Feasibility and safety of endoscopic ultrasound-guided liver biopsy to diagnose parenchymal liver disease: A multi-centre retrospective cohort study

Abstract

BACKGROUND

Liver biopsy is an important diagnostic tool to investigate patients with suspected liver disease. The efficacy and safety of endoscopic ultrasound-guided liver biopsy (EUS-LB) as a method for liver tissue acquisition remain uncertain.

AIM

To study the diagnostic yield and safety of EUS-LB in patients with suspected parenchymal liver disease.

METHODS

This is a retrospective observational cohort study of patients undergoing EUS-LB in 2 tertiary-care centers in Kuwait in the period between January 2022-June 2025. The primary outcome was sample adequacy, while secondary outcomes included histological quality of the specimen and adverse events. Predictors of increased diagnostic adequacy and specimen quality were explored.

RESULTS

A total of 50 patients [mean age 43.9 (15.5) years, 40% males] were included. The left liver lobe was targeted for biopsy in most patients (96%), and 19-gauge fine needle aspiration (FNA) was used in most cases (52%). The median number of passes performed was 3 (range 2-5), and the heparin-wet suction technique was used in 40% of patients. The overall diagnostic adequacy of EUS-LB was 86%, with no significant difference between 19-gauge FNA and 19-gauge fine needle biopsy (FNB) needles. Fulfillment of the European Association for the Study of Liver (EASL) and the American Association for the Study of Liver Diseases criteria was achieved in 54% and 34%, respectively, with a significantly higher number of patients fulfilling these criteria when FNB needle was used compared to FNA needle (83.3% vs 26.9%, P < 0.0001) and (62.5% vs 7.7%, P < 0.0001), respectively. Only 1 patient (2.0%) developed adverse post-procedure events, namely bleeding requiring transfusion. Multivariate regression analysis did not identify any factor that increased diagnostic adequacy; however, the use of FNB needles and wet heparin suction methods were associated with significantly increased odds of fulfilling EASL criteria, while performing more than 2 passes reduced the quality of the specimen.

CONCLUSION

EUS-LB is an effective and safe method for obtaining liver biopsy in patients with suspected parenchymal liver disease. EUS-LB demonstrated a favorable safety profile in our cohort, although larger prospective studies are required to validate bleeding risk. The use of 19-gauge FNB needles, wet-heparin suction technique, and performing ≤ 2 passes is associated with improved quality of the specimen obtained without increasing the risk of adverse events.

Key Words: Endoscopic ultrasound; Liver biopsy; Parenchymal liver disease; Fine needle aspiration; Fine needle biopsy

Core Tip: Endoscopic ultrasound-guided liver biopsy (EUS-LB) has recently been introduced as an endoscopic method for obtaining liver biopsy in patients with suspected parenchymal liver disease. However, the efficacy and safety of this approach remain unclear. Furthermore, some uncertainty exists in the most appropriate needle size and suction technique to achieve an optimal histological specimen. This multicenter retrospective study found a high diagnostic yield for EUS-LB with a low rate of serious adverse events. In addition, the use of a 19-gauge fine needle biopsy needle, the wet-heparin suction technique, and performing ≤ 2 passes was associated with improved quality of the specimen obtained without increasing the risk of adverse events.

INTRODUCTION

Liver biopsy represents the gold standard test in the diagnosis of several hepatic diseases, allowing histological assessment of liver parenchyma in patients with suspected liver disease[1]. For decades, liver biopsy has been commonly performed using percutaneous or transjugular approaches, yielding excellent diagnostic adequacy in most patients[2,3]. However, these approaches have been associated with several adverse events, including high proportions of post-procedure pain and occasionally serious adverse events, including intra-abdominal bleeding, bile duct injury, and vascular injuries[4].

Recently, endoscopic ultrasound-guided liver biopsy (EUS-LB) was introduced as a novel approach for obtaining liver biopsy in patients with suspected parenchymal liver disease[5,6]. A meta-analysis found a pooled rate of successful histological diagnosis of 93.3% with EUS-LB and an overall adverse event rate of 2.3%[7]. Furthermore, a more recent meta-analysis found similar diagnostic adequacy between EUS-LB and the percutaneous approach with lower post-procedure pain scores with EUS-LB[8]. These data support the efficacy and safety of EUS-LB for obtaining liver tissue. However, the optimal needle type and technique for obtaining EUS-LB remain unclear, and several prospective and randomized studies have compared fine needle aspiration (FNA) and fine needle biopsy (FNB) needles with mixed results highlighting ongoing controversies. In a small, randomized cross-over study, tissue adequacy was found to be higher for the 19-gauge FNA vs 22-gauge FNB (88% vs 68%, P = 0.03)[9]. However, this study used the fork-tip-type needle of a smaller gauge which may have affected the quality of the obtained tissue. This observation is further supported by the results of a retrospective study that found higher fragmentation of the specimens using 22-gauge Franseen-tip needle leading to inferior specimen adequacy compared to 19-gauge non-Tru-Cut needles[10]. Furthermore, the use of a 19-gauge FNB needle was found to produce superior liver biopsy samples compared to 22-gauge FNB needles, mainly by reducing the fragmentation of the samples[11]. Despite these results, the optimal size and type of needle to use in EUS-LB remains unclear.

Given these uncertainties in the literature, we conducted this study aiming to assess the efficacy and safety of EUS-LB and try to identify predictors that are associated with increased diagnostic yield and quality of histological specimens. We also aimed to compare the diagnostic yield and adverse events of FNA compared to FNB needles.

MATERIALS AND METHODS

Study design

A retrospective observational cohort study of patients undergoing EUS-LB for suspected parenchymal liver disease at Amiri and Mubarak Alkabeer Hospitals in Kuwait between January 2022 and June 2025. Data collection included patient demographics, procedural, histopathological, and follow-up data. Ethical approval was obtained from the Ministry of Health of Kuwait prior to the commencement of the study.

Patient selection

Adult patients (> 18 years) referred to EUS-LB to investigate parenchymal liver disease were considered for inclusion. Common reasons for referral included unexplained elevated liver enzymes, persistent jaundice without etiology, or to confirm the etiology of a suspected liver disease (e.g. autoimmune hepatitis). Patients with underlying severe coagulopathy (platelet count < 50000/uL and/or international normalized ratio > 1.5), taking antiplatelets (except aspirin) or anticoagulants (e.g. direct oral anticoagulant or warfarin) within 5 days, massive ascites, pregnancy, or unable to provide informed consent were excluded. In addition, patients with focal liver disease who were referred to EUS-LB for that specific lesion were not included in the study.

Procedure

All procedures were performed by experienced endoscopists with at least 5 years of experience. Patients were kept fasting for at least 6 hours before the procedure. No routine antibiotic prophylaxis was used. In our routine practice, procedures are performed on an outpatient basis, with the type of sedation determined by the cardiopulmonary status of the patient including either conscious sedation (midazolam and fentanyl) or general anesthesia given by an anesthesiologist. The patient is placed in the left lateral position, and the linear echoendoscope (EG-580UT, Fujifilm Co., Tokyo, Japan) is introduced into the stomach. The transgastric approach was used for the left lobe, while the transduodenal approach was used for the right lobe. The choice of the biopsy needle was left to the endoscopist, but all endoscopists used either a 19-gauge FNA needle (Areus Eco, Microtech, Nanjing, China) or 19-gauge three-prong asymmetric tip FNB needle (Trident, Microtech, Nanjing, China). Once the liver lobe was visualized, the liver parenchyma was punctured under doppler guidance to avoid any intervening blood vessel. In general, 1 to 5 passes were performed, with the number of actuations depending on the preference of the endoscopist (at least 3 and up to 10 per pass). The use of suction was also left to the discretion of the endoscopist. In the “wet heparin suction” technique, the needle is primed with heparin (1000 unit per mL) until liquid droplets come out of the needle but without air flush, followed by filling of a syringe with 2 mL saline and a vacuum suction of 20 mL that is then attached to the needle. After the puncture into the liver parenchyma, the vacuum is switched on while completing actuations into the liver[12]. In the “no suction” method, the stylet is removed, and no suction is applied while performing the biopsy. After removing the needle, the biopsy track is inspected for signs of bleeding using doppler. The tissue acquired is then placed into 10% formalin and sent for pathological evaluation. Rapid on-site evaluation is not part of the routine practice in our centres and hence was not utilized. After the procedure, patients are observed for 1-2 hours in the recovery room and allowed to be discharged home if they do not experience any significant pain. All patients were followed up, either in clinic or by phone call, within 1-2 weeks from the procedure to assess for any late complications.

Study outcomes

The primary outcome was “diagnostic adequacy”, defined as the ability to render a histopathological diagnosis, regardless of the specimen quality, as determined by the pathologist[8]. Secondary outcomes included determination of the quality of the specimens by fulfilment of the biopsy according to the European Association for the Study of Liver (EASL) and American Association for the Study of Liver Diseases (AASLD) criteria. EASL criteria were met if the specimen contained a total sample length ≥ 15 mm with ≥ 6 complete portal tracts (CPT)[1], while the AASLD required total specimen length (TSL) ≥ 20 mm and ≥ 11 CPT[2]. Other secondary outcomes were those of overall adverse events, including bleeding requiring blood transfusion or intervention, severe pain requiring admission to hospital, cardiopulmonary events, perforation, or death. Mild post-procedural pain that required analgesics but not requiring admission was recorded but not considered an adverse event.

Statistical analysis

Continuous data were reported as mean ± SD or median and range. Categorical data were expressed as frequency and percentage. Inferential analyses included between group comparisons for all outcomes using the χ² test and t-test (or nonparametric Wilcoxon rank-sum test), where appropriate. Stepwise multivariable analyses using a logistic regression model was performed to identify predictors of increased diagnostic adequacy and specimen quality with the respective associations expressed as odds ratios (OR) with a null value of “1”. A statistical significance threshold of P < 0.05 was adopted. All analyses were performed using STATA version 15.1 (StataCorp, College Station, TX, United States). Normality of continuous variables was tested using Shapiro-Wilk. Variables for models were selected based on univariate significance (P < 0.10) and clinical plausibility. Multicollinearity was assessed with variance inflation factor (VIF), and interaction terms (needle type × punctures) were tested.

RESULTS

A total of 50 patients with a mean age of 43.9 (SD 15.5) years and 20 (40.0%) males were included. Conscious sedation was used in 94.0% of cases. 19-gauge FNA needle was used in 26 (52.0%) patients while in the remaining patients, a 19-gauge FNB needle was used. The left liver lobe was targeted in the majority of patients (n = 48, 95.4%). Other baseline factors are shown in Table 1.

Table 1 Baseline patient and procedural characteristics (n = 50), n (%).

Variable	Overall (n = 50)	FNA (n = 26)	FNB (n = 24)	P value
Gender
Male	20 (40.0)	13 (50.0)	7 (29.2)	0.13
Female	30 (60.0)	13 (50.0)	17 (70.8)
Age, mean (SD)	43.9 (15.5)	43.3 (15.6)	44.7 (15.7)	0.75
Sedation
Conscious sedation	47 (94.0)	26 (100)	21 (87.5)	0.06
General anesthesia	3 (6.0)	0 (0)	3 (12.5)
Needle type
FNA	26 (52.0)	NA	NA	NA
FNB	24 (48.0)
Number of needle passes, median (range)	3 (2-5)	4 (3-5)	2 (2-5)	< 0.0001
Liver lobe biopsied
Left lobe	48 (96.0)	25 (96.2)	23 (95.8)	0.95
Right lobe	0 (0)	0 (0)	0 (0)
Both lobes	2 (4.0)	1 (3.8)	2 (4.2)
Aspiration technique
No suction	25 (50.0)	21 (80.8)	4 (16.7)	< 0.0001
Wet heparin suction	25 (40.0)	5 (19.2)	20 (83.3)

FNB: Fine needle biopsy; FNA: Fine needle aspiration.

Primary and secondary outcomes

Overall, diagnostic adequacy was achieved in 43 patients (86.0%), with 54.0% and 34.0% of specimens fulfilling the EASL and AASLD criteria, respectively. The mean number of CPTs obtained was 17.1 (SD 14.6), and the mean TSL was 24.2 mm (SD 23.8). The most common diagnosis was metabolic-dysfunction associated steatohepatitis and drug-induced liver injury (Table 2). Adverse events occurred in one patient (2.0%), namely post-procedure bleeding requiring blood transfusion, while 5 patients (10%) developed post-procedural pain requiring analgesics but not admission to hospital. Although FNB improved tissue quality, diagnostic adequacy remained similar as most diagnoses required minimal tissue. The higher number of punctures in FNA reflects lower per-pass yield.

Table 2 Primary and secondary outcomes, n (%).

Variable	Overall	FNA	FNB	P value
Diagnostic adequacy
Yes	43 (86.0)	22 (84.6)	21 (87.5)
No	7 (14.0)	4 (15.4)	3 (12.5)	0.77
Final histopathological diagnosis
MASLD	16 (32.0)	8 (30.8)	8 (33.3)	0.94
DILI	12 (24.0)	6 (23.1)	6 (25.0)
Hemosiderosis	2 (4.0)	1 (3.8)	1 (4.2)
AIH	5 (10.0)	3 (11.5)	2 (8.3)
PBC	3 (6.0)	1 (3.8)	2 (8.3)
PSC	1 (2.0)	1 (3.8)	0 (0)
Acute cellular rejection	1 (2.0)	0 (0)	1 (4.2)
Cholestasis	2 (4.0)	1 (3.8)	1 (4.2)
Sarcoid	1 (2.0)	1 (3.8)	0 (0)
Non-diagnostic	7 (14.0)	4 (15.4)	3 (12.5)
Complications	1 (2.0)	0 (0)	1 (4.2)	0.29
Post procedure pain	5 (10.0)	2 (7.7)	3 (12.5)	0.57
Fulfills EASL criteria
Yes	27 (54.0)	7 (26.9)	20 (83.3)	< 0.0001
No	23 (46.0)	19 (73.1)	4 (16.7)
Fulfills AASLD criteria
Yes	17 (34.0)	2 (7.7)	15 (62.5)	< 0.0001
No	33 (66.0)	24 (92.3)	9 (37.5)
Number of complete portal triads, mean (SD)	17.1 (14.6)	10.6 (9.6)	24.1 (15.9)	0.0006
Length of longest specimen (mm), mean (SD)	8.1 (8.0)	2.2 (0.80)	14.6 (8.4)	< 0.0001
Total specimen length (mm), mean (SD)	24.2 (23.8)	9.4 (6.4)	40.3 (25.4)	< 0.0001

AIH: Autoimmune hepatitis; DILI: Drug-induced liver injury; MASLD: Metabolic dysfunction-associated steatotic liver disease; PBC: Primary biliary cholangitis; PSC: Primary sclerosing cholangitis; FNB: Fine needle biopsy; FNA: Fine needle aspiration; EASL: European Association for the Study of Liver; AASLD: American Association for the Study of Liver Diseases.

FNA vs FNB

The diagnostic adequacy was similar between FNA and FNB needles (84.6% vs 87.5%, P = 0.77). However, FNB needle fulfilled EASL and AASLD criteria more frequently than FNA (83.3% vs 26.9%, P < 0.0001, and 62.5% vs 7.7%, P < 0.0001, respectively). The number of CPT and TSL was also significantly higher in the FNB compared to FNA group (Table 2). No difference in adverse events or pain was observed.

Predictors of diagnostic adequacy

Multicollinearity was assessed using VIF, with a value of 3.6, indicating no concerning significant collinearity among predictors. No factor was identified as a significant predictor of increased diagnostic adequacy (Table 3). A regression model was performed to examine the effect of needle type and number of passes, and their interaction on the outcome. The overall model was not statistically significant, indicating that the predictors explained little variance in the outcome.

Table 3 Multivariate logistic regression analysis of predictors of optimal diagnostic adequacy (adjusted for age and gender).

Variable	Adjusted odds ratio	95% confidence intervals	P value
Use of FNB needle	1.2	0.2-6.5	0.24
Use of wet heparin suction	1.4	0.3-7.6	0.67
Performing > 2 passes	1.22	0.22-6.92	0.82

FNB: Fine needle biopsy.

Predictors of specimen quality

The use of FNB needles [adjusted OR (aOR) 19.9 (4.2-94.2)], and the wet-heparin suction technique [aOR 7.8 (2.1-29.1)] were associated with a significantly increased odds of obtaining an optimal histological specimen according to EASL criteria (Table 4). The performance of > 2 needle passes were associated with lower odds of obtaining a specimen that fulfills EASL criteria [aOR 0.10 (0.02-0.47)]. Similarly, the use of FNB needle [aOR 19.9 (3.6-108.6)] and wet-heparin suction technique [aOR 42.9 (4.7-388.1)] were associated with significantly increased odds of obtaining a histological specimen that fulfills AASLD criteria, while the performance of > 2 passes was associated with lower odds of fulfilling AASLD criteria [aOR 0.13 (0.03-0.54)] (Table 5).

Table 4 Multivariate logistic regression analysis of predictors of optimal histopathological specimen according to European Association for the Study of Liver criteria (adjusted for age and gender).

Variable	Adjusted odds ratio	95% confidence intervals	P value
Use of FNB needle	19.9	4.2-94.2	< 0.0001
Use of wet heparin suction	7.8	2.1-29.1	0.002
Performing > 2 passes	0.10	0.02-0.47	0.003

FNB: Fine needle biopsy.

Table 5 Multivariate logistic regression analysis of predictors of optimal histopathological specimen according to American Association for the Study of Liver Diseases criteria (adjusted for age and gender).

Variable	Adjusted odds ratio	95% confidence intervals	P value
Use of FNB needle	19.9	3.6-108.6	0.001
Use of wet heparin suction	42.9	4.7-388.1	0.001
Performing > 2 passes	0.13	0.03-0.54	0.005

FNB: Fine needle biopsy.

DISCUSSION

Liver biopsy is the gold standard test to diagnose parenchymal liver disease, and several techniques are available for obtaining liver tissue. In this study, we have demonstrated that EUS-LB is a safe and effective modality for obtaining adequate histological tissue in most patients with a low risk of severe adverse events. The overall diagnostic adequacy in our study was 86%, which is similar to previous reports for EUS-LB[6-8,13] and comparable to those obtained by the percutaneous approach[1,2]. This observation strengthens the data supporting the use of EUS-LB to diagnose patients with suspected liver disease. Furthermore, the majority of patients did not experience any significant post-procedural pain, and only 5 patients (10%) required analgesia post-biopsy compared to what is usually > 30% among patients undergoing percutaneous liver biopsy[14]. In addition, only 1 patient developed post EUS-LB bleeding, which was managed conservatively with blood transfusions, without requiring any further intervention for hemostasis. This supports the safety of EUS-LB and may provide indirect evidence of its superior safety compared to percutaneous liver biopsy in carefully selected patients with no evidence of coagulopathy or other contraindications to undergoing such a procedure.

An important question that has remains controversial is the best endoscopic ultrasound (EUS) needle and suction technique for optimizing diagnostic yield and specimen quality during the EUS-LB procedure. A meta-analysis of 9 studies (n = 437 patients), all retrospective observational non-comparative studies, concluded that 19-gauge FNA needles provide significantly better biopsy specimens compared to core needles[7]. However, some of the included studies used an inferior core needle which may have biased the results in favor of FNA needle[15]. In fact, a small, randomized study that was not included in the previous meta-analysis found that 19-gauge Franseen tip FNB needles delivered longer specimen length, and more CPT compared to a 19-gauge FNA needle[16]. Even though we did not find any difference in diagnostic adequacy, as determined by experienced pathologists, between FNA and FNB needles, the specimen quality was significantly better with the use of FNB needle as measured by several histopathological measures including CPT, TSL, and fulfillment of EASL and AASLD criteria. On average, the number of CPT (24.1 vs 10.6, P = 0.0006), TSL (40.3 mm vs 9.4 mm, P < 0.0001), meeting EASL criteria (83.8% vs 26.9%, P < 0.0001), and meeting AASLD criteria (62.5% vs 7.7%, P < 0.0001) were significantly higher with a 19-gauge FNB compared to a 19-gauge FNA needle. These observations provide evidence to support the use of 19-gauge FNB needles for obtaining liver biopsies to improve the quality of the specimens obtained. In fact, on multivariate regression analysis after adjusting for age and gender, the use of FNB needle (vs FNA) was associated with an almost 20-fold increased odds of meeting EASL and AASLD criteria-a statistically and clinically significant set of results. The lack of a significant difference in the diagnostic yield between the 2 needles despite the superior quality of the tissue obtained by FNB needle is interesting but could be partially explained by the tissue assessors who were experienced liver pathologists who were able to reach a diagnosis even in highly fragmented, lower quality specimens, but could be related to the lack of statistical power to detect such outcome in our study.

Another aspect that we explored was the suction method that optimizes tissue acquisition and the number of passes required to achieve adequate sampling. The use of a wet-heparin suction method (vs no suction) was associated with a 7-fold in increased odds of fulfilling EASL criteria, while performing more than 2 passes was associated with lower odds of fulfilling these criteria (aOR 0.10). This observation could be related to the lesser fragmentation and blood content of the samples obtained by performing fewer passes, but could be confounded by the less frequent passes performed when the FNB needle is used. Hence, the optimal method for obtaining EUS-LB seems to be using a 19-gauge FNB needle, utilizing wet heparin suction method, and limiting the procedure to 1-2 needle passes only. A unique aspect of our study is the use of a three-prong tip needle design, which has not been reported previously in studies assessing EUS-guided liver tissue acquisition. The excellent quality of tissue obtained using this needle in our study may be related to the design of this needle, that reduces fragmentation. However, the impact of such design compared to others remains unclear due to the lack of direct comparative studies.

Our study has several strengths. It is the first study to assess the utility of EUS-LB in the region, and the multicenter nature adds further to the strength and generalizability of the study. The inclusion of experienced endoscopists and pathologists may have limited the generalizability of the study, but it ensured optimal endoscopic and pathological assessment techniques were utilized to minimize the risk of errors that may bias outcomes. We used established pathological parameters to assess the quality of the specimens, including TSL, CPT, EASL, and ASSLD criteria which increase the reliability of our findings. The main limitation of our study is the small sample size and retrospective nature of the study which may have introduced selection and reporting biases. However, all patients had complete information collected from health-care records and all had at least one follow-up visit 1-2 weeks post-procedure, minimizing the risk of introducing significant bias. Second, we did not compare EUS-LB to other approaches, hence our study does not provide direct evidence to support the safety and efficacy of EUS-LB over the percutaneous method. Furthermore, our results may not be generalizable to all FNB needles since we only used 19-gauge three-prong asymmetric FNB needles, and it is unclear if the same outcomes can be achieved with other designs and sizes of FNB needles. Additional limitations include non-blinded pathology review and operator-dependent needle choice. The pathological assessment was not conducted blindly, which may have introduced some assessment bias, but the utilization of standardized measures including EASL/AASLD criteria and CPT limits this likelihood. It should be emphasized that only experienced endoscopists performed the procedures in high-volume centers, hence the study’s findings may not be applicable to less experienced physicians or low-volume centers. Finally, cost was not measured in the current study, hence the cost-effectiveness of EUS-LB remains unclear. Nevertheless, in our centers, the use of EUS-LB is likely to be a cost-effective measure since all these procedures are done on an outpatient basis compared to the inpatient admission resources required for a percutaneous approach. Hence, cost-effectiveness analyses are needed to support wider adoption.

CONCLUSION

In conclusion, EUS-LB is a feasible modality in experienced centers with a favourable safety profile. The use of FNB needles with wet heparin suction and ≤ 2 passes improved specimen quality. However, larger multicenter comparative prospective studies with cost-effectiveness analyses, and comparisons with percutaneous biopsy are required before definitive recommendations can be made.