25: Bladder Aspiration (Suprapubic Urine Collection)

To obtain urine for culture when a less invasive technique is not possible. It is the most accurate and preferred culture source for infants and children <2 years of age when compared with urethral catheterization and bag urine specimens. Any bacteria or growth on a suprapubic culture is considered abnormal and requires treatment. Other common terms include suprapubic bladder aspiration (SBA), suprapubic aspiration (SPA), and bladder tap.

Safety-engineered needle: 23- or 25-gauge 1-inch needle or 21- to 22-gauge 1.5-inch needle (large infant) or 23-gauge butterfly (for preemie) attached to a 3-mL syringe, sterile gloves, povidone-iodine solution, 4 × 4 gauze pads, gloves, and sterile container; transillumination light source or portable ultrasound recommended.

1. Contraindications. Empty bladder, thrombocytopenia, presence of abdominal distension, bleeding disorders, genitourinary anomalies, cellulitis at the site, after recent lower abdominal or urologic surgery.

2. Note that before the age of 2 years, the bladder is an abdominal organ and this makes the procedure easier. After 2 years of age, the bladder moves into the pelvis.

3. Verify that voiding has not occurred within the previous hour so there will be enough urine in the bladder for the procedure. Has there been a recent wet diaper? Is the diaper wet now?

   1. 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.

   2. 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 40).

   3. Ultrasound of the bladder can help determine the size and location of the bladder and the volume of urine in the bladder. Portable ultrasound can significantly improve the diagnostic yield; a minimum volume on ultrasound of 10 mL 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 mm, the success rate approaches 100%.

4. Pain management. This procedure is significantly more painful than transurethral catheterization (as evidenced by brow bulging in one study). Nonpharmacologic pain procedures can be used. EMLA (eutectic mixture of lidocaine and prilocaine) alone or EMLA plus local injection of lidocaine can be used. In one study EMLA use 1 hour before the suprapubic aspiration was found to reduce pain scores more than without EMLA. Local injection of lidocaine often turns this from a “one stick” to a “two stick” procedure.

5. Bedside ultrasonography if available can be used to help guide needle insertion and puncture of the bladder wall. When used, fewer needle insertions are necessary.

6. An assistant should hold the infant in a supine position with the legs in the frog-leg position.

7. Locate the site of bladder puncture, which is ∼1–2 cm above the pubic symphysis in the midline of the lower abdomen (look for the transverse lower abdominal skin crease just above the pubic symphysis). See Figure 25–1A.

8. To avoid the bladder from emptying (reflex urination) when the needle is inserted, have an assistant hold pressure at the base of the penis in a male infant, or in a female infant apply anterior rectal pressure after inserting the fingertip in the anus.

9. Put on sterile gloves, and clean the entire suprapubic area of skin (from pubic symphysis to the umbilicus) with antiseptic solution three times. Place sterile drapes around the insertion site.

10. Palpate the pubic symphysis. Insert the needle with syringe attached 1–2 cm above the pubic symphysis (at the transverse lower abdominal skin crease in the midline) at a 90-degree angle (Figure 25–1B).

11. Advance the needle while aspirating ∽2–3 cm. Do not advance the needle once urine is seen in the syringe, to reduce risk of posterior wall bladder perforation. Use only gentle aspiration to prevent the needle from suctioning the bladder wall.

12. If no urine appears, do not advance or redirect the needle. Withdraw the needle and reattempt the procedure in a minimum of 1 hour; consider ultrasound to evaluate bladder filling.

13. Collect sample, withdraw the needle, maintain pressure over the site of puncture, and apply a bandage (optional). Place a sterile cap on the syringe or transfer the specimen to a sterile urine cup, and submit the specimen to the laboratory.

Serious complications are very rare.

1. Bleeding and hematomas. Hematuria is the most common complication; it is usually microscopic, rarely causes concern, and resolves. Gross hemorrhage is more likely if there is a bleeding disorder; transient gross hematuria is reported in up to 3.4% of cases. Thrombocytopenia is a contraindication. Hematomas (abdominal wall, pelvic, supravesical, and bladder wall), massive hemoperitoneum, and vaginal bleeding are rare.

2. Infection. Rare and not likely to occur if strict sterile technique is used. Sepsis, bacteremia, abdominal wall abscess, suprapubic abscess formation, and osteomyelitis of the pubic bone have all been reported.

3. Perforation of the bowel or other pelvic organs. With careful identification of the landmarks and not advancing the needle too far, this complication is rare. If the bowel is perforated (aspiration of bowel contents), close observation is recommended, and intravenous antibiotics should be considered. Surgical consultation may be obtained.

4. Needle breakage.