The pressure is the scalar proportionality constant that relates the two normal vectors:

  
    
      
        d
        
          
            F
          
          
            n
          
        
        =
        −
        p
        
        d
        
          A
        
        =
        −
        p
        
        
          n
        
        
        d
        A
        .
Endoscopy involves using a fibre-optic flexible camera to identify the phytobezoar, that can be evacuated from the stomach using various assisted devices (such as Roth baskets, snares, or Dormia baskets). If the phytobezoar cannot be removed due to size, electrohydraulic lithotripsy, mechanical lithotripsy, snares, or Nd:YAG laser therapy may be used to fragment the mass. Papain (meat tenderizer) and cellulase enzymes have been used to help reduce the size of phytobezoars. Carbonated soda ingestion has also been found to be useful to decrease the size of diospyrobezoars. A systematic review regarding initial treatment of phytobezoars with Coca-Cola found that Coca-Cola alone completely dissolved phytobezoars in half of cases, and that Coca-Cola combined with other endoscopic methods (particularly endoscopic fragmentation) was successful more than 90% of the time. The same review found that diospyrobezoars (which are considered more difficult to dissolve because of their hard consistency) were successfully treated with Coca-Cola alone in only 23% of cases, but that follow-up endoscopic fragmentation was successful in 84.6% of cases in the publications reviewed. When all other measures have failed, surgical gastrectomy is required to evacuate the bezoar. Physical and chemical properties
Generally, bezoars can be found in the stomach in less than 0.5% of patients having an esophagogastroduodenoscopy. The formation of phytobezoars from persimmons is due to a chemical reaction between stomach acid and phlobatannin contained in the persimmon. Tannin and shibuol found in the skin of unripe persimmons reacts with gastric acid and  forms a coagulum. This structure then accumulates cellulose, hemicellulose and protein.