To obtain urine for culture when a less invasive technique is not possible. It is the most invasive method of urine collection, but also the most accurate culture source for infants and children <2 years of age when compared with urethral catheterization and bag urine specimens. It is considered the gold standard of urine specimen collections because it has a relative rate of urine culture contamination of only 1%. Any bacteria or growth (unless clearly a contaminant) from a suprapubic culture is considered abnormal and may indicate an infection. The American Academy of Pediatrics (AAP) has made recommendations for infants age 2 to 24 months to obtain a catheterization or suprapubic aspiration for any urine specimen (urinalysis and urine culture) obtained in a febrile ill infant who has no apparent source for the fever and who is planning on receiving antibiotics.
Safety-engineered needle: 23- or 25-gauge 5/8- or 1-inch needle or 21-, 22-, or 23-gauge 1.5-inch needle (larger infant) or 23-gauge butterfly (for preemie), 3- or 5-mL syringe, sterile gloves, antiseptic solution, 4 × 4 gauze pads, sterile urine culture container (per institutional guidelines), topical anesthetic cream, 1% lidocaine (with or without epinephrine), transillumination light source, or portable ultrasound (optional).
Contraindications. Empty bladder, significant bleeding disorders, significant abdominal distension, massive organomegaly cellulitis/infection at the puncture site, major genitourinary anomalies, or recent lower abdominal or urologic surgery.
Verify that voiding has not occurred within the previous hour so there will be enough urine in the bladder for the procedure by one of the following methods:
Palpate or percuss the bladder. Dullness to percussion 2 fingers above the pubic symphysis suggests urine in the bladder. The neonatal bladder extends above the pubic symphysis as it fills.
Transillumination can determine bladder height and verify the presence of urine. With the lights dim, the transillumination source is pointed at the bladder. The area will glow red if urine is present. (See Chapter 44.)
Point-of-care ultrasound of the bladder can be used to help determine the presence and volume of urine in the bladder before attempting the procedure, thus increasing the likelihood of a successful tap. Using a high frequency linear-array transducer probe, apply it in a transverse position in the midline of the lower abdomen to locate the bladder. The bladder will be a dark cavity (if filled with urine) just below the abdominal musculature, usually round, with bright margins. A minimum volume on ultrasound of 10 mL in children <2 years of age is associated with a 90% successful bladder aspiration. If the cephalocaudal diameter of the bladder (sagittal view) is >20 mm and the anteroposterior diameter is >15 to 20 mm, the success rate approaches 100%.
Pain management. The majority of studies found that pain scores were significantly higher in suprapubic aspiration when compared to transurethral catheterization.
Nonpharmacologic pain reduction procedures...