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  1. To collect a urine specimen for culture when a suprapubic aspiration is contraindicated or cannot be performed and a clean-catch specimen is unsatisfactory. Bladder catheterization is an alternative to suprapubic aspiration. It has a higher false-positive rate than suprapubic aspiration (relative rate of urine culture contamination of 6%–12%) and can also introduce bacteria and cause a urinary tract infection. The American Academy of Pediatrics (AAP) has made recommendations to obtain a catheterization or suprapubic aspiration for any urine specimen (urinalysis and urine culture) obtained in a febrile ill infant who is >2 months of age, who has no apparent source for the fever, and who is planning on getting antibiotics.

  2. To monitor urinary output, relieve urinary retention, or to instill contrast to perform cystourethrography.

  3. To determine a bladder residual urine volume.

  4. To place contrast for diagnostic cystography.


Sterile gloves, cotton balls, povidone-iodine solution, sterile drapes, lubricant gel, a sterile collection bottle (often packaged together as a commercial set), and choice of catheter (see below); point-of-care ultrasound, if available.

  1. Urethral catheters. Use the smallest catheter possible. (Note: balloon retention catheters [eg, Foley] are not used in newborns.) Recommendations on urethral catheter choice vary widely; follow your institution’s guidelines if available.

    1. Commercially available urethral catheter sizes: 3.5, 5.0, 6.5, and 8F.

    2. Urethral catheter size recommendations by weight

      1. 3.5F for weight <1000 g.

      2. 5F for weight 1000 to 1800 g.

      3. 6.5F for weight 1800 to 4000 g.

      4. 8F for weight >4000 g.

    3. National Association of Neonatal Nurses (NANN) recommendations: 3.5F for weight <1000 g; 5F for weight 1000 to 1800 g; 8F for weight >1800 g.

    4. Feeding tubes. When used as an alternative, they may increase the risk of trauma or knotting (commercial urethral catheters are softer and not as long). A 5F feeding tube is sometimes used but not generally preferred.

    5. Umbilical catheter. May be used as an alternative: 3.5F for weight <1000 g; 5F for weight >1000 g.


  1. When performing catheterization to obtain a specimen, it is best to wait until 1 to 2 hours after voiding.

  2. POCUS of the bladder. Ultrasound of the bladder can help determine if there is sufficient urine in the bladder. Use a high frequency linear array transducer probe and apply it in a transverse position in the midline of the lower abdomen to locate the bladder. The bladder will be a dark cavity with a thin wall that is echogenic. Measure the urinary bladder index measurement (product of anteroposterior and transverse diameters, expressed in centimeters squared), which will identify whether there is sufficient urine in the bladder. A urinary bladder index <2.4 cm2 means there is lack of urine volume and the catheterization may be unsuccessful. A urinary bladder index >2.4 cm2 suggests an adequate urine volume. An ultrasound of the bladder at the bedside led to an increased ...

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