Can lap band be switched to sleeve?

It is possible to perform both surgeries at the same time. The only difference would be that preoperative endoscopic studies are necessary to see the state of the stomach and if there are changes due to the band.

I do these simultaneously if the band is not eroded. (Erosion is the very rare possible complication where the adjustable gastric band rubs a hole in the stomach.)  Many practices would remove the band first and do the sleeve another day, which is not wrong.  It's a physician preference thing.  I hope that your conversion, whether in one step or two, is smooth and successful.

Safest option is to do this in 2 steps: 1) remove the band first, and 2) return to surgery 3 or more months later to convert to sleeve.

This topic has been debated, and most surgeons now agree that conversion can be done safely in one step.  Risk is only slightly higher, but the advantages to the patient:  one operation instead of two, with less time, less recovery, etc., make it the obvious best option.There are several exceptions, however. If the band has eroded into the stomach, or if there is a severe slippage with swelling or loss of blood supply to the stomach, a two-stage approach is mandatory.  Otherwise they can generally be done in one step.  I do these routinely.