Bladder scanning

An invaluable bedside procedure that can be performed by any member of staff. Usually, an experienced nurse or HCA would be your best guide as they scan a good number of patients on a daily basis.

Indications:

1. Suprapubic pain - there’s no harm in bladder scanning these patients. In exceptional circumstances where the patient is a poor historian it may very well be a case of urinary retention and will avoid an unnecessary CT scan (which will show a distended bladder)

2. Diagnosing urinary retention

3. Assessment of residual volume after a TWOC

4. Uncertainty about the urine output / suspicion of a non draining catheter

Limitations and factors that will affect accurate estimation:

1. Obesity

2. Ascites

3. Pregnancy

4. Extensive abdominal scarring

A bladder scanner typically detects fluid of any nature. Therefore ascites or large ovarian cysts can be picked up on the scan which may cause confusion when there is minimal residual urine on catheterisation.

Procedure:

1. Position - supine

2. Ultrasound gel applied to the suprapubic area

3. The probe is directed towards the patient's bladder

4. VIsualise the collection of fluid (appears as a black area) and press down on the button to scan

5. The scanner may prompt you to reposition the probe with arrows indicating the recommended direction

6. Record the largest volume

Acceptable post TWOC residual volumes:
< 50mL - good

50 - 150 mL - acceptable if they have voided well post TWOC
> 200mL - inadequate and can be considered a failed TWOC

Reference:
https://www.ncbi.nlm.nih.gov/books/NBK539839/

Images:
Thumbnail image - Used under the Creative Commons license. Mikael Häggström (https://commons.wikimedia.org/wiki/File:Ultrasound_of_trabeculated_urinary_bladder.jpg), „Ultrasound of trabeculated urinary bladder“, https://creativecommons.org/publicdomain/zero/1.0/legalcode