Portacaval anastomosis

A portacaval anastomosis or portocaval anastomosis is a specific type of circulatory anastomosis that occurs between the veins of the portal circulation and the vena cava, thus forming one of the principal types of portasystemic anastomosis or portosystemic anastomosis, as it connects the portal circulation to the systemic circulation, providing an alternative pathway for the blood. When there is a blockage of the portal system, portocaval anastomosis enables the blood to still reach the systemic venous circulation. The inferior end of the esophagus and the superior part of the rectum are potential sites of a harmful portocaval anastomosis.[1]

Portacaval anastomosis
Other namesPorto-systemic anastomosis Portal caval system

In portal hypertension, as in the case of cirrhosis of the liver, the anastomoses become congested and form venous dilatations. Such dilatation can lead to esophageal varices and anorectal varices. Caput medusae can also result.[2]

A portacaval shunt is analogous in that it diverts circulation; as with shunts and anastomoses generally, the terms are often used to refer to either the naturally occurring forms or the surgically created forms.

Presentation

Clinical presentations of portal hypertension include:

RegionName of clinical conditionPortal circulationSystemic circulation
EsophagealEsophageal varicesEsophageal branch of left gastric veinEsophageal branches of azygos vein
RectalRectal varicesSuperior rectal veinMiddle rectal veins and inferior rectal veins
ParaumbilicalCaput medusaeParaumbilical veinsSuperficial epigastric vein
RetroperitonealSplenorenal shunt[3]Splenic veinRenal vein, suprarenal vein, paravertebral vein, and gonadal vein
(no clinical name)[4] Right colic vein, middle colic vein, left colic vein Retroperitoneal veins of Retzius
Intrahepatic Hepatic pseudolesions[5] Perihepatic veins of Sappey Superior epigastric vein
Patent ductus venosusLeft branch of portal veinInferior vena cava

A dilated inferior mesenteric vein may or may not be related to portal hypertension. Other areas of anastomosis include the bare area of the liver as it connects to the diaphragm, the posterior portion of the gastrointestinal tract as it touches the posterior abdominal wall, the posterior surface of the pancreas, and the inferior part of the esophagus.

References

  1. Sato, Takahiro; Akaike, Jun; Toyota, Jouji; Karino, Yoshiyasu; Ohmura, Takumi (2011). "Clinicopathological Features and Treatment of Ectopic Varices with Portal Hypertension". International Journal of Hepatology. 2011: 960720. doi:10.4061/2011/960720. PMC 3170857. PMID 21994879.
  2. Gray's Anatomy for Students Gray H, Drake R, Vogl W, Mitchell A, Tibbitts R, Richardson P. Philadelphia: Elsevier/Churchill Livingstone; 2010. p. 226
  3. D'Souza, Donna. "Portal-systemic collateral pathways | Radiology Reference Article | Radiopaedia.org". radiopaedia.org. Retrieved 2016-08-12.
  4. "Surgicomania: Portal Hypertension". surgicomania.blogspot.co.uk. 2009-11-23. Retrieved 2016-08-12.
  5. Khader.O.Thabet, Mohammed Al. "Hepatic pseudolesion near falciform ligament | Radiology Reference Article | Radiopaedia.org". radiopaedia.org. Retrieved 2016-08-12.
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