The prospective validation of cleanliness in the upper digestive tract according to polprep upper gastrointestinal cleanliness scale in reference to endoscopic findings - the visual study

Slaski Uniwersytet Medyczny w Katowicach, Poland; H-T. Centrum Medyczne, Poland; Academy of Silesia, Poland; Narodowy Instytut Onkologii im Marii Sklodowskiej-Curie Panstwowy Instytut Badawczy w Warszawie, Poland; Centrum Medyczne Sonomed, Poland; Uniwersytet Medyczny w Bialymstoku, Poland; Hospital of the Ministry of Internal Affairs in Szczecin, Poland; Pomorski Uniwersytet Medyczny w Szczecinie, Poland; Centre of Postgraduate Medical Education, Poland; University of Kansas School of Medicine, USA; Kansas City VA Medical Center, USA; Universitetet i Oslo, Norway.