Daily Archives: June 4, 2019

Not every anechoic thing in the pelvis is urine!

In this pelvic area sonogram, the Foley balloon (arrow) appears to be located outside the urinary bladder suggesting malposition of the catheter. However, the fluid collection anterior to the Foley is pelvic ascites and the Foley is in appropriate position as shown by the green dot in the illustration. Blood, serous fluid, and urine are all black on ultrasound. Note the margins of this ‘bladder-like’ structure are irregular which should make us suspect something isn’t right. To confirm the diagnosis, we should perform a long axis scan which will show that this fluid collection is in continuity with the peritoneal cavity. Moreover, a patient’s medical history should alert to the presence of pelvic ascites. It’s interesting to note that the bedside bladder scanning devices that are available in most hospitals these days can wrongly display ascitic fluid volume as bladder volume in this scenario.

Pleural effusion: The ‘Spine sign’

Spine sign: visualization of the vertebral bodies in the thoracic cavity above the diaphragm – indicative of pleural effusion.

In the absence of pleural effusion, the spine is obscured by air in the lung, and is cut off at the diaphragm. Because fluid is a good transmitter of sound waves, spine is seen when there is fluid around the lung.

Sometimes, pleural effusion may be noticed incidentally on abdominal scans. Below image shows transverse section of the liver with anechoic area in the posterior aspect, which corresponds to lung/pleural area; black = fluid. In such cases, go up and scan in the above mentioned coronal plane to confirm your findings.