In my opinion it is not necessary. It is useful to rule out the iatrogenic pneumothorax appreciating the lung sliding before and after the technique. It is also useful to assess the correct positioning of the central line managing agitated saline and seeing as it appears in the right cardiac cavities with echocardiogray.
Was Don states, not necessary as a routine central venous catheterization. Sonography should be used routinely to perform central venous catheterization for safety.
Once it is an ultrasound guided procedure, we generally do a bubble test, in which we inject ( push)10 cc normal saline through central venous catheter and see the transient bubble in rt heart. Routine echocardiography to rule out tamponade is not really necessary. This bubble test awaits validation.
If you are doing the above methods of the right atrial swirl sign RASS/ bubble test you will be getting a quick view of the heart. If there is any large pericardial effusion that would be clinically significant you would notice it at that time.