Changes in the Portal Venous System

n In portal hypertension, the luminal size (transverse diameter) of the portal veins correlates poorly with the portal pressure. Thus, the diagnosis of portal hypertension relies not only on increased portal vein diameter but also on the results of CDS with spectral analysis and the assessment of flow characteristics.

• Definite signs of portal hypertension (by CDS) are flow reversal and an absence of flow.

n The causes of raised portal venous pressure are classified as follows:

• Prehepatic (portal vein thrombosis)

• Intrahepatic (cirrhosis)

• Posthepatic (Budd-Chiari syndrome) n Examination: see p. 189.

n Overview: See Table 45.

Table 45 ■ Changes in the portal veins

Luminal dilatation (portal hypertension) Flow changes and collaterals

Dilatation of the portal vein (p. 257) Flow changes (p. 259)

Dilatation of the tributaries Portosystemic collaterals (p. 259)

(lack of compressibility, p. 258) Compression or occlusion of a tributary vein (segmental portal hypertension, p. 259)

Intraluminal changes Associated effects

Acute portal vein thrombosis (p. 260) Displacement, compression (p. 261)

Chronic portal vein thrombosis (p. 260) Infiltration (p. 261)

n Increased portal vein diameter, indirect signs (Fig. 364):

• > 11 mm intrahepatic, > 13-15 mm in the hepatoduodenal ligament

• Caliber variations < 2 mm or 50-100 % with respirations

• Detection of hepatic cirrhosis

• Splenomegaly

• Possible ascites

• Wall thickening of the gallbladder and stomach 257 Schmidt, Ultrasound © 2007 Thieme

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Recanalized Umbilical Vein Ultrasound

Fig. 364 Incipient portal hypertension. The portal vein (PV) is marginally dilated: 12.9mm intrahepatic, 13.7mm in the hepatoduodenal ligament (cursors). L = liver n Dilated tributaries, lack of compressibility (Figs. 365, 366):

• Superior mesenteric vein dilated to > 10 mm (often exceeding the portal vein diameter)

• Good visualization of the inferior mesenteric vein

• Splenic vein, usually with splenomegaly

Fig. 365a, b Portal hypertension, portosystemic collaterals. a Superior mesenteric vein dilated to 14 mm (cursors). Arrow: dilatation of the left gastric vein, which descends to the portal vein (PV) from the left side. b Scan higher and to the left demonstrates the left gastric vein (LGV) passing from the venous confluence (CO) to the esophagus (note varices). ES = esophagus, PVA = perigastric varices

Caput Medusae Ultrasound

Fig. 366a, b Recanalized umbilical vein, paraumbilical vein (UV) arising from the umbilical branch of the left portal vein (VP). CDS: portosystemic collaterals with tortuous periumbilical vessels ("caput medusae") that generally empty into the right or left iliac vein. a High upper abdominal longitudinal scan. b Right subcostal oblique scan. AO = aorta, CT = celiac trunk, C = venous confluence

Fig. 366a, b Recanalized umbilical vein, paraumbilical vein (UV) arising from the umbilical branch of the left portal vein (VP). CDS: portosystemic collaterals with tortuous periumbilical vessels ("caput medusae") that generally empty into the right or left iliac vein. a High upper abdominal longitudinal scan. b Right subcostal oblique scan. AO = aorta, CT = celiac trunk, C = venous confluence n Compression or occlusion of a tributary vein (Fig. 367): segmental portal hypertension

• Usually encased by tumor masses

• With splenic vein involvement, also inflammatory obliteration or thrombosis due to chronic pancreatitis.

Recanalized Paraumbilical Vein

Fig. 367a, b Segmental portal hypertension resulting from superior mesenteric lymph node metastasis (T). Tumor stenosis with dilated portal tributaries. a Superior mesenteric vein (SMV) dilated to 12.4 mm (cursors). b Splenic vein (SV)

dilated to 17.6mm (cursors). PV = portal vein

Fig. 367a, b Segmental portal hypertension resulting from superior mesenteric lymph node metastasis (T). Tumor stenosis with dilated portal tributaries. a Superior mesenteric vein (SMV) dilated to 12.4 mm (cursors). b Splenic vein (SV)

dilated to 17.6mm (cursors). PV = portal vein

• Flow velocity is slowed to < 10cm/s (normal = 15-20 cm/s) (Fig. 368a)

• Luminal diameter > 15 mm, does not vary with respirations

• Bidirectional, absent or reverse flow in the portal vein or its tributaries (Fig. 368b)

n Collaterals (Fig. 369): detection of portosystemic collaterals

Portal Hypertension Sonographic Findings

Fig. 368a, b Portal hypertension in liver cirrhosis. CDS: decreased flow velocity with absence of flow in the portal vein. a Flow is in the normal hepatopetal direction (encoded in red), but its velocity is slowed to 9 cm/s. b Absence of flow in the portal vein (PV). Additional sign: large-caliber hepatic artery (A), arterial waveform

Fig. 368a, b Portal hypertension in liver cirrhosis. CDS: decreased flow velocity with absence of flow in the portal vein. a Flow is in the normal hepatopetal direction (encoded in red), but its velocity is slowed to 9 cm/s. b Absence of flow in the portal vein (PV). Additional sign: large-caliber hepatic artery (A), arterial waveform u

Portosystemic Collaterals Sites
Fig. 369 Portosystemic collaterals: 1 = fundal and esophageal varices, 2 = recanalized paraumbilical and umbilical veins, 3 = hemorrhoidal venous collaterals, 4 = splenic hilar collaterals

n Acute portal or mesenteric vein thrombosis (see Fig. 116, p. 85):

• Echogenic filling defect

• Vascular dilatation

• Absence of color Doppler flow signals

H Note: Clinical picture of acute abdomen. n Chronic portal vein thrombosis (Fig. 370):

• Little or no luminal dilatation

• Echogenic intraluminal thrombus

• No measurable flow by Doppler ultrasound, resulting in collateral formation and recanalization (cavernous transformation of the portal vein, see Fig. 371 )

Fig. 370 Chronic portal vein thrombosis (PVT) in the setting of a paraneoplastic syndrome. Hepatic metastases: very little increase in luminal diameter, intraluminal echoes in thrombosed portal vein segments. Intrahepatic portal vein (PV) is clear

Fig. 371 Cavernous transformation of the portal vein. Tortuous vessels resulting from tumor infiltration of the portal vein (patchy red/blue vessels representing tortuous collaterals) and portal vein occlusion (arrows). PV = intrahepatic portal vein with normal course,

VC = inferior vena cava

n Displacement, compression:

• Intrahepatic due to cirrhosis or tumors

• Extrahepatic due to chronic pancreatitis or pancreatic tumors n Infiltration (Fig. 371):

• Faint, irregular vascularity

• The causative malignancy can usually be detected (see Search for Occult Tumors, p. 447)

n Sonography: CDS with the analysis of spectral indices has become the standard method of choice for evaluating the portal venous system. n Pressure measurements and splenoportography: These are no longer used in routine examinations. n Esophagoscopy and conventional esophagography: Gastroscopy or esophago-graphy is essential for the detection of esophageal varices in patients with hepatic cirrhosis.

Sonographic Hepatic Portal System
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