Figure 1
Colour Doppler
Colour Doppler USG images showing left sided hydronephrosis with an aberrant inferior polar renal artery arising from the aorta and crossing the UPJ
Congenital UPJ obstruction due to an abberant accessory renal artery
SectionUroradiology & genital male imaging
Case TypeClinical Cases
Authors
Ibne Ahmad1, Sanna Kirmani2, Muddassir Rashid3.
1) Professor, Department of radiodiagnosis, jawaharlal nehru medical college and hospital, AMU Aligarh, UP, India. 2) Department of radiodiagnosis, jawaharlal nehru medical college and hospital, AMU Aligarh, UP, India.3)Department of medical imaging, The royal children hospital, Melbourne, Australia.
Connected authors
10 years, male
Clinical History
A 10 year old boy presented in surgery outpatient department with history of dull aching, intermittent and non radiating pain in left flank, off and on for past 2 years. There was no history of fever, burning during micturition or hematuria. On examination there was mild tenderness in left flank region.
Imaging Findings
The patient was referred to the department of radiodiagnosis and X- ray KUB was advised. No radio-opaque lesion, signifying a calculus, could be detected on X-ray.
Further patient was advised USG abdomen, which revealed dilated pelvicalyceal system on left side with abrupt tapering of the dilated pelvis at the UPJ (ureteropelvic junction). There was no evidence of obstructing calculus at the UPJ. Doppler USG revealed normal renal vasculature, however scanning inferiorly through the left kidney; an aberrant accessory renal artery crossing the UPJ posteriorly was noted.
A computed tomography (CT) scan of the abdomen was performed which showed dilated renal collecting system on left side with a vessel arising from the abdominal aorta crossing adjacent and posterior to the UPJ, located under the point of the UPJ obstruction.
Further patient was advised USG abdomen, which revealed dilated pelvicalyceal system on left side with abrupt tapering of the dilated pelvis at the UPJ (ureteropelvic junction). There was no evidence of obstructing calculus at the UPJ. Doppler USG revealed normal renal vasculature, however scanning inferiorly through the left kidney; an aberrant accessory renal artery crossing the UPJ posteriorly was noted.
A computed tomography (CT) scan of the abdomen was performed which showed dilated renal collecting system on left side with a vessel arising from the abdominal aorta crossing adjacent and posterior to the UPJ, located under the point of the UPJ obstruction.
Discussion
UPJ obstruction ascribes to various causes of impaired drainage at the UPJ. Regardless of the cause, the end result is the same: impedance in the normal flow of urine from the renal pelvis into the ureter, resulting in hydronephrosis and renal damage.
UPJ obstruction may be due to intrinsic or extrinsic causes. Intrinsic physiological defects at the UPJ are responsible for most of the cases in paediatric population. Anomalous number and arrangement of smooth muscle cells and excessive deposition of collagen, causing peristaltic dysfunction, have been implicated in intrinsic UPJ obstruction. Causes of extrinsic UPJ obstruction included bands of tissue, crossing vessels, high insertions of the ureter on the renal pelvis and retroperitoneal fibrosis.
Crossing vessels compressing or distorting the UPJ may be the sole cause of ureteral outflow obstruction. Alternatively, they may coexist with other causes of UPJ obstruction. These aberrant vessels may arise from the aorta, IVC or renal vessels itself. Van Cangh et al (1) reported that crossing vessels had a statistically significant negative effect on the outcome of endoureteropyelotomy, reducing the success rate from 82% to 33%. Aberrant lower polar crossing vessels, as a cause of pelviureteric junction (PUJ) obstruction, have a reported incidence between 11-49% (2).
These crossing vessels at the UPJ may be arteries, veins or both. They may cross anterior or posterior to the UPJ. Exact determination of the nature of the vessels (artery or vein), relation with the UPJ (anterior or posterior) and their number can be achieved with current diagnostic modalities
Vascular PUJ obstruction presents particular clinical and imaging features within the spectrum of congenital hydronephrosis. Its intermittent nature may
explain why it is detected later in life (2,3) .
Doppler ultrasonography, CT scan, MR imaging and DSA can depict vascular causes of UPJ obstruction. However, newer diagnostic modalities such as endoluminal ultrasonography(EUS) and CTA have replaced the conventional imaging modalities. EUS although an invasive procedure, has been shown to be superior to CT angiography for detecting crossing vessels (4). It can also aid in pre operative localization of the vessels so as to direct the incision away from them.
Helical CT can also provide an accurate depiction of renal vasculature. When compared with selective renal angiography and surgical findings, helical CT proved to depict 96-100% of the renal arteries (5,6). Helical CT and EUS provide similar accuracy in the diagnosis of crossing vessels. Khaira et al(7) reported a sensitivity of 91% and specificity of 100% with the helical computed tomography with 3D reconstructions for the identification of crossing vessels in UPJ obstruction.
MR imaging including MR urography and MRA are non invasive diagnostic techniques for the detection of aberrant vessels. MR urography can also delineate the anatomic and functional information to a better extent then sonography and renal scintigraphy.
MR urography can identify the patients who will benefit most from pyeloplast(8).
Dismembered Anderson-Hynes pyeloplasty with pelvi-ureteric re-anastomosis remains the mainstay of treatment in such patients to avoid the vascular complications that may be associated with endoscopic pyelotomy.
UPJ obstruction may be due to intrinsic or extrinsic causes. Intrinsic physiological defects at the UPJ are responsible for most of the cases in paediatric population. Anomalous number and arrangement of smooth muscle cells and excessive deposition of collagen, causing peristaltic dysfunction, have been implicated in intrinsic UPJ obstruction. Causes of extrinsic UPJ obstruction included bands of tissue, crossing vessels, high insertions of the ureter on the renal pelvis and retroperitoneal fibrosis.
Crossing vessels compressing or distorting the UPJ may be the sole cause of ureteral outflow obstruction. Alternatively, they may coexist with other causes of UPJ obstruction. These aberrant vessels may arise from the aorta, IVC or renal vessels itself. Van Cangh et al (1) reported that crossing vessels had a statistically significant negative effect on the outcome of endoureteropyelotomy, reducing the success rate from 82% to 33%. Aberrant lower polar crossing vessels, as a cause of pelviureteric junction (PUJ) obstruction, have a reported incidence between 11-49% (2).
These crossing vessels at the UPJ may be arteries, veins or both. They may cross anterior or posterior to the UPJ. Exact determination of the nature of the vessels (artery or vein), relation with the UPJ (anterior or posterior) and their number can be achieved with current diagnostic modalities
Vascular PUJ obstruction presents particular clinical and imaging features within the spectrum of congenital hydronephrosis. Its intermittent nature may
explain why it is detected later in life (2,3) .
Doppler ultrasonography, CT scan, MR imaging and DSA can depict vascular causes of UPJ obstruction. However, newer diagnostic modalities such as endoluminal ultrasonography(EUS) and CTA have replaced the conventional imaging modalities. EUS although an invasive procedure, has been shown to be superior to CT angiography for detecting crossing vessels (4). It can also aid in pre operative localization of the vessels so as to direct the incision away from them.
Helical CT can also provide an accurate depiction of renal vasculature. When compared with selective renal angiography and surgical findings, helical CT proved to depict 96-100% of the renal arteries (5,6). Helical CT and EUS provide similar accuracy in the diagnosis of crossing vessels. Khaira et al(7) reported a sensitivity of 91% and specificity of 100% with the helical computed tomography with 3D reconstructions for the identification of crossing vessels in UPJ obstruction.
MR imaging including MR urography and MRA are non invasive diagnostic techniques for the detection of aberrant vessels. MR urography can also delineate the anatomic and functional information to a better extent then sonography and renal scintigraphy.
MR urography can identify the patients who will benefit most from pyeloplast(8).
Dismembered Anderson-Hynes pyeloplasty with pelvi-ureteric re-anastomosis remains the mainstay of treatment in such patients to avoid the vascular complications that may be associated with endoscopic pyelotomy.
Differential Diagnosis List
UPJ obstruction due to abberant accessory renal artery
UPJ obstruction due to vascular( extrinsic) cause
UPJ obstruction due to physiological( intrinsic) cause
Final Diagnosis
UPJ obstruction due to abberant accessory renal artery
References
[1] Van Cangh PJ, Nesa S, Galeon M, et al. (1996) Vessels around the ureteropelvic junction: significance and imaging by conventional radiology. J Endourol 10:111–119 (PMID: 8728675)
[2] Rooks VJ, Lebowitz RL (2003) Extrinsic ureteropelvic junction obstruction from a crossing renal vessel: Demography and imaging. Pediatr Radiol 31:120-4
[3] Lowe FC, Marshall SF. (1984) Ureteropelvic junction obstruction in adults. Urology 23: 331–5
[4] Keeley FX, Moussa SA, Miller J, Tolley DA. (1999) A prospective study of endoluminal ultrasound versus computerised tomography angiography for detecting crossing vessels at the ureteropelvic junction. J Urol 162: 1938–41
[5] Cochran ST, Krasny RM, Danovitch GM (1997) Helical CT angiography for examination of living renal donors. AJR 168: 1569-1573
[6] Galansky M, Prokop M, Chavan A, Schaefer CM, Jandeliet K, Nischelsky JE. (1993) Renal artery stenosis: spiral CT angiography. Radiology 189: 185-192
[7] Khaira HS, Platt JF, Cohan RH, Wolf JS, Faerber GJ. (2003) Helical computed tomography for identification of crossing vessels in ureteropelvic junction obstructioncomparison with operative findings. Urology 62: 35-39
[8] Stephen B. Little & Richard A. Jones & Stephen B. (2008) Evaluation of UPJ obstruction before and after pyeloplasty. Pediatr Radiol 38 (Suppl 1):S106–S124
Case information
| URL: | https://www.eurorad.org/case/8916 |
| DOI: | 10.1594/EURORAD/CASE.8916 |
| ISSN: | 1563-4086 |
Figure 2
Colour Doppler
Normal renal vasculature of the same patient on Colour Doppler USG.
Figure 3
Axial contrast enhanced helical CT
Axial contrast enhanced helical CT showing left sided hydronephrosis with an accessory renal artery crossing posterior to the UPJ.
Colour Doppler
Colour Doppler USG images showing left sided hydronephrosis with an aberrant inferior polar renal artery arising from the aorta and crossing the UPJ
Colour Doppler
Normal renal vasculature of the same patient on Colour Doppler USG.
Axial contrast enhanced helical CT
Axial contrast enhanced helical CT showing left sided hydronephrosis with an accessory renal artery crossing posterior to the UPJ.