Institutional Study on Unsatisfactory Pap Smears: Causes and Clinical Impact

Cervical cancer screening using cervical Papanicolaou (Pap) smears has been well established since the mid-20th century. Specimen adequacy is considered the most relevant quality assurance component since the invention of the Bethesda system for reporting cervical cytology. Cervical smears that are reported as unsatisfactory (US) can significantly delay diagnosis and increase the risk of cancer in follow-up tests. They also lead to unnecessary use of resources.

The cases signed out as US for one and half year duration in the cytology laboratory were retrieved, and demographic details were collected.

Among the 4,139 Pap tests accepted and reported for the period, 240 (5.8%) were signed out as US. The ratio of conventional to ThinPrep smears was 2.4:1. 70% cases were conventional Pap smears. 66% (159/ 240) cases of the patients were in the fourth and fifth decade age group. Low squamous cellularity was the most common cause (80%) of US smears, obscured by inflammation (12%); other causes were obscuration by blood (0.8%) and mucus (0.4%), drying artifacts (1.6%) and cytolysis (0.4%).

US smears largely depend on various factors, that is, the expertise of the person taking a sample, the date of collection in the menstrual cycle, the method of sampling, sampling devices and staining procedures. The variability in sample collection, including occasional collection by personnel with inadequate training, may also have contributed to the US smears. The result of our study is expected to have a significant impact on proper sampling and the use of adequate quality control measures. In addition, through our follow-up data, we could emphasize the importance of follow-up and human papilloma virus co-testing in patients with US smears.