I have a pinched nerve in my sacral area. I got it when I was riding in the car for 13 hours on the way to visit my son and his family. The surgeon wants to treat it with an epidural steroid injection. They call the procedure an ESI. The operation was explained to me but I can’t help wondering if they can really get a needle in that small area. I confess I’m about 200 pounds overweight. Won’t the fat get in the way?

Ultrasound could be used as a screening tool before giving the injection. This 3-D, real-time video provided by ultrasonography of the sacrum shows the surgeon exactly where to insert the needle for the most accurate injection.

Ultrasound images give the surgeon precise measurements to use when deciding whether there’s enough space for the needle. The surgeon can use the images to guide the needle into the epidural space. If the diameter of the opening is too small, a smaller gauge needle can be inserted instead. Absence of the opening or a too small diameter would be just cause to cancel the procedure.

Body weight and body fat does not seem to be a problem with this type of pre-test screening and/or injection treatment. With the assistance of a surgical tech, the patient’s buttocks can be pulled apart and away from the sacrum, thus providing a flat surface to apply the ultrasound transducer (head or wand). If necessary, a specially shaped transducer can be used to curve over the soft tissue down to the bone. Physicians using this method on obese patients report that the layer of fat over the sacrum where the needle must be inserted is not very thick even in obese individuals.