Putting in new mud-floor tile shower. After extending sewer line to center of shower, the line will only be about 2 inches below top of slab (not below the slab). My concern is, that to put a new p-trap under new shower drain, I may not be able to connect the p-trap directly to the sewer line. With the shower drain flange resting on slab, the shower drain connection may extend down too low to allow the p-trap to connect directly to the sewer line.

As long as the top of the shower drain is about 2 inches above the slab and the sewer line is about 2 inches below "top" of slab, can I place the p-trap
lower and connect to sewer line with short pipe riser and elbow? It seems that only difference is that the p-trap may hold more water than if conncected directly to sewer line.

Asked question because when I removed the tub, the p-trab was conncected directly to sewer line and all of my sink p-traps are connected directly.

Also, is it ok to fill in around the sewer line with concrete, in order to fill area in the slab that needs to be cut away.

Don't think I explained myself well in previous posting and not sure this is ok either. Appreciate your help!