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Spleen
Core Procedures
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Open splenectomy
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Laparoscopic splenectomy
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Hand-assisted laparoscopic splenectomy
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Partial splenectomy
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Open/laparoscopic splenulectomy
The spleen is a large, encapsulated, complex mass of vascular and lymphoid tissue situated in the upper left quadrant of the abdominal cavity between the fundus of the stomach and the diaphragm ( Fig. 64.1 ). For centuries, the spleen was thought to be the seat of melancholy. In 1521, the great German artist Albrecht Dürer (1471–1528) sent a sketch to his physician, requesting that his spleen be removed because he was depressed. It is clear from the sketch that Dürer knew the correct anatomical location of the spleen, although at that time its function was not understood. Henry Gray was 26 years old when he received the Astley Cooper Prize for his dissertation on the spleen ; in 1858, he published the first edition of the book that would eventually become known as Gray's Anatomy .
The gross appearance of the spleen in situ . An intra-abdominal image of the spleen (1) and its relation with the diaphragm (2), liver (3), stomach (4), greater omentum (5) and colon (6).
(From S. Standring (ed.), Gray's Anatomy, forty-first ed. © Elsevier, 2016, Fig. 70.4.)
The first report of splenectomy in the Western world is credited to Adriano Zaccaria (1549) for the treatment of splenomegaly secondary to malaria. The first ‘partial splenectomy’ was reported by Franciscus Rosetti in 1590. The first splenectomy for malignancy is credited to Karl Quittembaum (1826), although his patient did not survive. In 1895, Zikoff was the first to report operative repair, splenorrhaphy, of a lacerated spleen, and Campos Christo is credited with the first partial splenectomy. Splenectomy may be indicated in a very broad range of quite uncommon diagnoses ( Table 64.1 ). Asplenic patients are at higher risk for infectious complications and at risk for overwhelming post-splenectomy infection (OPSI). Lifelong vigilance on the part of patient and caregivers allows the vast majority of splenectomized individuals to live for a normal lifespan.
Table 64.1
Indications for splenectomy
| Trauma iatrogenic |
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| Haematological conditions |
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| Erythrocyte enzyme deficiencies |
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| Haemoglobinopathies |
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| Neoplastic diseases |
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| Primary tumours |
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| Metastatic tumours |
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| Non-malignant conditions |
|
Embryology
The developing spleen is first seen at the end of the fifth week post fertilization (stages 13–14) as local proliferations of the coelomic epithelium of the dorsal mesogastrium. The epithelium produces mesenchyme cells, which form condensed foci, vascularized by local angiogenic mesenchyme, and coalesce to constitute a lobulated spleen. By 8–9 weeks, the spleen contains thin-walled vascular loops and a vascular reticulum with immature reticulocytes. From week 11, erythrocyte precursors can be seen, followed by macrophages and lymphocytes. Primitive white pulp can be seen from 22 weeks, and by 24 weeks T and B lymphocytes become aggregated. Movements of the dorsal mesogastrium, associated with the formation of the lesser sac, rotation of the stomach and development of its greater curvature, affect the position of the spleen. As it enlarges, it projects to the left ( Fig. 64.2 ). The spleen remains connected to the dorsal abdominal wall by the splenorenal ligament and to the stomach by the gastrosplenic ligament. A number of congenital splenic anomalies may occur and these include agenesis, polysplenia, accessory spleens and persistent lobulation.
Clinical anatomy
Vascular supply
The surgeon should be familiar with variations in the anatomy of the splenic blood vessels, specifically the splenic artery, left gastroepiploic artery and splenic vein.
Splenic artery
The splenic artery is the largest branch of the coeliac trunk. Occasionally, it arises directly from the abdominal aorta, and very rarely from the common hepatic or superior mesenteric artery. Its course is commonly suprapancreatic, but it may also be antero-, intra- or retropancreatic, and other rare variants have been described. An aberrant course related to the pancreas makes the splenic artery vulnerable to iatrogenic injury during pancreatic surgery.
The anatomy of the terminal branches of the splenic artery is of particular importance during splenectomy. Although the artery typically divides into two, more than six terminal branches have been described; it may pass through the splenic hilum without dividing at all. In a classic cadaveric study (n=100), Michaels described the splenic artery as having either a short trunk that divided into many long branches in a ‘magistral’ (bundled) distribution (30%), or a long trunk that divided near the hilum into as many as twelve branches in a ‘distributed’ arrangement (70%) ( Fig. 64.3 ). Recognizing the pattern of terminal branching is important, especially if the surgeon dissects out and ligates each branch individually. Most surgeons performing contemporary splenectomy use an endovascular stapler, in which case such distinctions are less important (the hilar stapling technique is the author's preference).
The splenic vessels do not anastomose, which means that there are two or three distinct vascular segments; intersegmental planes are avascular and can be used to minimize blood loss during subtotal splenectomy. The splenic artery can be quite tortuous, a characteristic that seems to develop with age, since it is much more apparent in adults than in children. The artery can also be atherosclerotic in older patients, an important point to bear in mind when stapling the hilum because stapling may fail to control bleeding from an atherosclerotic splenic artery (see later).
Left gastroepiploic artery
The left gastroepiploic artery arises from the splenic artery proximal to the splenic hilum and anastomoses with the right gastroepiploic artery along the greater curvature of the stomach. A significant arterial branch may occasionally arise from the gastroepiploic arteries and supply the inferior pole of the spleen.
Splenic vein
Blood from the parenchyma of the spleen is collected by trabecular veins that merge to form the segmental veins that drain individual splenic segments. In general, there are no anastomoses between intrasegmental venous tributaries ( Fig. 64.4 ). Segmental veins join to form two (superior and inferior) or three (superior, middle and inferior) ‘lobar’ veins that emerge along the length of the splenic hilum, and unite either at, or within 2 cm of, the hilum to form the splenic vein within the splenorenal ligament ; communicating veins may interconnect lobar veins. The splenic vein runs medially below the splenic artery, posterior to the tail and body of the pancreas. It crosses the posterior abdominal wall anterior to the left kidney, renal hilum and abdominal aorta, separated from the left sympathetic trunk and left crus of the diaphragm by the left renal vessels, and from the abdominal aorta by the superior mesenteric artery and left renal vein. It terminates posterior to the neck of the pancreas, where it joins the superior mesenteric vein and forms the portal vein. Along its course, it receives the short gastric veins, left gastroepiploic veins, retroperitoneal veins (Retzius's retroperitoneal venous plexus), pancreatic veins, posterior gastric vein, left gastric vein (occasionally) and the inferior mesenteric vein. Approximately 60% of portal vein blood flow is derived from the gut and the remainder from the spleen and pancreas.
Preoperative planning
Immunizations
The primary purpose of immunizations for splenectomized patients is to provide better defence against encapsulated bacteria that cause pneumonia and meningitis, Streptococcus pneumoniae being the most common. It is recommended that vaccinations against pneumococci, Haemophilus influenzae type b, meningococci and influenza virus are also administered. For elective surgery, immunizations are started several weeks before splenectomy and continued at intervals postoperatively. Specific recommendations for immunization vary both with jurisdiction and over time. The availability of improved and broader vaccines means that the specific recommendations for pre- and postoperative immunization schedules may change. Annual vaccination against influenza virus is recommended because influenza infection confers a predisposition to bacterial pneumonia and sepsis caused by S. pneumoniae and Staphylococcus aureus. The most recent immunization guidelines may be found at the national disease surveillance centre (for example, Centers for Disease Control and Prevention at cdc.gov ).
Blood transfusion
Blood products should always be available during splenectomy, for transfusion if required. For patients without thrombocytopaenia, at least 1 unit of packed red blood cells should be available before commencing surgery. For patients with a low platelet count, platelets should also be on standby for transfusion. In contrast to the classic teaching, which is to transfuse patients with immune thrombocytopaenic purpura (ITP) routinely once the splenic artery is taken, the authors do not transfuse blood products unless there is significant bleeding either during or after surgery; in their experience, the majority of ITP patients do not require blood products in the perioperative period.
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