Is hematologist consult needed for mildly enlarged spleen 13cm on CT? My GI doc said no, it's at upper limit of nml- but it has to say it on report.

No. Hematologist of value, not in handling slightly enlarged spleen, but in managing any hematologic problem associated with it such as possible lymphoma where spleen could be enlarged. Many even slightly enlarged spleens are associated with liver problems and portal hypertension where liver scarring can impede portal blood to liver and shunt it to spleen which then enlargers.