Perinatal Urinary Tract Dilation — Management Based on Prenatal Ultrasound Risk Stratification — Clinical Pathway: Inpatient, Outpatient Specialty Care and Primary Care

Perinatal Urinary Tract Dilation Clinical Pathway — ICU, Inpatient, Outpatient Specialty Care, Primary Care

Management Based on Prenatal Ultrasound Risk Stratification

  • Ultrasound Findings of UTD
  • Central or peripheral calyceal dilation
  • Abnormal parenchymal thickness
  • Abnormal parenchymal appearance
  • Abnormal ureters
  • Abnormal bladder
  • Abnormal urethra

16-27 weeks AP RPD ≥ 10mm, even if ≥ 28 weeks is < 7mm, should follow guidelines for A1.
(e.g. A2-3 UTD in the 2nd trimester that resolves in the 3rd trimester should have follow-up)

16-27 weeks AP RPD 4 to 6.9 mm with repeat AP RPD at ≥ 28 weeks < 7 mm does not require postnatal follow-up unless there is another clinical concern.
(e.g. A1 UTD in the 2nd trimester that resolves in the 3rd trimester does not require follow-up)

UTD Management Based on Prenatal Ultrasound Risk Stratification

Low Risk (A1) Unilateral 7 to < 10 mm
  • Urology
    • Follow-up as outpatient in Urology at 2-8 weeks with RBUS
  • Ultrasound
    • Obtain at 2-8 weeks of age
  • Antibiotics
    • No antibiotics recommended
  • VCUG/CeVUS
    • Not recommended
Bilateral 7 to < 10 mm
Increased Risk (A2-3) Unilateral or bilateral ≥ 10 mm and/or any abnormal ultrasound finding
  • Urology
    • Consult or call urology while inpatient
  • Ultrasound
    • Obtain at ≥ 24 hours of age at birth hospital
  • Antibiotics
    • Begin ABX after ultrasound obtained
      • Amoxicillin 10 mg/kg PO QD
      • Continue antibiotics until follow-up with urology
  • VCUG/CeVUS

Prenatally detected UTD is often transient. However, there can be significant causes that would require surgical treatment and it is critical to identify these patients. Ureteropelvic junction (UPJ) obstruction may be present in 10-30% of antenatally detected UTD, VUR in 10-20%, UVJ obstruction in 5-10%, and posterior urethral valves in 1-2%. Other rare diagnoses that can have significant impacts1. It is also important to note that 25-33% of patients will worsen over time, so ongoing observation is essential2. The UTD grading system helps predict which patients are at increased risk of developing urinary tract infections (UTIs), require VUR imaging, and potentially need surgical intervention; those with increased risk (A2/A3) have been shown to have a higher likelihood of all events than those with prenatal A1 risk stratification.3

Regarding the use of antibiotic prophylaxis or earlier follow-up (i.e., imaging or appointment), all practitioners should use their clinical judgment.

In the case of inadequate information about the extent of presumed mild fetal urinary tract dilation, follow the recommendations for A1 unilateral or bilateral depending on the fetal imaging.

References

  • 1. Nguyen, Herndeon, Cooper. The Society for Fetal Urology consensus statement on the evaluation and management of antenatal hydronephrosis.
  • 2. Davenport, Merguerian, Koyle. Antenatally detected hydronephrosis: current postnatal management. Ped Surg Int 2013.