From the Guidelines
The workup for delayed passage of urine in newborns should begin with a thorough history and physical examination, focusing on the timing of the first void, and initial assessment should include checking for bladder distention by palpation or bedside ultrasound, reviewing maternal medication history, and assessing for signs of dehydration. The initial evaluation should prioritize the identification of potential causes of urinary retention, such as posterior urethral valves in males or other anatomic abnormalities. Normally, 95% of newborns void within 24 hours of birth, and nearly all should void by 48 hours. If a newborn hasn't passed urine by 24-48 hours, immediate evaluation is warranted. Laboratory tests should include serum electrolytes, blood urea nitrogen, and creatinine to evaluate kidney function. A renal ultrasound should be performed promptly to assess for urinary tract abnormalities such as posterior urethral valves in males, urethral strictures, or ureteropelvic junction obstruction, as recommended by the American College of Radiology 1. If the bladder is distended, catheterization may be necessary both diagnostically and therapeutically. For persistent concerns, further imaging such as a voiding cystourethrogram (VCUG) may be indicated to evaluate for vesicoureteral reflux or other anatomic abnormalities, particularly in cases of moderate or severe hydronephrosis 1. However, routine VCUG is not recommended after the first urinary tract infection, according to the American Academy of Pediatrics 1. Consultation with pediatric urology or nephrology is appropriate if structural abnormalities are identified or if the infant remains anuric despite normal fluid status. Early diagnosis is critical as prolonged obstruction can lead to kidney damage, while prompt intervention can preserve renal function. Key considerations in the workup include:
- Timing of the first void
- Maternal medication history
- Signs of dehydration
- Bladder distention
- Urinary tract abnormalities
- Need for catheterization or further imaging.
From the Research
Delayed Passage of Urine in Newborns
- Delayed passage of urine in newborns is a concern that requires prompt evaluation and management.
- A study published in 1991 2 found that delayed passage of the first urine (greater than 24 hours) was noted in 4% of adequate birth weight infants and 3.8% of low birth weight infants.
Causes and Risk Factors
- The causes of delayed passage of urine in newborns are not well understood, but may be related to factors such as gestational age, birth weight, and presence of respiratory distress syndrome.
- A study published in 2015 3 summarizes the initial assessment of normal newborns and describes common variations that may occur, but does not specifically address delayed passage of urine.
Diagnosis and Management
- There is limited information available on the diagnosis and management of delayed passage of urine in newborns.
- Studies on acute urinary retention in adults 4, 5, 6 provide information on the causes, diagnosis, and management of this condition, but may not be directly applicable to newborns.
- A thorough history, physical examination, and selected diagnostic testing may be necessary to determine the cause of delayed passage of urine in newborns.
- Management may involve supportive care, such as monitoring of urine output and overall health, and may require consultation with a pediatric specialist.