Outcome of antenatal hydronephrosis in northeastern Thailand

Background: Antenatal hydronephrosis (ANH) is a condition characterized by fetal renal pelvic dilatation during pregnancy. It is detected in 1%-5% of all pregnancies. Most cases of ANH are physiological in nature, but some are pathological and can cause morbidity.

Objective: To determine: (a) the causes of ANH; (b) the factors associated with complications; and, (c) the factors associated with surgical intervention.

Methods: We reviewed the medical records of infants diagnosed with ANH; defined by a renal pelvic anteroposterior diameter ≥5 mm (based on antenatal ultrasonography) and being followed-up at Srinagarind Hospital.

Results: Forty-six infants (32 boys and 14 girls) with ANH were identified. Over half (57%) were born in our hospital (in-hospital) with the condition. The two most common causes of ANH were ureteropelvic junction obstruction (32%) and transient hydronephrosis (22%). Of the 63 abnormal kidneys, 52% needed surgical intervention. Twenty-two patients (48%) had urinary tract infections and most had more than 1 episode. None of the 46 patients had end-stage renal disease, but one died because of lung hypoplasia during the neonatal period. The severity of ANH and time of first postnatal ultrasonography were related to medical complications, while bilateral ANH and more severe ANH were associated with the need for surgical intervention. A milder degree of ANH and postnatal ultrasound findings were significantly associated with transient hydronephrosis.

Conclusion: Most cases of ANH were pathological and half required surgical intervention. Severe ANH and delayed investigation were associated with poor outcomes.