QA and QC of the complete cervical screening process

Protocols for quality control (QC) and quality assurance (QA)

  • A pathology test that screens an entire healthy population to find the few with disease must have clearly defined protocols for QA and QC in order to become an acceptable and viable screening test.  
  • The same protocols are required for cytology as a triage test along with primary HPV testing.

 

Avoiding false negatives and false positives

  • Although avoiding false negative tests is the most obvious concern, avoiding unnecessary investigation and treatment is equally important.  
  • Deficiencies in quality control of cytology were identified in a previous chapter as factors limiting the effectiveness of screening, which underpins the importance of the present chapter. 

 

Collecting, preparing and processing the cellular sample

  • Apart from accuracy in screening and reporting the cytological sample, the cervix must be sampled with care, and the smear prepared and processed correctly. 
  • If any of these processes fail, the integrity of the test is lost.

 

Additional tests in the screening process

  • HPV tests, colposcopy and histopathology must be carried out to acceptable standards in accredited departments (Cubie & Cuschieri 2013; Jordan et al. 2008; 2009). 
  • QC and QA or these procedures is beyond the scope of this teaching module but the accuracy and limitations of these procedures has to be taken into account when considering cytology in the context of multidisciplinary teamwork.

 

Monitoring the outcome of cytology results

  • Monitoring the follow-up of cytology tests and outcome in terms of results of repeat tests, colposcopy and histopathology are included in the activities of a cytology laboratory.
  • Mechanisms should be in place for recording the outcome and ensuring that appropriate action has been carried out on abnormal cytology results

 

  • Quality assurance is the responsibility of everyone in the laboratory
  • Understanding the areas of the process at risk for error helps to avoid them.

 

The principles dealt with in this chapter are consistent with the European guidelines for quality assurance: recommendations for cytology laboratories (Wiener et al. 2007). The complete guidelines, second edition (Arbyn et al. 2008) are available online at http://screening.iarc.fr/doc/ND7007117ENC_002.pdf

 

  • This chapter concerns laboratory quality assurance and quality control in cervical cancer screening with or without HPV testing
  • All stages of the screening process affect its quality: collecting the samples, cytology, HPV tests, colposcopy, histopathology, treatment, follow up, and monitoring the results and outcome
  • The principles in this chapter are consistent with the European guidelines for quality assurance: recommendations for cytology laboratories
  • Everyone in the laboratory has a responsibility for quality assurance and understanding the areas of the process at risk for error helps to avoid them

 

Accurate cytological screening depends on three processes, each of which is potentially subject to error and requires training, quality control and quality assurance:

  • Collecting, preparing and fixing the cellular sample
  • Processing the sample in the laboratory
  • Screening and reporting the cytology
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