Suprapubic Aspiration
Answer: D
This child presents with a common challenge in the ED: obtaining a quality urine sample in the toilet-trained child. In general, a calm atmosphere, productive parental involvement, and some patience are key to good technique and a successful, useable specimen.
In a well appearing afebrile child with dysuria and normal vital signs, sufficient urinary output, no comorbidities, and good follow up, an emergent urinalysis may be deferred and good precautionary advice given. Cystitis may be caused by infection (bacterial, viral, fungal, parasites; E. coli is found in 90% of uncomplicated infectious cystitis) or non-infectious etiologies such as autoimmune disease, vasculitis, or medication. Urethritis may be confused for dysuria in children, and also may be infectious or non-infectious (e.g. mechanical or chemical, “bubble-bath urethritis”).
In this child with recent urethral instrumentation and history or urologic procedure, the need for reliable assessment of a possible urinary tract infection is more urgent. Recent guidelines re-emphasize early treatment of suspected urinary tract infection to prevent renal scarring.
A preliminary diagnosis in the ED may be made in a symptomatic patient with a urinalysis (UA) consistent with infection. Components of the UA vary in diagnostic certainty: pyuria (≥ 5 WBC/hpf): LR+ 3, LR- 0.4; bacteriuria: LR+ 5, LR- 0.2; nitrite: LR+ 25, LR- 0.5; leukocyte esterase: LR+ 4; LR- 0.2.
(Recall that likelihood ratios require Bayesian thinking: pretest probability x LR = post-test probability).
The criterion standard for diagnosis of urinary tract infection is urine culture.
A bag specimen is not suitable for culture (A).
Placing a urinary catheter may be more traumatic than a simple suprapubic aspirate, especially in this recently instrumented, post-operative child. In addition, Foley catheters are not used to dilate the urethra or treat stricture (B). Urethral dilation may be performed non-emergently if a stricture is subsequently diagnosed after the infection is treated. This is performed by urologists under general anesthesia.
Observation may be an option (C). However, this fearful child who refuses now to cooperate may delay care and disposition with less than promising results in technique. After a reasonable period of observation, the clinician may consider a more reliable method of obtaining urine in this child at-risk for complicated cystitis.
Suprapubic aspiration (SPA) is a safe, effective method of urine collection in children and adults (D). It is most commonly used in the assessment of the younger child, especially if there is technical difficulty in urethral catheterization, as in labial adhesions or urethral anomalies.
To perform SPA, the child’s arms are restrained by the caregiver, and a health care provider gently restrains the child’s legs, in “frog-leg” position. Older children may need light anxiolysis or procedural sedation (intranasal fentanyl and/or midazolam may be a helpful adjunct). Younger infants do well with oral sucrose for such minor procedures.
The practitioner uses sterile technique to cleanse the skin between the genitalia and the umbilicus. The overlying skin may be anesthetized prior to procedure with a topical or subcutaneous agent. A small gauge needle (22-25 gauge) is attached to a 5-10 mL syringe and introduced 1-2 cm (approximately one finger-breadth) above the symphysis pubis in a trajectory perpendicular to or 10° cephalad to the abdominal wall. Remember that the urinary bladder is an abdominal organ in the child. In an adult, it is a pelvic organ – a longer spinal needle is used and introduced perpendicular to or 10° caudad to abdominal wall. Gently aspirate until urine is collected. Withdraw the needle. Typically no special bandage or pressure is required after the procedure. Ultrasound may be used before the procedure to verify quantity of urine and/or to guide the procedure.
This child presents with a common challenge in the ED: obtaining a quality urine sample in the toilet-trained child. In general, a calm atmosphere, productive parental involvement, and some patience are key to good technique and a successful, useable specimen.
In a well appearing afebrile child with dysuria and normal vital signs, sufficient urinary output, no comorbidities, and good follow up, an emergent urinalysis may be deferred and good precautionary advice given. Cystitis may be caused by infection (bacterial, viral, fungal, parasites; E. coli is found in 90% of uncomplicated infectious cystitis) or non-infectious etiologies such as autoimmune disease, vasculitis, or medication. Urethritis may be confused for dysuria in children, and also may be infectious or non-infectious (e.g. mechanical or chemical, “bubble-bath urethritis”).
In this child with recent urethral instrumentation and history or urologic procedure, the need for reliable assessment of a possible urinary tract infection is more urgent. Recent guidelines re-emphasize early treatment of suspected urinary tract infection to prevent renal scarring.
A preliminary diagnosis in the ED may be made in a symptomatic patient with a urinalysis (UA) consistent with infection. Components of the UA vary in diagnostic certainty: pyuria (≥ 5 WBC/hpf): LR+ 3, LR- 0.4; bacteriuria: LR+ 5, LR- 0.2; nitrite: LR+ 25, LR- 0.5; leukocyte esterase: LR+ 4; LR- 0.2.
(Recall that likelihood ratios require Bayesian thinking: pretest probability x LR = post-test probability).
The criterion standard for diagnosis of urinary tract infection is urine culture.
A bag specimen is not suitable for culture (A).
Placing a urinary catheter may be more traumatic than a simple suprapubic aspirate, especially in this recently instrumented, post-operative child. In addition, Foley catheters are not used to dilate the urethra or treat stricture (B). Urethral dilation may be performed non-emergently if a stricture is subsequently diagnosed after the infection is treated. This is performed by urologists under general anesthesia.
Observation may be an option (C). However, this fearful child who refuses now to cooperate may delay care and disposition with less than promising results in technique. After a reasonable period of observation, the clinician may consider a more reliable method of obtaining urine in this child at-risk for complicated cystitis.
Suprapubic aspiration (SPA) is a safe, effective method of urine collection in children and adults (D). It is most commonly used in the assessment of the younger child, especially if there is technical difficulty in urethral catheterization, as in labial adhesions or urethral anomalies.
To perform SPA, the child’s arms are restrained by the caregiver, and a health care provider gently restrains the child’s legs, in “frog-leg” position. Older children may need light anxiolysis or procedural sedation (intranasal fentanyl and/or midazolam may be a helpful adjunct). Younger infants do well with oral sucrose for such minor procedures.
The practitioner uses sterile technique to cleanse the skin between the genitalia and the umbilicus. The overlying skin may be anesthetized prior to procedure with a topical or subcutaneous agent. A small gauge needle (22-25 gauge) is attached to a 5-10 mL syringe and introduced 1-2 cm (approximately one finger-breadth) above the symphysis pubis in a trajectory perpendicular to or 10° cephalad to the abdominal wall. Remember that the urinary bladder is an abdominal organ in the child. In an adult, it is a pelvic organ – a longer spinal needle is used and introduced perpendicular to or 10° caudad to abdominal wall. Gently aspirate until urine is collected. Withdraw the needle. Typically no special bandage or pressure is required after the procedure. Ultrasound may be used before the procedure to verify quantity of urine and/or to guide the procedure.
Clinical pearl: have a clean catch specimen container ready before you start – the maneuvers for preparation may cause the child to void spontaneously before aspiration!
Urine culture results depend on sampling technique, organism identified, and symptoms. In non-immunocompromised adults and adolescents, a culture is positive with a single organism of ≥100,000 CFU/mL from a clean catch specimen. In children, a culture result via clean catch or catheter of ≥50,000 CFU/mL is positive. Any growth (typically reported as ≥1,000 CFU/mL) on a suprapubic aspiration is indicative of infection. The suprapubic specimen should be carefully labeled accordingly to avoid confusion with interpretation of culture results later. A result of 10,000 to 50,000 CFU/mL on a non-SPA specimen should be interpreted in the clinical context of signs and symptoms. Some bacteria such as Lactobacillus, Corynebacterium, and coagulase-negative Staphylococcus are not uropathogenic and are not considered a positive urine culture.
References
Subcommittee on Urinary Tract Infection, Steering Committee on Quality Improvement and Management, Roberts KB. Urinary tract infection: clinical practice guideline for the diagnosis and management of the initial UTI in febrile infants and children 2 to 24 months. Pediatrics. 2011; 128:595.
Finnell SM, Carroll AE, Downs SM, Subcommittee on Urinary Tract Infection. Technical report—Diagnosis and management of an initial UTI in febrile infants and young children. Pediatrics. 2011; 128:e749.
Urine culture results depend on sampling technique, organism identified, and symptoms. In non-immunocompromised adults and adolescents, a culture is positive with a single organism of ≥100,000 CFU/mL from a clean catch specimen. In children, a culture result via clean catch or catheter of ≥50,000 CFU/mL is positive. Any growth (typically reported as ≥1,000 CFU/mL) on a suprapubic aspiration is indicative of infection. The suprapubic specimen should be carefully labeled accordingly to avoid confusion with interpretation of culture results later. A result of 10,000 to 50,000 CFU/mL on a non-SPA specimen should be interpreted in the clinical context of signs and symptoms. Some bacteria such as Lactobacillus, Corynebacterium, and coagulase-negative Staphylococcus are not uropathogenic and are not considered a positive urine culture.
References
Subcommittee on Urinary Tract Infection, Steering Committee on Quality Improvement and Management, Roberts KB. Urinary tract infection: clinical practice guideline for the diagnosis and management of the initial UTI in febrile infants and children 2 to 24 months. Pediatrics. 2011; 128:595.
Finnell SM, Carroll AE, Downs SM, Subcommittee on Urinary Tract Infection. Technical report—Diagnosis and management of an initial UTI in febrile infants and young children. Pediatrics. 2011; 128:e749.