Improved Tissue Sections for Medical Liver Biopsies
Background Most medical liver biopsies in the UK are now taken in radiology departments using 18 g biopsy needles. Subjectively, the resulting biopsies are narrow and fragile.
Aim To compare the quality of liver biopsy tissue sections obtained from 16 and 18 g biopsy needles.
Method Fifty consecutive routine medical liver biopsies obtained with 16 and 18 g needles, processed identically in the same laboratory, were measured using digital pathology software. We recorded their fragmentation, length, width, area and number of portal tracts.
Results Biopsies obtained with 16 g needles more often resulted in an intact core in tissue sections than those with 18 g needles (71% vs 24%, p<0.001) and were significantly wider (average width of tissue 0.88 vs 0.53 mm, p<0.001). The average total area of tissue per pass was 11.38 mm compared with 8.34 mm (p<0.001). The number of complete portal tracts per length of biopsy was very variable, but double for 16 vs 18 g biopsies. Routinely taking two passes with the 18 g needle compensated for the reduced area, but the resulting liver in tissue sections was fragmented and distorted.
Conclusions Our results support the routine use of 16 g rather than 18 g biopsy needles for routine ultrasound-guided medical liver biopsies. A second pass should be considered if the first biopsy core is short, especially for investigation of disease stage.
Liver biopsy has a central role in investigation and management for many patients with medical liver disease. Factors affecting the biopsy diagnosis include sampling error, the sample size in relation to the distribution of the pathological features in the liver, the technical quality of the slides, the experience of the pathologist and the opportunity for clinical–pathological correlation. Inherent in all liver biopsies is the need to balance the diagnostic benefit with the risks of the invasive procedure. Introduction of non-invasive tests for disease stage is reducing the requirement for biopsy purely for staging purposes.
Most biopsies for the investigation of medical liver disease are now performed in radiology departments under image guidance, using Tru-cut cutting-type biopsy gun devices, and a recent Royal College of Radiologists (RCR) audit showed that 70% of these used 18 g needles. There have been many studies designed to establish what should be considered an 'adequate' biopsy size, and there is recognition that biopsies with less than 11 portal tracts underestimate disease stage and grade in chronic hepatitis. Based on these, the American Association for the Study of Liver (AASLD) Position Paper recommends two passes with a 16 g needle. However, a systematic review found that this standard was almost never achieved in practice. An alternative standard of ≥6 portal tracts for diagnosis (as opposed to reproducible staging) has been proposed.
In Leeds, because of concern over inadequate biopsy size, our routine protocol for medical liver biopsies was changed from 18 to 16 g needle size in 2005. This increase in biopsy width resulted in significantly larger tissue sections that distort and fragment less than narrower cores, and therefore are preferable for interpretation.
The aim of this study is to quantify the improved sample yielded by the use of the wider gauge needle to support its recommendation in the Royal College of Pathologists tissue pathways for medical liver biopsies by comparing 18 and 16 g biopsies processed concurrently in the same laboratory.
Abstract and Introduction
Abstract
Background Most medical liver biopsies in the UK are now taken in radiology departments using 18 g biopsy needles. Subjectively, the resulting biopsies are narrow and fragile.
Aim To compare the quality of liver biopsy tissue sections obtained from 16 and 18 g biopsy needles.
Method Fifty consecutive routine medical liver biopsies obtained with 16 and 18 g needles, processed identically in the same laboratory, were measured using digital pathology software. We recorded their fragmentation, length, width, area and number of portal tracts.
Results Biopsies obtained with 16 g needles more often resulted in an intact core in tissue sections than those with 18 g needles (71% vs 24%, p<0.001) and were significantly wider (average width of tissue 0.88 vs 0.53 mm, p<0.001). The average total area of tissue per pass was 11.38 mm compared with 8.34 mm (p<0.001). The number of complete portal tracts per length of biopsy was very variable, but double for 16 vs 18 g biopsies. Routinely taking two passes with the 18 g needle compensated for the reduced area, but the resulting liver in tissue sections was fragmented and distorted.
Conclusions Our results support the routine use of 16 g rather than 18 g biopsy needles for routine ultrasound-guided medical liver biopsies. A second pass should be considered if the first biopsy core is short, especially for investigation of disease stage.
Introduction
Liver biopsy has a central role in investigation and management for many patients with medical liver disease. Factors affecting the biopsy diagnosis include sampling error, the sample size in relation to the distribution of the pathological features in the liver, the technical quality of the slides, the experience of the pathologist and the opportunity for clinical–pathological correlation. Inherent in all liver biopsies is the need to balance the diagnostic benefit with the risks of the invasive procedure. Introduction of non-invasive tests for disease stage is reducing the requirement for biopsy purely for staging purposes.
Most biopsies for the investigation of medical liver disease are now performed in radiology departments under image guidance, using Tru-cut cutting-type biopsy gun devices, and a recent Royal College of Radiologists (RCR) audit showed that 70% of these used 18 g needles. There have been many studies designed to establish what should be considered an 'adequate' biopsy size, and there is recognition that biopsies with less than 11 portal tracts underestimate disease stage and grade in chronic hepatitis. Based on these, the American Association for the Study of Liver (AASLD) Position Paper recommends two passes with a 16 g needle. However, a systematic review found that this standard was almost never achieved in practice. An alternative standard of ≥6 portal tracts for diagnosis (as opposed to reproducible staging) has been proposed.
In Leeds, because of concern over inadequate biopsy size, our routine protocol for medical liver biopsies was changed from 18 to 16 g needle size in 2005. This increase in biopsy width resulted in significantly larger tissue sections that distort and fragment less than narrower cores, and therefore are preferable for interpretation.
The aim of this study is to quantify the improved sample yielded by the use of the wider gauge needle to support its recommendation in the Royal College of Pathologists tissue pathways for medical liver biopsies by comparing 18 and 16 g biopsies processed concurrently in the same laboratory.
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