Minimally Invasive Surgical and Image-Guided Interventional Approaches to the Spleen

Trauma

Trauma is the most common cause of death in people under the age of 45 years. Moreover, recent data from the Centers for Disease Control and Prevention show that nearly 200,000 people die from injury every year. Among these patients, the prevalence of intraabdominal injuries is about 15%, with the spleen being the most injured organ. Accordingly, trauma is the most common indication for splenectomy, with the vast majority of these being performed via laparotomy. However, over the past 30 years, efforts to preserve functional splenic tissue wherever feasible have been increasingly emphasized. As a consequence of this, the treatment of patients with blunt splenic injury has shifted from operative to nonoperative management. The current literature shows that 60% to 90% of patients are treated nonoperatively, and the accepted criteria for operative management are hemodynamic instability and associated intraabdominal or pelvic injury, which all require surgery. In the management of the injured spleen, the laparoscopic approach appears to have limited indications, and most trauma surgeons view minimally invasive surgery as contraindicated in major abdominal trauma. Only a few studies in literature report the performance of LS in the setting of blunt trauma, without conversion or major morbidity, and it has been suggested that laparoscopy may be reasonable in hemodynamically stable patients with spleen injury grade III ( Table 138.1 ). Instead, there is absolute contraindication in patients with hemodynamic instability and high bleeding rate (>500 mL/h). Furthermore, delayed LS may also be safe—especially if combined with adjunctive preoperative embolization, which appears to reduce the risk of continued or delayed hemorrhage. Delayed splenectomy is required in some of these patients because of continued bleeding or infarction with abscess formation. Successful delayed LS in this setting has been reported. In addition, laparoscopic techniques can be used to selectively apply electrocautery, fibrin, Gelfoam, suture repair, or to perform a partial splenectomy to control bleeding and preserve splenic tissue.

Although some authors have shown that laparoscopy can be a safe tool in the armamentarium for the treatment of splenic injury, additional studies are needed to define the selection criteria for these patients.

Hematologic Disorders

Indications for elective LS are similar to “open” splenectomy, and the most common is hematologic disorders. For a normal-sized spleen, LS has now achieved standard-of-care status. Benign hematologic diseases such as idiopathic thrombocytopenic purpura (ITP), thrombotic thrombopenic purpura, human immunodeficiency virus (HIV)-related thrombocytopenia, hereditary spherocytosis, autoimmune hemolytic anemia, thalassemia intermedia, thalassemia major, sickle cell disease, and Evans syndrome are the absolute indications. Relative indications are unresponsiveness to medical therapy, disease relapse, splenomegaly, frequent transfusions, adverse effects, or dependency on steroid therapy. Current literature suggests that in patients who come under any of the previously mentioned indications, LS should be offered as the surgical treatment of choice. Among hematologic disorders, the most common indication is idiopathic thrombocytopenic purpura. Kovaleva et al. reviewed their 20-year experience with more than 1000 ITP patients. First-line treatment for ITP remains medical therapy, usually steroids. Second-line treatment after failure of medical therapy is splenectomy, which achieves 80% remission, with good long-term results (60 months or longer) in 32% of patients.

Box 138.1 summarizes the indications for LS.

Contraindications

Absolute contraindications in the setting of hematologic disorders are uncorrected coagulopathy, severe comorbidities that increase the operative risks, and hematologic malignancies localized outside of the spleen. A low platelet count (<10 × 10 ⁹ /L) should no longer be considered as an absolute contraindication. Current literature states that the increased surgical experience, as well as advances in laparoscopic techniques and instruments, have made it possible to operate on patients with low platelet counts safely and effectively. Although the European Association for Endoscopic Surgery guidelines consider portal hypertension as an absolute contraindication for LS, several publications reported on the safety of this method in patients with cirrhosis and portal hypertension. Cai et al., for instance, described 24 successful cases of splenectomy for hypersplenism in cirrhotic patients.

Absolute contraindications in the setting of trauma are splenic injury grade IV and V (see Table 138.1 ), and acute hemorrhage, with a bleeding rate greater than 500 mL/h on serial ultrasound examinations.

Imaging

Preoperative imaging with ultrasound and/or CT scan is essential for operative planning. Imaging can help assess spleen size and can also delineate useful anatomic relationships that impact the conduct of surgery. The normal spleen measures about 11 cm in length. Moderate splenomegaly, from 11 to 25 cm, should be noted in preoperative planning. Massive splenomegaly, greater than 25 cm length, may change preoperative and intraoperative strategy. Preoperative imaging may also identify accessory spleens, reported in 10% to 20% of patients. In addition, ultrasound is critical in trauma settings because it helps the decision-making process by assessing the bleeding rate.

Although not indicated for a normal-sized spleen, preoperative splenic artery embolization can be useful in patients with massive splenomegaly. Timing is important because patients can develop significant pain from infarcted splenic tissue; it is suggested to perform angioembolization within 24 hours before surgery. Preoperative angioembolization of the splenic artery for LS is safe and reduces the conversion rate.

General Considerations: Antibiotic Prophylaxis, Deep Venous Thrombosis Prophylaxis, Bowel Preparation

A broad-spectrum antibiotic prophylaxis should be administered at the time of induction to anesthesia and continued postoperatively for at least 24 hours. Patients undergoing splenectomy for a hematologic disorder should undergo the same preparation that they would for open splenectomy, which may include administration of steroids, immune globulin, fresh-frozen plasma, cryoprecipitate, or platelets. Blood products must be available intraoperatively, especially platelets for patients with severe thrombocytopenia. Prophylactic platelet transfusions are typically given only when the platelet count is below 50,000 and the platelets are administered only after the splenic artery has been ligated.

All patients require deep venous thrombosis (DVT) prophylaxis, including pneumatic sequential compression devices, pre- and postoperative low-dose subcutaneous unfractionated heparin prophylaxis, and early postoperative ambulation. Controversy remains over the length of postoperative DVT prophylaxis. For high-risk patients, DVT prophylaxis should be considered up to and beyond 14 days after surgery.

Bowel preparation before splenectomy is not mandatory. A limited prep the night before surgery may clear the left colon of stool bulk, with the purposes of improving colon mobilization and avoiding postoperative constipation.

Immunization Against Overwhelming Postsplenectomy Infection

Patients who undergo splenectomy are at increased risk of overwhelming postsplenectomy infection (OPSI), with a lifetime risk of 3% to 5%. The annual incidence of OPSI is between 0.23% and 0.42%. Risk is highest in three groups: (1) patients at the extremes of age, (2) immunocompromised patients, and (3) patients with hematologic disorders. Previously healthy patients who require splenectomy due to trauma are the lowest risk groups. When OPSI occurs, it is a true emergency, can be lethal, and requires immediate parenteral antibiotics and intensive care support. Intravenous immunoglobulin may play a beneficial role. OPSI carries a mortality rate of 38% to 69%. In general, OPSI results from decreased antigenic clearance, loss of opsonization, and decreased immunologic response. Streptococcus pneumoniae is the most common infective agent, isolated in 50% to 90% of patients, followed by Haemophilus influenzae type B (Hib), Streptococcus group B, Staphylococcus aureus , Escherichia coli, and other coliforms. Increased susceptibility to parasites and malaria is noted in endemic areas. Increased risk to Neisseria meningitidis infection has not been documented but remains a theoretical risk. Ideally, immunization against encapsulated organisms should be given 14 days prior to surgery. Recommended immunizations include polyvalent pneumococcal, meningococcal, and Haemophilus vaccinations. Pneumovax provides protection against 73% of OPSI-causing organisms. Data on revaccination remain unclear, but current consensus favors a Pneumovax booster every 5 to 10 years, which may be protective against all OPSI bacteria. Hib/Meningococcal/Influenza vaccine benefit is unconfirmed but recommended. For patients who do not receive recommended OPSI immunizations prior to surgery (such as trauma patients), vaccination is performed just before hospital discharge and is preferred over relying on patient compliance.

Anatomic Considerations

LS is not a forgiving procedure. Methodical control of the hemostasis is the key for success. The splenic parenchyma is fragile, has a rich blood supply, and is particularly vulnerable to capsular tear and hemorrhage. Understanding the variation of splenic anatomy is essential for a safe intraoperative management.

Michels' 1942 review of 100 spleens suggested that no two spleens have the same anatomy. Michels divided splenic blood supply into two types: distributed and magistral—with the distributed type being present in 70% of patients. Splenic size does not correlate with the number or distribution of splenic arteries, although the number of splenic notches and tubercles does. Splenic hilar anatomy can include numerous branches with various division levels. In addition, six or more short gastric arteries may be found in the gastrosplenic ligament arising from the fundus of the stomach. The lienorenal ligament contains hilar vessels and the tail of the pancreas. In nearly three-quarters of patients, the tail of the pancreas lies within 1 cm from the spleen, and direct contact between pancreas and spleen is found in about one-third of patients.