We usually use a 20 mL syringe filled with some dialysate ; with that size, it’s easier to really test the resistance within the PD catheter. Do not hesitate to inject with some pressure and to alternate injection/aspiration to dislodge the fibrin clot within the catheter. If it doesn’t work, make a plain abdominal X Ray to see the catheter position ; if correct, you can inject a dye product within the catheter to differentiate between a fibrin clot within the catheter or a omental wrapping.