Ultrasound Case 042


A 70 year old man presented with acute urinary retention. Insertion is difficult and ultrasound is used to ensure the catheter reaches the bladder before it is inflated.

Describe and interpret these scans

Image 1: Longitudinal view bladder. The IDC is seen emerging from the base of the prostate where an enlarged protate can just be made out.

Side lobe artefact causes the horizontal echogenic line through the bladder posteriorly – this is not layering sediment. It is exacerbated by having the TGC (time gain compensation) poorly adjusted.

The very distended bladder was drained to everyone’s relief!


Urinary catheter balloon being inflated

As water is injected into the catheter balloon tiny air bubbles are seen swirling – this is what agitated saline looks like and it occurs whenever fluid is rapidly injected.

We may see this incidentally – when we watch a catheter balloon inflate, or when we ultrasound a vein or the heart during a resuscitation.

Alternatively it is deliberately done for diagnostic purposes.

  • When placing a pericardial drain the operator may inject a small volume of saline to ensure the needle tip is in the pericardial space.
  • When searching for an ASD (atrial septal defect) agitated saline is deliberately injected into the veins and bubbles are observed passing into the right heart. The bubbles do not pass through the lungs and so do not appear in the left heart unless there is abnormal communication between the right and left heart.



An Emergency physician based in Perth, Western Australia. Professionally my passion lies in integrating advanced diagnostic and procedural ultrasound into clinical assessment and management of the undifferentiated patient. Sharing hard fought knowledge with innovative educational techniques to ensure knowledge translation and dissemination is my goal. Family, wild coastlines, native forests, and tinkering in the shed fills the rest of my contented time. | SonoCPDUltrasound library | Top 100 | @thesonocave |

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