hyperlipoproteinemia and hypoproteinemia defining nephrotic syndrome. Computed tomography of the abdomen and iliocavography further revealed compression of left renal vein between aorta and superior mesenteric artery with distention of left ovarian vein as a possible cause of nephrotic syndrome (i. e. nutcracker syndrome). After excluding other possible causes of nephrotic syndrome, we decided against an interventional procedure due to poor compliance of the patient and potential risk of secondary stent dislocation. Instead, we opted for a surgical approach (i. e. veno-venous bypass, meaning transposition of left vena ovarica on vena cava inferior). The operative and postoperative course was uneventful. Postoperatively, proteinuria, microhematuria, arthralgia and edema receded.