Absent/Small Bladder



Absent/Small Bladder


Paula J. Woodward, MD



DIFFERENTIAL DIAGNOSIS


Common



  • Normal


  • Bilateral Renal Anomalies



    • Bilateral Multicystic Dysplastic Kidneys


    • Bilateral Ureteropelvic Junction Obstructions


    • Bilateral Renal Agenesis


  • Autosomal Recessive Polycystic Kidney Disease


Less Common



  • Severe IUGR


  • Twin-Twin Transfusion Syndrome


Rare but Important



  • Bladder Rupture


  • Bladder Exstrophy


  • Cloacal Exstrophy


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Reasons for absent/small bladder



    • Urine is not be produced



      • Primary renal anomaly


      • Poor fetal perfusion leading to poor fetal urine production: Twin-twin transfusion syndrome (TTTS), severe intrauterine growth restriction (IUGR)


      • Bladder not truly absent, just not seen because of lack of distention


    • Bladder is “leaking”



      • Cloacal exstrophy


      • Bladder exstrophy


      • Bladder rupture


  • Amniotic fluid assessment is important part of identifying cause of absent/small bladder



    • Oligohydramnios/anhydramnios in singleton



      • Renal agenesis


      • Bilateral multicystic dysplastic kidneys (MCDK)


      • Bilateral uteropelvic junction (UPJ) obstructions


      • Autosomal recessive polycystic kidney disease (ARPKD)


      • Intrauterine growth restriction (IUGR)


    • Twin with oligohydramnios



      • TTTS or any of the above fetal anomalies


    • Normal or increased fluid suggests abdominal wall defect as cause of absent bladder



      • Bladder exstrophy


      • Cloacal exstrophy


  • Document bladder on every exam



    • Normal bladder will be flanked on either side by the umbilical arteries



      • Seen best in axial plane


Helpful Clues for Common Diagnoses



  • Normal



    • Bladder filling/voiding is dynamic & changes during course of examination



      • Recheck at end of exam if bladder is empty at beginning


    • If amniotic fluid & kidneys are otherwise normal, then a pathologic process is unlikely


  • Bilateral Multicystic Dysplastic Kidneys



    • Renal tissue replaced by cysts of varying sizes


    • Affected kidneys are non-functional


    • Unilateral MCDK has normal bladder & amniotic fluid


    • Bilateral MCDK has no visualized bladder or amniotic fluid



      • Bilateral in 20%


    • Contralateral renal anomaly (non-MCDK) in 40%



      • If severe (e.g., agenesis), may also result in no urine production


  • Bilateral Ureteropelvic Junction Obstructions



    • Calyceal & pelvis distention which ends abruptly at UPJ


    • ↑ Risk of renal impairment if prenatal AP diameter > 10 mm


    • 10% bilateral



      • Can progress causing complete obstruction with “absent” bladder & anhydramnios


  • Bilateral Renal Agenesis



    • No demonstrable renal tissue


    • Flattened, discoid adrenals in renal fossa


    • No urine in fetal bladder


    • Anhydramnios


  • Autosomal Recessive Polycystic Kidney Disease



    • Bilateral, large, echogenic kidneys



      • Normal hypoechoic cortex may be seen



      • Look for thin hypoechoic rim around echogenic medulla


    • Degree of bladder filling & amniotic fluid is variable depending on severity of disease


Helpful Clues for Less Common Diagnoses



  • Severe IUGR



    • Placental insufficiency most common cause



      • Usually late onset, asymmetric IUGR


    • High resistance placental perfusion



      • Blood returning to fetus shunted to cerebral and coronary circulations


      • ↓ Renal perfusion → ↓ urine production → “absent” bladder + oligohydramnios


  • Twin-Twin Transfusion Syndrome



    • Monochorionic twins with artery-to-vein anastomoses in placenta


    • Donor twin partly perfuses recipient twin


    • Fetuses often discordant in size



      • Donor small, recipient large


    • Donor twin: Oligemic → ↓ urine production → “absent” bladder + oligohydramnios



      • Amniotic membrane tightly adherent, giving a “shrink-wrapped” appearance


      • May appear suspended from uterine wall


    • Recipient twin: Plethoric, polyhydramnios, at risk for hydrops


    • Presence of urine in bladder important in staging TTTS



      • Stage 1: Donor bladder visible, normal Doppler


      • Stage 2: Donor bladder empty, normal Doppler


      • Stage 3: Donor bladder empty, abnormal Doppler


      • Stage 4: Hydrops in recipient


      • Stage 5: Demise of one or both


Helpful Clues for Rare Diagnoses

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Aug 10, 2016 | Posted by in OBSTETRICS | Comments Off on Absent/Small Bladder

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