Ebook The washington manual of surgery: Part 2

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(BQ) Part 2 book The washington manual of surgery presentation of content: Colon and rectum, anorectal disease, cerebrovascular disease, thoracoabdominal vascular disease, peripheral arterial disease, hemodialysis access, cardiac surgery, pediatric surgery, plastic and hand surgery,...and other contents. > Table of Contents > 23 - Spleen 23 Spleen Timothy M Nywening Maria B Doyle A Anatomy The spleen is derived from the mesoderm and resides in the left upper quadrant of the abdomen, where it is protected by the ninth to eleventh ribs The average adult spleen is 12 cm long × cm wide × cm thick and weighs between 1,000 and 1,500 g The spleen is highly vascularized, receiving up to 5% of cardiac output The splenic artery, a branch of the celiac axis, runs posterior to the pancreas and most commonly arborizes into multiple small arteries to enter the hilum of the spleen The inferior mesenteric vein drains into the splenic vein, which ultimately joins with the superior mesenteric vein to form the portal vein Accessory spleens are found in 10% to 20% of the population and can be located anywhere in the abdomen but are most commonly found in the splenic hilum (Fig 23-1) B Function Histology of the spleen reveals highly vascularized red pulp interspersed with areas of white pulp Red pulp consists of branching, thin walled sinuses and splenic cords filled with red blood cells (erythrocytes) and phagocytic cells White pulp consists of T-cell rich periarteriolar sheaths, B-cell containing lymphoid nodules, and the marginal zone that serves as an interface between the lymphoid-dominant white pulp and erythrocyte-rich red pulp These two histologies constitute the two major functions of the spleen: Reticuloendothelial system: The red pulp serves to cull senescent erythrocytes and remodel healthy red cells The spleen also serves as a reservoir for platelets While extramedullary hematopoiesis uncommon in adults, the spleen may be a site of erythrocyte production in some disease states (i.e., myelofibrosis) Immune system: The spleen is involved in both the innate (opsonization) and adaptive (antigen presentation) immune system Opsonization of pathogens by the complement system results in enhanced phagocytosis and clearance in the spleen The white pulp also acts as a site of antigen presentation to lymphocytes that, along with an appropriate cytokine milieu, leads to effective T-cell mediated cytotoxic activity and B-cell antibody responses C Indications for Splenectomy (Table 23-1) Hematologic conditions a Thrombocytopenias (1) Idiopathic Immune Thrombocytopenic Purpura (ITP) is the most common indication for elective splenectomy It is an acquired disease that results from autoantibodies to platelet glycoprotein and results in immune mediated thrombocytopenia The spleen P.408 is both the major site of production of these antibodies as well as the principal site of platelet destruction Figure 23-1 Location of accessory spleens Usual location of accessory spleens: (1) Gastrosplenic ligament, (2) Splenic hilum, (3) Tail of the pancreas, (4) Splenocolic ligament, (5) Left transverse mesocolon, (6) Greater omentum along the greater curvature of the stomach, (7) Mesentery, (8) Left mesocolon, (9) Left ovary, (10) Douglas pouch, and (11) Left testis (a) Children: Most commonly present with acute ITP, in 70% to 90% of cases symptoms will remit regardless of therapy (NEJM 2002;346:995) In refractory cases a waiting period of 12 months is recommended, especially in children below years of age where risk of postsplenectomy sepsis is increased (Blood 1996.88:871-875) UnitedVRG (b) Adults: Usually present with chronic ITP First-line treatment with steroids results in a 50% to 75% response rate and may be combined with other modalities such as intravenous immune globulin (IVIG) and/or anti-Rh(D) infusions However, 80% will have recurrence after cessation of therapy Splenectomy results in 65% long-term remission (>5 years) and remains the treatment of choice in patients with platelets less the 30,000/mm3 or with a high risk of bleeding Most patients will achieve a response to splenectomy within P.409 10 days postoperatively (Am J Surg 2004;187:720-723) Alternatives to splenectomy include Rituximab (anti-CD20 monoclonal antibody) and thrombopoietin receptor antagonists which have shown efficacy as second-line agents (Blood 2012;120:960-969) Rituximab has also been shown to have some efficacy in patient failing to respond to splenectomy (Am J Hematology 2005;78:275-280) (Fig 23-2) TABLE 23-1 Clinical Conditions Requiring Splenectomy Category Common Uncommon Thrombocytopenias Immune thrombocytopenic purpura Thrombotic thrombocytopenic purpura Anemias Hereditary spherocytosis Autoimmune hemolytic anemias Sickle cell anemia Thalassemias Hereditary elliptocytosis Myeloproliferative and myelodysplastic disorders Ñ Chronic myelogenous leukemia Polycythemia vera Myelofibrosis Myeloid metaplasia Essential thrombocytosis Lymphoproliferative disorders Ñ Chronic lymphocytic leukemia Hairy-cell leukemia Non-Hodgkin lymphoma Hodgkin lymphoma Neutropenias Ñ Felty syndrome Nonhematologic Etiologies Trauma Incidental/iatrogenic splenectomy Splenic artery aneurysm Splenic abscess Splenic cyst/pseudocyst Glycogen storage diseases (2) Thrombotic Thrombocytopenic Purpura (TTP) is a systemic disease of resulting in the pentad of thrombocytopenia, microangiopathic hemolytic anemia (MAHA), altered mental status, renal failure, and fever It is a result of decreased ADAMT13, a protease responsible for cleaving von Willebrand factor, leading to platelet aggregation and thrombosis of the microvasculature It is most common in adults and usually idiopathic or drug (cyclosporine, gemcitabine, clopidogrel, quinine) related P.410 UnitedVRG Figure 23-2 Treatment approach in ITP in adults This diagram represents a simplified approach to the treatment of patients with ITP A threshold platelet count of 30,000/µL for clinical decisions, rather than a range of platelet counts, is presented, but clinical symptoms and patients' concerns are more important for treatment decisions (Adapted from George J, Leung LLP Treatment and prognosis of immune (idiopathic) thrombocytopenic purpura in adults UpToDate, 2011.) (a) First-line treatment: Medical management with plasmapheresis, which had improved initial response and 6-month survival compared with plasma infusion (NEJM 1991;325:393-397) Steroid therapy in addition to plasmapheresis is used in the treatment of relapse Second-line agents include rituximab, cyclosporin, and increased frequency of plasmapheresis (Br J Haematol 2012;158:323-335) (b) Splenectomy: Reserved for those who not respond to medical therapy or with chronically relapsing disease Furthermore, splenectomy has only shown benefit when used in conjunction with plasmapheresis in order to achieve durable remission (Br J Haematol 2005;130:768-776) b Anemias (1) Hemolytic anemias constitute a group of diseases for which splenectomy is almost universally curative (a) Hereditary spherocytosis is an autosomal dominant disorder characterized by a defect in an RBC membrane protein The most common mutation is in the protein spectrin, but P.411 other mutations in ankyrin, band 3, and palladin have been found This defect results in small, spherical, rigid erythrocytes that fail to deform adequately to transverse the splenic microcirculation This ultimately leads to the sequestration and destruction of erythrocytes in the spleen Symptoms include anemia, jaundice (indirect bilirubinemia), and pigmented gallstones Diagnosis is confirmed by the presence of spherocytes on peripheral blood smear, + osmotic fragility test, and decreased eosin-5-maleimide (EMA) binding (Blood Rev 2013;27:167-178) Treatment includes folate supplementation and splenectomy for moderate to severe cases (b) Hereditary elliptocytosis is an autosomal dominant disorder in which an RBC cytoskeletal protein defect results in elliptical shaped erythrocytes Most patients are asymptomatic with a mild anemia and not require additional treatment For select patients with symptomatic anemia splenectomy is usually curative (2) Acquired autoimmune hemolytic anemias (a) Warm autoimmune hemolytic anemia occurs when IgG autoantibodies interact optimally with antigens at 37¡C Diagnosis is confirmed with a positive direct Coombs test (incubation with anti-IgG serum results in RBC agglutination) Etiology is most often idiopathic but may also include chronic lymphocytic leukemia (CLL), non-Hodgkin lymphoma, collagen vascular disease, and drugs Splenectomy is reserved for nonresponders or those requiring high steroid doses and is 60% to 70% effective in achieving remission Rituximab has also shown efficacy and is suitable second-line treatment for those patients who not desire to undergo splenectomy (Blood 2010;116:1831-1838) (b) Cold autoimmune hemolytic anemias are mediated by C3 complement fixation to IgM autoantibodies resulting in hemolysis at temperatures approaching 0¡C Features include Reynaud like symptoms along with anemia Most cases respond to protective clothing; however severe episodes may require cyclophosphamide, rituximab, or interferon Splenectomy does not play a role in the treatment of cold autoimmune hemolytic anemias c Congenital hemoglobinopathies (1) Sickle cell anemia is a result of homozygous inheritance of the S variant of the hemoglobin beta chain Autosplenectomy usually occurs secondary to repeated vaso-occlusive events and splenectomy is rarely required However, splenectomy may be reasonable for selected patients with splenic abscess, symptomatic splenomegaly, hypersplenism, or acute splenic sequestration crisis (2) Thalassemias are hereditary anemias that result from a defect in hemoglobin synthesis βthalassemia major is typically treated UnitedVRG P.412 with iron chelation therapy as most patients will succumb to hemosiderosis at an early age Splenectomy is reserved for palliation of symptomatic splenomegaly or splenic infarcts d Myeloproliferative and myelodysplastic disorders (1) Chronic myelogenous leukemia is a myelodysplastic disorder characterized by the bcr-abl fusion oncogene, known as the Philadelphia chromosome This oncogene results in a constitutively active tyrosine kinase (a) Treatment: First-line therapy utilizes the tyrosine kinase inhibitor (TKI) imatinib mesylate (Gleevec) Alternative TKI treatments (dasatinib and nilotinib) are used in cases of intolerance or suboptimal response Stem cell transplantation is used for cases of treatment failure in eligible patients (Blood 2006;108:1809-1820) (b) Splenectomy: A large prospectively randomized trial compared splenectomy plus chemotherapy or chemotherapy alone in the treatment of early phase of CML Splenectomy had no effect on survival or disease progression, but it did increase the rate of thrombosis and vascular accidents (Cancer 1984;54:333-338) Splenectomy is indicated only for palliation of symptomatic splenomegaly or hypersplenism that significantly limits therapy (2) Polycythemia vera and essential thrombocytosis are chronic diseases of uncontrolled RBC and platelet production, respectively These diseases are treated medically, but splenectomy can be required to treat symptomatic splenomegaly or pain from splenic infarcts Splenectomy can result in severe thrombocytosis, causing thrombosis or hemorrhage, which requires perioperative antiplatelet, anticoagulation, and myelosuppressive treatment (3) Myelofibrosis and myeloid metaplasia are incurable myeloproliferative disorders that usually present in patients older than 60 years The condition is characterized by bone marrow fibrosis, leukoerythroblastosis, and extramedullary hematopoiesis, which can result in massive splenomegaly Indications for splenectomy include symptomatic splenomegaly and transfusiondependent anemias Although the compressive symptoms are effectively palliated with splenectomy, the cytopenias frequently recur In addition, these patients are at increased risk for postoperative hemorrhage and thrombotic complications after splenectomy e Lymphoproliferative disorders (1) CLL, a B-cell leukemia, is the most common of the chronic leukemias and is characterized by the accumulation of mature but nonfunctional lymphocytes Primary therapy is medical, with splenectomy reserved for those patients with symptomatic splenomegaly and severe hypersplenism (2) Non-Hodgkin lymphoma is a diverse group of disorders with a wide range of clinical behaviors, ranging from indolent to highly aggressive As with other malignant processes, splenectomy is P.413 indicated for palliation of hypersplenism and cytopenias or for diagnosis in patients with suspected persistent or recurrent disease after systemic therapy Splenectomy plays an important role in the diagnosis and staging of patients with isolated splenic lymphoma (known as malignant lymphoma with prominent splenic involvement) In these cases, improved survival has been shown in patients undergoing splenectomy (Cancer 1993;71: 207-215) (3) Hodgkin lymphoma historically had utilized splenectomy for diagnostic staging However, due to refinements in imaging techniques and progress in the methods of treatment splenectomy for Hodgkin lymphoma is rare Indications for surgery are similar to those for non-Hodgkin lymphoma (4) Hairy cell leukemia is a rare disease of elderly men that is characterized by B lymphocytes with membrane ruffling Splenectomy was previously regarded as the primary therapy for this disease, but improvements in systemic chemotherapy have reduced the role of splenectomy, which is now reserved for patients with massive splenomegaly or refractory disease f Neutropenias (1) Felty syndrome is characterized by rheumatoid arthritis, splenomegaly, and neutropenia The primary treatment is steroids, but refractory cases may require splenectomy to reverse the neutropenia Patients with recurrent infections and significant anemia may benefit from splenectomy Granulocytopenia is improved in approximately 80% of patients (Arch Intern Med 1978;138:597-602) The clinical course of the arthritis is not affected Nonhematologic conditions a Trauma is the most common indication for splenectomy In the unstable trauma patient the procedure is traditionally performed via laparotomy With current imaging modalities grading of splenic injuries (Table 23-2) allows for conservative management in selected patients b Incidental splenectomy occurs when the spleen is iatrogenically injured during an intraabdominal procedure Injury may result from a retractor placed in the left upper quadrant or during mobilization of the splenic flexure Small injuries such as capsular tears may be controlled with hemostatic agents or electrocautery, but injuries resulting in significant blood loss may require splenectomy to achieve rapid hemostasis c Vascular (1) Splenic artery aneurysm is the most common visceral artery aneurysm and is typically an incidental finding It occurs more commonly in females and associated with a high incidence of rupture during pregnancy with significant maternal and fetal mortality Asymptomatic aneurysms in a patient whom pregnancy is not anticipated may be observed Indications for intervention P.414 include size ≥2 cm, females of child-bearing age who may become pregnant and inflammatory pseudoaneurysms Management depends on the location of the aneurysm during the course of UnitedVRG the splenic artery Proximal and middle third aneurysms may be excluded by proximal and distal ligation of the artery Splenic perfusion persists via collateralization from the short gastric vessels For more distal lesions proximal ligation with splenectomy is required Alternatives treatments include endovascular approaches with transcatheter embolization TABLE 23-2 The American Association for the Surgery of Trauma (AAST) Spleen Injury Scale (2008 Edition) Grade Injury Type Injury Description I Hematoma Laceration Subcapsular: 3 cm or Involving trabecular vessel IV Laceration Laceration involving segmental or hilar vessels producing major devascularization (>25% of spleen) V Laceration Vascular Shattered spleen Hilar vascular injury aAdvance one grade for multiple injuries up to grade III Adapted from Tinkoff G, Esposito TJ, Reed J, et al American Association for the Surgery of Trauma Organ Injury Scale 1: Spleen, liver and kidney J Trauma 2008;207(5):646655 d Infectious (1) Parasitic infections account for more than two-thirds of splenic cysts worldwide but are rare in the United States The majority are hydatid cysts caused by Echinococcus species They are typically asymptomatic but may rupture or cause symptoms due P.415 to splenomegaly The primary treatment is splenectomy, with careful attention not to spill the cyst contents The cyst may be aspirated and injected with hypertonic saline prior to mobilization if concern about rupture exists (2) Splenic abscesses are rare, but potentially lethal if not accurately diagnosed and timely treatment instituted Two-thirds arise from seeding of the spleen by a distant site, most commonly endocarditis and urinary tract infections Abdominal CT and/or ultrasound imaging are the diagnostic modalities of choice CT images reveal a low intensity lesion that does not enhance with contrast Staphylococcus and streptococcus account for the most commonly identified organisms, accounting for >50% of cases Fungal infections are rare, and may resolve with antifungal treatment alone Percutaneous drainage may be used in select cases; however, splenectomy and appropriate antibiotic therapy is definitive treatment e Cystic lesions of the spleen may be either true cysts or pseudocysts, but this differentiation is difficult to make preoperatively (1) True cysts (or primary cysts) have an epithelial lining and are most often congenital Other rare true cysts include epidermoid and dermoid cysts (2) Pseudocysts (or secondary cysts) lack an epithelial lining and make up more than two-thirds of nonparasitic cysts They typically result from traumatic hematoma formation and subsequently resorb (3) Treatment of splenic cysts depends on the size of the lesion and associated symptoms Most are typically asymptomatic, but they may present with left upper abdominal or shoulder pain Those smaller than cm can be followed with ultrasonography and often resolve spontaneously Larger cysts risk rupture and require cyst unroofing or splenectomy Percutaneous aspiration is associated with infection and reaccumulation and is not indicated Laparoscopic management of splenic cysts yields shorter hospital length of stay and fewer complications with no adverse effects (Surg Endosc 2007;21:206-208) D Preoperative Preparation UnitedVRG 10 Answer: d Pexying the cecum does not have any benefit in a Ladd procedure Appendectomy is performed to eliminate any future appendicitis from arising in a nonanatomical position CHAPTER 33 Answer: b In a patient with a low cardiac index after open heart surgery, it is important to rule out hemorrhage and tamponade Transfusion would not be the correct answer since there is no evidence of hemorrhage Other causes of low cardiac index after open heart surgery are hypovolemia and LV dysfunction Since the CVP is elevated in this scenario, the preload is adequate, and one can increase the cardiac index by increasing the contractility (i.e., adding Dobutamine) or reducing afterload (i.e., adding a vasodilator such as nitroglycerin) An intraaortic balloon pump is reserved for patients who are in cardiogenic shock refractory to inotropes or volume Answer: e Since the patient is hemodynamically stable, there is no indication for reexploration in the ICU or operating room Indiscriminately transfusing platelets or FFP in patients who are hemodynamically stable is also not recommended Patients who have just returned from the operating room may be cold and have inadequate reversal of their heparin Therefore, warming the patient and giving protamine is the best first step in management of this patient Answer: b The indications for IABP are preoperative low-cardiac-output states, preoperative unstable angina refractory to medical therapy, intraoperative weaning from cardiopulmonary bypass after inotropic agents alone are maximized, and postoperative low cardiac output states In the case of aortic insufficiency, a balloon pump is contraindicated because the balloon inflates during diastole, which increases the P.914 regurgitant volume, and thereby exacerbating the deleterious effects of the aortic insufficiency Answer: d Current guidelines recommend that CABG be performed to improve survival in patients with significant (≥50% stenosis) left main coronary artery stenosis, in patients with significant (≥70% stenosis) in three major coronary arteries or in the proximal LAD plus one other major artery, in patients with significant stenosis in two major coronary arteries with severe or extensive myocardial ischemia or target vessels supplying a large area of viable myocardium, in patients with LV dysfunction (ejection fraction 35% to 50%) and significant stenosis when viable myocardium is present in the area of intended revascularization, in patients with significant stenosis in the proximal LAD and evidence of extensive ischemia, in patients with complex threevessel CAD with or without involvement of the LAD who are good candidates for surgery, and in in patients with multivessel CAD with diabetes mellitus Contraindications include porcelain aorta, no adequate conduits or targets, and unacceptably high perioperative risk Answer: d Relative indications for cardiac transplant include refractory cardiogenic shock, instability in fluid balance or renal function despite optimal medical therapy, severe persistent angina not amenable to revascularization, markedly reduced exercise capacity (peak VO2 45 yo with abnormal bleeding, or women of any age with risk factors for endometrial cancer and abnormal bleeding are recommended to undergo an endometrial biopsy In this case, the patient has abnormal bleeding (daily) and a risk factor (obesity) Answer: a The gravid uterus can compress the inferior vena cava resulting in decreased blood return to the mother and poor placental perfusion resulting in maternal hypotension and fetal hypoxia Answer: c The standard of care for stage IIIB cervical cancer is radiation therapy with sensitizing cisplatin Stage IIIB cervical cancer by definition extends to the sidewall or obstructs ureteral flow and is therefore not resectable without significant morbidity Answer: b An incomplete abortion is an ongoing spontaneous abortion such that the cervix is open and there continue to be products of conception within the endometrial canal The cervix is closed in a missed abortion, inevitable abortion, and complete abortion P.928 CHAPTER 45 Answer: c Chi-square test is used for categorical or nominal data In this instance, patients either received prehydration with sodium bicarbonate or they did not The outcome represents the presence or absence of contrast-induced nephropathy This data can be summarized in a 2×2 contingency table Answer: c A t-test allows for comparison of means between two separate treatment groups If more than two treatment groups were compared, ANOVA would be the statistical test of choice In order to use a t-test, data must be normally distributed Answer: d While positive and negative predictive values are affected by the prevalence of a disease, sensitivity and specificity are not As the prevalence of a disease increases, the positive predictive value increases and negative predictive value decreases Answer: a Case-control studies are useful for rare diseases, as is the case with appendiceal cancer and pseudomyxoma peritonei In the above question, the cases would be presented by patients with pseudomyxoma peritonei from appendiceal cancer and the controls would be patients with appendiceal cancer alone Exposures in both groups could be evaluated to determine factors associated with the development of pseudomyxoma peritonei The correct answer for no is C, for no is A, and for no is C The false positive rate is equal to the false positives divided by the sum of the false positive patients and the true negative patients CHAPTER 46 Answer: b Run charts display a measured value plotted sequentially in time They are particularly useful for measuring the effect of a quality improvement intervention by measuring the change in the measured value following the intervention Answer: c Value stream mapping is a component unique to the Lean method of quality improvement that in which processes are mapped as a series of steps for which efficiency is defined as time during each step in which value is added for the customer (or patient) compared to time spent without any value added Answer: d Normalization of deviance takes place when people repetitively and often progressively violate standard practices until the deviant practice becomes the new norm and creates conditions that are prone to error Answer: a PDSA cycles describe a four-phase cycle to develop, test, and implement changes in health care, best used to test small changes before broad implementation In combination with a P.929 series of three questions, the PDSA cycle constitutes the Model for Improvement Answer: e Root cause analysis is a retrospective team-based approach to delve deeper into a medical error or Ònear missÓ event to identify possible latent errors within a system It is accomplished through defining the problem at hand, creating a detailed timeline of events, exploring possible causes to find their source, brainstorming possible solutions, and then implementing and intermittently reviewing these solutions to measure effect of changes made through the process ... polyps of the proximal two-thirds of the rectum can be treated as colon polyps; however, there is some controversy regarding the treatment of malignant polyps of the distal one-third of the rectum... in Table 23 -3 a Splenomegaly increases the complexity of the laparoscopic approach because of the difficulty of manipulating the organ atraumatically and achieving adequate exposure of the ligaments... important factor in the treatment of malignant polyps is the level of invasion typically classified using the Haggitt (Table 24 -3) and Kudo classifications (Table 24 -4) P.4 32 TABLE 24 -2 Screening Recommendations
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