The spleen

THE SPLEEN

It develops from condensation of mesoderm in the dorsal mesogasrium. Its weight in the normal adult is 75- 250 g and is about (12 X 7 X 4 cm) in size. It is one of the most vascular organs in the body. Approximately 350 L of blood pass through the adult spleen each day. It filters an estimated 10% to 15% of total blood volume every minute. It lies in the left hypochondrium, with its long axis lying along the 10th rib. Its concave visceral surface lies in contact with the stomach, tail of pancreas & the left kidney.
Anatomy :
Relation :
Anteriorly : Stomach, tail of pancreas, left colic flexure. Posteriorly : Diaphragm, left lung & pleura, 9th, 10th, & 11th ribs (fracture of any of these ribs may be associated with splenic laceration causing severe haemorrhage). Inferiorly : Left colic flexure. Medially : left kidney
Blood supply : Splenic artery which is the largest branch of celiac trunk. It is tortuous, runs along the upper border of the pancreas. It divides up into 6 branches, which enter the spleen at the hilus. Splenic vein leaves the hilus, runs behind the tail & body of pancreas. It joins superior mesenteric vein behind the neck of pancreas to form portal vein.
Lymphatic drainage : Celiac lymph nods
Nerve supply : From celiac plexus
Splenic functions :
1-Immune function : The spleen is the major site of IgM production. It synthesized opsonins, properdin ,& ruftsin that stimulate the phagocytic, bactericidal, & tumoricidal activity of the macrophages & leucocytes.
2- Filter function : The endothelial macrophages in the sinuses & the splenic cords capture cellular (effete platelets &RBC) & non- cellular material (bacteria , in particular pneumococci) from the blood & plasma. Also iron is removed from the degraded haemoglobin & is returned to the plasma.
3- Pitting : Removal of inclusions from red cells & return of the repaired red cells to the circulation. These include Howell-jolly & Heinz bodies.
4- Cytopoiesis : From the 4th month of intrauterine life, some degree of haemopoiesis occurs in fetal spleen. Proliferation of macrophages, T& B cells following antigenic challenge.

Investigations of the spleen :

Full blood count. Specially in blood diseases associated with splenomegaly (in some cases bone marrow aspiration cytology may be needed)
Lymph node biopsy. When splenomegaly associated with lymphadenopathy.
Radiological imaging:
Plain radiology is rarely used in investigation. The incidental finding of calcification of the splenic artery or spleen may raise the possible diagnosis of a splenic artery aneurysm, an old infarct, a benign cyst or hydatid disease. Multiple areas of calcification may suggest splenic tuberculosis.
Abdominal ultrasonography
Contrast - enhanced CT scan
MRI
Radioisotope scanning (occasionally). The use of technetium-99m (99mTc)-labelled colloid is useful in determining whether the spleen is a significant site of destruction of red blood cells.
Congenital abnormalities of the spleen:
Splenic agenesis : Is rare, presents in 10% of children with congenital heart disease.
Polysplenia : Is rare.
Spleneculi : Single or multiple accessory spleens, found in 10-30% of population. They are located near the hilum of the spleeen (50%), related to splenic vessels or behind the tail of pancreas (30%). The remainder (20%) are located in the mesocolon or splenic ligaments. Their significance lies in the fact that failure to identify and remove these at the time of splenectomy may give rise to persistent disease.
Hamartomas are rare.
Non-parasitic splenic cysts are rare.
True cysts include dermoid and mesenchymal inclusion cysts. These are lined by flattened epithelium and should be differentiated from False cysts.
False cysts that may result from trauma and contain serous or haemorrhagic fluid.
Pseudocyst may follow a severe attack of pancreatitis . Intervention is required for symptomatic lesions that persist following a period of observation.
Splenic artery aneurysm :
It is twice as common in female, usually situated in the main trunk, generally single, but more than one aneurysm is found in a quarter of cases. it may be a consequence of intra-abdominal sepsis & pancreatic necrosis, & in elderly patients it is associated with arteriosclerosis. It is symptomless unless it ruptures & is more likely to be detected on a plain abdominal radiograph or scan. It is unlikely to be palpable, although a bruit may be present. Symptoms of rupture usually mimic those of splenic rupture, & a quarter of cases occure in pregnant women usually in third trimester or at labour. Treatment: Embolization, endovascular stenting , partial or complete splenectomy. Elderly patient with a calcified aneurysm, needs observation as there is less risk of rupture. In patients with pancreatic necrosis, the treatment includes drainage of septic focus.
Splenic infarction :
It occurs in patients with a massively enlarged spleen from myeloproliferative syndrome, portal hypertension, or vascular occlusion produced by pancreatic disease, splenic vein thrombosis or sickle cell disease. It is usually a symptomatic or give rise to left upper quadrant & left shoulder tip pain. A contrast-enhanced CT scan shows the perfusion defect in the enlarged spleen. Treatment: Conservative, splenectomy is needed when septic infarct causes an abscess.
Splenic abscess :
In general surgical practice it may be associated with pancreatic necrosis or other intra-abdominal infection. It may arise from an infected splenic emboli or in association with typhoid & paratyphoid fever, osteomyelitis, otitis media, & puerperal sepsis. It may rupture & form left subphrenic abscess or result in peritonitis. Treatment : Treatment of the underlying cause & percutaneous drainage under US guidance.
Splenic injury (rupture):
A ruptured spleen is a serious condition it may cause a life-threatening bleeding. It is more common in children than adults. Although the spleen is protected by the bony ribcage, it remains the most commonly affected organ in blunt abdominal injury (caused by a direct blow to the belly, car and motorcycle accidents, falls, sports accidents, and fights). Spleen may be injured by stab wound, high velocity missiles like bullets, shells & shell fragments. An enlarged spleen may be injured by violent coughing or (this type of rupture is known as an atraumatic rupture) or even may be ruptured by a doctor or during palpation of the patient's abdomen by medical student. The spleen may be damaged by a surgeon in the course of an operation on other abdominal organs. The tears range from small ones that stop bleeding spontaneously to very large ones that cause potentially fatal hemorrhage.
The clinical presentation is highly variable. Most patients with minor focal injury to the spleen complain of left upper quadrant abdominal pain & tenderness. Left shoulder pain (Kehr’s sign) may also be present as a result of sub-diaphragmatic nerve root irritation by the blood with referred pain. Fractured ribs may be present. With free intra-peritoneal blood, diffuse abdominal pain, peritoneal irritation, and rebound tenderness with features of shock include tachycardia, tachypnea, restlessness, anxiety, thirst, pale or clammy skin, weak pulse, low blood pressure, dizziness, fainting, & sweating.
In a critical situation, a physical exam may be the only diagnostic test before emergency surgery. In other cases diagnostic peritoneal lavage (DPL) may be needed & if time allows, in the stable trauma patient, CT scanning provides the most ideal noninvasive means for evaluating the spleen. However, hypotension or unstable vital signs are a contraindication to CT scanning, because death may occur in the radiology suite.
Treatment:
Non-operative treatment: The recognition that splenectomy renders patients susceptible to lifelong risks of septic complications has led to routine attempts at splenic conservation after trauma. Most isolated splenic injuries, especially in children are treated nonoperatively, patients are monitored closely, often in intensive care units for several days with intravenous fluid and possible blood transfusions. Follow-up scans may be used to observe the healing process.
Selective angioembolisation: In certain situations selective angioembolisation of the spleen can play a role.
Operative treatment: Splenic trauma patients require surgery when non-operative treatment fails, when major or prolonged internal bleeding exists and for gunshot and many stab wounds, when associated with other organs injury, physiological instability, & coagulopathies. Laparotomy with splenorrhaphy, packing, using a mesh bag, partial or total splenectomy. In patients who are stable, every effort should be made to preserve part or all of the splenic tissue. In all patients who are unstable, a total splenectomy should be performed.
Splenomegaly :
Is a common feature of many diseases. Splenectomy may be required in few cases like, hereditary spherocytosis, idiopathic thrombocytopenic purpura (ITP), autoimmune haemolytic anaemia, thalassaemia, sickle cell disease, Hodgkins lymphoma, segmental portal hypertension that resulted in symptomatic oesophagogastric varices, & tropical splenomegaly (with massive splenomegally caused by malaria, schistosomiasis, kala-aza, & malnutrition).
Splenic neoplasm :
Benign : Haemangioma which may rarely develop into a haemangiosarcoma that is managed by splenectomy.
Malignant : Lymphoma, which is the most common cause of neoplastic enlargement. Splenectomy may play a part in its management. Splenectomy may be required to achieve a diagnosis in the absence of palpable lymph nodes or to relieve symptoms of gross splenomegally.


Splenectomy :
Indications for splenectomy :
Trauma :

Accidental

Operative :During surgical procedure
Oncological :

Part of en bloc resection eg. Radical gastrectomy in gastric carcinoma ,total pancreatectomy in pancreatic cancer.
Diagnostic
Therapeutic : Splenic neoplasm.

Haematological :

Haemolytic anaemia : Includes : hereditary spherocytosis , acquired autoimmune haemolytic anaemia, thalassaemia (Cooley’s anaemia, Mediterranean anaemia), sickle cell disease,
Idiopathic thrombocytopenic purpura (ITP)
Hypersplenism : Characterised by splenic enlargement & any combination of anaemia, leucopenia, or thrombocytopenia.

Hereditary spherocytosis: It is an autosomal dominant hereditary disorder, characterised by the spherocytic red cells with increased fragility of the membrane with increased permeability to sodium. Presentation is usually in childhood but may be delayed until later life with mild intermittent jaundice, mild anaemia, splenomegally, & gallstones. Severe crisis of RBC destruction may occur (precipitated by acute infection) with pyrexia, abdominal pain, nausea, vomiting & extreme pallor with increased jaundice. In adult chronic leg ulcer may occur.
Investigations : 1-Fragility test: Haemolysis occures in 0.6% saline solution or even stronger. 2 – Increased reticulocyte (immature RBC) count 3- Increased faecal urobilinogen 4 –Daily scanning over the spleen shows increased RBC sequestration by the spleen. 5- Abdominal ultrasonography should be performed preoperatively to determine the presence or absence of gallstones. All patients should be treated by splenectomy. In juvenile cases splenectomy should be delayed until 6 years of age to minimise the risk of post splenectomy infection, but before gallstones have had time to form.

Portal hypertension : Shunt or variceal surgery.

Preoperative preparation
In the presence of a bleeding tendency, transfusion of blood, fresh-frozen plasma, cryoprecipitate or platelets may be required. Coagulation profiles should be as near normal as possible at operation, and platelets should be available for patients with thrombocytopenia at operation and in the early postoperative period. Antibiotic prophylaxis appropriate to the operative procedure should be given, and consideration should be given to the risk of post-splenectomy sepsis

Postsplenectomy complications :

Haemorrhage from slipped ligature.
Haematemesis from gastric mucosal damage
Left basal atelectasis
Pleural effusion
Gastric fistula from damage to greater curvature of stomach
Pancreatitis, localised abscess, or pancreatic fistula from damage to the tail of pancreas.
The blood platelet count may rise and, if this exceeds 1 × 106ml–1, prophylactic aspirin is recommended to prevent axillary or other venous thrombosis.
Post-splenectomy septicaemia may result from Streptococcus
Post-splenectomy septicaemia: May result from Streptococcus pneumoniae, Neisseria meningetides, Haemophilus influenzae, & Escherichia coli.
Opportunist post-splenectomy infection (OPSI): Most infections after splenectomy could be avoided through measures that include offering patients appropriate & timely immunization, antibiotic prophylaxis, education & prompt treatment of infection.

Children who have undergone splenectomy before the age of 5 years should be treated with a daily dose of penicillin until the age of 10 years.

Prophylaxis in older children should be continued at least until the age of 16 years, but its use is less well defined in adults. As the risk of overwhelming sepsis is greatest within the first 2-3 years after splenectomy, it seems reasonable to give prophylaxis (oral penicillin, erythromycin, or amoxicillin) during this time.

Suspected infection can be treated intravenously with penicillin, cefotaxime, or chloramphenicol in patients allergic to penicillin & cephalosporins.


In elective splenectomy vaccination against pneumococcuc, meningococcus (repeated every 5 years), & haemophilus influenzae (repeated every 10 years) & yearly influenza vaccination. Such vaccinations should be given 2 weaks before surgery & as soon as possible after recovery but before discharge from the hospital.

In the trauma victim, vaccination can be given in the postoperative period, and the resulting antibody levels will be protective in the majority of cases.

Diagnostic peritoneal lavage

Diagnostic peritoneal lavage (DPL) is a test used to assess the
presence of blood in the abdomen. A gastric tube is placed to
empty the stomach and a urinary catheter is inserted to drain the
bladder.
A cannula is inserted below the umbilicus, directed caudally
and posteriorly. The cannula is aspirated for blood (> 10 ml is
deemed as positive) and, following this, 1000 ml of warmed
Ringer’s lactate solution is allowed to run into the abdomen and
is then drained out. The presence of > 100 000 red cells μl–1 or
> 500 white cells μl–1 is deemed positive (this is equivalent to
20 ml of free blood in the abdominal cavity). Drainage of lavage
fluid via a chest drain indicates penetration of the diaphragm.
Although DPL has largely been replaced by focused abdominal
sonar for trauma (FAST; see below), it remains the standard
in many institutions where FAST is not available or is
unreliable. DPL is especially useful in the hypotensive, unstable
patient with multiple injuries as a means of excluding intraabdominal
bleeding.
DPL has a 97–98% sensitivity rate for blood and a 1% complication
rate.


Focused abdominal sonar for trauma
FAST is a technique whereby ultrasound imaging is used to assess
the torso for the presence of blood, either in the abdominal
cavity or in the pericardium. The purpose of the ultrasound evaluation
of the injured casualty is to determine the presence of free
intra-abdominal or pericardial fluid.