Endoscopic ultrasonography can diagnose distal biliary strictures without a mass on computed tomography

Table 1 Patient characteristics

Final diagnosis	Benign stricture and normal case (n = 17)	Malignant stricture (n = 17)	Statistical significance
Age (yr)	71.5 (23-90)	69.0 (56-84)	NS
Sex (male/female)	9/8	8/9	NS
Presenting symptoms			NS
Jaundice	5	8
Elevated liver enzymes	2	6
Abdominal pain	5	1
Abnormal imaging	5	2

NS: Not significant.

Table 2 Final diagnosis

	n
Benign bile duct stricture	11
Fibrotic or inflammatory stricture	4
Dilatation of the bile duct	3
Chronic pancreatitis	2
Anomalous arrangement of pancreaticobiliary duct	1
Congenital choleductal cyst	1
Malignant bile duct stricture	17
Peripancreatic cancer	8
Bile duct cancer	7
Carcinoma of the papilla of Vater	2
Normal study	6

Table 3 Malignant strictures correctly judged as malignant on EUS

Final diagnosis	EUS findings	n (%)
Peripancreatic cancer (n = 8)	Mass adjacent to the stricture site in the pancreas head	8 (100)
	Disruption of the bile duct by the mass	6 (75)
	Continuation into adjacent structures	6 (75)
	Invasion of the main pancreatic duct	5 (62.5)a
	LN swelling	4 (50)
	Ascites	1 (12.5)
Biliary cancer (n = 6)	Mass adjacent to the stricture site in the pancreas head	6 (100)
	Disruption of the bile duct by the mass	5 (83.3)
	Continuation into adjacent structures	5 (83.3)
	Invasion of the main pancreatic duct	0 (0)
	LN swelling	3 (50)
Cancer of the ampulla of Vater (n = 2)	Mass mainly located on the luminal side	2 (100)
	Infiltration of the muscularis propria by the mass	2 (100)
	LN swelling	1 (50)

^aP = 0.026 vs Biliary cancer. EUS: Endoscopic ultrasonography; LN: Lymph nodes.

Table 4 Benign strictures correctly judged as benign on EUS

Final diagnosis	Reason to diagnose as benign stricture	EUS findings
Inflammatory stricture clinically diagnosed as acute cholangitis (n = 1)	No exacerbation during follow-up (> 23 mo)	Stenosis of the distal end of the bile duct
		The normal layered structure of the bile duct wall
		No mass adjacent to the stricture site
Biliary dilation (n = 3)	No change for > 18 mo	The dilated bile duct gradually tapering at the ampulla of Vater (n = 2)
		A 1-cm long narrowing portion at the distal end of the duct smoothly continuous from the dilated proximal duct (n = 1)
Chronic pancreatitis including 1 autoimmune pancreatitis (n = 2)	No exacerbation during follow-up (> 10 mo)	Smooth tapering of the distal end of the bile duct without a mass adjacent to the stricture site (in case of autoimmune pancreatitis)
		Marked calcification at the stricture site (n = 1)
Anomalous arrangement of the pancreaticobiliary duct (n = 1)	Confirmed by MRCP	Connection of the pancreatic duct to the biliary duct outside the papilla of Vater
Congenital choleductal cyst (n = 1)	Confirmed by surgery	Cystic dilatation at the distal end of the bile duct

MRCP: Magnetic resonance cholangiopancreatography.

Table 5 EUS for recognizing various features of biliary obstruction

Diagnostic ability	%
Sensitivity	90.5
Specificity	100
PPV	100
NPV	86.7
Accuracy	94.1

PPV: Positive predictive value; NPV: Negative predictive value.

Table 6 Diagnosis of malignant vs benign causes (%)

	Sensitivity	Specificity	PPV	NPV	Accuracy
EUS (n = 34)	94.1	82.3	84.2	93.3	88.2
Brushing (n = 24)	62.5a	100	100	57.2c	75.0
Tumor marker (CA19-9 > 37 U/mL) (n = 34)	76.5	70.6	72.2	75.0	73.5
Tumor marker (CA19-9 > 100 U/mL) (n = 34)	53.0b	82.4	75.0	63.6	67.7

^aP = 0.039 vs EUS;

^bP = 0.017 vs EUS;

^cP = 0.035 vs EUS. CA19-9: Carbohydrate antigen 19-9.

Table 7 Classification of EUS Imaging

	Benign stricture (n = 11)	Malignant stricture (n = 17)	Statistical significance (P)
Mass			0.0069
+	5	16
-	6	1
Size of mass (mm)			NS
≤ 10	3	3
> 10	2	13
Shape			0.025
Round	4	3
Irregular	1	13
Internal echo			0.004
Hyperechoic	4	1
Hypo or mixedechoic	1	15
Disruption of the common bile duct			0.0013
+	1	13
-	10	4
Invasion to surrounding tissue			< 0.001
+	1	16
-	10	1