Table 1 Ultrasonographic manifestations, diagnostic grading, prognosis and perinatal management of new classification of congenital abnormalities of UPVS

Type I: Anatomy and morphological abnormalities of the portal vein

Preduodenal portal vein (PDPV)

Prenatal ultrasound may demonstrate duodenal obstruction as “double bubble” sign

Difficult

A majority of patients with PDPV are asymptomatic, but various clinical presentations and coexisting conditions can be present, the most common being duodenal obstruction

No special management is needed in the case with no clinical symptoms, and symptomatic work-up and treatment are required in the case with clinical symptoms, such as plain abdomen radiography examination and duodenoduodenostomy

Portal vein and bile duct inverted variation

There is no report related to prenatal ultrasound diagnosis of the abnormality

Difficult

Most patients may have no obvious clinical symptoms, or mild abdominal distension or jaundice

No special management is needed in the case with no clinical symptoms

Duplication of the portal vein (DPV)

There is no report related to prenatal ultrasound diagnosis of the abnormality

Difficult

The condition may be a cause of abdominal pain and can give rise to portal hypertension, with the development of esophagogastric varices, and may provide a source of fatal hemorrhage during childhood

No special management is needed in the case with no clinical symptoms, and symptomatic work-up and treatment are necessary in the case with clinical symptoms, such as postnatal ultrasonography and enhanced computed tomography

Cavernous transformation of portal vein (CTPV)

There is no report related to prenatal ultrasound diagnosis of the abnormality

Difficult

Clinical symptom of CTPV can include portal hypertension, splenomegaly, ascites, gastrointestinal varices, obstructive jaundice, mesenteric venous congestion and ischemia, ascending cholangitis and biliary cirrhosis

Postnatal utrasonography or enhanced computed tomography can be performed for follow-up; the Rex bypass shunt is considered the gold standard strategy

Portal vein stenosis or atresia

There is no report related to prenatal ultrasound diagnosis of the abnormality

Difficult

Portal vein obstruction, splenomegaly, variceal hemorrhage and portal hypertension could be the results of the anomaly; the prognosis is closely related to clinical symptoms

Postnatal utrasonography or enhanced computed tomography can be performed for follow-up, and symptomatic operative treatment are necessary

Portal vein hypoplasia

There is no report related to prenatal ultrasound diagnosis of the abnormality

Difficult

Portal vein hypoplasia is a known comorbidity of biliary atresia, in addition to an enlarged hepatic artery; primary hypoplasia of the portal vein can cause secondary portal hypertension that presented with the severe but typical clinical manifestations of ascites and hepatic encephalopathy

Postnatal ultrasonography or enhanced computed tomography can be performed for follow-up, and symptomatic operative treatment and liver transplant evaluation is necessary

Portal venous aneurysm (PVA)

Ultrasonography demonstrates dilatation of the PV system

Amenable

Most congenital cases are asymptomatic

Perinatal management primarily entails periodic surveillance of the aneurysm through medical imaging, Doppler ultrasonography is the most useful method

Portal vein variants

Type 1—portal vein trifurcation, where the MPV divides into three branches: the LPV, the RAPV and the RPPV

Type 2—the RPPV arises directly from the MPV as its first branch

Type 3—the RAPV originates from the LPV

Type 4—the portal vein gives only a single right portal branch in the liver hilum, and the left PV arises from the right anterior segmental branch

Unnecessary

Most patients are asymptomatic

No special management is required for isolated cases

Transposition of the left and right portal vein

There is no report related to prenatal ultrasound diagnosis of the abnormality

Unnecessary

Most patients are asymptomatic

No special management is needed in the case with no clinical symptoms

Type II: Anatomy and morphological abnormalities of the umbilical vein

Intrahepatic persistent right umbilical vein (IPRUV)

The sonographic criteria included: (1) an aberrant course of the PV toward the stomach; (2) the fetal gallbladder being medial to the UV; (3) The UV fuses with the RPV instead of the LPV

Amenable

The prognosis of isolated intrahepatic PRUV has a very low risk for an adverse neonatal outcome; the prognosis of non-isolated cases depends on the severity of accompanied anomalies

An IPRUV should prompt an extended anatomic survey and a fetal cardiac evaluation; if the survey and cardiac anatomy are reassuring, no further follow-up is needed; if additional findings are identified, genetic counseling and invasive testing should be considered

Duplication of the umbilical vein (DUV) (IPRUV)

Ultrasonography demonstrates two UVs in a transverse section of the fetal abdomen, which drain into the LPV and the RPV, respectively; the umbilical cord is also visible in four vessels

Amenable

Isolated DUV (intrahepatic PRUV) has a better outcome, and the prognosis of non-isolated cases depends on the severity of additional findings

A DUV (intrahepatic PRUV) should prompt an extended anatomic survey; no further follow-up is needed for isolated cases; if additional findings are identified, genetic counseling and invasive testing should be considered

Umbilical vein varix (UVV) (normal direction)

Sonographically, UVV appears as whole course ectatic anechoic UV or limited mass, and color Doppler sonography detects the bidirectional turbulent flow, at the level of the dilated segment of the umbilical vein

Amenable

The prognosis of isolated case has a very low risk for an adverse neonatal outcome

A systematic structural examination should be performed; no further follow-up is needed for isolated cases; genetic testing is recommended in the fetus with non-isolated UVV

Umbilical vein constriction

Prenatal ultrasound shows the diameter of the UV is narrower than the normal range, and pulsed Doppler detects high-speed blood flow, which can be as high as 150 ~ 200 cm/s

Necessary

The pregnancy complications include IUFD, IUGR and oligohydramnios

Close fetal ultrasonographic surveillance is necessary

Type III: Vascular connection abnormalities

Portal-systemic shunts (PSS)

IHPSS

The prenatal ultrasound is shown the connection with the IHPVS and the HV, and the DV should be focused

Necessary

Fetuses with IHPSS have the highest live birth rate compared to other types of shunt fetuses, which can be naturally closed after delivery

Hemodynamic surveillance should be performed in fetal period; for the cases cannot be closed naturally, surgery was performed to repair the shunt

EHPSS

The antenatal ultrasound visualizes the SpV and the SMV shunting into the IVC

Necessary

The prognosis of EHPSS depends on the size of shunt volume, the present of associated malformations, and the development of hemodynamic imbalance; the prognosis of most cases of the complete absence of the IHPVS are poor

Hemodynamics should be closely monitored before delivery

Umbilical–systemic shunts (USS)

The prenatal ultrasound detects that the UV directly connects to the systemic circulation, such as the right atrium, the IVC, the renal vein, or the iliac vein

Necessary

USS is often associated with deficiency of the DV and dysplasia of portal venous system; the risk of chromosome abnormality and other structure malformations is high; fetuses with USS have the poorest prognosis, and the lowest rates of live birth and postnatal survival are observed

Given the high prevalence of congestive heart failure and edema, hemodynamic surveillance should be performed in fetal period

Ductus venosus-systemic shunts (DVSS)

Prenatal ultrasound shows abnormal shunt between the DV and the abdominal IVC, the hepatic vein or the coronary sinus

Necessary

The fetuses with the DVSS are associated with a high incidence of chromosomal malformation and a low risk of other structural malformations; fetuses with isolated DVSS have a good prognosis and normal liver function

Genetic examination should be recommended for fetuses with DVSS detection to exclude chromosomal abnormalities

Congenital hepatoportal arteriovenous fistula (CHPAVF)

Prenatal ultrasound shows single or multiple direct communications between the hepatic artery and the portal vein branches; additional findings include hepatic artery enlargement, portal vein dilatation at the site of fistula and abdominal aorta tapering beyond the celiac artery

Necessary

The CHPAVF can lead to high out-put heart failure with a mortality rate of 50% ~ 90%

The prenatal diagnosis of CHPAVF enables better planning of postpartum management

Isolated absence or atresia of ductus venosus

Prenatal ultrasound demonstrates that the DV is absent or presents as a thin band connecting the LPV and the IVC, and that CDFI examination could not detect the blood flow signal

Necessary

Isolated absence or atresia of DV had good prognosis in 67.2% cases, and died in perinatal period as a result of fetal edema in 15.6% cases

Close surveillance of fetal hemodynamic changes is recommended

Abnormal entry of the umbilical vein into the portal vein

Prenatal ultrasound shows the UV connecting with the MPV after entering the abdominal cavity, and the confluence of the UV and the MPV presents as an aneurismal dilatation. There is a variety of variations of influent blood vessel at the joint, most are the SMV and the SV

Necessary

Prognosis is depended on thrombus formation, a persistent portal thrombosis can cause portal cavernoma with portal hypertension that led to esophageal varices

Sonographic surveillance and amniocentesis was counseled; close postpartum ultrasonographic follow-up is necessary; the case without thrombosis can be conservatively observed and followed up; if a thrombosis is suspected, early surgery is proposed in order to avoid persistent portal thrombosis and its specific complications