CASE 12688 Published on 23.04.2015

MDCT 3D reconstructed features of posterior urethral valve

Section

Uroradiology & genital male imaging

Case Type

Clinical Cases

Authors

Third year Resident of Radiology
French medical institute for children
Radiology Department;
Kabul, Afghanistan;
Email:hedayatullah.hamidi@gmail.com

Patient

75 days, male

Categories

Area of Interest Urinary Tract / Bladder ; Imaging Technique CT, Fluoroscopy

Procedure Contrast agent-intravenous, Computer Applications-Virtual imaging, Cystography / Uretrography ; Special Focus Congenital ;

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Clinical History

75-day-old boy was brought to a tertiary paediatric hospital with complain of gross haematuria since birth. Primary ultrasound reported bilateral hydronephrosis and hydroureter.
He was referred to the radiology department of our hospital for abdominal CT examination and subsequently Voiding Cystourethrogram.

Imaging Findings

Contrast-enhanced CT examination with 10 ml non-ionic contrast.
Figure 1:
Corticomedullary phase:
Early cortical enhancement with bilateral moderate hydronephrosis.

Figure 2
One hour delay axial, coronal and sagittal images:
Delayed contrast excretion, bilateral hydronephrosis, dilated tortuous ureters, irregularly thick-walled bladder with multiple diverticula, dilated posterior urethra with narrow end.

Figure 3:
3D VRT reconstructed images; AP, PA and lateral views:
Bilateral marked hydronephrosis and hydroureter, abnormal calibre of bladder, dilated posterior urethra with narrow end and compression line on its posterior aspect probably due to valve.

Figure 4:
Voiding Cystourethrogram (VCUG)
Irregularly thick-walled bladder with multiple diverticula, dilated and elongated posterior urethra, circumferential filling defect with central small orifice representing posterior urethral valve.

Due to very small orifice of the valve, F6 catheter could not be passed to the bladder, therefore the catheter was placed in fossa navicularis for VCUG.
Due to infant’s irritability and frequent early urination, vesicoureteral reflux was not evaluated.

Discussion

Background

Posterior urethral valve (PUV), is the most common cause of congenital lower urinary tract obstruction and subsequent bilateral renal obstruction. [1] It has an incidence of 1 in 5,000 to 8,000 male births. [2]

PUV results from formation of a thick, valve-like membrane from tissue of Wolffian duct that courses obliquely from verumontanum to the most distal portion of the prostatic urethra. [3] Essentially, the valve is a diaphragm, but because it is more rigid along its line of fusion, progressive distention during voiding causes it to become bilobed or sail-like. [4]

Clinical presentation:

Neonatal presentation may be with delayed voiding, poor urinary stream, abdominal mass, failure to thrive, poor feeding, lethargy, urosepsis or urinary ascites.
In infants, poor urinary stream and recurrent urinary tract infection are common presentations. [1] Gross haematuria is a rare presentation. [5]

Imaging workup

Maternal ultrasound is the usual method of prenatal detecting of PUV. [6] Ultrasound may detect suggesting evidence in neonates and infants as well like thickened bladder wall, dilated and elongated posterior urethra and variable degrees of hydronephrosis, but the key workup is voiding cystourethrography (VCUG). [1]

VCUG findings are thickened trabeculated bladder, dilated and elongated posterior urethra and vesicoureteric reflux. [1] The bladder neck becomes hypertrophic and appears narrow in relation to the dilated posterior urethra. [2] Occasionally, a linear radiolucent band can be seen corresponding to the valve. [7]

Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) are not routinely used in the diagnostic workup, however, they may reveal dysplastic and/or dilated kidneys with delayed renal function and excretion, hydroureter, dilated bladder with wall thickening, trabeculation, and diverticula. A dilated posterior urethra might be seen, although leaflets may be easily missed. [8]

Features of 3D reconstructed CT images are not described in the literature.

Here we present the contrast-enhanced Multidetector CT images with 3D reconstructed Virtual rendered images of this infant with unusual presentation (gross haematuria) of posterior urethral valve. A VCUG image with typical posterior urethral valve of the same patient is also included.

These Multiplanar reconstruction (MPR) and 3D Virtual rendered technique (VRT) reconstructed images depict all the features of posterior urethral valve:

- Bilateral significant hydronephrosis
- Dilated and tortuous bilateral ureters
- Irregular outlines of the urinary bladder with thickened walls and diverticula formation
- Dilated posterior urethra with narrow end and compression line in posterior aspect probably due to the valve

However, due to high radiation dose, CT is not the imaging modality of choice for evaluation of this entity especially in infants.

Differential Diagnosis List

Posterior urethral valve

Prune belly syndrome

Anterior urethral valves

Final Diagnosis

Posterior urethral valve

References

[1] Nasir AA, Ameh EA, Abdur-Rahman LO (2011) Posterior urethral valve. World J Pediatr 7:205-216. (PMID: 21822988)

[2] Krishnan A, de Souza A, Konijeti R, Baskin LS. (2006) The anatomy and embryology of posterior urethral valves. J Urol 175:1214-1220. (PMID: 16515962)

[3] Berrocal T1, López-Pereira P, Arjonilla A, Gutiérrez J. (2002) Anomalies of the distal ureter, bladder, and urethra in children: embryologic, radiologic, and pathologic features. Radiographics 22(5):1139-64 (PMID: 12235344)

[4] Cremin BJ (1975) The “spinnaker sail” appearance of the posterior urethral valve in infants. J Can Assoc Radiol 26:188–196. (PMID: 1194326)

[5] Diamond DA, ford C. (1992) Neonatal gross hematuria as a presenting sign of posterior urethral valves. Urology 40: 267–269 (PMID: 1523754)

[6] Dinneen MD, Dhillon HK, Ward HC (1993) Antenatal diagnosis of posterior urethral valves. Br J Urol 72:364–369. (PMID: 8220998)

[7] Chatterjee SK, Banerjee S, Basak D, et al. (2001) Posterior urethral valves: the scenario in a developing center. Pediatr Surg Int 17:2–7. (PMID: 11294260)

[8] John S Wiener, (2013) Posterior Urethral Valve Imaging. http://emedicine.medscape.com/article/412226-overview#showall May 29

Case information

URL:	https://www.eurorad.org/case/12688
DOI:	10.1594/EURORAD/CASE.12688
ISSN:	1563-4086

Figure 1

CT image of kidneys, bladder and urethra

Coronal CT section through the midline. Image taken one hour after IV contrast injection. Bilateral significant hydronephrosis, dilated toruous ureters, thick-walled urinary bladder wall thickening with irregular outlines and dilated distal urethra are seen.

Sagittal CT section through the midline. Image taken one hour after IV contrast injection. Abnormal calibre of urinary bladder lumen and neck. Significantly dilated and elongated posterior urethra with narrow end.

Axial CT section at the level of the urinary bladder neck. Image taken one hour after IV contrast injection. Thick-walled urinary bladder with hypertrophied bladder neck between urinary bladder and dilated posterior urethra.

Figure 2

VCUG

Voiding Cystourethrography image: Irregularly thick-walled urinary bladder with multiple diverticula formation. Dilated and elongated posterior urethra. Circumferential filling defect with central small orifice representing posterior urethral valve.

Figure 3

Corticomedullary phase: Bilateral hydronephrosis

Contrast-enhanced CT corticomedullary phase. Coronal section through both kidnes shows bilateral moderate hydronephrosis.

Figure 4

3D VRT reconstructed images

3D virtual rendered reconstructed image, anterioposterior view. Bilateral significant hydronephrosis and hydroureter, abnormal calibre of bladder and dilated posterior urethra.

3D virtual rendered reconstructed image, posterioanterior view. Bilateral significant hydronephrosis and hydroureter, abnormal calibre of bladder and significantly dilated posterior urethra with narrow end and compression line in posterior aspect probably due to the valve.