Question

A 32-year-old woman, gravida 2, para 1, at 32 weeks gestation comes to the physician for a routine prenatal visit. Her pregnancy has been uncomplicated. Vital signs are within normal limits. Ultrasonography shows a female fetus with moderately severe unilateral hydronephrosis and a normal contralateral kidney; the amniotic fluid volume is normal. Which of the following is the most appropriate next step in management?

A) Term delivery
B) Administration of prenatal diuretics
C) Induction of labor at 33 weeks gestation
D) Amniocentesis
E) In utero surgical urinary diversion of the hydronephrotic kidney

Correct Answer: Option A Term delivery

Ureteropelvic junction (UPJ) obstruction
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🧠 Key Insight: Most common cause of fetal hydronephrosis
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 Urine flow ⬇️ from affected kidney due to obstruction
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Urine accumulation in renal pelvis → Hydronephrosis (dilation)
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Unilateral obstruction (only one kidney affected)
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🧠 Key Insight: Contralateral kidney compensates, maintaining function
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Normal contralateral kidney maintains urine production
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 Amniotic fluid volume normal
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🧠 Key Insight: Adequate amniotic fluid indicates sufficient fetal kidney function
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No signs of fetal distress: Stable condition for the fetus
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🧠 Key Insight: Conservative management is appropriate
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 Management Decision:

Option A: Term delivery
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🧠 Correct Answer: Allows for normal fetal development and evaluation post-delivery

Why Other Answers Are Wrong?

B) Administration of prenatal diuretics:
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🧠 Wrong: Diuretics will not treat the structural problem of UPJ obstruction and can cause complications like oligohydramnios

C) Induction of labor at 33 weeks:
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🧠 Wrong: Induction of labor preterm (33 weeks) increases the risk of complications for the fetus, such as respiratory distress, with no benefit as the fetal condition is stable

D) Amniocentesis:
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🧠 Wrong: There is no evidence of chromosomal or genetic abnormalities; amniocentesis is not indicated in this scenario

E) In utero surgical urinary diversion:
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🧠 Wrong: Invasive intervention is reserved for severe bilateral hydronephrosis with oligohydramnios → This fetus has unilateral hydronephrosis and normal amniotic fluid

Flashcards

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