It is a prospective case control study of 200 cases carried out in the Department of Pathology over a period of two years. All the cases of palpable thyroid lesions referred to the Department of Pathology by various clinical departments including Endocrinology, General Surgery, Surgical Oncology and cases referred from outside hospitals were subjected to both FNS and FNA technique.

All the cases of palpable thyroid lesions were included in the study irrespective of consistency, size of lesions, age and sex of the patients. Cases of non-palpable thyroid lesions requiring imageological guided FNA and patients not willing to participate in the study were excluded from the study. Institutional Ethics committee approval was taken for the study. The procedure was explained to the patient and written consent was obtained prior to performing the procedure.

Examination of the thyroid was done with the patient in upright position and noticing the swelling during deglutition. Aseptic conditions were maintained by using hand gloves and cleaning the thyroid swelling with povidone-iodine solution followed by spirit. During the procedure the patient was asked to keep still and to refrain from swallowing. Both techniques were executed on the same thyroid swelling / nodule in the same clinical session beginning with FNS followed by FNAC. First a 24 gauge needle was put in the thyroid swelling. The needle held between thumb and forefinger of aspirating hand was inserted into the nodule and moved in different directions within the nodule. The material entering the hub of the needle by capillary action was then expressed onto already labelled clean glass slide after attaching an air filled syringe to it. Next a 24 gauge needle with 10ml syringe attached to it was used for aspiration from the same thyroid swelling. The material obtained was similarly spread over a glass slide. Uniform, thin, evenly spread smears were obtained by superimposing another glass slide (spreader) at right angle to the slide with the expressed cellular material sandwiched between them, exerting gentle optimal pressure for a few seconds and then rapidly pulling the slides apart horizontally, resulting in well spread smear. One glass slide each was kept for drying and others put in isopropyl alcohol for wet smear preparation. The dry smears were stained by Leishman and May-Grunwald-Giemsa (MGG) stains and wet smears with Hematoxylin & Eosin stain.

In a couple of cases there was no cellularity by either method and in such cases repeat FNAC was performed using only aspiration technique and those smears were used purely for diagnostic purposes and were not included in the study. The observation of the present study was based on the parameters of scoring system proposed by Mair S et al., [10] [Table/Fig-1]. The two sampling techniques were compared using five objective parameters.

All available cytologic smears were initially handled for clinical diagnostic purposes, immediately after that they were assessed by two pathologists separately for the study purpose and scoring performed. An average score of the two pathologists was taken for each parameter as well as for each case. A cumulative score between 0 and 10 points was obtained for each specimen which was then categorized into one of the following three categories:

Category 1(Score 0–2): Unsuitable for diagnosis

Category 2(Score 3–6): Adequate for cytological diagnosis

Category 3(Score 7–10): Diagnostically superior.

Comparison between the two techniques was done by Student’s paired t-test using SPSS 13 software. All the results were analysed considering the statistical significance at a level of p<0.05.

A total of 200 cases were studied. The youngest patient was 9y female and the oldest 80y female. There were 26 males and 174 females (1:6.7).

The non-aspiration technique yielded less diagnostically adequate but more diagnostically superior smears when compared with aspiration technique [Table/Fig-2].

The average score per case was 5.31 by aspiration technique and 6.35 by non-aspiration technique [Table/Fig-3].

FNAC, since its inception in 1847, has passed through two phases of initial scepticism and interim enthusiasm and has successfully reached the final stage of acceptance as identified by Orell in his analysis of steps by which the assessment of innovative diagnostic practice progresses [11].

It has been suggested that fine needle sampling technique, by eliminating the negative suction pressure employed in FNAC, decreases the dilution of cells by blood and the scientific basis of which was explained by Santos and Leiman [12]. The technique employing the insertion of fine needle into a lesion without attachment of a syringe depends on the property of capillary tension in narrow channel. The physical principle is to state that a fluid or a semisolid substance will ascend spontaneously in a narrow tube in reverse proportion to diameter of tube or capillary.

The ascent of fluid into a narrow channel is governed by the formula h=2T/pgr, where h is the height attained, T is the surface tension of the fluid, p is density of the fluid, g is the gravity and r is radius of the capillary tube [12].

Although both aspiration and non-aspiration techniques use syringe and needle, in FNS the syringe is used to expel the material after the procedure is completed, whereas in FNA it is used to create a suction force to aspirate the cells in to the needle. A fresh sterile syringe is therefore not necessary for FNS, thus reducing the cost of procedure.

The patient also would be much less apprehensive when a large syringe, a syringe holder and a needle are not seen. Thus FNS is obviously more patient friendly [13]. FNS allows greater ease of sampling with better control of the hand during the procedure and a good perception of the lesion consistency, enabling more precise entry into the mass and thus more user friendly also [8].

The disadvantage of FNS technique observed in our study was whenever there was a colloid cyst or cystic degeneration – immediately brownish colloidal fluid drained out and drenched the fingers holding the needle. This problem was handled by keeping a syringe ready, which was immediately attached to the needle and the fluid collected in the syringe – to be cyto-centrifuged for better cellularity.

Our practical experience of using FNS technique in organs other than thyroid found its limitation in yielding scant material in calcific, fibrous and hard lesions and also in very soft lesions like lipoma. In such cases one has to compulsorily go for aspiration technique.

Similar to Raghuveer CV et al., [8], in our study two experienced pathologists studied and scored the smears and an average of the two was taken as final score, thereby eliminating the inter-observer bias.

Our results when compared for background blood contamination [Table/Fig-3] supported the non-aspiration technique in the present study similar to most of the studies including those by Kamal MM et al., [15], Maurya AK et al., [18] and Mahajan P et al., [19] except one study by Mair S et al., [10] who found more blood in sampling technique. The amount of cellular yield was found to be better by aspiration technique in the present study similar to reported by Mair S et al., [10] and contrary to the result by Kamal MM et al.,[15], Maurya AK et al., [18] and Mahajan P et al., [19] who reported more cellular smears by sampling technique.

Cellular degeneration and trauma were more in aspiration technique [Table/Fig-4] in the present study similar to the studies by Mahajan P et al., [19], Maurya AK et al., [18] and whereas Mair S et al., [10] is the only study who reported more degeneration and trauma by sampling technique. Kamal MM et al., [15] had more degeneration by sampling technique whereas trauma was more in aspiration technique. In the present study the sampling smears yielded better retention of architecture [Table/Fig-5] similar to the findings reported by Mahajan P et al., [19], Kamal MM et al., [15] and Maurya AK et al., [18] whereas Mair S et al., [10] is the only study who reported better maintenance of cell architecture by aspiration technique.

[Table/Fig-4]:

Aspiration smear from thyroid shows rich cellularity, abundant blood in the background, entangled follicular cells with ill-preserved architecture and degeneration and trauma to cells [H&E x 40]

[Table/Fig-5]:

Photomicrograph from FNS technique smear showing richly cellular smear with well-preserved microfollicular cell clusters/rosettes in a repetitive pattern with minimal blood in the background [MGG x 100]

There was statistically significant difference in favour of non-aspiration technique in our study similar to that observed by Dey and Ray [20] and SA Ali Rizvi et al., [16]. Kamal MM et al., [15] had statistically significant difference for the parameter of ‘amount of cellularity’. Romitelli F et al., [14] reported statistically significant result only in case of number of inadequate smears, which were more by aspiration technique. In studies by Mair S et al., [10] and Maurya AK et al., [18] there was no statistically significant difference in the two techniques.

Studies by Mair S et al., [10], Raghuveer CV et al., [8] and Ghosh A et al., [9] included multiple site FNACs including thyroid, lymph node, breast, salivary gland, liver and soft tissues. Raghuveer CV et al., [8] didn’t categorise the cases into diagnostically superior, adequate and unsuitable as done by others.

In the present study, more diagnostically superior and less diagnostically adequate samples were obtained by non-aspiration technique in comparison to aspiration technique [Table/Fig-6], which was similar to the results obtained by Maurya AK et al., [18] and Mahajan P et al., [19] and contrary to Santosh & Leiman [12]. Kamal MM et al., [15] reported both diagnostically superior as well as adequate samples more by sampling technique.

In our study even when the aspiration technique is suggestive of higher cellular yield, the number of unsuitable cases was more in aspiration technique. This paradox may be because of the more haemorrhagic aspirate leading to entanglement of the cellular component in the blood clot and thus yielding diagnostically inadequate smears.