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Yang et al. Hepatoma Res 2020;6:37 I http://dx.doi.org/10.20517/2394-5079.2020.09 Page 3 of 13

be one cause of the early stage of splenomegaly, there are still many causes to maintain splenomegaly, such as
[23]
abnormal hyperplasia of white pulp, red pulp and fibrous tissues .

[18]
Splenomegaly reduces the greater portal vein return flow after operation, inducing platelet aggregation . It
[24]
has been reported that spleen weight (> 650 g) is associated with the development of PVT and that spleen
[25]
weight (≥ 1311.5 g) is a significant independent predictor of PVT . Patients with PVT had a significantly
[26]
greater splenic weight (median = 216 g) than those without PVT (median = 82 g) , and some authors
suggest that spleen weight is the only predictive factor of postoperative thrombosis after laparoscopic
[27]
splenectomy (LS) . Here, there is a consensus among researchers that an increasingly larger and heavier
[28]
spleen would finally be able to cause PVT after splenectomy if there is no medical intervention .
Splenomegaly is a useful indicator of PVT, which can be conveniently evaluated before splenectomy by
[10]
computed tomography .
Splenectomy
Splenectomy is a major risk factor of PVT. Patients after splenectomy have a significantly higher incidence
[29]
rate of PVT than those who have not undergone splenectomy . During the operation, the use of cutting
tools and ligation causes thermal or mechanical damage to vascular endothelial cells, inducing thrombus
formation [30,31] . Different surgical procedures cause different levels of PVT risk. In China, the Hassab

operation has been adopted widely because of the benefits it brings andless tissue damage compared with
[32]
shunt surgery , but some clinicians believe that selective decongestive devascularization combined with

gastrosplenic shunt is superior to the Hassab operation, because this surgical method results in a lower long-
[33]
term incidence of re-bleeding and PVT compared with the Hassab group . However, some studies have
[12]
found that there is no relationship between different surgical methods and PVT formation .
After splenectomy, reflux blood through the splenic vein almost disappears, and portal vein pressure and
[13]
portal vein blood flow decrease by 20%-35% . If portal vein blood flow decreases sharply in the short-term,
it will be easy for the portal vein to form eddies or other hemodynamic abnormalities, which is more likely to
form a blood thrombus. In addition, after splenectomy, the distal end of the splenic vein becomes a dead end,
[34]
which fosters blood retention, and the splenic vein thrombus is inclined to spread to the portal vein trunk .
Although devascularization blocks the collateral circulation of the portal vein and draws some of the blood
back to the portal vein system, it is often not enough to make up for the blood loss of the portal vein after
splenectomy. Some researchers recommend partial splenectomy (PS) or partial splenic embolization instead
of splenectomy, because after PS or embolization, the blood flow velocity of the portal vein is higher in
comparison with whole splenectomy, and besides, PS can retain the immune function of the spleen to some
degree [35,36] . Some authors used an animal model of portal hypertension to determine the effect of PS, and
after PS and intramuscular spleen transposition, portocaval collaterals developed and the portal venous
pressure was reduced, while portocaval pressure difference was maintained to prevent deprivation of the
liver. In a case report on the treatment of pediatric patients with portal hypertension, an 11-year-old girl
underwent one-stage surgery, that is, PS with a view of transferring the remaining spleen to the thoracic
cavity in the future. During follow-up, it was found that the patient’s collateral circulation was well formed
and that portal hypertension disappeared. The researchers believed that this case demonstrated that PS
[37]
can be used as an alternative therapy to whole splenectomy . Another clinical study on the treatment of
extrahepatic portal vein occlusion in children showed that through distal spleen and kidney shunt and PS
with 20%-30% spleen retention, the platelet and white blood cell counts of the patients returned to normal
after operation, which indicates that shunt surgery plus PS is an effective and safe method for treating portal
[38]
hypertension and hypersplenism .

Nowadays, LS combined with devascularization or LS combined with shunt surgery is carried out in
many hospitals. And, LS is considered to be more likely to cause PVT than open splenectomy. A clinical