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 2018-03-24  Case of the week # 467  © Fabien Ho  www.TheFetus.net

Answer to the case of the week # 467
March 29, 2018 - April 12, 2018
Fabien Ho1,Dr Cuillier F.1, Dr Leroy V.2, Dr Balu M3, Dr Michel J-L.4  

1. Department of Gynecology-Obstetrics, Félix Guyon Hospital, 97400 Saint-Denis, Ile de la Réunion, France. 
2. Department of Pediatrics, Pediatric Nephrology Unit, Félix Guyon Hospital, 97400 Saint-Denis, Ile de la Réunion, France. 
3. Radiology Practice, Private sector, 97400 Saint-Denis, Ile de la Réunion, France. 
4. Department of Pediatric surgery, Félix Guyon’Hospital, 97400 Saint-Denis, Ile de la Réunion, France. 



Case report

A 25-year-old woman, G3P1 (1 healthy child, 2,7kg; 1 abortion), had been followed up in out center for her third pregnancy.  Her pregnancy was discovered at 21 weeks of gestation, hence no NT nor maternal serum markers had been done. The patient was referred to our hospital at this time of the gestation. We found the following urinary anomalies in a female fetus starting from 26WG and onwards :

 


Image 1 - 26 week of pregnancy: bilateral megaureters were followed all the way from the renal pelvis to below the bladder. 

 

 



Images 2, 3, 4 and 5 - 28 weeks of pregnancy: bilateral megaureters as seen on US. The most important findings of MRI were: normal meconial filling of the colon with physiological rectal pouch, normal spinal cord and no sign of sacral defect, 
no hydrometrocolpos. These findings were important to rule out a cloacal malformation in a female fetus.
A sharp eye may witness a separate pyelix at the lower pole of the right kindney on the coronal T2 image.


   

 


Images 6, 7 and 8 - 31 weeks of pregnancy: bilateral megaureters were followed all the way down from the renal pelvis to below the bladder. Bladder was identified thanks to the umbilical arteries at its borders drawing a Y shape. Bladder did not appear distended, no internal image of ureterocele. Enlarged kidneys, with normal parenchyma.
A sharp eye may witness a separate pyelix at the lower pole of the right kindney on the axial US scan.
Oddly, calyces are not dilated and amniotic fluid remains normal, while oligohydramnios might have been expected.
Careful US examination reveals normal small bowel. Large transverse bowel is clearly seen, normal, non-dilated. Fetal anal sphincter was normal (not shown).

 

  

 

 

The mother delivered at 41 weeks of pregnancy a female baby weighting 3800 gr. Serum creatinine level and ionogram were normal on day 3. Neonatal ultrasound (images 9,10,11,12 and 13) revealed bilateral complete kidney duplication (image 11: left kidney; image 12,13: right kidney), hence a complete duplex collection system with dilation of both superior pyelices and megaureters. In such configuration, the following superior ureters classically have ectopic insertion in the bladder. Uterus appeared normal.

 

     


This is a case of megaureters in a female fetus.
The most important differential diagnosis to rule out in such clinical context in prenatal diagnosis is a persistent cloaca, for it bears a poor prognosis (severe perineal malformation with bladder extrophy and a common uro-genito-rectal sinus with or without sacral and spine cord defects). Detailed US is critical, and MRI has a significant plus-value to assess the meconial physiological colon filling and spine cord examination. In this case, cloaca has been ruled out. 

The bladder remained normally filled, non-distended: this is not a case of Lower Urinary Tract Obstruction (LUTO) (i.e. below bladder obstacle), but rather a case of bilateral lower ureter obstacle or ectopic insertion. On strict axial scan, the ureteral end-pouches were seen lower than the bladder. Uterus was not seen on prenatal imaging (no obvious hydrometrocolpos). The amniotic fluid remained oddly normal throughout pregnancy, indicating normal diuresis.

 

References:
 
1.Dias T, Sairam S, Kumarasiri S. Ultrasound diagnosis of fetal renal abnormalities. (2014) Best practice & research. Clinical obstetrics & gynaecology. 28 (3): 403-15. 
 
2.Adiego B, Martinez-Ten P, Perez-Pedregosa J, Illescas T, Barron E, Wong AE, Sepulveda W. Antenatally diagnosed renal duplex anomalies: sonographic features and long-term postnatal outcome. (2011) Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine. 30 (6): 809-15. 

3.Chen CP, Liu YP, Huang JP, Chang TY, Tsai FJ, Tsai JD, Sheu JC, Wang W. Prenatal evaluation with magnetic resonance imaging of a giant blind ectopic ureter associated with a duplex kidney. (2008) Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology. 31 (3): 360-2.

4.Whitten SM, McHoney M, Wilcox DT, New S, Chitty LS. Accuracy of antenatal fetal ultrasound in the diagnosis of duplex kidneys. (2003) Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology. 21 (4): 342-6. 
 
 
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