Keywords

Introduction

The spleen is composed of two distinct zones of tissue, the red and white pulp, as well as an intermediate marginal zone that is considered to be part of the white pulp. Understanding the individual functions of each portion of the spleen can aid in the understanding of splenic disorders, as well as the various physiologic and pathophysiologic effects and clinical presentations of splenic disease. Furthermore, the clinical and pathologic findings associated with hyposplenic and asplenic individuals can be anticipated.

The red pulp is composed of sinusoids and splenic cords (cords of Billroth) and serves as the largest filter of blood in the body. The red pulp comprises the majority of the spleen, accounting for 80% of the total volume of the spleen. Only 10% of blood passing through the spleen moves through the red pulp, with the remaining 90% passing directly through the margin zone and into the venous sinusoids of the spleen. The red pulp is where abnormal or apoptotic erythrocytes are captured for subsequent phagocytosis. Associated with erythrocyte phagocytosis, iron recycling begins in the red pulp. Solid waste (e.g., Howell-Jolly bodies) and foreign material (e.g., Plasmodium) can also be eliminated from within erythrocytes as they pass through the narrow cords. However, the red pulp does not only serve as an elimination site for damaged or abnormal erythrocytes. It also serves as a storage site for normal erythrocytes, platelets, and iron, all for subsequent use during times of systemic stress or infection. Lastly, it has some defensive properties against bacteria via iron metabolism by macrophages.

The marginal zone and white pulp mediate the immune functions of the spleen, arguably the most important function of the spleen. The marginal zone generates both innate and adaptive immune responses, while the white pulp only generates adaptive immune responses. The marginal zone is a narrow rim of tissue that surrounds the white pulp. Marginal zone macrophages are responsible for the phagocytosis of microorganisms and immune complexes in the blood stream. Additionally, T lymphocyte antigen presentation in the marginal zone can lead to B lymphocyte development and subsequent release. The white pulp is structurally similar to lymph nodes, containing lymphoid follicles with B lymphocytes and periarteriolar lymphatic sheaths with T lymphocytes. Immune mediators that assist in bacterial clearance (i.e., complement, opsonins, properdin, and tuftsin) are also produced within the white zone. Lastly, it serves as a storage site for B and T lymphocytes.

Hyposplenia is a general description of insufficient or absent splenic function. Hyposplenia may be immunologic alone or involve a combination of suppressed or absent red and white pulp function. A variety of disease states and congenital abnormalities are associated with hyposplenia (Table 1). While an in-depth discussion of hyposplenia is beyond the scope of this chapter, surgeons should be aware of the potential for splenic-mediated immunodeficient states associated with a variety of surgical diseases.

Table 1 Disorders associated with hyposplenism
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Anatomy

The spleen resides in the left upper quadrant of the abdomen behind the 9th to 12th ribs. It has attachments to adjacent visceral and peritoneal surfaces, all of which are necessary to maintain a normal position for the spleen. The splenic artery arises from the celiac trunk and travels along the superior border of the pancreas, until it branches into five or more terminal branches at the splenic hilum. Additionally, there are several small vessels from the splenic artery that feed the pancreas. The splenic vein forms at the splenic hilum and travels back to join the superior mesenteric vein to become the portal vein. A normal spleen is approximately 7 × 12 cm, weighing 150–200 g. Abnormalities in the location, appearance, structure, and function of the spleen are all possible, some of which are idiopathic and others are congenital in nature.

Anatomic Abnormalities

Accessory Spleens

Additional or accessory spleens are the most common anatomic abnormality associated with the spleen, occurring in up to 30% of all children (Yildiz et al. 2013). They can occur anywhere in the peritoneal or retroperitoneal cavity, but the majority of them are located in or near the splenic hilum, or along the vascular supply for the spleen. Rarely, accessory spleens have also been described in the scrotum, descending along with the testicle during normal testicular descent. The scrotal splenic tissue can be discrete or directly attached and fused to the testicle (splenic gonadal fusion). This finding occurs almost exclusively in male children and only with the left testicle (Varga et al. 2009). Accessory spleens can also be found within the pancreas, often mimicking a pancreatic tumor (Uchiyama et al. 2008; Lauffer et al. 1999). Accessory spleens can lead to a recurrence of splenic disorders (hemoglobinopathy or immune dysfunction) if not correctly identified and removed at the time of primary splenectomy. Fortunately, the vast majority of children with accessory spleens only have a single accessory found at time of splenectomy, with less than 15% having two or more accessory spleens. In the absence of splenic disorders necessitating splenectomy, accessory spleens typically are not identified. However, rarely, an epidermal inclusion cyst within an accessory spleen has been described as a finding during laparotomy for acute onset of left upper quadrant abdominal pain.

Asplenia and Polysplenia

The congenital absence of a spleen is termed asplenia. Polysplenia, on the other hand, is the presence of two or more splenic tissue deposits in the absence of a normal spleen. Both of these disorders are associated with congenital abnormalities and/or syndromes, with congenital heart disease overwhelmingly the most common associated anomaly (Ikeda et al. 2005; McElhinney et al. 2011). Specific to polysplenia, anomalies of intestinal rotation, biliary atresia, situs inversus, heterotaxy, interrupted inferior vena cava, portosystemic shunts, hepatopulmonary syndrome, and preduodenal portal veins have all been described in the literature (Davenport et al. 2006; Gupta et al. 2007; Kim et al. 2004; Prendiville et al. 2010). In both of these anomalies, the risk of hyposplenia (insufficient spleen function) places these children at risk of overwhelming sepsis, necessitating immediate antibiotic prophylaxis and ongoing close surveillance for early signs and symptoms of infection. Infants with asplenia are at a particularly high risk of overwhelming sepsis during infancy.

Wandering Spleen

A wandering spleen occurs when the normal peritoneal (colon and diaphragm) and retroperitoneal attachments are absent. It can be associated with congenital anomalies, including diaphragmatic hernia, omphalocele, and prune belly syndrome. A wandering spleen is often first identified when it undergoes acute torsion around its vascular pedicle. Children presenting with acute splenic torsion typically have sudden onset of severe abdominal pain with an associated solid, mobile, tender mass in the epigastrium on physical examination. Abrupt onset of nonbilious vomiting may indicate that gastric volvulus has also occurred. Diagnostic confirmation can be obtained with Doppler ultrasonography, confirming the abnormal location of the spleen, with an associated reduction or loss of blood flow through the parenchyma (Yildiz et al. 2013). Other children with a wandering spleen will present with chronic and/or intermittent abdominal pain of variable duration and severity, usually from intermittent torsion and detorsion of the spleen. Less frequently, a solid epigastric mass is identified on routine physical examination, with subsequent imaging confirming the diagnosis.

Elective or urgent splenopexy is recommended for asymptomatic or intermittently symptomatic patients, to reduce the risk of acute torsion and splenic loss. Acute torsion of the spleen requires immediate surgical intervention, with the goal of the operation being splenic preservation. Detorsion of the spleen can be accomplished either by a laparotomy or via laparoscopic techniques. Once viability of the spleen is confirmed, some form of fixation of the spleen is required. Splenopexy has been performed using a variety of mesh and nonmesh techniques, including vicryl mesh baskets tacked to the diaphragm and retroperitoneum, retroperitoneal pockets, and/or direct suture splenopexy (Schaarschmidt et al. 2005; Peitgen et al. 2001; Steinberg et al. 2002). Complications of splenopexy include ischemia with subsequent necrosis and lack of permanent fixation (recurrent wandering spleen).

Splenic Cysts

Splenic cysts can be classified as primary, originating from abnormal embryologic development and containing a true epithelial lining, or secondary. The most often cited, though rarely reported, secondary cyst is a post-traumatic cyst (Wu and Kortbeek 2006). A splenic cyst may be entirely asymptomatic and only found on incident imaging, or may present with pain, rupture, abscess, and/or early satiety from gastric compression. The majority of symptomatic cysts are greater than 8 cm (Tsakayannis et al. 1995). A number of different techniques have been described for the treatment of nonparasitic cysts (Hassoun et al. 2018). Percutaneous drainage, with or without sclerosis, has a high rate of recurrence. Marsupialization of the external cyst wall and partial cystectomy are also associated with a high risk of recurrent cyst formation. Laparoscopic partial splenectomy offers the lowest risk of cyst recurrence with preservation of splenic function (Delforge et al. 2017). Enlarged, infected, and symptomatic cysts should all be excised, preferably via partial splenectomy.

Indications for Splenectomy

There are a number of different indications for splenectomy in children. However, a thorough investigation and multidisciplinary discussion are critical to ensure that the appropriate risk/benefit ratio exists to support performing the procedure. Children, especially younger than 5 years of age, are particularly susceptible to overwhelming postsplenectomy sepsis. This lifetime risk should guide preoperative discussions with children and parent(s), choice of surgical procedure (partial vs. complete), and the preoperative preparation and subsequent postoperative care of the postsplenectomy patient.

Spherocytosis

Hereditary spherocytosis is the most common hemoglobinopathy affecting Caucasians and Latinos, with an autosomal dominant inheritance pattern (Bolton-Maggs et al. 2012, 2004; Perrotta et al. 2008). A mutation in one of the membrane skeletal proteins (ankyrin or spectrin) leads to poor deformability of red blood cells. Mutation of the ANK-1 gene is the most common, and inheritance is autosomal dominant in 75% of cases (Lazzareschi et al. 2019). The resultant spherical cells are subject to sequestration and premature destruction as they pass through the red pulp of the spleen, leading to hypersplenism (splenic enlargement, anemia, and thrombocytopenia). A secondary consequence of increased hemolysis is a marked increased risk for the development of gallstones. Classification of disease severity is based on hemoglobin, reticulocyte, and bilirubin levels, along with the number of spectrin molecules per erythrocyte (Table 2) (Perrotta et al. 2008; Eber et al. 1990). While the laboratory classification of any individual patient can serve as a general guide for decisions about splenectomy, the ultimate decision is based on clinical symptoms and any potential complications of the disease (i.e., gallstones) (Bolton-Maggs et al. 2012, 2004). In general, though, splenectomy is indicated for all patients with severe disease, preferably after 6 years of age to reduce the risk of postsplenectomy infection. In moderately severe disease, splenectomy may be indicated based on severity of symptoms. A splenectomy is typically not indicated in patients with mild disease, although some argue that quality of life indicators and other subjective measures (exercise intolerance) may define a subset of these patients who would also benefit from a splenectomy (Roy et al. 2013).

Table 2 Spherocytosis disease severity
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Gallstones are a frequent finding in children with hereditary spherocytosis, occurring in 21–63% of all patients (Rutkow 1981). The incidence appears to further increase with co-inheritance of Gilbert’s disease. Current recommendations are to remove the gallbladder only in those patients with demonstrated cholelithiasis at the time of splenectomy (Bolton-Maggs et al. 2012). In recent years, a number of authors have advocated for partial or near-total splenectomy, as an alternative to a total splenectomy, in the treatment of hereditary spherocytosis (Vasilescu et al. 2006; Morinis et al. 2008; Slater et al. 2010). Despite varied technical aspects for a partial splenectomy, the majority of studies document a low risk of patients ultimately requiring a completion splenectomy for recurrent symptoms. Yet, despite these early promising data, long-term follow-up data are lacking in sufficient strength to fully support partial splenectomy as the operation of choice in hereditary spherocytosis. Concerns with the procedure include persistent hemolysis, risk for subsequent cholelithiasis, and inadequate characterization of residual immune function in the remnant spleen. Therefore, until these data are fully realized, all patients undergoing partial splenectomy require close observation and continued antibiotic prophylaxis, much the same as those patients who undergo a complete splenectomy.

Sickle Cell Disease

Sickle cell disease (SCD) is an autosomal recessive disease characterized by an abnormal β-globin chain of hemoglobin. The resultant hemoglobin S reversibly polymerizes during deoxygenation, resulting in an abnormal sickle-shaped red blood cell. The sickled red blood cells are sequestered and/or prematurely destroyed as they attempt to pass through the red pulp of the spleen, resulting in anemia, vascular congestion, and microvascular occlusion. Children with SCD require chronic transfusion therapy to prevent or treat the end-organ complications of the disease, including stroke, acute chest syndrome, severe pain syndrome, and acute splenic sequestration. The majority of patients with SCD ultimately become functionally asplenic secondary to continued microvascular occlusion, ischemia, infarction, and subsequent fibrosis of the spleen (Brousse et al. 2012). However, in a subset of patients with recurrent acute splenic sequestration episodes and/or severe hemolysis from hypersplenism, a splenectomy may be indicated.

Acute splenic sequestration is diagnosed when a child presents with severe worsening of anemia, reticulocytosis, and a tender and enlarging spleen (Topley et al. 1981). Splenic sequestration can be life-threatening, secondary to hypovolemia and end-organ ischemia (Airede 1992). Unfortunately, splenic sequestration is not typically a single event, recurring in up to 67% of patients (Brousse et al. 2012; Airede 1992; Haricharan et al. 2008). In the majority of children, splenectomy is recommended after the child recovers from an acute episode of splenic sequestration (Brousse et al. 2012). Hypersplenism (severe anemia, thrombocytopenia, and splenomegaly) is also a relative indication for splenectomy in SCD, particularly in children receiving frequent red cell transfusions.

The preoperative preparation and postoperative care of a patient with SCD require special mention. Children with SCD are chronically anemic and remain at lifelong risk of recurrent vaso-occlusive crises. Current recommendations are that SCD patients should be transfused to a hemoglobin level of 10 g/dL and then aggressively hydrated prior to induction of anesthesia (Howard et al. 2013). Simple blood transfusion has been shown to be as effective as exchange transfusions in decreasing postoperative complications related to sickle cell disease (Vichinsky et al. 1995). A type and cross for compatible blood should be done at least 1 day prior to the planned operation, as alloimmunization is common and can lead to difficulty in finding compatible blood that can be used in case of intraoperative misadventure or postoperative complications (Rosse et al. 1990; Vichinsky et al. 1990). Intraoperatively, hypoxemia and hypothermia should be avoided, as these conditions can lead to increased sickling of red blood cells. Postoperatively, acute chest syndrome is one of the most frequently identified complications after splenectomy, occurring in up to 20% of all SCD patients undergoing abdominal surgery (Kokoska et al. 2004; Hyder et al. 2013). Acute chest syndrome is characterized by the development of a new pulmonary infiltrate, chest pain, temperature greater than 38 °C, and tachypnea, wheezing, or a cough. Treatment is mainly supportive with appropriate hydration, transfusion and antibiotics as indicated, and pain control. Other postoperative complications include stroke and vaso-occlusive pain crises (Hyder et al. 2013).

The surgical approach for SCD has traditionally been a total splenectomy. Since SCD patients are all considered functionally asplenic by their second decade of life, preservation of a portion of the spleen has typically not been considered a viable alternative to a total splenectomy. However, as partial or near-total splenectomy has gained in popularity for hereditary spherocytosis, some authors have begun to advocate for the same in young SCD patients (Mouttalib et al. 2012). No matter the surgical approach to the spleen, all children with SCD should be preoperatively screened for cholelithiasis and gallbladder sludge. More than 65% of pediatric patients with SCD have abnormalities on biliary imaging (McCarville et al. 2012). If biliary disease is found on preoperative screening, the patient should undergo a simultaneous cholecystectomy and splenectomy.

Patients with SCD are currently living longer due to improvements in diagnosis and comprehensive care. Due to these advances, long-term chronic complications pose a greater challenge in the management of patients with SCD, particularly sickle cell neuropathy which is associated with significant morbidity and mortality (Olaniran et al. 2019). The earliest manifestation is an increase in the glomerular filtration rate. Significant albuminuria is observed early and is the most common presentation in childhood. Regarding the therapeutic approach, the renin-angiotensin system inhibitors and angiotensin receptor blockers seem to be effective in adults with SCD, although new studies are needed in children (Belisário et al. 2019).

Beta Thalassemia

Beta thalassemia is a hereditary hemoglobinopathy characterized by reduced or absent beta globin synthesis. The resultant relative excess of unbound alpha globin chain causes membrane damage to peripheral erythrocytes, leading to removal of these erythrocytes as they pass through the red pulp of the spleen. The most common surgical indications for splenectomy in these patients include an annual transfusion requirement greater than 180–200 mL/Kg, hypersplenism, leukopenia, thrombocytopenia, and increasing iron overload (Galanello and Origa 2010). Similar to other hemoglobinopathies, biliary imaging should be completed preoperatively given the increased risk of cholelithiasis and sludge. While total splenectomy remains the favored approach, partial splenectomy is gaining increased attention in the treatment of complications of this disease as well.

Immune Thrombocytopenia

Immune thrombocytopenia (ITP) is an autoimmune disease against platelets, resulting in isolated thrombocytopenia and risk for bleeding complications. More than 75% of children that present with ITP will have disease remission within 6 months of diagnosis (Neunert et al. 2013). Children also appear to be at low risk for severe thrombocytopenia and serious bleeding events. First-line therapy for ITP is corticosteroids. Second-line therapy has traditionally been a splenectomy, as it can be safely performed with few complications, and has the highest remission rate of any second-line therapy. However, with recent advances in alternative therapies and a better understanding of patterns of remission, splenectomy may ultimately be reserved for those patients with severe bleeding complications (British Committee for Standards in Haematology General Haematology Task, F. 2003). The surgical procedure of choice is total splenectomy, with the goal of removing an important site of antiplatelet antibody formation and the primary site of platelet destruction. Biliary disease is not a feature of ITP; therefore preoperative evaluation of the gallbladder is not typically indicated.

Splenectomy

Preoperative Immunizations

All children who undergo partial or total splenectomy should receive appropriate immunizations at least 2 weeks prior to the planned splenectomy. In the event of an emergent splenectomy, patients should receive postoperative vaccinations as soon as possible. Current recommendations for children greater than 2 years of age include pneumococcal polysaccharide vaccine-23, Haemophilus influenzae type b conjugate vaccine, and meningococcal vaccine (Rubin et al. 2013). In addition, all asplenic children should receive annual flu vaccinations to decrease the risk of a secondary bacterial infection associated with flu.

Laparoscopic Splenectomy

Laparoscopic splenectomy can be completed in supine, semi-lateral, and lateral positions. For purposes of this chapter, the supine position will be described, as a significant percentage of patients will require a combined splenectomy and cholecystectomy. Once fully anesthetized, the patient is positioned in a supine position with a rolled towel bump under the left costal margin. The entire abdomen and left flank are then prepped and draped with appropriately. The umbilicus is accessed with a 12 mm trocar using a direct transumbilical fascial incision. Once gas insufflation has been satisfactorily obtained, a 5 mm working port is placed in a midepigastric position in the midline of the abdomen. A 5 mm retracting port is then placed at the left costal margin, near the anterior axillary line. In patients with marked splenomegaly, the spleen may need to be retracted superiorly in order to safely place the trocar without injury to the splenic parenchyma. The retracting port should not migrate lower than the costal margin, as the anterior iliac crest will then begin to interfere with retraction. The second 5 mm working port is then placed in the left lower abdomen, approximately 1–2 cm below the umbilicus at the lateral edge of the rectus sheath. While this port may be placed more medially through the rectus sheath, care must be taken to ensure that the inferior epigastric artery is not injured during port placement.

Initial release of the phrenicocolic ligament will allow the colon to fall away from the operative field and begin to expose the lower pole of the spleen. Release of the splenorenal ligament will further expose the lower pole of the spleen and begin to expose the inferior border of the tail of the pancreas. Subsequent release of the gastrosplenic ligament, with division of the short gastric vessels medial to the spleen, will allow entry into the lesser sac. Careful dissection around the hilar vessels can then begin. Once a window has been obtained around the splenic vessels, an endomechanical stapling device can be deployed across the splenic vein and artery as a single fire load. Occasionally, the tail of the spleen prevents a safe transection angle of the hilum when the stapling device is deployed from the umbilical port. In these events, the left lower abdominal 5 mm port may be upsized to a 10 mm port for a more direct approach to the hilar transection. If the tail of the pancreas is still not free of the transection plane, additional hilar dissection is indicated, including individual distal ligation of vascular branches in select cases. Once the spleen has been devascularized, the splenophrenic ligament can be released. At this point, a careful evaluation of the perisplenic tissue should be performed for identification of accessory splenules. The spleen and any identified splenules are then placed inside a 12 cm endomechanical specimen retrieval bag placed through the umbilical port. A 15 cm port and endomechanical specimen bag may be needed for patients with marked splenomegaly. Once all splenic tissue is completely within the specimen bag, the deployment device is withdrawn with the access port, bringing the most proximal portion of the cinched specimen bag through the abdominal incision. The edges of the specimen bag are then everted; ring forceps are used to morcellate and remove the spleen. Care must be taken during splenic morcellation, as a tear in the specimen bag can be associated with iatrogenic intestinal or vascular injury and increases the risk of secondary splenosis and recurrent anemia.

Partial Splenectomy

A partial splenectomy is an alternative to a complete splenectomy in the treatment of hereditary spherocytosis and beta thalassemia. The goals of the operation are to remove the majority of the splenic tissue yet preserved enough of the spleen to maintain effective humoral immunity. The range of preserved splenic tissue is anywhere from as little as 5% and up to 25% of the native splenic volume. The remnant can be based off of the short gastric arteries or the splenic artery to the upper or lower pole of the spleen. The operative setup for a partial splenectomy is similar to that for a complete splenectomy. However, greater care is taken during the dissection of the splenic hilum and short gastric vessels. If the short gastric vessels are the chosen blood supply for the remnant, the hilum is dissected and transected in similar fashion as a total splenectomy. Once the main splenic artery and vein are transected, demarcation of the blood supply to the spleen should quickly become visible. The spleen is then divided along the line of demarcation, using one or more endosealing, electrocautery, or argon beam devices for adequate hemostasis of the remnant’s cut edge. The phrenosplenic ligament is ideally left intact at the upper margin of the remnant, to decrease its risk of subsequent torsion. For upper or lower pole artery-based remnants, a meticulous dissection of the hilar blood vessels is necessary to prevent injury, while preserving flow. A test clamp of the endomechanical stapler is required to confirm preservation of flow through the preserved vessel. Lower pole remnants are at highest risk of subsequent torsion. Therefore, fixation of the remnant to the lateral peritoneal surface or the greater curvature of the stomach may be necessary. The devascularized segment of spleen and any accessory splenules are then removed using the same techniques as described above.

Open Splenectomy

An open splenectomy is traditionally performed through a left subcostal incision but may also be performed through a midline vertical incision. The relevant operative steps are the same as the laparoscopic approach discussed above. However, once the spleen has been devascularized and the phrenosplenic ligaments are released, the spleen and any associated splenules are removed as intact specimens.

Postoperative Antibiotic Prophylaxis

All children undergoing partial, near-complete, and near-total splenectomy should start oral penicillin on postoperative day 1 and continue to take it once daily for the remainder of their life. In children who are unable to take oral medication, intravenous administration of a first-generation cephalosporin may be used until the child is able to take oral medication.

Intraoperative and Postoperative Complications

A number of intraoperative and postoperative complications have been described during and after splenectomy, including bleeding, colonic perforation, diaphragmatic perforation and/or hernia, missed accessory spleen with recurrent symptoms, acute chest syndrome (SCD), pneumonia, portal vein thrombosis, priapism, hemolytic uremic syndrome, and trocar hernias (Cadili and de Gara 2008; Rescorla et al. 2007). However, outside of patients with sickle cell disease, the overall risk of any one of these events is extremely low. A few select complications that have not been discussed elsewhere in this chapter deserve special mention.

Overwhelming Postsplenectomy Sepsis

Overwhelming postsplenectomy sepsis (OPSS) is a fulminant sepsis, meningitis, or pneumonia that occurs at a much higher frequency in functionally or anatomically asplenic patients, compared to normal children. Children less than 5 years of age are at particularly high risk for OPSS and also have a higher mortality rate compared to older children. The risk of death with OPSS can be greater than 50% if it is not recognized within the first several hours of the infection beginning to manifest the clinical signs or symptoms. Mortality rates are closer to 10% when immediate care is provided at the onset of symptoms. The most common bacterial pathogens are encapsulated bacteria, including Streptococcus pneumococcus, Haemophilus influenzae, and Meningococcus. However, other gram-positive and gram-negative bacteria have also been described in the literature as causative agents and are increasingly identified among patients previously vaccinated against encapsulated bacteria. Clinical signs and symptoms include a brief prodrome of fever, myalgia, vomiting, diarrhea, and headache. Septic shock then quickly develops, often within a few hours of onset of prodromal symptoms. All patients at risk and with any signs or symptoms of OPSS should receive immediate, broad-spectrum parenteral antibiotics that cover the typical causative organisms, with close observation for signs of clinical deterioration (Di Sabatino et al. 2011). The most effective means of preventing OPSS include preoperative immunizations prior to removal of the spleen, continued postoperative prophylaxis with penicillin, annual flu vaccination, and frequent reeducation of patients and parents about the signs, symptoms, and risks associated with OPSS.

Thromboembolic Disease

Splenic vein thrombosis, with or without extension in the superior mesenteric and portal veins, is a particular concern in adult patients immediately after splenectomy. However, this complication occurs less frequently in children. Therefore, routine antiplatelet therapy (acetylsalicylic acid) is not indicated in children, even those children with marked thrombocytosis after splenectomy. However, risk factors for thromboembolic events include marked splenomegaly and lymphoproliferative or myeloproliferative disorders as the underlying disease process necessitating splenectomy (Rodeghiero and Ruggeri 2012).

Cardiac Complications Postsplenectomy

Ischemic heart disease and pulmonary hypertension occur with increased frequency in patients who are asplenic (Rodeghiero and Ruggeri 2012). The majority of patients who develop cardiac complications are decades out from the original splenectomy. Interestingly, patient with spherocytosis who are able to retain their spleen have a lower risk of ischemic heart disease later in life, while asplenic patients tend to have the same risk as non-spherocytosis patients. This represents a relative increased risk, but the risk does not exceed baseline population risks for ischemic heart disease. For asplenic patients without spherocytosis, data support a 1.5–2 times increased risk of ischemic heart disease, compared to population controls. Pulmonary hypertension is less well characterized or understood, but the risk appears to be highest in patients with disorders associated with ongoing hemolysis.

Conclusions and Future Directions

The spleen has a combined function of immune defense and quality control of senescent or altered blood cells. Many pediatric disorders of splenic functions may require partial or complete splenectomy as the definitive treatment of the disorder. It is well acknowledged that the splenectomized child is at increased risk of infection, overwhelmingly postsplenectomy infection. Overwhelming postsplenectomy sepsis can be prevented by vaccination, chemoprophylaxis, and education.