Excretory Case Study 4

Fetal UTI Case Study


A pregnant 25-year-old woman was referred for evaluation of a fetal lower urinary tract obstruction. Initial ultrasound evaluation at 20 weeks gestation revealed a male fetus with a significantly enlarged bladder, severely decreased amniotic fluid volume (oligohydramnios). The sonographic appearance of the fetal bladder was that of a “keyhole sign,” indicating a proximal urethral obstruction.  No other anomalies were visualized. The fetal echocardiogram was normal.


The family was counseled regarding the natural history of bladder outlet obstruction, and the associated poor prognosis if left untreated.  The family chose to proceed with an evaluation to assess renal function. Three ultrasound guided bladder drainages were performed at intervals two days apart. Chorionic villous sampling was also performed to rule out a fetal chromosomal anomaly that occurs in 6 to 8  percent of such cases. Results revealed normal male chromosomes (46, XY). The urine electrolytes and proteins revealed a borderline pattern.  One kidney was suspected to be damaged as indicated by its echogenic appearance and the presence of several cysts within the renal tissue. The other kidney, however, demonstrated minimal increased echogenicity, had no visible cortical cysts and was presumed to be less damaged.  Urine from this kidney showed only a mild degree of damage with potential for salvage with intervention.


After treatment, delivery occurred vaginally at 36 weeks following spontaneous onset of labor. The baby had a vesicostomy placed after delivery, followed by correction of the outlet obstruction. One kidney was damaged with minimal function, while the other continues to function normally. The child is now thriving, happy and 5 years old.



1. Explain the role of the nephron in excretory system biochemistry.


2. Why is it important to differentiate between a bladder infection and a kidney infection? What is the function of the kidneys compared to the bladder?


3. Is urine normally sterile? Are bacteria, leukocytes and "casts" normal in a urine sample? What is their diagnostic significance? 


4. Can amniotic fluid be of diagnostic value in this case? Explain.


5. How common are lower tract urinary obstructions?


6. What is the probable cause of the obstruction in the fetus?


7. What is the probability  of the patient having a second child with this conditions?


8. Discuss treatment options for the fetal patient, pre- and post- delivery.