Clinical Practice Guidelines

Suprapubic Aspirate

  • See also:

    Background 

    Suprapubic aspirate is the gold standard for obtaining urine specimens for culture. Any growth of pathogenic bacteria in an SPA specimen is felt to be significant. It is a simple, safe, rapid and effective technique.

    Indications:

    • Young unwell infants for whom there is a need to obtain specimens as part of a septic work-up where  antibiotic administration should not be delayed while awaiting a clean-catch urine.
    • For a child (< 2 years) when it is deemed important to confirm a UTI. Eg in a child with recurrent urinary tract infections with positive cultures but minimal cellular response.
    • Children with previous UTIs with unusual or resistant organisms
    • Children on prophylactic antibiotics

    Contraindications:

    • Bleeding diathesis
    • Abdominal distension
    • Massive organomegaly

    Complications:

    Microscopic haematuria is common. There are some rare complications which include: macroscopic haematuria, bladder haematoma, bladder haemorrhage, intestinal perforation. 

    Equipment 

    • One assistant to hold the infant (not parent)
    • Specimen jar for urine
    • 23G needle (25G for premature infants)
    • 3ml or 5 ml syringe
    • Ultrasound/Bladder scanner and gel 

    Analgesia/Anaesthesia 

    • Topical anaesthetic cream (AnGELTM) should ideally be used except where specimens are required urgently (e.g. prior to starting antibiotic treatment in a septic infant)
    • Oral sucrose should be used for infants <3 months (see Analgesia guideline) 

    Procedure

    • Never undo the nappy until you have a urine jar handy and someone ready to catch!
    • Do the SPA before collecting blood or CSF unless the patient has voided recently.
    • 'Blind' SPA has an approximately 50% chance of obtaining urine. The use of ultrasound increases the chance of success to 80-90%. Ultrasound is a useful tool to determine when NOT to do an SPA. There are two types of ultrasound that can be utilized:
      • Real time 2D ultrasound provides visualisation of the bladder and an estimation of its fullness. It is more accurate than the automated bladder ultrasound and should be used in preference to this if expertise in using a 2D ultrasound is available.
      • Automated bladder ultrasound provides a urine volume in mls. It does not visualise the bladder. Its ability to detect volumes less than 20 mls is poor. It should be used only when 2D ultrasound equipment or expertise is not available.
    • To minimise likelihood of voiding it is helpful to use warmed gel which should be placed on the ultrasound probe and not directly on the skin.
       

    Real time ultrasound images:  

    Full bladder  
     Transverse image  Longitudinal image
     Transverse image	 Longitudinal image
       
    Empty bladder  
     Tranverse image  Longitudinal image
     Tranverse image  Longitudinal image2


    Flow chart for use of ultrasound
    Ultrasound1 new

    What to do if a bladder ultrasound is not available

    Factors increasing the likelihood of a successful SPA:

    • History of no voiding in the past 30 minutes, and the presence of a dry nappy
    • Prehydration
    • Bladder dull to percussion
    Flow Chart if no ultrasound or bladder scanner available

    Ultrasound2 new


    SPA Method

    • Assistant to hold infant supine with legs extended and together. To prevent voiding in boys, the shaft of the penis should be squeezed to occlude the urethra.
    • Identify insertion point midline, lower abdominal crease. See - SPA Procedure - Identifying insertion point .
    • Wipe the overlying skin with an alcohol swab.
    • Insert needle perpendicular to the skin in all directions. Do not aim the tip of the needle down into the pelvic region. (The bladder in a baby is predominantly an abdominal rather than pelvic organ). The skin should be punctured quickly as if popping a balloon with a needle. Insert needle to the hub and aspirate. If urine is not immediately aspirated, continue aspirating as the needle is withdrawn.
    • If unsuccessful, withdraw the needle to just under the skin, and advance at an angle with the needle aimed further away from the pelvis. Do not repeat this procedure more than once.
    • If urine is obtained, remove needle and place urine into sterile urine jar.


     

     Post-Procedure-Care

    Post-Procedure Care
    • No specific care required. See parent handout.