ABSTRACT
Fetal splenic tissue develops from condensations of mesoderm in the dorsal mesogastrium. This peritoneal fold attaches the dorsal body wall to the fusiform swelling in the foregut that develops into the stomach. The weight of the normal adult spleen is 75–250 g and it measures up to 10 × 7 × 3 cm. It lies in the left hypochondrium between the gastric fundus and the left hemidiaphragm, with its long axis lying along the 10th rib. Although the spleen was previously thought to be dispensable, it is now recognised that an incidental splenectomy during the course of another operative procedure increases the risk of complications and death. The surgeon should therefore normally endeavour to preserve the spleen to maintain the following functions: immune function; filter function; pitting; reservoir function; and cytopoiesis. Splenic agenesis is rare but is present in 5% of children with congenital heart disease. Polysplenia is a rare condition resulting from failure of splenic fusion.
