• Vol. 39 No. 5, 359–362
  • 15 May 2010

An Audit Study of the Sensitivity and Specificity of Ultrasound, Fine Needle Aspiration Cytology and Frozen Section in the Evaluation of Thyroid Malignancies in a Tertiary Institution



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Introduction: The aim of this study was to conduct an audit of the sensitivity and specificity of ultrasound, fine needle aspiration cytology (FNAC) and frozen section in the evaluation of thyroid malignancies in our practice.

Materials and Methods: The medical records of all the patients who underwent thyroid surgery in a tertiary institution’s General Surgery Department between January 2005 and December 2007 were retrospectively reviewed using a standardised data collection template. Results of the ultrasounds, FNACs and frozen sections were compared with the final histological diagnosis.

Results: A total of 112 patients underwent thyroid surgery in the 3-year study period. Thyroid malignancy constituted 34 (30%) of all patients who underwent thyroid surgery. The most popular diagnostic tools used were ultrasound (81%), FNAC (69%) and frozen section (59%). The sensitivity of ultrasound, FNAC and frozen section were 41.4%, 86.4% and 68.8%, respectively. FNAC was shown to be a superior diagnostic test in detecting malignancy compared to ultrasound. FNAC was able to pick up 53% of thyroid cancers missed by ultrasound. Frozen section was able to pick up 33% of thyroid cancers that were missed by both ultrasound and FNAC.

Conclusion: FNAC is the most reliable tool in detecting malignancies and ought to form the mainstay for investigation of thyroid nodules. The utilisation of ultrasonographic features in the evaluation of thyroid nodules might not necessary improve the detection rate of thyroid malignancy. Frozen section helps to improve the detection rate of thyroid malignancy but further studies into its cost-effectiveness ought to be performed.

Thyroid lesions constitute a considerable bulk of surgical practice, majority of which are thyroid nodules. A large population study revealed that clinically apparent thyroid nodules were present in 6.4% of women and 1.5% of men.

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