We thank you for your question. The authors of the latest 2016 ISPD peritonitis guidelines recommend:
 
“The WBC count in the effluent depends in part on the length of the dwell. For patients on APD with rapid cycle treatment, the clinician should use the percentage of PMN rather than the absolute WBC count to diagnose peritonitis, and a proportion above 50% PMN is strong evidence of peritonitis, even if the absolute WBC count is less than 100/μL. On the other hand, APD patients without a daytime exchange who present with abdominal pain during the daytime may have no effluent to drain. In this case, 1 L of dialysis solution should be infused, dwelled for 1 to 2 hours, and then drained for inspection and laboratory testing” (1,  page 487).
 
Thus, we believe it is fine for a patient on CCPD with suspected peritonitis to drain the PD fluid that is “last fill”, inspect for cloudiness, and send for PD fluid culture and WBC cell count. We would add though, if the patient has only had 30 minutes of the last fill, then you would need to wait 1 – 2 hours before draining. Only if the patient has “dry days” do you need to first instil I L of PD fluid and wait 1 – 2 hours before draining, inspect the PD fluid for cloudiness, and send the fluid for culture and WBC cell count.
 

1. Li PK, Szeto CC, Piraino B, de Arteaga J, Fan S, Figueiredo AE, Fish DN, Goffin E, Kim YL, Salzer W, Struijk DG. ISPD peritonitis recommendations: 2016 update on prevention and treatment. Peritoneal Dialysis International. 2016 Sep;36(5):481-508. Available at: https://journals.sagepub.com/doi/pdf/10.3747/pdi.2016.00078