Principles of Surgery, Companion Handbook - page 33

Chapter 31 Spleen

Principles of Surgery Companion Handbook

CHAPTER
31
SPLEEN

Anatomy
Physiology and Pathophysiology
Diagnostic Considerations
Rupture of the Spleen
Hematologic Disorders for which Splenectomy is Potentially Therapeutic
 Hemolytic Anemias
 Idiopathic Thrombocytopenic Purpura (ITP)
 Thrombotic Thrombocytopenic Purpura (TTP)
 Secondary Hypersplenism
 Myeloid Metaplasia
 Hodgkin's Disease, Lymphomas, and Leukemias
 Miscellaneous Diseases
Miscellaneous Lesions
Splenectomy

ANATOMY

The spleen arises along the left side of the dorsal mesogastrium. Its weight in the average adult is 75–100 g. Located in the left upper quadrant, its superior relationship is the left leaf of diaphragm, and it is protected on all sides by the rib cage. It is supported by the splenophrenic, splenorenal, splenocolic, and gastrosplenic ligaments. These ligaments are all avascular except the gastrosplenic, which contains the short gastric vessels. The splenic artery arises from the celiac axis; the splenic vein joins the superior mesenteric vein to form the portal vein.

Accessory spleens are found in 14–30 percent of patients; they are found in decreasing order of frequency in the splenic hilus, gastrosplenic and splenocolic ligaments, gastrocolic ligament, splenorenal ligament, greater omentum, female pelvis, and rarely, the scrotum (Fig. 31-1).



FIGURE 31-1 Location of accessory 3 spleens. A. Splenic hilus. B. Along splenic vessels; tail of pancreas. C. Splenocolic ligament. D. Greater omentum; perirenal regions. E. Mesentery. F. Presacral region. G. Adnexal region. H. Peritesticular region. (From: Schwartz SI, Adams JT, Bauman AW: Splenectomy for hematologic disorders. Curr Probl Surg, May 1971. Copyright 1971, Chicago, Year Book Medical Publishers. Used by permission.)



The spleen is surrounded by a 1–2-mm capsule. Its pulp is divided into white, red, and marginal zones. The marginal zone surrounds white pulp and contains end-arterial branches of the central arteries. Lymphocytes, macrophages, and red cells are found in the marginal zone. The red pulp surrounds the marginal zone and consists of cords and sinuses.

Blood traverses the trabecular arteries that enter the white pulp as central arteries. These central arteries give off vessels at right angles or cross the white pulp and end in the marginal zone or red pulp, where they collect in splenic sinuses and then into the pulp veins, the trabecular veins, and the main splenic vein. Splenic cords are located between the sinuses. Red blood cells must deform to pass from sinus to cord. Total splenic blood flow is 300 mL/min.

PHYSIOLOGY AND PATHOPHYSIOLOGY

The spleen forms red and white blood cells that enter the circulation only between the fifth and eighth months of fetal life. Reticuloendothelial tissue removes cellular elements from circulating blood. With splenomegaly, blood elements pool in the spleen.

Abnormal and aged erythrocytes, abnormal granulocytes, normal and abnormal platelets, and cellular debris are cleared from the circulation by the spleen.

Pathologic reduction of cellular elements by the spleen may be due to (1) excessive destruction and (2) splenic production of antibody directed at a particular cellular element. Hypersplenism refers to overactivity of splenic function leading to accelerated removal of any or all of the circulating elements.

Howell-Jolly bodies, nuclear remnants of erythrocytes, are removed by the spleen. Postsplenectomy blood smears therefore contain red cells with Howell-Jolly bodies.

Each day 20 mL of aged red blood cells is removed. A hypoxic, acidotic, and glucose-deprived environment promotes further cell injury, compounded by low ATP levels. Red cell surface area is lost with each passage.

Neutrophils are removed from the circulation with a half-life of 6 h. Neutropenia occurs in some hypersplenic states because of accelerated sequestration or enhanced removal of altered granulocytes.

The platelet survives 10 days in circulation. One-third of the total platelet pool is sequestered in the spleen, but up to 80 percent may be sequestered in hypersplenism. Postsplenectomy platelet counts may reach as high as 1 million cells/mm3. It may be transient but in the extreme situation may result in intravenous thrombosis. Immunologic states without hypersplenism (e.g., idiopathic thrombocytopenic purpura, thrombotic thrombocytopenic purpura) also cause increased sequestration.

DIAGNOSTIC CONSIDERATIONS

Evaluation of Size Normally, the spleen is not a palpable organ except in 2 percent of adults. With enlargement, it may be felt below the left costal margin with a notching on its anteromedial surface.

Routine radiographs are useful. Splenomegaly is suggested by medial or caudal displacement of the stomach bubble and caudal displacement of the splenic flexure. Computed tomographic (CT) scans and magnetic resonance imaging (MRI) both depict abnormalities such as cysts, abscesses, and tumors. Radioisotopic scanning with technetium-99m (99mTc) sulfur colloid also is useful.

Evaluation of Function Hypersplenism is manifest by a reduction in the number of red cells, neutrophils, or platelets in the peripheral blood smear; marrow production should increase unless there is concomitant marrow disease. The diagnosis of hemolysis, increased red cell turnover, is supported by a reticulocytosis and increase in the serum bilirubin level.

The spleen's role in hemolytic anemia can be assessed by determining relative uptake of chromium-51 (51Cr)-tagged red cells by the spleen and liver. A 2:1 spleen-liver ratio implicates the spleen and anticipates beneficial effects of splenectomy. Radioisotope labeling also is used to evaluate neutrophil and platelet survival.

RUPTURE OF THE SPLEEN

See Chap. 6.

HEMATOLOGIC DISORDERS FOR WHICH SPLENECTOMY IS POTENTIALLY THERAPEUTIC

Hemolytic Anemias

These are disorders in which there is accelerated destruction of mature red cells. They are classified as congenital, in which there is an intrinsic red cell defect, and acquired, in which the red cells are normal. Abnormal red blood cell survival may be demonstrated by measuring the disappearance of 51Cr-labeled red cells.

Hereditary Spherocytosis This disorder is transmitted as an autosomal dominant trait. The erythrocyte membrane is defective, and the cell has a thickened and spherical shape and is small. There is increased osmotic fragility; i.e., lysis occurs at a higher than normal concentration of sodium chloride. The abnormal spherocytic red cells are unable to pass through the spleen and are more susceptible to trapping and disintegration with each passage. Decreased red cell ATP may be a precise defect.

Clinical features are anemia, reticulocytosis, jaundice, and splenomegaly. Fatal crises have been reported rarely. Cholelithiasis is present in 30–60 percent. Leg ulcers are uncommon.

Diagnosis is by peripheral blood smear, which shows spherocytic cells with a smaller diameter and increased thickness. Increased osmotic fragility is diagnostic, but such tests are rarely performed.

Splenectomy is the only therapy and should be delayed until age 4. Intractable leg ulcers mandate early splenectomy. Results are uniformly good. The underlying erythrocyte defect is unchanged, but hemolysis and jaundice resolve, and erythrocyte life span becomes normal. Preoperative ultrasound or an oral cholecystogram should be done, and if gallstones are present, cholecystectomy should be performed concomitant with splenectomy.

Thalassemia Also known as Mediterranean anemia, this disorder is transmitted as an autosomal dominant trait. There is a defect in hemoglobin synthesis. Heinz bodies are present as intracellular precipitates. The disease is classified into alpha, beta, and gamma types, depending on the specific chain involved. Beta thalassemia results in a decreased rate of beta-chain synthesis and a decrease in hemoglobin A (Hb-A).

Two degrees of severity have been determined: thalassemia major (homozygous) and minor (heterozygous). Thalassemia major occurs in the first year of life with pallor, retarded body growth, and a large head. It may result in a severe chronic anemia with icterus, splenomegaly, and early death. Most thalassemia minor patients lead normal lives. Thalassemia major is diagnosed by blood smear. Nucleated red cells are present. The reticulocyte count is elevated. There is persistence of hemoglobin F (Hb-F) and a decrease in Hb-A. In thalassemia minor, Hb-A2 is increased.

Treatment is indicated only for symptomatic patients; transfusions are given as needed, and splenectomy may reduce transfusion requirements and the hemolytic process. Other indications for splenectomy include marked splenomegaly and repeated splenic infarcts.

Hereditary Hemolytic Anemia with Enzyme Deficiency Included are anaerobic glycolytic deficiencies, e.g., pyruvate-kinase (PK) deficiency, and hexose monophosphate shunt deficiencies, e.g., glucose-6-phosphate (G-6-PD) deficiency. Red cells are more susceptible to hemolysis. Most patients are asymptomatic, with hemoglobin levels above 8 g/dL. Transfusion is appropriate for significant anemia. Splenectomy may help severe PK deficiency but plays no role in G-6-PD deficiency. Postsplenectomy mesenteric or caval thrombosis may occur in PK deficiency. Splenectomy worsens those with hereditary high red cell phosphatidylcholine anemia.

Sickle Cell Disease This is a hereditary hemolytic anemia that occurs predominantly in blacks. Hb-A is replaced by hemoglobin S (Hb-S), the sickle hemoglobin. Hb-F is also mildly increased. With reduced oxygen tension, the Hb-S molecule crystallizes, and the cells elongate and distort. This increases blood viscosity and stasis, leading to thrombosis, ischemia, necrosis, and organ fibrosis. Early in the disease the spleen enlarges, but with repeated infarction, autosplenectomy occurs.

Most patients with the trait are asymptomatic. In those with the disease, chronic anemia and jaundice may be interrupted by acute crises related to thrombosis. Symptoms include bone or joint pain, hematuria, priapism, neurologic symptoms, ulcers of the malleolus, abdominal pain, and splenic abscess.

Diagnosis is made by blood smear and hemoglobin electrophoresis. Leukocytosis, thrombocytosis, and hyperbilirubinemia may be present.

Treatment is palliative. Sodium cyanate prevents sickling of Hb-S. Hydration and exchange transfusions are performed for crises. Splenectomy rarely is indicated unless hypersplenism is present. There usually is autosplenectomy from infarction.

Idiopathic Autoimmune Hemolytic Anemia This is a disorder in which there is a shortened erythrocyte life span secondary to an endogenous hemolytic mechanism with normal red cells. The cause is unknown but presumed to be autoimmune. The spleen may serve as a source of destructive antibody. “Warm” and “cold” antibodies have been described; most are hemagglutinins rather than hemolysins. Immunologically altered cells are trapped and destroyed by the reticuloendothelial system of the spleen.

This disorder is more common in women and in those older than age 50. Mild jaundice is present. Splenomegaly is present in 50 percent and gallstones in 25 percent. Tubular necrosis occurs in severe cases, and the prognosis in this group is grave.

Diagnosis is made by demonstrating anemia, reticulocytosis, and products of red cell destruction in the urine, blood, and stool; hypercellular bone marrow; and a positive direct Coombs' test.

Treatment is not necessary for those who run a self-limiting course. Corticosteroids and transfusions may be required. With “warm” antibody, splenectomy is indicated when steroids are ineffective, required in excess, cause toxic manifestations, or are contraindicated. Splenic sequestration as demonstrated by 51Cr-tagged red cells is useful in predicting success after splenectomy. Relapses may occur after splenectomy.

Idiopathic Thrombocytopenic Purpura (ITP)

This is an acquired disorder in which platelets are destroyed when exposed to immunoglobulin G (IgG) antiplatelet factors. The spleen is both the source of antibody and the site of sequestration. Features include a bone marrow with normal to increased megakaryocytes and no evidence of systemic disease or drug ingestion known to cause thrombocytopenia. This disorder occurs in some patients with HIV/AIDS.

There is a 3:1 female-male ratio. Clinical manifestations include petechiae, bleeding gums, vaginal bleeding, gastrointestinal bleeding, and hematuria. Central nervous system bleeding occurs in 1–2 percent. The spleen is normal in size and rarely palpable.

Laboratory data include platelet counts of less than 50,000/mm3, a prolonged bleeding time, and a normal clotting time. There is no anemia or leukopenia. Bone marrow examination shows normal to increased megakaryocytes in addition to qualitative histologic changes.

Acute ITP resolves in 80 percent of children under age 16 without specific therapy; 75–85 percent of adults with chronic ITP respond permanently to splenectomy without further steroid requirements. Platelet counts should increase to over 100,000/mm3 within 7 days.

Treatment begins with 6–8 weeks of steroid therapy; occasionally, gamma-globulin infusions and plasmapheresis have been useful. Splenectomy is performed if there is no response; if there is a response, the steroids are tapered. Splenectomy is indicated if thrombocytopenia recurs. Emergent splenectomy is indicated for any intracranial bleeding.

Even if platelet levels approach zero, platelets should not be given until the spleen is removed. Accessory spleens may be responsible for recurrence and may be treated effectively by removal.

Systemic Lupus Erythematosus (SLE) Splenectomy may benefit SLE patients with refractory cytopenias.

Thrombotic Thrombocytopenic Purpura (TTP)

TTP is a disease of arterioles and capillaries, but in some patients splenectomy is beneficial. The etiology is probably immune; 5 percent occur during pregnancy. Histologically, there is widespread occlusion of capillaries and arterioles.

The pentad of clinical features includes fever, purpura, hemolytic anemia, neurologic manifestations, and renal disease. Laboratory data include anemia, reticulocytosis, thrombocytopenia, and leukocytosis. Occasionally, hyperbilirubinemia, proteinuria, hematuria, casts, and azotemia are seen. A blood smear shows fragmented, distorted red cells.

Most cases show a rapid fulminant and fatal course, usually secondary to renal failure or an intracranial bleed. Treatment includes heparin, exchange transfusions, plasmapheresis, and administration of dextran, antimetabolites, and steroids. Splenectomy with high-dose steroids may be useful if there is no response to the preceding.

Secondary Hypersplenism

Pancytopenia may occur with splenomegaly or splenic congestion. This is seen in portal hypertension. Bleeding and petechiae, however, are uncommon. Hypersplenism per se is not an indication for surgery in portal hypertension. If splenectomy becomes necessary, it should be combined with a splenorenal shunt to decrease the portal pressure.

Myeloid Metaplasia

This is a panproliferative process with connective tissue proliferation of the bone marrow, liver, spleen, and lymph nodes, as well as simultaneous proliferation of the hemopoietic elements in the liver, spleen, and long bones. The cause is unknown. Splenic enlargement may occur. Portal hypertension also may occur as a result of hepatic fibrosis or increased forward flow.

The presenting manifestations (not until middle age) usually are that of anemia and increasing splenomegaly. Symptoms include abdominal pain of splenic infarction, fullness after meals, spontaneous bleeding, secondary infection, bone pain, pruritus, and hyperuricemia. Hepatomegaly is common.

A hallmark is the peripheral blood smear. Red cells are fragmented with poikilocytosis and teardrop and elongated forms. The white blood cell count is usually below 50,000/mm3 but may be much higher. The platelet count may be low, normal, or high. Marrow biopsy shows fibrous replacement of elements.

Treatment consists of transfusions, hormones, chemotherapy, and radiation therapy. Busulfan and cyclophosphamide have been used. Although not curative, splenectomy is indicated for control of anemia, thrombocytopenia, and symptoms secondary to an enlarged spleen. In patients with esophagogastric varices, splenectomy alone usually is sufficient. Postoperative thrombocytosis and thrombosis of the splenic vein extending into the portal and mesenteric veins commonly occur in these patients. Operative mortality is 13 percent, with morbidity of 45 percent.

Hodgkin's Disease, Lymphomas, and Leukemias

Splenectomy is indicated for symptomatic splenomegaly, with anemia and increasing transfusion requirements, or with cytopenia limiting systemic therapy.

Hairy cell leukemia, or reticuloendotheliosis, is characterized by malignant cells with filamentous cytoplasmic projections. Splenectomy is indicated when neutropenia, thrombocytopenia, and anemia occur. This may result in improvement in 67–75 percent. Failures are managed with steroids and chemotherapy.

Staging of Hodgkin's Disease and Non-Hodgkin's Lymphoma Diagnosis usually is made by biopsy of suspicious lymphadenopathy or splenomegaly. The Sternberg-Reed cell is pathognomonic. There are four major histologic types: lymphocyte predominant, nodular sclerosis, mixed cellularity, and lymphocyte depletion. Survival is related to the histology and presence or absence of symptoms. Stage I is limited to one anatomic region; Stage II shows two or more regions of disease on the same side of the diaphragm; Stage III shows disease on both sides of diaphragm, with disease limited to lymph nodes, spleen, and Waldeyer's ring; and Stage IV shows involvement of bone marrow, lung, liver, skin, gastrointestinal tract, and any nonnodal tissues.

A staging laparotomy is indicated for Stage I patients or patients with supradiaphragmatic Stage II nodular sclerosis without clinical symptoms. The indications for staging are decreasing because of greater reliance on CT scans and increasing use of chemotherapy.

A staging laparotomy is performed in the following fashion: (1) wedge liver biopsy before any retraction/manipulation, (2) splenectomy, (3) lymph node sampling from entire periaortic chain, mesentery, and hepatoduodenal ligament, and (4) iliac crest marrow biopsy. After laparotomy, surgical staging upgraded clinical stage in 27–36 percent and downgraded in 7–15 percent. Regarding non-Hodgkin's lymphoma, routine staging is not accepted by many.

Miscellaneous Diseases

Felty's Syndrome This disorder involves the triad of rheumatoid arthritis, splenomegaly, and neutropenia. Mild anemia, thrombocytopenia, and gastric achlorhydria are seen occasionally. Corticosteroids and splenectomy are used to treat neutropenia and reduce susceptibility to infection.

Splenectomy is indicated for (1) neutropenic patients with serious or recurrent infections, (2) patients requiring transfusions for anemia, (3) patients with profound thrombocytopenia, and (4) patients with intractable leg ulcers. The course of the arthritis usually is not altered, whereas the neutrophilic response to infection is improved.

Sarcoidosis This is a disease of young adults, with cough, dyspnea, generalized lymphadenopathy, pulmonary and mediastinal involvement, and skin lesions. Splenomegaly is present in 25 percent.

No specific treatment is known. Spontaneous recovery is the rule. Splenectomy is indicated for splenomegaly with hypersplenism.

Gaucher's Disease This is a familial disorder. There is abnormal storage or retention of glycolipid cerebrosides in reticuloendothelial cells. Spleen, liver, and lymph node enlargement occur. Clinical manifestations include an abdominal mass (spleen or liver), yellow-brown pigmentation of the head and extremities, bone pain and pathologic fractures, and hypersplenism. Treatment is either splenectomy or partial splenectomy.

Erythropoietica Porphyria This is a congenital disorder of erythrocyte pyrrole metabolism resulting in excessive deposition of porphyrins in the tissues. Splenectomy is indicated for splenomegaly and hemolysis.

MISCELLANEOUS LESIONS

Ectopic Spleen This is a rare condition resulting from lengthening of ligaments and extreme mobility of the spleen. Acute torsion may occur, requiring surgery.

Cysts and Tumors These are rare. Parasitic cysts usually are echinococcal. Nonparasitic cysts are dermoid, epidermoid, epithelial, and pseudocysts (after trauma).

Primary and malignant tumors of the spleen are sarcomatous. Metastases in the absence of widespread disease are extremely rare.

Abscesses Clinical manifestations include fever, chills, splenomegaly, and left upper quadrant tenderness. Diagnosis is by CT scan or ultrasound. Splenectomy is the treatment of choice. Splenotomy and drainage have been successful in some patients. Fungal abscesses are found in patients on steroids and chemotherapy. Treatment includes antifungal drugs and splenectomy.

SPLENECTOMY

Technique The incision may be left subcostal or midline. Short gastric vessels are divided. Ligamentous attachments are divided for mobilization of the spleen. The splenic artery and vein in the hilus are divided, taking care to avoid injury to the tail of the pancreas. It is necessary to search for accessory spleens when performing splenectomy for hematologic disease. Drainage of the bed not performed routinely unless circumstances dictate. In the case of normal sized or slightly enlarged spleens, laparoscopic removal can be performed.

Postoperative Course and Complications Characteristic blood smear changes include (1) Howell-Jolly bodies and siderocytes and (2) leukocytosis and thrombocytosis. Complications include left lower lobe atelectasis, subphrenic hematoma and abscess, pancreatic fistula and pancreatitis, and thrombocytosis.

Overwhelming postsplenectomy infection (OPSI) is a rare occurrence and is seen more frequently after splenectomy for disease than that for trauma.

Immunologic defects include poor response to immunizations, deficiency in phagocytosis-promoting peptide, decreased serum immunoglobulin M (IgM), and decreased properdin. Most common organisms causing OPSI are Streptococcus pneumoniae and Haemophilus influenzae.

Pneumococcus vaccine and vaccine against H. influenzae should be given as prophylaxis; these are best given 10 days before elective splenectomy and preoperatively in anticipation of splenic trauma. Oral penicillin should be given until age 18. Splenectomy should be avoided or delayed, if possible, in pediatric patients.

For a more detailed discussion, see Schwartz SI: Spleen, chap. 31 in Principles of Surgery, 7th ed.

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Copyright © 1998 McGraw-Hill
Seymour I. Schwartz
Principles of Surgery Companion Handbook