Percutaneous Core Biopsy Devices: A Detailed Review and Comparison of Different Needle Designs

ABSTRACT

Percutaneous core-needle biopsy (PCNB) plays a growing and essential role in many medical specialties. Proper and effective use of various PCNB devices requires basic understanding of how they function. Current literature lacks a detailed overview and illustration of needle function and design differences, a potentially valuable reference for users ranging from early trainees to experts who are less familiar with certain devices. This pictorial aims to provide such an overview, using diagrams and magnified photographs to illustrate the intricate components of these devices. Following a brief historical review of biopsy needle technology for context, we emphasize distinctions in design between 2 major classes of PCNB devices (side- and end-cutting devices), focusing on practical implications for how each device is most effectively used. We believe a nuanced understanding of biopsy device function sheds light on certain lingering ambiguities in biopsy practice, such as the optimal needle gauge in organ biopsy, the benefits and risks associated with coaxial technique, the impact of needle selection and technique on bleeding, and the risk of unsuccessful sampling. In a subsequent pictorial, we will draw on the concepts presented here to illustrate examples of biopsy needle failure and how unrecognized needle failure can be an important and often preventable cause of increased biopsy risk and lower tissue yield.

Prospective comparison of an 18-gauge versus 16-gauge needle for percutaneous liver core-needle biopsy in children

PURPOSE

The objective of this study was to analyzed the impact of needle gauge (G) on the adequacy of specimens and hemorrhagic complications in pediatric patients undergoing ultrasound (US)-guided transplanted liver biopsies.

METHODS

The study included 300 consecutive biopsies performed in 282 pediatric patients (mean age 6.75 ± 3.82 years, range 0.84-17.90) between December 2020 and April 2022. All pediatric patients that referred to our institution for US-guided core-needle liver biopsy (CNLB) were randomized to undergo 16-G or 18-G CNLB. Hemorrhagic complications were qualitatively evaluated. The number of complete portal tracts (CPTs) per specimen was counted and specimen adequacy was assessed based on the American Association for the Study of Liver Diseases guidelines.

RESULTS

The incidence of bleeding was 7.00% (n = 21) and adequate specimens for accurate pathological diagnosis were obtained from 98.33% (n = 295) of patients. There was no significant difference in the incidence or amount of bleeding between the 16-G and 18-G groups (11 vs 10, p = 0.821; 35.0 mL vs 31.3 mL, p = 0.705). Although biopsies obtained using a 16-G needle contained more complete portal tracts than those obtained using an 18-G needle (20.0 vs 18.0, p = 0.029), there was no significant difference in specimen inadequacy according to needle gauge (2 vs 3, p = 1.000).

CONCLUSIONS

Biopsy with a 16-G needle was associated with a greater number of CPTs but did not increase the adequate specimen rate. There was no significant difference in the complication rate between 16-G biopsy and 18-G biopsy.

Quality of Tissue Samples Obtained by Endoscopic Ultrasound-Guided Liver Biopsy: A Randomized, Controlled Clinical Trial

INTRODUCTION

Liver biopsy (LB) remains essential for the diagnosis and staging of parenchymal liver diseases. Endoscopic ultrasound-guided LB (EUS-LB) has emerged as an attractive alternative to percutaneous and transjugular routes. We aimed at comparing the adequacy of samples obtained by EUS-LB with percutaneous LB.

METHODS

A single-center, randomized, controlled clinical trial was designed. Patients undergoing LB were randomly assigned to EUS-LB or percutaneous LB groups. EUS-LB was performed with a 19-gauge Franseen core needle through a transduodenal and transgastric route. Percutaneous LB was performed with a 16-gauge Tru-Cut needle. The main outcome was the percentage of adequate samples obtained. Secondary outcomes were the percentage of accurate histologic diagnosis, number of complete portal tracts (CPT), total and longest specimen length (TSL and LSL), sample fragmentation, adverse events, and patients' satisfaction. An adequate specimen was defined as TSL ≥20 mm and including ≥11 CPT.

RESULTS

Ninety patients were randomized (44 to EUS-LB and 46 to percutaneous LB) and included in the analysis. The percentage of adequate tissue samples was 32.6% and 70.4% for percutaneous LB and EUS-LB, respectively ( P < 0.001). A final histologic diagnosis was provided in all cases but one. TSL was longer after EUS-LB (23.5 vs 17.5 mm, P = 0.01), whereas the number of CPT was similar in both groups. Sample fragmentation occurred more often after EUS-LB ( P < 0.001). No differences in adverse events were found. Satisfaction reported with both procedures was high.

DISCUSSION

EUS-LB is safe and accurate and may be considered an alternative to percutaneous LB for the evaluation of parenchymal liver diseases.

Needle types used in abdominal cross-sectional interventional radiology: a survey of the Society of Abdominal Radiology emerging technology commission

PURPOSE

To identify commonly used needle types in cross-sectional interventional radiology (CSIR) and to review features and safety profiles of those needles.

METHODS

Members of the Society of Abdominal Radiology (SAR) emerging technologies commission (ETC) on CSIR were sent a 13-question survey about what needles they use for common CSIR procedures: random and targeted solid organ biopsy, ultrasound-guided paracentesis, and ultrasound-guided thyroid fine needle aspiration (FNA). Results were compiled with descriptive statistics, and features of the most commonly used needles were reviewed.

RESULTS

19 surveys were completed (response rate 57.6%, 19/33) from 16 institutions. For solid organ biopsies, the majority of respondents reported using an 18-gauge needle with an automatic firing mechanism and a variable throw length option. The most commonly used needle for both random and targeted biopsies was the Argon BioPince (26.3%, 5/19) The three most commonly used needles for solid organ biopsies all featured automatic firing, variable throw length options, and 18-gauge size. A 5 French Cook Yueh needle was most the most commonly used paracentesis needle (36.8%, 7/19). For thyroid FNA, all respondents used spinal needles, and 25-gauge was the most common size (72.2%, 13/18).

CONCLUSION

Abdominal radiologists use a variety of needles when performing common interventional procedures. Members of the SAR CSIR ETC commonly use automatic, 18-gauge, variable throw length needles for solid organ biopsies, 5 French catheter style needles for paracentesis, and 25-gauge spinal needles for thyroid FNA.

Reducing Recovery Times in Outpatient Liver Biopsies: Role of the GI Nurse

This project is aimed to identify whether recovery times could be reduced in patients undergoing an outpatient liver biopsy. Liver biopsies are typically performed in a hospital setting, and many facilities require patients to recover for multiple hours, sometimes ranging from 4 to 6 hours. This can discourage the patient from undergoing the biopsy. Multiple studies have examined recovery times and determined patients can safely recover and be discharged within 1-2 hours post-liver biopsy. In this retrospective review, the data of 60 outpatients who underwent a liver biopsy from June to December 2020 were analyzed. Analysis included comparing vital signs and symptoms at the 2-hour recovery period and 4-hour discharge time also to see whether there were any hospital admissions 1 week post-liver biopsy. Descriptive statistics were utilized for the data collected in this study. Results demonstrated that after 2 hours, 55 (91.7%) patients had vital signs within safe parameters, pain less than 5 on a 10-point pain scale and denied any other symptoms. The remaining five patients (8.3%) did not meet discharge criteria at the 2-hour mark because of pain greater than 5 on the pain scale yet were still discharged safely at the 4-hour mark.

Incidence of Complications from Percutaneous Biopsy in Chronic Liver Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Approaches to liver biopsy have changed over the past decade in patients with chronic liver disease.

AIMS

We conducted a systematic review and meta-analysis on the incidence of all complications and technical failure associated with percutaneous liver biopsy.

METHODS

We systematically searched PubMed and the Cochrane Library for cohort studies reporting on complications resulting from liver biopsy published between 2010 and 2020. Studies on participants of any age and sex, who underwent any percutaneous biopsy for non-focal liver disease, were selected. All events except mild pain, minor hematoma, vasovagal episodes, fever and fistula were defined as major complications. Random-effect model meta-analyses with and without covariates were performed, to examine the effect of publication year, patient characteristics, outcome collection, and biopsy type on incidences.

RESULTS

We identified 30 studies reporting on complications resulting from percutaneous liver biopsy procedures (n = 64,356). Incidence of major complications was 2.44% (95% CI 0.85, 6.75), with mortality at 0.01% (95% CI 0.00, 0.11), hospitalization at 0.65% (95% CI 0.38, 1.11), major bleeding at 0.48% (95% CI 0.22, 1.06), and moderate/severe pain at 0.34% (95% CI 0.08, 1.37). Minor complications at 9.53% (95% CI 3.68, 22.5) were mainly pain at 12.9% (95% CI 5.34, 27.9). Technical failure was high at 0.91% (95% CI 0.27, 3.00). Decreasing patient age significantly increased incidence of hospitalization and major bleeding (P < 0.0001). Hospitalization incidence also significantly increased with disease severity.

CONCLUSIONS

Incidence of major (2.4%) and minor (9.5%) complications, and technical failure (0.91%) in percutaneous liver biopsies continues.

Image-guided Percutaneous Biopsy of the Liver

Percutaneous Biopsy of the Liver (PBL) is a cornerstone in the diagnosis of parenchymal liver disease and focal hepatic lesions. The indications for PBL can broadly be divided into those used to garner information regarding diagnosis, prognosis, or treatment. While the diagnosis of many common liver diseases can usually be made with imaging and serologic testing alone, PBL may be indicated in situations where the diagnosis is in question. Furthermore, liver biopsies are a foundational element for personalized treatment approaches for cancer patients; increasing emphasis is being placed on acquiring sufficient tissue for molecular profiling. While a variety of image guidance and procedural techniques have been applied to PBL, following conventional principles can ensure technical success and minimize complication risks. In this technique article, we review the practical periprocedural considerations of PBL with emphasis on recent advancements and societal recommendations.

Subcapsular local anesthesia approach in percutaneous liver biopsy: less pain, more comfort

Background/aim

To compare the subjective level of pain in patients who underwent an ultrasound-guided percutaneous liver biopsy (PLB) after either pericapsular anesthesia (PA) or subcapsular anesthesia (SA), based on the numeric rating scale (NRS).

Materials and methods

A total of 323 patients, mean age 51, range 21–82 years; 160 (49.5%) male, referred to the Interventional Radiology Clinic of Kocaeli University Faculty of Medicine for image-guided PLB, between June 2019 and May 2020 were included and randomized into two groups by anesthetic type; the first (n = 171) consisted of patients undergoing SA while the second (n = 152) included patients undergoing PA. The intensity of pain at 0, 1, and 6 h after PLB was evaluated between the groups using NRS.

Results

At hours 0, 1, and 6, the median [range] NRS scores in the subcapsular and pericapsular groups were 2 [1–2] versus 3 [2–4] (P < 0.001), 1 [0–1] versus 1 [1–2] (P < 0.001), and 0 [0–0] versus 1 [0–1] (P < 0.001), respectively. Subgroup analysis revealed that the patients who underwent the subcostal procedure with subcapsular anesthesia reported the lowest pain scores and intercostal procedure with pericapsular anesthesia reported the worst pain scores for each time point: 0 h 1 [1–2] versus 3 [3–4], P < 0.001; 1 h 1 [0–1] versus 1 [1–2], P < 0.001; and 6 h 0 [0–0] versus 0 [0–1], P < 0.001, respectively.

Conclusion

Subcapsular anesthesia is a well-tolerated procedure compared to a pericapsular procedure. Furthermore, the application of a subcapsular anesthetic with a subcostal approach was reported to result in the lowest pain and greatest patient comfort.

Improvement of Pediatric Liver Core Biopsy Adequacy by Reducing Laboratory-Related Tissue Fragmentation and Increasing Portal Tract Yield

OBJECTIVES

We aimed to identify potential laboratory causes of suboptimal liver biopsy quality and sought to implement corresponding measures to improve biopsy adequacy.

METHODS

We prospectively measured the number and size of tissue fragments and the amount of portal tracts in 200 consecutive pediatric medical liver biopsies before and after quality improvement processes were initiated.

RESULTS

We identified laboratory-related tissue fragmentation as a significant cause of low biopsy adequacy. The principal approaches to reduce fragmentation included establishment of multistep monitoring of tissue integrity, adjustment of specimen-processing conditions, and laboratory staff education and awareness. These adjustments collectively led to lower overall tissue fragmentation (decreasing from 59% to 24%, P < .01) and higher biopsy adequacy rates (increasing from 32% to 56%, P < .01). The number of evaluable portal tracts increased from 4.4 to 5.7 portal tracts per centimeter of core biopsy tissue (P < .01).

CONCLUSIONS

We demonstrated a sustainable improvement in the overall quality of pediatric needle core liver biopsies by reducing tissue fragmentation. Effective laboratory adjustments included monitoring of tissue integrity, modifications of processing conditions, and laboratory staff education.

Clinical assessment and management of liver fibrosis in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is among the most frequent etiologies of cirrhosis worldwide, and it is associated with features of metabolic syndrome; the key factor influencing its prognosis is the progression of liver fibrosis. This review aimed to propose a practical and stepwise approach to the evaluation and management of liver fibrosis in patients with NAFLD, analyzing the currently available literature. In the assessment of NAFLD patients, it is important to identify clinical, genetic, and environmental determinants of fibrosis development and its progression. To properly detect fibrosis, it is important to take into account the available methods and their supporting scientific evidence to guide the approach and the sequential selection of the best available biochemical scores, followed by a complementary imaging study (transient elastography, magnetic resonance elastography or acoustic radiation force impulse) and finally a liver biopsy, when needed. To help with the selection of the most appropriate method a Fagan′s nomogram analysis is provided in this review, describing the diagnostic yield of each method and their post-test probability of detecting liver fibrosis. Finally, treatment should always include diet and exercise, as well as controlling the components of the metabolic syndrome, +/- vitamin E, considering the presence of sleep apnea, and when available, allocate those patients with advanced fibrosis or high risk of progression into clinical trials. The final end of this approach should be to establish an opportune diagnosis and treatment of liver fibrosis in patients with NAFLD, aiming to decrease/stop its progression and improve their prognosis.

Guidelines on the use of liver biopsy in clinical practice from the British Society of Gastroenterology, the Royal College of Radiologists and the Royal College of Pathology

Liver biopsy is required when clinically important information about the diagnosis, prognosis or management of a patient cannot be obtained by safer means, or for research purposes. There are several approaches to liver biopsy but predominantly percutaneous or transvenous approaches are used. A wide choice of needles is available and the approach and type of needle used will depend on the clinical state of the patient and local expertise but, for non-lesional biopsies, a 16-gauge needle is recommended. Many patients with liver disease will have abnormal laboratory coagulation tests or receive anticoagulation or antiplatelet medication. A greater understanding of the changes in haemostasis in liver disease allows for a more rational, evidence-based approach to peri-biopsy management. Overall, liver biopsy is safe but there is a small morbidity and a very small mortality so patients must be fully counselled. The specimen must be of sufficient size for histopathological interpretation. Communication with the histopathologist, with access to relevant clinical information and the results of other investigations, is essential for the generation of a clinically useful report.

Ultrasound-Guided Percutaneous Liver Biopsy: A Review on Obtaining Adequate Specimens

This literature review was conducted to evaluate liver biopsy adequacy, including total core length (TCL), number of portal tracts (PT), fragmentation, and complication rates, as a function of needle type and gauge. A systematic electronic search was performed in the Web of Science and Google Scholar databases, according to the PRISMA statement. Eligible data, describing in vivo percutaneous ultrasound-guided human liver biopsy quality outcomes, were compared to adequacy criteria of the American Association for the Study of Liver Diseases (AASLD, TCL ≥ 20 mm, PT ≥ 11). An adequate mean number of PTs was found in 83% of biopsy needles assessed between 2012 and 2019, compared to 0% between 1998 and 2004. For TCL, this was 44% and 33%, respectively. Increasing the needle diameter enhanced TCL (result in 50% of included studies) and PT count (100%), and reduced fragmentation rates (75%), whereas no effect on pain or complications was found (83%). In total, five needle types achieved adequate PT counts, using 16 G (3×), 17 G (1×), or 18 G (1×) needles. Adequacy was reached using either a core needle biopsy (CNB, 3×) approach with one pass, or a fine needle aspiration (FNA, 2×) approach with two passes. The recommendations for biopsy adequacy can be met using 16/17 G FNA or 16/18 G CNB needles. Currently, many publications still present substandard liver biopsy quality outcomes. Although minimizing biopsy invasiveness is desirable, a decreased diameter or number of passes is ill-judged when reliability of biopsy outcomes is at stake.

Complications After Percutaneous Ultrasound-Guided Liver Biopsy: A Systematic Review and Meta-analysis of a Population of More Than 12,000 Patients From 51 Cohort Studies

OBJECTIVES

Percutaneous liver biopsy (LB) has been considered the reference standard in distinguishing the degree of liver disease, but there has been no definitive systematic review to assess complication rates or potential risk factors for them.

METHODS

In this study, we searched the PubMed, Embase, Web of Science, and Scopus databases for studies appraising complication rates after percutaneous ultrasound (US)-guided LB published until October 11, 2018. The safety and efficacy of US-guided LB were estimated according to major and minor complications. Subgroups including the biopsy style, needle styles, mean number of needle insertions, study period, and specific complication items were analyzed.

RESULTS

Among 12,481 patients from 51 studies, pooled results showed a low rate (0; 95% confidence interval, 0-0) of major and minor complications. The subgroup analysis indicated that US-guided LB had a low major complication rate of 0 (0-0) for both fine-needle aspiration and core biopsy, with rates of 0.016 (0-0.032) for 14-gauge, 0.010 (0.003-0.017) for 15-gauge, 0.002 (-0.001-0.005) for 20-gauge, and 0 (0-0) for 16-, 17-, 18-, 21-, and 22-gauge needles, and low minor complication rates of 0 (0-0) for fine-needle aspiration and 0.001 (0-0.002) for core biopsy, with rates of 0.164 (0.137-0.191) for 15-gauge, 0.316 (0.113-0.519) for 16-gauge, and 0 (0-0) for 14-, 17-, 18-, 20-, 21-, and 22-gauge needles. Furthermore, specific complication rates of bleeding, pain, pneumothorax, vasovagal reactions, and death were all 0 (0-0).

CONCLUSIONS

These findings suggest that it is possible to safely perform percutaneous US-guided LB.

Optimizing small liver biopsy specimens: a combined cytopathology and surgical pathology perspective

Both fine-needle aspiration (FNA) and core needle biopsy (CNB) are widely used to obtain liver biopsy specimens, particularly from mass lesions. However, the advantages and disadvantages of FNA versus CNB in terms of appropriate use, diagnostic yield, complications, and whether or not specimens should be handled by cytopathologists, surgical pathologists, or both remain subjects of controversy. This review addresses the issues of sample adequacy, appropriate use of each technique and complications, and challenges regarding the diagnosis of both hepatic tumors and non-neoplastic liver disease.

Enhancing the Value of Histopathological Assessment of Allograft Biopsy Monitoring

Traditional histopathological allograft biopsy evaluation provides, within hours, diagnoses, prognostic information, and mechanistic insights into disease processes. However, proponents of an array of alternative monitoring platforms, broadly classified as "invasive" or "noninvasive" depending on whether allograft tissue is needed, question the value proposition of tissue histopathology. The authors explore the pros and cons of current analytical methods relative to the value of traditional and illustrate advancements of next-generation histopathological evaluation of tissue biopsies. We describe the continuing value of traditional histopathological tissue assessment and "next-generation pathology (NGP)," broadly defined as staining/labeling techniques coupled with digital imaging and automated image analysis. Noninvasive imaging and fluid (blood and urine) analyses promote low-risk, global organ assessment, and "molecular" data output, respectively; invasive alternatives promote objective, "mechanistic" insights by creating gene lists with variably increased/decreased expression compared with steady state/baseline. Proponents of alternative approaches contrast their preferred methods with traditional histopathology and: (1) fail to cite the main value of traditional and NGP-retention of spatial and inferred temporal context available for innumerable objective analyses and (2) belie an unfamiliarity with the impact of advances in imaging and software-guided analytics on emerging histopathology practices. Illustrative NGP examples demonstrate the value of multidimensional data that preserve tissue-based spatial and temporal contexts. We outline a path forward for clinical NGP implementation where "software-assisted sign-out" will enable pathologists to conduct objective analyses that can be incorporated into their final reports and improve patient care.

The efficacy and safety of endoscopic ultrasound-guided liver biopsy versus percutaneous liver biopsy in patients with chronic liver disease: a retrospective single-center study

BACKGROUND AND AIMS

There is limited literature on endoscopic ultrasound-guided liver biopsy (EUS-LB), a new method of obtaining liver biopsy (LB).

METHODS

We conducted a retrospective study of the efficacy and safety of EUS-LB compared to percutaneous liver biopsy (PC-LB) in patients with chronic liver disease at our center between January 2018 and August 2019.

RESULTS

Thirty patients underwent EUS-LB and 60 patients underwent PC-LB were identified (median follow-up post-LB was 8 days; interquartile range (IQR), 3-5 days). The median number of portal tracts was significantly higher in the PC-LB group (13 vs. 5; P < 0.0001). A histologic diagnosis was established in 93% of the EUS-LB group, compared to 100% in the PC-LB group (P = 0.841). Patients in EUS-LB group had significantly shorter hospital stay (median time of hospital stay was 3 vs. 4.2 h in the EUS-LB vs. PC-LB group, respectively; P = 0.004) and reported less pain compared to PC-LB group (median pain score was 0 vs. 3.5; P = 0.0009). EUS-LB were performed using a 19-gauge (n = 27) or 22-gauge (n = 3); there was a tendency towards higher number of portal tracts in the 22- vs. the 19-gauge needle group (6 vs. 5; P = 0.501). No patient in either group had significant adverse events such as bleeding or death.

CONCLUSION

EUS-LB is safe and is associated with less pain, shorter hospital stay, and high diagnostic yield (93%) compared to PC-LB. Randomized trials are needed to standardize the utility of EUS-LB.

Negative Biopsy of Focal Hepatic Lesions: Decision Tree Model for Patient Management

OBJECTIVE

The purpose of this study was to investigate patient- and procedure-related variables affecting the false-negative rate of ultrasound (US)-guided liver biopsy and to develop a standardized patient-tailored predictive model for the management of negative biopsy results.

MATERIALS AND METHODS

We retrospectively included 389 patients (mean age ± SD, 62 ± 12 years old) who had undergone US-guided liver biopsy of 405 liver lesions between January 1, 2013, and June 30, 2015. We collected multiple patient- and procedure-related variables. By comparing pathology reports of biopsy and the reference standard (further histology or imaging follow-up), we were able to categorize the biopsy results as true-positive, true-negative, and false-negative. Diagnostic accuracy and diagnostic yield were measured. Univariate and multivariate analyses were performed to identify variables predicting false-negative results. A standardized patient-tailored predictive model of false-negative results based on a decision tree was fitted.

RESULTS

Diagnostic accuracy and diagnostic yield were 93.8% (380/405) and 89.4% (362/405), respectively. The false-negative rate was 6.5% (25/387). Predictive variables of false-negative results at univariate analysis included body mass index, lesion size, sample acquisition techniques, and immediate specimen adequacy. The only independent predictors at multivariate analysis were patient age and Charlson comorbidity index. By combining lesion size and location with patient age and history of malignancy, we developed a decision tree model that predicts false-negative results with high confidence (up to 100%).

CONCLUSION

False-negative results are not negligible at US-guided liver biopsy. The combination of selected lesion- and patient-specific variables may help predict when aggressive management is warranted in patients with likely false-negative results.

Pain in percutaneous liver core-needle biopsy: a randomized trial comparing the intercostal and subcostal approaches

PURPOSE

Effective pain control during and after percutaneous core needle liver biopsy is important with regard to ethical considerations and patient comfort. In this randomized double-blind study, we compared post-biopsy pain in the patients undergoing liver core-needle biopsy using either subcostal or intercostal approaches.

METHODS

All patients referred for ultrasound-guided CNLB between July 2017 and January 2018 to our interventional radiology department were randomized into two groups. Biopsy was performed through intercostal approach in the first group and through subcostal approach in the second group. The intensity of pain 0, 2, and 4 h after the procedure was compared in two groups using a 100-mm visual analogue scale. All biopsies were performed without procedural IV sedation. If patients' discomfort  demanded administration of IV analgesics during or after the procedure, then the patients were excluded from the study.

RESULTS

In patients without routine procedural IV sedation, there was no significant difference in the pain level between the intercostal and subcostal groups immediately after the procedure (p = 0.055), but we found a significant difference in the pain level between the two groups 2 (7.5 mm, p = 0.001) and 4 (2 mm, p = 0.001) h after the procedure.

CONCLUSION

The minimum amount of change in the VAS score that is considered clinically important is 13 mm on a 100-mm scale. Pain differences at 2 and 4 h in the two groups in this study were statistically but not clinically significant. Therefore, the authors suggest the use of subcostal route for ultrasound-guided liver biopsy whenever possible, but the results do not warrant the routine use of post-procedure analgesics in whom biopsy is performed via intercostal route.