Transurethral catheterisation and suprapubic bladder aspiration

23.16 Transurethral catheterisation and suprapubic bladder aspiration



Conor Deasy, Judith Klein



Background


Obtaining an uncontaminated specimen of urine is essential to diagnose urinary tract infection (UTI). UTIs are a common aetiology of fever and serious bacterial infection in infants. In children who cannot provide clean-catch urine specimens, the diagnosis of UTI involves obtaining a urine sample directly from the bladder. Urine specimens obtained via bags attached temporarily on to the perineum are frequently contaminated samples, particularly with infant girls. Waiting for bagged urine specimens is also time-consuming and frustrating in the emergency department (ED) setting. Hence, urinary bag specimens frequently confuse diagnosis of UTI, and often result in false positive specimens and unnecessary treatment.


Obtaining an appropriate urine specimen requires either transurethral catheterisation or suprapubic aspiration. Unfortunately, in very young females and circumcised males with small foreskins, the urethra can be difficult to find and even more difficult to cannulate. In these cases, perform suprapubic aspiration of urine directly from the bladder, whenever possible under ultrasound guidance. This is an easy procedure that requires minimal equipment. Suprapubic aspiration provides a sterile urine specimen with less trauma to the infant than repeated, failed attempts at urethral catheterisation.


Transurethral catheterisation and placement of an indwelling bladder catheter is also useful in the management of critically ill and injured children, to monitor urine output in the setting of shock or trauma. Urine output is one of the best measures of core perfusion and can help guide fluid resuscitation of a child in shock. The combination of heart rate and urinary bladder output are two excellent measurements of intravascular volume and response to treatment.



Indications



Indications for transurethral catheterisation



• Collection of a diagnostic urine specimen.

• Intermittent bladder decompression for neurogenic bladder.

• Urological study.

• Measurement of urine output in critically ill or injured child.

• Acute urinary retention.


Indications for suprapubic bladder aspiration


Collection of a clean diagnostic urine specimen when transurethral catheterisation is impossible or unsuccessful.



Contraindications



Urethral catheterisation



• Obvious pelvic trauma.

• Blood at the urethral meatus.

• Upward displacement of the prostate in males following trauma.

• Perineal haematoma.

In these circumstances, perform a retrograde urethrogram prior to cannulation of the urethra. Placement of a catheter without such a study could convert a partial urethral tear into a complete transection. Urethral injuries are uncommon in females because of the relatively short distance between the urethral meatus and the bladder. Bladder injuries, however, are more common in females and children in general because of the higher abdominal location of the organ in children versus adults. If blood appears following urethral catheterisation in trauma, perform a retrograde cystogram to search for bladder injury.



Suprapubic aspiration



• Coagulopathy.

• Thrombocytopenia.

• Significant abdominal distension.

• Recent abdominal surgery.

In addition, if ultrasound is available, do not perform suprapubic aspiration if the bladder diameter is less than 3.5 cm or if a volumetric scan demonstrates less than 10 mL of urine (Fig. 23.16.1). Under these circumstances, delay the procedure because it is unlikely to be successful.


image

Fig. 23.16.1 Using ultrasound for suprapubic aspiration.



Transurethral catheterisation



Equipment


The equipment required for transurethral catheterisation is often available in prepackaged trays to which only the appropriately sized catheter need be added. Determine the appropriate catheter size either by using a length-based resuscitation tape, by using the formula 2× (endotracheal tube size), or by using a table listing equipment sizes by age (Table 23.16.1). Remember to use lidocaine jelly in a syringe, particularly when catheterising the male urethra.







Table 23.16.1 Catheter sizing for children
image


Preparation



Review the male and female anatomy of the perineum.

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Sep 7, 2016 | Posted by in EMERGENCY MEDICINE | Comments Off on Transurethral catheterisation and suprapubic bladder aspiration

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