Aortomesenteric Portion Research Articles

Diagnostic accuracy of the jetting sign and a dilatation ratio of left renal vein in CT urography for detecting anterior nutcracker syndrome

To investigate the diagnostic value of computed tomography (CT) urography findings of anterior nutcracker syndrome (NCS). The study included patients with left renal vein (LRV) compression at the aortomesenteric portion at CT urography who underwent renal venography or cystoscopy. Patients with a renocaval pressure gradient of ≥3 mmHg on renal venography or bloody urine jetting from the left ureteral orifice on cystoscopy were defined as the NCS group; the remaining patients comprised the non-NCS group. CT findings were analysed using the jetting of contrast medium flow from the LRV to the inferior vena cava (jetting sign), aortomesenteric distance, presence of collateral veins, and a dilatation ratio of LRV diameter at the aortomesenteric portion (arterial phase/delayed phases). Clinical findings, including age, gender, and body-mass-index, were also analysed. CT features and clinical findings were compared between the NCS and non-NCS groups. Diagnostic performance of CT parameters was assessed using receiver operating characteristic curve analysis. A total of 70 patients (21 men, mean age 44.4±17.2 years) with NCS (n=13) and non-NCS (n=57) were included. Younger age (<40 years), presence of the jetting sign, and a lower dilatation ratio of LRV diameter between the arterial and delayed phases (<1.7) were found to be significant independent factors for predicting the NCS group (OR 24.5, 18.9, 19.4, respectively, p<0.05 for all). The combination of the presence of the jetting sign and a dilatation ratio of LRV diameter of <1.7 obtained the highest AUC of 0.88. The jetting sign and the dilatation ratio of LRV diameter between the arterial and delayed phases can both be very useful in the diagnosis of anterior nutcracker syndrome during CT urography.

Microsurgical gonadal-inferior epigastric vein anastomosis to treat the nutcracker phenomenon with left gonadal vein varices with reflux.

To evaluate the effectiveness and safety of microsurgical gonadal-inferior epigastric vein anastomosis for the treatment of the nutcracker phenomenon (NCP) associated with left gonadal vein varices with reflux. Thirty-five patients with NCP associated with left gonadal vein varices with reflux diagnosed in our hospital from June 2016 to June 2018 were included. All patients underwent a shunt operation consisting of microsurgical gonadal-inferior epigastric vein anastomosis, and the patients were followed up for 1year. All patients were successfully operated on, with an average operation time of 96.5 ± 12.3min. After a 1-year follow-up, the symptom of gross hematuria disappeared in 3 patients (including 1 woman). For the other 32 patients, the sperm concentration (27.43 ± 8.68 × 106/ml) and motility (33.06 ± 4.27%) postoperatively were significantly higher than that preoperatively (16.21 ± 6.43 × 106/ml and 23.48 ± 4.43%, respectively) (P < 0.05); among these patients, 2 had natural pregnancies with their spouses. The peak velocity (PV) at the aortomesenteric portion of the left renal vein (LRV) and the PV ratio between the aortomesenteric and hilar portion of the LRV significantly decreased after surgery (117.9 ± 30.4cm/s vs 76.6 ± 18.5cm/s; 7.3 ± 0.7 vs 4.1 ± 0.4). Two patients had complications of mild hydroceles requiring no intervention, and no major complications were observed during and after surgery. Our results suggest that the microsurgical gonadal-inferior epigastric vein anastomosis is both effective and safe to treat patients with gonadal varicose veins caused by the nutcracker phenomenon.

Doppler US and CT Diagnosis of Nutcracker Syndrome.

Nutcracker syndrome (NCS) is a syndrome caused by compression of the left renal vein (LRV), between the abdominal aorta and the superior mesenteric artery, resulting in hypertension of the LRV and hematuria. Doppler ultrasonography (US) has been commonly used for the diagnosis of NCS. However, several technical issues, such as Doppler angle and sample volume, need to be considered to obtain satisfactory results. In addition, morphologic changes of the LRV and a jetting phenomenon across the aortomesenteric portion of the LRV on contrast-enhanced computed tomography (CECT) are diagnostic clues of NCS. With proper Doppler US and CECT, NCS can be diagnosed noninvasively.

Nutcracker Syndrome in Children: Role of Doppler Ultrasonographic Indices in Detecting the Pattern of Symptoms.

The purpose of this study was to evaluate the clinical characteristics of 44 pediatric patients who were diagnosed as having nutcracker syndrome (NCS). We also investigated the left renal vein Doppler ultrasonography (DUS) results, to determine whether or not there was an association between clinical symptoms and DUS findings among these patients. The clinical data from 44 pediatric patients who were diagnosed as having NCS from January 2008 to December 2015 were retrospectively reviewed. We grouped the patients according to the presenting symptoms as symptomatic (loin pain; macroscopic hematuria or both) and non-symptomatic (microscopic hematuria and proteinuria were detected incidentally) and evaluated the left renal vein DUS indices in these two groups separately. Asymptomatic NCS was found in 27 (61.4%) patients; 21 (47.7%) of whom were admitted for the evaluation of proteinuria. The most frequent presenting symptoms were left flank pain (20.5%) and macroscopic hematuria (13.6%); and 2 (4.5%) patients presented with a combination of left flank pain and macroscopic hematuria. The mean ratio of the diameter of the hilar portion of the left renal vein (LRV) to that of the aortomesenteric portion was 4.36 ± 1.55. The mean ratio of the peak velocity (PV) between the two sites of the LRV was 7.32 ± 2.68 (3.1–15.6). The differences in the ratio of the diameters were statistically significant between the two groups and significantly higher in children with asymptomatic NCS (p = 0.025). The PV ratios of the LRV (p = 0.035) were significantly higher in asymptomatic children with NCS than in the symptomatic group. Our study identifies that increased compression ratio of the LRV entrapment is most observed in orthostatic proteinuria and microscopic hematuria.

Stent migration after endovascular stenting in patients with nutcracker syndrome.

In this study, we sought to investigate the incidence of stent migration after endovascular stenting (EVS) in patients with nutcracker syndrome (NCS) and to discuss the related factors. We retrospectively evaluated the data of all patients with NCS who were treated by EVS at our single center between January 2004 and October 2014. Data collection included details on clinical findings, radiologic evaluation, laboratory values, EVS procedure, stent size, and morbidity of stent migration. Sex, size of stents, interval (between EVS and stent migration), and preoperative parameters of the left renal vein (LRV) on duplex ultrasound (anteroposterior diameter in aortomesenteric portion and renal hilum of LRV, peak velocity in aortomesenteric portion and renal hilum of LRV) were analyzed. A total of 75 patients (49 men) with a median age of 27 years (range, 16-43 years) underwent EVS for NCS. During a mean 55 months (range, 6-126 months) of follow-up, stent migration occurred in five patients (6.7%), and all of them were male. The stent migrated into the right ventricle in one patient, right atrium in one patient, inferior vena cava in two patients, and left side of the LRV in one patient. There were no significant differences in preoperative anteroposterior diameter and peak velocity of the aortomesenteric portion and renal hilum of the LRV on duplex ultrasound between patients with and without stent migration. There were also no significant differences in these parameters between patients with deployment of 12-mm and 14-mm-diameter stents. Stent migration after EVS in patients with NCS is not as rare as we originally thought. Preoperative anatomic parameters of the LRV need to be more accurately measured. Stent choice for the individual patient and accurate stent deployment are important to avoid stent migration. Closer follow-up and early detection and treatment can reduce the number of stent migrations into the heart.

Microsurgical Spermatic-inferior Epigastric Vein Anastomosis for Treating Nutcracker Syndrome-associated Varicocele in Infertile Men: A Preliminary Experience

To assess the therapeutic effectiveness of microsurgical spermatic-inferior epigastric vein anastomosis for the treatment of nutcracker syndrome (NCS)-associated varicocele in infertile men. We prospectively analyzed 5 infertile men with NCS-associated varicocele between April 2010 and January 2012. All patients underwent microsurgical spermatic-inferior epigastric vein anastomosis. The mean operation time was 85.0 ± 13.2minutes, and the mean postoperative hospital stay was 6.0 ± 0.7days. During a 1-year follow-up, hematuria completely resolved in 66.7% of patients (2/3) and flank pain resolved in the single patient affected. The peak velocity (PV) at the aortomesenteric portion of the left renal vein (LRV) significantly decreased after surgery (167.24 ± 41.68cm/s vs 46.98 ± 4.22cm/s). The PV ratio between the aortomesenteric and hilar portion of the LRV also significantly decreased (12.28 ± 2.32 preoperatively vs 3.40 ± 0.67 postoperatively). The mean sperm count and motility at 6months (24.38× 10(6)/mL ± 1.58× 10(6)/mL and 53.96% ± 6.28%, respectively) and 12months (30.02× 106/mL ± 3.52× 106/mL and 59.40% ± 8.59%, respectively) postoperatively were significantly higher than their preoperative values (15.8× 106/mL ± 4.53× 106/mL and 26.76% ± 8.68%, respectively). Overall, 80% of the spouses of patients (4/5) went on to conceive naturally. The complications observed were scrotal edema in 1 patient (20%) and wound infection in 1 patient (20%). Microsurgical spermatic-inferior epigastric vein anastomosis is a safe and efficient surgical treatment for infertile men with NCS-associated varicocele.

Surgical management of nutcracker phenomenon presenting as left varicocele in adolescents: A novel approach

ObjectiveTo present a new approach using a shunt operation for the management of nutcracker phenomenon presenting as left varicocele in adolescent patients. Materials and methods12 adolescent patients with the nutcracker phenomenon presenting as left varicocele underwent a shunt operation consisting of anastomosis of the proximal part of the spermatic vein and inferior epigastric vein to lower the left renal vein (LRV) pressure. A simple ligation of the left spermatic vein was then used to repair the varicocele. Results12 patients underwent surgery, and symptoms of hematuria, proteinuria, scrotum discomfort, and flank pain disappeared post surgery in all patients. Patients were followed for 24–72 months (mean 48 months). The diameters of the proximal LRV and the peak velocities in the aortomesenteric portion of the LRV were significantly decreased after surgery (p < 0.001). Left testicular volume significantly increased after surgery. One patient had recurrence of the left varicocele and one adolescent had minimal hydrocele requiring no intervention. No major complications were observed during and after surgery. ConclusionAnastomosis of the proximal part of the spermatic vein and inferior epigastric vein is an efficacious and safe surgical approach for the management of nutcracker phenomenon presenting as left varicocele in adolescents.

Nutcracker phenomenon and idiopathic IgA nephropathy.

Sir, Entrapment of the left renal vein between the aorta and the superior mesenteric artery is a documented cause of both postural proteinuria as well as intermittent gross haematuria associated with left flank pain. Idiopathic IgA nephropathy typically presents with recurrent episodes of gross haematuria, usually following an acute febrile illness. Rarely, the disease presents as microscopic haematuria and usually mild proteinuria. We present the first case of postural proteinuria caused by left renal vein entrapment and recurrent gross haematuria caused by an IgA nephropathy. In an 11-year-old boy with postural proteinuria, renal ultrasonic Doppler disclosed left renal vein entrapment: the anteroposterior diameter at the hilar portion divided by that at the aortomesenteric portion was 13.3 (reference ≤ 4.0) and the peak flow velocity at the aortomesenteric portion divided by that at the hilar portion 15.1 (reference ≤ 4.0). Two years later, three episodes of acute febrile diarrhoea were followed by gross haematuria that was not associated with flank pain. The kidney biopsy showed mild diffuse mesangial proliferation and matrix expansion. The diagnosis of IgA nephropathy was made on immunofluorescence microscopy, which demonstrated isolated prominent globular deposits of IgA, C3 and IgG in the mesangium. The link between left renal vein entrapment and postural proteinuria is well documented. Furthermore, both left renal vein entrapment and IgA nephropathy are recognized causes of recurrent gross haematuria. There are five reported patients affected with both left renal vein entrapment and idiopathic IgA nephropathy [1–4]. A 12-year-old German girl with microscopic haematuria was found to have left renal vein entrapment and mesangial deposits of IgA [1]. Similarly, left renal vein entrapment and mesangial deposits of IgA were reported in a 9-year-old Korean girl with isolated microscopic haematuria and recurrent gross haematuria [2] and in a 25-year old Taiwanese woman with recurrent gross haematuria and left flank pain [3]. Left renal vein entrapment and IgA nephropathy were also disclosed in a 20-year-old woman and in a 22-year-old Japanese man, who, in the context of a pharyngitis, developed gross haematuria and a tendency to microscopic haematuria with persisting proteinuria [4]. In addition, left renal vein entrapment was disclosed in two Korean children a 13-year-old Korean girl with Henoch–Schonlein syndrome and IgA nephropathy [5]. Finally, a 10-year-old Korean boy with a clinically characteristic and rapidly resolving form of Henoch–Schonlein syndrome followed by microscopic haematuria persisting for 26 months was found to have left renal vein entrapment; haematuria subsided in accordance with radiological improvement of renal vein entrapment [6]. Our patient is the first case with concurrent existence of postural proteinuria caused by left renal vein entrapment and recurrent gross haematuria caused by an idiopathic IgA nephropathy. Renal venous congestion may induce both proteinuria and haematuria, which have been implicated as a cause of renal damage. So, a causal relationship between left renal vein entrapment and IgA nephropathy cannot be ruled out. Further investigations are necessary to detect this correlation.

Endovascular Stenting for Treatment of Nutcracker Syndrome: Report of 61 Cases With Long-Term Followup

We report the efficacy and safety of endovascular stenting for nutcracker syndrome at long-term followup. We retrospectively evaluated the endovascular stenting experience with 61 patients with a median age of 26 years. Symptoms were hematuria, proteinuria or flank pain. Median followup was 66 months. Peak velocity in the aortomesenteric portion, and the anteroposterior diameter ratio of the renal hilum and the aortomesenteric portion of the left renal vein on Duplex ultrasound after stenting was significantly decreased compared to that on Duplex ultrasound before stenting (p<0.05). However, peak velocity in the hilar portion did not statistically differ (p>0.05). Symptoms resolved or improved in 15, 24 and 20 of the 61 patients within 1 week, and 1 and 6 months, respectively, after endovascular stenting. Symptoms remained unchanged in 2 patients and recurred in 1. A perioperative complication was noted in 1 patient, that is a stent that was mistakenly moved and poorly deployed in a left renal vein collateral required operative intervention. Postoperative complications included stent migration into the right atrium, stent protrusion into the inferior vena cava and stent migration into the hilar left renal vein in 1 case each. Based on our long-term followup endovascular stenting is a safe, effective procedure in select adults. We recommend endovascular stenting as primary option for nutcracker syndrome.

Varicocele and Nutcracker Syndrome

Varicocele is a vascular lesion commonly associated with infertility. Its etiology is only partly understood; hence, the purpose of the study was to establish its correlation with intrinsic anatomic differences and nutcracker syndrome. A total of 93 patients with varicocele and 76 patients without varicocele were enrolled. The diagnosis of varicocele was based on physical examination, followed by sonographic evaluation of the hilar portion and aortomesenteric portion (AMP) of the left renal vein (LRV). The anteroposterior diameter in millimeters and peak flow in centimeters per second in each region were measured. A total of 28 patients with the nutcracker syndrome were identified in the study group (30.10%), and 2 were identified in the control group (2.63%). The mean diameters of the hilar portion and AMP of the LRV were significantly different in varicocele-affected patients compared with the control group (P < .0001 for both). The mean peak velocities in the hilar portion and AMP were significantly different in patients with varicocele (P < .0001). Patients with varicocele and nutcracker syndrome did not have a significant difference in either the hilar or AMP diameter compared with patients with varicocele without nutcracker syndrome. They had a significant difference in both the hilar and AMP peak flow velocity (P = .0001 for both). Our findings indicate that nutcracker syndrome is a frequent finding in varicocele-affected patients and should be routinely excluded as a possible cause of varicocele. In addition, intrinsic anatomic differences in the AMP and hilar portion of the LRV could be directly responsible for the onset of varicocele.

Nutcracker Syndrome in Children

The purpose of this study was to evaluate the pathophysiologic characteristics of nutcracker syndrome (NS) and to assess the role of upright position imaging and superior mesenteric artery (SMA) angle measurement in the diagnosis. Doppler sonographic findings in 23 children with NS and in 26 healthy control subjects were compared. The mesenteric angle, peak velocity (PV), and anteroposterior diameter of the left renal vein (LRV) at the hilar and aortomesenteric portions were measured in both the supine and upright positions. The means +/- SD of the SMA angle, anteroposterior diameter, and PV ratio between the two portions were calculated, and cutoff levels for the diagnosis of NS were established. The diameter and PV ratios were significantly different between the patient and control groups in both the supine and upright positions (P < .001). Differences between the supine and upright positions were also significant for the diameter of the LRV at the aortomesenteric portion, diameter ratio, and SMA angle in both groups. Upright position imaging revealed comparatively narrower SMA angles and more pronounced entrapment findings in patients with NS. The SMA angle measurement had sensitivity and specificity of 69.6% and 61.5%, respectively, in the supine position and 87.0% and 76.9% in the upright position when the cutoff values were set to less than 41 degrees and 21 degrees , respectively. The upright position has significant effects on the LRV hemodynamics and angle of the SMA in both patients and healthy subjects. Superior mesenteric artery angle measurement may be a useful adjunct parameter in the diagnosis of NS.

Effect of renal Doppler ultrasound on the detection of nutcracker syndrome in children with hematuria

To assess the detection rate of nutcracker syndrome in children with isolated hematuria, renal Doppler ultrasound examinations were routinely performed on 216 consecutive children (176 microscopic hematuria and 40 gross hematuria). Renal Doppler ultrasound was also performed on 32 healthy normal children. The peak velocity (PV) was measured at the hilar portion of the left renal vein (LRV) and at the LRV between the aorta and the superior mesenteric artery. The PV at the aortomesenteric portion (P=0.003) and the PV ratios of the LRV (P=0.003) were significantly higher in children with hematuria than in normal children, while the PV at the hilar portion was not different. If a PV ratio of the LRV of at least 4.1 (the cut-off level set at the mean ±2 SD of the value for the normal children) was defined as abnormal, 72 cases (33.3%) in children with hematuria and no cases in normal children were diagnosed as having nutcracker syndrome. The prevalence of nutcracker syndrome is relatively high in children with isolated hematuria, and the inclusion of renal Doppler ultrasound as a screening examination has a substantial effect on the detection of nutcracker syndrome.

Hemodynamic Investigation of the Left Renal Vein in Pediatric Varicocele: Doppler US, Venography, and Pressure Measurements

To evaluate prospectively the hemodynamic state of the left renal vein with Doppler ultrasonography (US) and venography in pediatric patients with varicocele to assess the "nutcracker phenomenon." The institutional review board considered this study ethically sound, and parental informed consent was obtained for all subjects. Doppler US of the left renal vein was performed in 27 consecutive boys with varicocele (age range, 7-15 years; mean, 11.9 years) and in 20 boys without varicocele as control subjects (age range, 7-17 years; mean, 11.4 years). Doppler US was used to evaluate left renal vein diameters and peak velocities in the proximal left renal vein near the renal hilum and in the left renal vein between the aorta and superior mesenteric artery (aortomesenteric portion). The diameter ratios and peak velocity ratios between two sites were obtained. For statistical comparison of results, the t test was used. Left renal venography and renocaval pressure measurement were performed in 13 patients with varicocele. The Fisher exact test was used to evaluate the associations between the nutcracker phenomenon (renocaval pressure gradient >/=3 mm Hg) and the development of collateral veins. The diameters of the proximal left renal vein and the peak velocities in the aortomesenteric portion of the left renal vein were significantly different between the varicocele group and the control group (P < .001). The diameter ratios (5.7 +/- 1.8 [standard deviation]) and peak velocity ratios (5.2 +/- 2.6) in patients with varicocele were significantly higher than those in control subjects (3.5 +/- 1.0 and 3.1 +/- 0.8, respectively) (P < .005). According to findings at left renal venography (n = 13), 10 patients (77%) met the criteria for the nutcracker phenomenon. The nutcracker phenomenon was significantly associated with the development of collateral veins (P = .035). Doppler US and venography of the left renal vein can show hemodynamic changes of the left renal vein and depict the presence of the nutcracker phenomenon in pediatric varicocele.

Nutcracker syndrome in children with gross haematuria: Doppler sonographic evaluation of the left renal vein

Nutcracker syndrome is characterized by gross haematuria caused by left renal vein (LRV) entrapment. To assess the role of LRV ultrasonography in the diagnosis of the nutcracker syndrome in children. Twelve children (eight male, four female; mean age 12.8 years) with venographically confirmed nutcracker syndrome (LRV-IVC pressure gradient > or = 3 mm Hg) underwent LRV sonography including Doppler spectral analysis (n=7). The diameter and peak velocity (PV) were measured at two sites of the LRV (renal hilum and aortomesenteric portion). The US findings of nutcracker syndrome were compared with those of 20 control subjects using the t-test. We identified the optimal cut-off value of the US parameters for the diagnosis of the nutcracker syndrome using ROC analysis. The PV at the aortomesenteric portion and the ratio of the PV between the two measured points showed significant differences between the two groups (P<0.0001). The optimum cut-off values were found to be 4.7 for the PV ratio (sensitivity 100%, specificity 90%, accuracy 93%), and 93 cm/s for the PV at the aortomesenteric portion (sensitivity 100%, specificity 85%, accuracy 89%). LRV sonography, including Doppler spectral analysis, can demonstrate LRV entrapment haemodynamically.

Factors affecting spontaneous resolution of hematuria in childhood nutcracker syndrome

To identify factors affecting spontaneous resolution of hematuria in children with nutcracker syndrome, 20 patients diagnosed as having nutcracker syndrome using renal Doppler ultrasound (US) were analyzed retrospectively. Sixteen patients had microscopic hematuria, and four had gross hematuria at presentation. The mean age was 10.6 years (range 2.5-14 years). All underwent a follow-up Doppler US examination after a mean period of 1.4 years (range 0.5-3.5 years) after the first US was performed, and height and weight were measured at the time of US. At the time of follow-up US, hematuria disappeared in 15 patients and improved in 3. The peak velocity (PV) ratios of the left renal vein (LRV) at the follow-up US decreased significantly when compared to the first US examination (7.74+/-2.64 vs 3.50+/-1.09, p<0.0001), and height (147.4+/-20.1 vs 152.3+/-18.8 cm) and weight (36.1+/-10.9 vs 42.3+/-12.7 kg) increased (p<0.0001). Changes in the PV ratios of the LRV correlated positively with changes in the PV at the aortomesenteric portion (r=0.569, p=0.009). Changes in the PV at the aortomesenteric portion correlated negatively with changes in body mass index (BMI) (r=-0.543, p=0.013). Although spontaneous resolution of hematuria in children with nutcracker syndrome is obscure, our findings suggest the increase in BMI may be a possible hemodynamic factor.

Reflux in the Left Ovarian Vein: Analysis of MDCT Findings in Asymptomatic Women

The aim of this study was to clarify the CT features of ovarian vein reflux in asymptomatic women and to determine the possible cause of the reflux. One hundred ten multiparous or uniparous and 41 nulliparous asymptomatic women were examined on MDCT. Degree, pathway, and associated findings of ovarian vein reflux were evaluated. We measured the diameters of the left renal vein (LRV), the ovarian veins, and the parauterine veins. Ratios of LRV diameters (lateral-aortomesenteric) were obtained. These data were then compared between the women with reflux and those without reflux. Reflux was found in 44% (48/110) of parous and 5% (2/41) of nulliparous women. Reflux flowed into the right ovarian vein through the parauterine and uterine veins in 25 women. Twenty-four of these 25 women were multiparous. In these cases, the parauterine veins showed varicose dilation (5.9 +/- 1.6 mm [mean +/- SD]). There was a statistically significant difference in left ovarian vein diameter (8.3 +/- 2.1 mm vs 4.9 +/- 1.3 mm, p < 0.0001) between parous women with reflux and those without reflux, respectively. The LRV diameter ratio (lateral-aortomesenteric) was also statistically significant (3.6 +/- 1.3 vs 1.7 +/- 0.7, p < 0.0001) between the same two groups. Reflux into the left ovarian vein is seen up into the contralateral ovarian plexus by passing through the dilated parauterine and uterine veins. This CT finding is common in asymptomatic multiparous women. Narrowing of the LRV at its aortomesenteric portion can be one of the causes of such reflux.

Diagnosis of nut-cracker phenomenon using renal Doppler ultrasound in orthostatic proteinuria.

We evaluated the efficacy of non-invasive renal Doppler ultrasound (US) to detect the nut-cracker phenomenon (NCP) and we studied the prevalence of NCP in children with orthostatic proteinuria. Among a total 66 cases of orthostatic proteinuria, 39 cases of NCP were found, with 27 cases being detected in a normal control group. Using Doppler US, the anteroposterior (AP) diameter and peak velocity (PV) of the left renal vein (LRV) were measured at the hilar and aortomesenteric portion. We calculated the ratio of AP and PV diameters between the two portions. The parameters were analysed using Student's t-test. The AP diameters and the ratio in the hilar and narrow portions were all significantly different between the two groups (P<0.01). The PV in the narrow portion and the ratio of PV were significantly different (P<0.01), but the PV in the hilar portion was not statistically different between the two groups (P>0.05). If the diagnostic criteria for NCP was that the ratio of PV was more than 5, then 22 subjects (56.4%) in the orthostatic proteinuria group and none in the control group could be diagnosed as NCP. If, however, the cut-off values for the diagnosis of NCP were set at the mean+/-2 SD of the ratio (PV ratio 3.98 and size ratio 4.16), then the orthostatic proteinuria group showed abnormal AP diameter in 25 (64.1%), peak velocity in 28 (71.8%), and both in 21 patients (53.8%), and the control group showed an abnormal AP diameter in one subject (3.7%). NCP may be one of the leading causes of orthostatic proteinuria, and non-invasive renal Doppler US may be a useful diagnostic tool in the screening of NCP. In the future, the diagnostic criteria of NCP must be redefined in children.