Background. Congenital absence of the portal vein (CAPV) is an extremely rare malformation that is caused by aberrant venous development during embryogenesis and is usually associated with congenital portosystemic shunts (CPSS). This hemodynamic allows mesenteric blood to bypass the liver metabolism and causes an imbalance between vasodilators and vasoconstrictors in the pulmonary circulation, which, again, might lead to the development of secondary portopulmonary hypertension (PoPH). Establishing the exact morphology of the splanchnic venous system is important when evaluating possible therapeutic options (differentiating type I and II CAPV), because some variants enable the closure of the shunt, and this represents a potential cure for pulmonary arterial hypertension (PAH). Once PoPH is diagnosed, complex care in a specialized expert centre is necessary. If possible, CPSS closure is recommended. For long-term successful patient management, specific targeted PAH therapy administration is crucial. Significant morbidity and mortality in these patients may result not only from PAH itself but also due to specific PoPH complications, such as compression of the left main coronary artery by pulmonary artery aneurysm. Case Report. We report on two patients with PoPH due to CAPV and CPSS (without any liver disease) who presented as severe PAH and who, before admission to our expert centre, were misdiagnosed as idiopathic PAH. The case reports also represent our experience with respect to the long-term follow-up and PAH-specific medical treatment of these patients, as well as the possible (even fatal) complications of these rare and complex patients.

OBJECTIVE: To review our experience with the prenatal diagnosis of congenital portosystemic shunt (CPSS).
METHODS: This is a retrospective study of CPSS cases examined at an ultrasonographic tertiary referral center from 2013 to 2019. The anatomical origin and drainage of the shunt were assessed. Feto-maternal clinical characteristics and long-term outcomes were investigated via medical files and telephone interviews with the mothers.
RESULTS: Eleven cases were reviewed. Based on the anatomical origins, before or after portal vein division, cases were classified into extrahepatic portosystemic shunt (EHPSS, n = 3, 27.3%) and intrahepatic portosystemic shunt (IHPSS, n = 8, 72.7%). Additional abnormalities were also observed in the EHPSS (n = 2, 66.7%) and IHPSS (n = 3, 37.5%) groups. Intrauterine growth restriction was the most common abnormality (n = 4, 80%). The median age of the pregnant women was 31.9 years (range 26 ~ 43 years). Most cases (n = 8, 72.7%) were diagnosed in the third trimester, and the median gestational age was 31+5 weeks (range 24 ~ 36+6 weeks). Three cases underwent karyotype examinations, and one had trisomy 13. The median time after birth was 2 years (range 0.7 ~ 5.7 years). The overall postnatal live-birth rate was 60% (6/10), not including one case with no data on pregnancy outcome. The mothers of the six live births indicated that their children were in excellent health.
CONCLUSIONS: This study indicates that prenatal CPSS diagnosis is feasible, especially in the third trimester. IHPSS is more common than EHPSS. Complicated cases most often occur with EHPSS. Intrauterine growth restriction is the most common concomitant abnormality. The prognosis of most cases is good.