H1B is Pending
Return to US
PENDING / DENIED: Use Old Emp Visa Stamp
APPROVED: Use new i797
New i94 will not be issued with H1B Approval
Use new i797 & visa stamp to enter US
Change of Status
No Entry without valid H1B or other visa stamp
Automatically abandoned by USCIS on Exit
Valid H1B visa stamp required to re-enter US.
Get H1B i797 hard copy mailed to you outside the USA. Then get H1B stamp using DS-160 in US Embassy.
Return to US using previous valid H1B visa stamp
Apply H1B transfer, extension or Amendment from outside USA.
I suggest upgrading to H1B premium, get approval in 15 days and then travel to be on absolute safe side.
if you can