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I. PROBLEM

The nurse alerts you that the infant has had decreased urine output for the past 24 hours. In a newborn, passage of the first urine is usually a sign of well-being, and if no urine output is seen by 24 hours of life, the infant should be evaluated. The following are common definitions relating to urine output:

  1. Normal urine output: ≥2mL/kg/h after the first 24 to 48 hours (<1 mL/kg/h the first 12–18 hours of life).

  2. Oliguria is defined as urine output <0.5 to 1.0 mL/kg/h for 24 hours.

  3. Anuria is defined as absence of urine output usually by 48 hours of age.

    Decreased urine output can be from undocumented voiding, stressful or prolonged delivery, oliguria typically seen in the first 24 hours of life or in a premature infant, mild dehydration, syndrome of inappropriate antidiuretic hormone (SIADH), acute kidney injury (AKI), or chronic kidney disease.

II. IMMEDIATE QUESTIONS

  1. Was the infant born in the past 24 hours? At birth, a normal infant has approximately 6 to 44 mL of urine in the bladder. In 1977, Clark reported that 100% of healthy premature, full-term, and postterm infants void by 24 hours of age. Mataj and colleagues (2003) reported that 17% of infants void at birth, 92% by 24 hours, and 99% by 48 hours.

  2. Is the bladder palpable? If a distended bladder is present in an infant, it is usually palpable. A palpable bladder suggests there is urine in the bladder. Credé maneuver (manual compression of the bladder) may initiate voiding, especially in infants receiving medications causing muscle paralysis.

  3. Has bladder catheterization been performed? Catheterization determines whether urine is present in the bladder. It is commonly done in more mature infants.

  4. Is the infant term or premature? Term infants are more likely to have delayed voiding than preterm infants (Table 73–1). Premature infants <32 weeks are at increased risk of AKI because of their immature kidneys and increased risk of hypovolemia.

  5. What is the blood pressure? Hypotension can cause decreased renal perfusion and urine output. Hypertension may indicate renal/renovascular disease (if severe, suspect renal artery or venous thrombosis).

  6. Was the delivery prolonged or stressful? Delayed voiding can be related to a prolonged and stressful birth. A study showed that infants with delayed voiding (>24 hours) were more likely to have primiparous mothers; in addition, the duration of labor was longer (first and second stage) in these infants, and they had abnormal electronic fetal monitoring. Stress increases ADH (arginine vasopressin) and aldosterone levels, which decreases urine output. Both ADH and aldosterone levels were increased in these infants with delayed voiding and stressful birth.

  7. Has the infant ever voided? Did the infant void, and was it not recorded on the bedside chart? Table 73–1 shows the time after birth at which the first voiding occurs. Remember: Voiding can be missed (occurred in the delivery room or with the parents and was ...

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