Ultrasound guided aspiration cytology--a valuable diagnostic aid.
RP Kedar, VH Patel, SA Merchant, V Aggarwal, AA Pandit
Department of Radiology, Seth G. S. Medical College Parel, Bombay Maharashtra.
R P Kedar
Department of Radiology, Seth G. S. Medical College Parel, Bombay Maharashtra.
Ultrasonography (US) remains underutilized as a guidance tool for performing fine needle aspiration cytology (FNAC) mainly because of a lack of understanding and experience in this technique. We describe here our experience in performing 346 FNACs. In our opinion, US guided FNACs are highly accurate and safe procedures which can be done on an out-patient basis, with routinely available equipment.
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Kedar R P, Patel V H, Merchant S A, Aggarwal V, Pandit A A. Ultrasound guided aspiration cytology--a valuable diagnostic aid. J Postgrad Med 1991;37:84-7
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Kedar R P, Patel V H, Merchant S A, Aggarwal V, Pandit A A. Ultrasound guided aspiration cytology--a valuable diagnostic aid. J Postgrad Med [serial online] 1991 [cited 2021 Oct 20 ];37:84-7
Available from: https://www.jpgmonline.com/text.asp?1991/37/2/84/783
Interventional procedures have been performed by physicians for decades. Sir Wifflam Osler routinely performed blind biopsies and drainage of palpable masses, using large bore needles. (quoted by Terance et al)
Aspiration cytology is the study of cells, obtained by a fine needle puncture. It is not a recent development. It was pioneered by Martin and Ellis and by Stewart (as quoted by Rowley and Cooperberg) in New York in the early 1930s. However, the technique was ignored for several decades though it was being assessed in Scandinavia. There are several reasons for the delay in the acceptance of FNAC in our country, prominent amongst them would be that, few pathologists were skilled in cytologic interpretations, while most believed that diagnosis could be made only from plentiful tissue samples which permit the pathologists to determine intercellular relationships.
US guided, FNAC is now widely accepted as a safe diagnostic procedure in various neoplastic and non-plastic disorders. We present here, our experience of a series of 346 US guided FNACs of various abdominal and pelvic lesions.
During a 12 month period, we have performed 346 US guided FNACs (using Aloka 256 and GE 2800 units with a 3.5 MHz linear probe) of various abdominal and pelvic lesions. These included lesions of liver, gall bladder, pancreas, spleen, kidneys, bowel, lymph nodes, ovaries and miscellaneous other regions (psoas, soft tissue masses, retroperitoncal masses, uterine and adrenal pathologies). The commonest indication was to exclude primary or metastatic lesions. The reason for the biopsy, the procedure itself and the absence of any significant risks were explained to the patient before starting the FNAC. FNACs were routinely performed on outpatients also. No pre-procedural preparation was required. During scanning, the optimum skin puncture site that would minimise cephalocaudal and mediolateral angulations was selected and a simple vertical approach was performed. FNACs were performed like any routine intramuscular injection, dispensing with gloves, masks, sterile draping or local anaesthesia. Gloves were occasionally needed for estabilising the needle shaft during advancement of a long flexible needle. The aspiration sites were prepared with a topical antiseptic. Our fine needle (20-23 gauge) length was limited to 1.5 to 3 inches in most cases (90%). Fine needles of 23 gauge for superficial lesions and 9 cm 21-22 gauge spinal needles were also used. No other specific biopsy needles were used. After inserting the needle into the lesion, strong suction was applied and the needle tip was moved in and out by about 5 mm, (once it had entered the lesion) and after withdrawing the needle smears were prepared and slides were sent to the cytopathologists in a Koplin's jar. Whenever required, care was taken to obtain material from the most solid portion of the lesion.
Of the 346 FNACs, the smallest sized lesion was 1 cm in diameter. The majority were greater than 5 cm in size.
The results are listed in [Table:1]. The success rate for obtaining material was almost 90% in the first attempt and 99% in the second attempt. The size of the lesion varied from 1 to 15 cm. The results show a sensitivity (percentage of patients with a positive lesion who had positive FNAC) of 90.75%. A diagnosis of primary malignancy was established in 24.85% and that of secondary in 5.78%. The total failure rate was 9.25%. This included (a) inadequate lesion samples, (6.07%), and (b) inability in cytological interpretation (3.18%). The 'a' category included (i) lesions where inspite of confirmation of the needle within the lesion, only blood, necrotic material or hypocellular specimens were obtained, (ii) small sized lesion less than 1 cm in diameter and (iii) inaccessible lesions. In our series, the maximum success rate was achieved with gall bladder, spleen and adrenal pathologies (each 100%), (however the number of lesions in these regions is limited), liver pathologies (95.16%), bowel and ovarian pathologies (94.12%) and kidney pathologies (87.50%). The lowest success rate was noted with pathologics related to lymph nodes (58.33%), and pancreatic pathologies (77.77%). We have not observed any significant complications except minimal discomfort at the time of needle puncture.
In our series, there are examples available where FNAC had changed the management because of correct tissue diagnosis. These included (1) a suspected primary liver malignancy which turned out to be a metastasis, (2) a suspected hyperechoic fiver abscess turned out to be a hepatoma, (3) a well defined hypoechoic mass apearing as a renal cell carcinoma turned out to be a renal abscess of tuberculous origin, (4) a suspected infected pseudocyst of the pancreas turned out to be a cystadenocarcinoma of the pancreas, (5) a malignant looking gall bladder mass turned out to be an empyema of the gall bladder.
US guided FNAC is a rapid, accurate, economical and safe diagnostic procedure that can be used in various neoplastic and non-neoplastic diseases. As diagnosis is rapidly available on FNAC, appropriate medical or surgical therapy can be started earlier, at a same time avoiding unnecessary, expensive and often invasive diagnostic procedures and needles surgery. In lesions requiring surgical removal, operative time is reduced, as frozen section biopsy may not be necessary. The aforesaid factors reduce or eliminate surgical morbidity and mortality as well as hospitalization, thereby benefiting the patient as well as the health-care system.
In our series, FNACs were avoided in known cases of uncontrollable bleeding diathesis and suspected hydatid cysts.
The major causes of failure identified in our series are: (1) failure due to sampling error (due to a small or necrotic tumour, inadequate samples due to tumour heterogenicity, vascularity or fibrosis), (2) a cytological error (due to poor sample quality, preparation or interpretation). Attempts have k been made to minimise tissue sampling error, by accurate needle placement with real time US and to minimise interpretation error by developing good understanding between radiologists and pathologists (as far as amount of tissue and its US characteristics are concerned).
We have not observed any complication following FNAC except minimal discomfort at the time of needle puncture. A comparative complication rate of various procedures is listed in [Table:2].
An accuracy upto 90.75% in the absence of a sector scanner or a special biopsy probe attachment is probably mainly due to the fairly large size of the masses in our series. In addition, the cost effectiveness and rapidity of US guided FNAC, and non- availability of computed tomography, coupled with the higher incidence of advanced malignancy due to public awareness, over-burdened surgical units with meagre resources, establishes this procedure as indispensable for cancer management in developing countries. One of the most interesting features of this series is the high yield and uncomplicated nature of aspiration performed at various sites.
Thus, this series, substantiates the accuracy of (real time) US guided FNAC in a wide spectrum of abdominal and pelvic neoplastic and non-neoplastic disorders. No other diagnostic technique can be so simple, safe, rapid and inexpensive while giving such valuable information as US guided FNAC. Adequate sampling, experience and caution in interpreting the aspirate, and a close working relationship between clinician, sonologists and cytopathologists are factors essential for its success.
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