Spleen size and weight vary with age and pathologic conditions. The average adult spleen is 7 cm to 11 cm in length and weighs 150 g (range, 70 g to 250 g). Splenomegaly is described variably and the surgical literature reflects a lack of consensus. Spleen size is expressed in terms of the maximum interpole length and is generally classified into three categories: normal size (<11 cm), moderate splenomegaly (11 cm to 20 cm or >500 g in weight) and severe or massive splenomegaly (>20 cm or >1,000 g in weight) [4].

The most common anomaly of splenic embryology is the accessory spleen (AS). Present in ≤20% of the population, one or more ASs may also occur in ≤30% of patients with hematologic disease. More than 80% of ASs are found in the region of the splenic hilum and vascular pedicle. Other locations for ASs (in descending order of frequency) are the gastrocolic ligament, pancreas tail, greater omentum, greater curve of the stomach, splenocolic ligament, small and large bowel mesentery, left broad ligament in women, and left spermatic cord in men [5]. For these reasons, ASs should always be considered, even if the hematologic significance of the presence of AS and the impact of their removal on results are not clear. The role of ASs in failed splenectomy has been studied extensively, and the prevalence of residual splenic tissue (as detected by post-splenectomy scintigraphy) reaches .48%, even if the efficacy of accessory splenectomy varies from 27% to 75% [6].

Surprisingly, also after laparoscopic splenectomy, residual splenic tissue was noted in 50% of patients, [7] even if it could be related to the surgical approach. The problem of ASs can be managed by careful videoscopic examination of the abdominal cavity during splenectomy, whereas the use of preoperative imaging methods for the detection of ASs is limited by the insufficient sensitivity of these methods [8].

The relationship of the pancreas to the spleen also has important clinical implications. In one cadaveric anatomic series, the tail of the pancreas was demonstrated to lie within 1 cm of the splenic hilum in 75% of cases and in 30% to the border with the spleen [9]. Considering that injuries to the pancreatic tail can cause important postoperative complications such as pancreatitis or pancreatic fistulas, the pancreatic tail should be carefully visualized and dissected from the spleen, avoiding damage by electrocautery or a linear stapler.

The main arterial blood supply occurs through the splenic artery (the longest and most tortuous of the three main branches of the celiac artery). The spleen also receives some of its blood supply from the short gastric vessels that branch from the left gastroepiploic artery running within the gastrosplenic ligament. The splenic artery can be characterized by the pattern of its terminal branches. The distributed type of splenic artery is the most common (70%) and is distinguished by a short trunk with many long branches entering over three-fourths of the medial surface of the spleen. The less common magistral type of splenic artery (30%) has a long main trunk dividing near the hilum into short terminal branches, and these enter over 25% to 30% of the medial surface of the spleen [10]. Early identification of the type of splenic blood supply can help the surgeon to estimate how difficult the splenectomy is likely to be.

Outside the spleen, the arteries also frequently form transverse anastomoses with each other and, as a consequence, attempts to close a splenic-artery branch by clips or embolization, if undertaken proximal to these anastomosis, may fail to devascularize the corresponding splenic segment. Before division of the splenic trunk, it usually gives few small branches (the most important is the pancreatica magna) to the tail of the pancreas. Occlusion or section of these branches could result in pancreatitis. The main venous drainage is through the splenic vein, which joins the superior mesenteric vein behind the neck of the pancreas to form the portal vein.

The spleen combines the innate and adaptive immune system in a uniquely organized way. The structure of the spleen enables it to remove older erythrocytes from the circulation and leads to the efficient removal of blood-borne microorganisms and cellular debris. This function, in combination with a highly organized lymphoid compartment, makes the spleen the most important organ for antibacterial and antifungal immune reactivity [11].

The spleen, which has important hematopoietic functions during early fetal development (until the fifth month), has no significant hematopoietic function remaining in adults, but continues to function as a “sophisticated filter” because of the unique circulatory system and lymphoid organization, and it has blood-cell monitoring and management functions as well as important immune functions throughout life. However, under certain pathological conditions (such as myelodysplasia), the spleen can reacquire its hematopoietic function.

Removal of the spleen results in loss of immunologic and filtering functions. It is well established that, after splenectomy, patients are at a significantly higher risk for overwhelming post-splenectomy nfection (OPSI) with fulminant bacteremia, pneumonia, or meningitis, as compared with those with normal splenic function. Asplenic subjects have defective activation of complement by the alternative pathway, leaving them more susceptible to infection. Asplenic patients also have a normal response to re-immunization to an antigen first encountered before splenectomy, but do not have an optimal response to exposure to new antigens, especially if the antigen is administered intravenously.

The spleen is a major site of production of opsonins (molecules that target an antigen for an immune response), properdin (important for initiation of the alternative pathway of complement activation) and tuftsin (a tetrapeptide that enhances the phagocytic activity of polymorphonuclear leukocytes and mononuclear phagocytes). Removal of the spleen results in decreased serum levels of these factors. As a result, neutrophil function is decreased in asplenic patients, and the defect appears to be related to the absence of circulating mediators [12].

For these reasons, it is suggested that splenectomized persons receive the following vaccinations (ideally before planned splenectomy):

Currently, we consider all patients evaluated for elective splenectomy to be potential candidates for laparoscopic splenectomy (Fig. 11.3). Large case series and non-randomized comparative trials have consistently reported better outcomes from laparoscopic splenectomy than from open splenectomy. Although operating times were longer among patients who underwent LS, the duration of hospital stay, transfusion requirements, and morbidity and mortality were reduced [13].

Contraindications to a laparoscopic approach include severe portal hypertension, uncorrectable coagulopathy, severe ascites, and most traumatic injuries to the spleen. Extreme splenomegaly also remains a relative contraindication.

Because most patients scheduled for splenectomy have a hematologic disorder, a multidisciplinary treatment protocol should be adapted to each patient, in particular about the use of corticosteroids, gamma-globulins, and platelet transfusion.

Patients undergoing elective splenectomy should be vaccinated preoperatively (or within 30–40 days postoperatively) with pneumococcal, meningococcal, and Haemophilus vaccines. Low-molecular-weight heparin (LMWH) prophylaxis for thromboembolism and antibiotics are administered according to standard guidelines (and if there are no hematologic contraindications). Bowel preparation is not routinely necessary. Patients need to be given all the information about the consequences of the asplenic state.

The literature reports that, with sufficient experience, even massive spleens can be removed safely using minimally invasive methods [14]. In any case, rather than the absolute size of the spleen, the relationship between the same and amplitude of the laparoscopic chamber is more important [15]. Knowledge of anatomy is essential for preparation of the splenic hilum and liberation of the organ. Moreover, preoperative embolization of the splenic artery and the hand-assisted method allowed extension of the laparoscopic indications for massive splenomegaly [16]. In the process of hand-assisted laparoscopic splenectomy for splenomegaly, tactile senses may help to identify dissection planes, to define ASs, and to prevent splenic capsular injury by trocars and instruments. The hand may function as a retractor to hold the stomach, colon and pancreas moderately while holding the spleen laterally simultaneously. Furthermore, dissection of the splenic hilum could be easier with the tactile sense of the hand combined with a laparoscopic dissector in the other hand even in the setting of a spleen with dense adhesion.

However, because of the larger-sized spleen that narrows the operative space, exposure is limited and the manipulation difficult, LS becomes more technically challenging. The hypervascularization and dense adhesion around the spleen also hampers the procedure. Moreover, once the dissection is completed, extraction of the giant spleen with a totally laparoscopic approach by placing into a retrieval bag followed by morcellation can be difficult, and the procedure time can be longer. LS for splenomegaly has been associated with longer operating time, more blood loss, and higher intraoperative and postoperative complication rates than LS for normal-sized spleens,and with a higher conversion rate [17].

Spleens removed by an anterior laparoscopic approach are extracted through the umbilical trocar site after fragmentation in a plastic bag. It is rarely necessary to enlarge the incision by >2–3 cm. If the lateral approach is undertaken, extraction is more readily carried out through one of the ports situated anteriorly. This extraction site also requires little or no enlargement. On occasion, for spleens longer than 20 cm, a Pfannenstiel incision should be made or the spleen can be readily extracted through the accessory incision used for hand assistance during hand-assisted laparoscopic surgery.

Special mention should be made for laparoscopic splenectomy in patients with malignant disease. If lymphoma (Hodgking or non-Hodgkin) is suspected, neither preoperative splenic artery embolization nor spleen fragmentation should be performed, for avoid compromising the histological diagnosis. In practice, however, the histological diagnosis was made preoperatively in the majority of the patients, then this measure may not be necessary.

Historically, image-guided percutaneous biopsy of the spleen has been approached with trepidation by radiologists because of concerns regarding accessibility and the risk of hemorrhage. This reluctance may be related to an early report of a high rate of major complications (13%) for percutaneous biopsy of the spleen performed with a 14-G needle [18]. Several more recent studies have reported much lower complication rates with smaller needle diameters (≤18 G gauge), similar to that reported for kidney or liver biopsies [19]. Diseases that commonly affect the spleen can pose a diagnostic challenge to the clinician, radiologist, and pathologist. The reported diagnostic accuracy of splenic biopsy varies, ranging between 84% and 90% [20].

For cases in which the spleen is the only abnormal or most accessible organ for biopsy and a tissue diagnosis is required, the use of image-guided percutaneous biopsy of the spleen could be considered a safe alternative to splenectomy with a high overall diagnostic accuracy (but only in experienced hands) [21].

Preoperative embolization of the splenic artery can reduce the operating time and decrease intraoperative blood loss when compared with laparoscopic or open splenectomy alone [22]. However, besides higher costs, radiation exposure for the patient and the unavailability of the procedure in each hospital, there are other problems related to the angiographic embolization, in particular the higher risk of portal-vein thrombosis (≈15%) and the pain related to ischemic damage [23]. In fact, ≈45% of patients report some degree of pain [24].

As the use of splenic arterial interventions increases in interventional radiology practice, clinicians must be familiar with splenic vascular anatomy, the indications and contraindications for carrying out interventional procedures, the technical considerations involved, and the potential use of other interventional procedures (such as radiofrequency ablation) in combination with splenic arterial interventions. Familiarity with the complications that may result from these interventional procedures, including abscess formation and pancreatitis, is also important [25].