In the tropics and subtropics, splenic surgery is undertaken not only for conditions found almost exclusively in the tropics, but also for most splenic conditions which are also found in temperate regions. Splenomegaly, parasitic disease, haemolytic processes, and trauma are common and occur in various combinations. This discussion is confined to those splenic conditions likely to present to the surgeon and which occur predominantly in the tropics.

A moderate degree of chronic splenomegaly is common in individuals in rural and less-developed tropical countries especially in malarious areas. Splenic enlargement affects from 10 to more than 50 per cent of the population in parts of Africa, south-east Asia, Melanesia, and the Pacific. Although there are regional variations in aetiology, malaria is the most common cause. Schistosomiasis and visceral leishmaniasis are common in some regions. Evaluation of the individual patient requires consideration of numerous possible diagnoses (Table 2) 650. Moderate splenomegaly per se is not a common reason for presentation to the surgeon in the tropics; however, trauma to the abnormal spleen and non-traumatic rupture occur most frequently.

Gross splenomegaly (including tropical splenomegaly syndrome, big spleen disease, or hyper-reactive malarial splenomegaly)

Splenic enlargement below the umbilicus and across the midline is certainly ‘gross’; some clinicians regard any enlargement more than 10 cm below the costal margin as gross splenomegaly. Such spleens often weigh more than 4 kg—30 times the mass of a normal spleen (Fig. 1) 2707. A weight of 1500 g is often used as the lower limit of gross splenomegaly.

Patients with gross splenomegaly most often present to surgical clinics complaining of a mass, abdominal discomfort, or a complication of their splenic disease. In a minority of these patients a specific aetiology for the splenomegaly will be found (Table 2) 650. In areas endemic for malaria, the majority will have the features of the tropical splenomegaly syndrome.

The aetiology, pathogenesis, and treatment of tropical splenomegaly syndrome are now being clarified principally by studies from Africa and Papua New Guinea. The syndrome is associated with an abnormal and perhaps inadequate immune response to chronic malaria in a genetically predisposed host. ‘Hyper-reactive malarial splenomegaly’ is perhaps a more accurate name for the condition. There is evidence to suggest that these patients have a genetic defect in their cell-mediated immune response to malarial infestation and consequently suffer persistent low-level parasitaemia, which they are unable to entirely eradicate. The low-level, but persistent parasitaemia may be a constant stimulus to the immune system causing an abnormal humoral response, with very high levels of polyclonal IgM and malaria-specific antibody. T-suppressor cell numbers are reduced. Circulating immune complexes are sequestered by splenic and hepatic phagocytes. Individuals and racial groups newly exposed to endemic malaria are especially at risk.

In a region where malaria is endemic, hyper-reactive malarial splenomegaly is the most likely cause of gross splenomegaly in children or young adults. Definite diagnosis depends on the exclusion of the other causes of splenic enlargement and demonstration of the features of the condition, especially high levels of IgM and specific antimalarial antibody in the absence of acute parasitaemia. Infectious and neoplastic causes of gross splenomegaly must be actively excluded.

Routine blood counts and examination of thick films for malaria parasites, needle biopsy of the liver, and endoscopy for oesophageal varices may be helpful.

Sudden death, presumably due to overwhelming malarial or bacterial infection, is the most common complication of untreated hyper-reactive malarial splenomegaly.

Untreated hyper-reactive splenomegaly has a high mortality, and although controlled trials of therapy have not been performed, long-term antimalarial medication (and reduced exposure to malaria infestation, where possible) is the current basis of treatment. Splenic size has been shown to diminish in about 70 per cent of patients after 1 year of treatment, with 25 per cent of spleens no longer palpable after this time. Very large, scarred spleens may remain palpable after several years of antimalarial therapy. The adverse features of hyper-reactive malarial splenomegaly diminish as splenomegaly decreases, but relapse if medication is ceased and exposure to malaria persists. Life-long antimalarial prophylaxis is indicated.

Immunosuppression has been used to treat patients in Africa and Vietnam; however the treatment is hazardous and the results uncertain.

In patients with uncomplicated hyper-reactive malarial splenomegaly, splenectomy seems to produce initial symptomatic improvement, with correction of anaemia, IgM levels, and hypersplenism, with an acceptable operative mortality. However subsequent mortality rates, apparently due to overwhelming sepsis or malaria, are very high. Although only small numbers of patients have been monitored over a long period, there appears to be a mortality rate of around 30 per cent in the first 12 months after splenectomy. In addition, splenectomy does not seem to alter the underlying immunological defect, and lifelong antimalarial medication is required to prevent relapse.

Splenectomy seems indicated in the minority of patients who do not respond to prolonged antimalarial medication and have persistent gross splenomegaly, hypersplenism, abdominal pain, or general debility. Specific complications such as splenic abscess, or suspected malignant change may also necessitate splenectomy. Splenectomy may also have a place in the management of portal hypertension and bleeding oesophageal varices due to hyper-reactive malarial splenomegaly. The pathogenesis of raised portal pressure in these patients is not entirely clear, but greatly increased splenic blood flow is certainly a major factor. Patients with hyper-reactive malarial splenomegaly usually do not have cirrhosis or portal fibrosis. The small number of dynamic studies of portal flow which have been performed in these patients have produced varying results, but no convincing evidence of significantly increased hepatic vascular resistance. This correlates with the usual histological finding of sinusoidal lymphocytosis, which would seem unlikely to produce increased hepatic resistance to portal blood flow. Splenic artery ligation or splenectomy to reduce excessive splenic venous flow, in conjunction with local obliteration of oesophageal varices has proven effective in treating patients with massive haematemesis associated with hyper-reactive malarial splenomegaly.

Perioperative antibiotics and antimalarials should be given and following splenectomy, patients require life-long supervision of antimalarial therapy and precautions against overwhelming sepsis. Their long-term management is fraught with major logistic and compliance problems in most tropical countries.

Blood transfusion should be available and good anaesthesia is essential. Autotransfusion may be appropriate.

Although various incisions are used for splenectomy, a long upper midline incision generally provides the best access, as the mobilized spleen swings into the midline after division of the lienorenal reflection. This allows good access to the splenic hilum and short gastric vessels. This incision also allows the splenic artery to be approached through the lesser sac and ligated at the upper border of the pancreas, if this seems advantageous. Most very large spleens can be mobilized by freeing the splenic flexure of the colon and division of the lienorenal reflection in the usual manner. Vascular adhesions between the diaphragm and the spleen are fortunately not common; when present they often constitute a major technical problem which requires good exposure of the left hemidiaphragm; this may be achieved by use of a substernal or costal margin retractor. In exceptional cases, a lateral extension of the midline incision or even left thoracotomy may be helpful. Some surgeons have found that a bilateral subcostal incision provides good access in difficult cases.

Once the spleen has been mobilized into the wound, the hilum can be controlled by digital pressure and individual vessels isolated and ligated. Closed suction drainage of the splenic bed should be used where technical or haematological factors indicate a risk of postoperative haemorrhage.

In the tropics, most ruptured spleens are abnormal; the majority are moderately enlarged by malaria, but most other causes of moderate splenomegaly can be associated with rupture.

Reliable studies are few and clinical impressions variable, but most clinicians agree that traumatic rupture of the spleen is common in the tropics, particularly in children and young adults whose spleens are moderately enlarged and friable due to malaria. Isolated rupture of the spleen may be more frequent in rural tropical communities where low-energy injuries are more common and the enlarged spleen more vulnerable. This contrasts with the high-energy injuries seen in developed countries where rupture of the normal well-protected spleen is more frequently associated with multiple visceral and musculoskeletal injuries.

The importance of preserving splenic function for both children and adults living in the tropics is now well recognized, just as it is in the Western world. Asplenic patients have a increased risk of overwhelming bacterial sepsis, especially due to pneumococcal or Gram-negative infection, as well as undue susceptibility to severe or fatal malaria. They may also be at increases risk of other protozoal infections and schistosomiasis. Sudden unexplained death months or years after splenectomy for trauma is not uncommon in the tropics.

The key to management of patients with traumatic rupture of the spleen in the tropics is preservation of the organ if at all possible. This is often possible without surgery, as the incidence of associated injury, persistent haemorrhage, or delayed complications requiring laparotomy is low. Adequate facilities for resuscitation, diagnosis, prolonged accurate observation, and timely surgical intervention are essential for the proper management of patients with ruptured spleen. These facilities are not always available in tropical regions.

Diagnosis is based on clinical findings and confirmation of haemoperitoneum by lavage if necessary, undertaken whilst vigorous resuscitation with intravenous fluids and antimalarials is under way. Ultrasound scanning or CT, if available, may have a role once the patient is stabilized. Laparoscopy can be performed under local anaesthetic and used rather than lavage to confirm haemoperitoneum. In addition, it may detect any persistent haemorrhage or associated intraperitoneal injury and allow the possibility of autotransfusion.

Continuing haemorrhage or associated injuries necessitate laparotomy in a minority of cases, but even in these patients, splenic preservation by repair or partial splenectomy should be successful in about 50 per cent of cases. The spleen of a patient suffering acute malaria may be enlarged, vascular, and friable, making suture repair technically difficult. Removal of devitalized spleen and application of haemostatic agents or omental flaps are nevertheless effective in many cases. Major injuries involving hilar vessels usually require splenectomy, as may the need for surgical expediency.

The early complications of non-operative management of ruptured spleen include failure to detect continuing splenic haemorrhage and associated injury requiring laparotomy. In the longer term, delayed rupture of a subcapsular haematoma or post-traumatic cysts may occasionally follow splenic preservation and should also be managed by conservative surgery, such as capsular repair, partial splenectomy, or unroofing and drainage of cysts, whenever possible.

Intraperitoneal implantation of splenic fragments does not seem to provide asplenic patients with protection from severe infection or malaria, and the procedure is no substitute for splenic preservation or appropriate lifetime prophylaxis.

Non-traumatic rupture of an entirely normal spleen arguably does not occur in the absence of a coagulopathy, and even the diseased spleen rarely ruptures spontaneously. Subcapsular haemorrhage in an acutely inflamed, enlarged, and congested spleen is probably the most common mechanism of pathological rupture. Trivial trauma may have been forgotten or disregarded.

Acute malaria is the most common cause of non-traumatic splenic rupture in the tropics. The incidence is highest during initial attacks of malaria, but even in this situation it is rare. The chronically enlarged spleen may undergo a degree of capsular fibrosis which protects it somewhat from rupture.

Infectious causes of spontaneous rupture such as salmonella, Epstein-Barr virus, and hepatitis virus probably occur more commonly in the tropics, while haematological and neoplastic causes have a similar incidence in tropical and temperate areas.

As with traumatic rupture, the spleen which undergoes ‘spontaneous’ rupture in the tropics should be preserved if at all possible.

In certain parts of Asia, Africa, and Papua New Guinea there is a condition of uncertain aetiology, known as ‘primary or idiopathic splenic abscess’. This condition is certainly not a true abscess, as the fluid obtained from these lesions is always sterile and may contain cholesterol crystals similar to those seen in the fluid from branchial cysts. The disease is uncommon and occurs mainly where malaria and sickle-cell anaemia coexist. It is less frequent in areas where malaria occurs without sickle-cell disease, such as Papua New Guinea. The condition is distinct from true pyogenic or fungal splenic abscess, from which organisms are cultured in almost all cases. Most pyogenic abscesses are associated with a distant site of infection and presumed haematogenous spread, while a minority follow splenic trauma or direct spread from an adjacent site. True splenic abscesses occur at a low incidence throughout the world, whereas sterile ‘abscesses’ closely linked to malaria and sickle-cell anaemia are more common in the tropics.

Sterile or tropical splenic abscess usually has the features of a liquefied splenic infarct and presumably follows occlusion of a segmental artery by aggregations of sickled erythrocytes, or thrombosis in acute malaria. The condition is rare and diagnosis requires an alert clinician. Protracted fever, left upper quadrant pain, and a mass should suggest the diagnosis. Erect chest and abdominal radiographs may show a raised left hemidiaphragm with a soft tissue mass and an air - fluid level due to gas in the abscess. Contrast radiography of the stomach or left kidney may show displacement of these organs, but ultrasound scan or CT, if available, are the most useful means of diagnosis. Radioactive isotope scanning and selective angiography have also been used.

Treatment requires resuscitation with antimalarial and usually antibiotic cover. Timely splenectomy to avoid rupture of the abscess has been advocated; however, drainage of the abscess with splenic preservation is now recognized as preferable in most cases. Drainage at laparotomy is usually the safest and most reliable technique; however, percutaneous and laparoscopic drainage should be considered for selected cases. A team approach by surgical and imaging personnel may be appropriate.

Elongation of the splenic pedicle and an increase in its mass predispose the organ to torsion and subsequent infarction. This rare condition occurs in multiparous women and in children. An elongated pedicle without torsion results in an ectopic or ‘wandering’ spleen. This is thought to be congenital and due to a persistent dorsal mesogastrium in children, but may be acquired in multiparous women.

Diagnosis of acute splenic torsion requires some clinical awareness, and is often made only at laparotomy. Splenectomy is indicated if the spleen remains non-viable after untwisting the pedicle, and may be necessary if the mobile organ cannot be safely fixed in the left upper quadrant. Splenic preservation has been achieved by plication of the elongated pedicle with splenic fixation to the abdominal wall or left hemidiaphragm.

All the well-known effects and risks of splenectomy such as haematological changes, injury to adjacent organs, haemorrhage, left lower lobe collapse, and subphrenic collection are encountered in the tropics. In addition, acute malaria is common immediately after splenectomy, especially when blood transfusion is used. Infestation of donated blood is common in endemic areas and the infective dose of parasites is small. The risk of acute and chronic malaria after splenectomy in patients with hyper-reactive malarial splenomegaly is probably increased by the genetic defect these patients have in their immune response to the parasite. A therapeutic course of an antimalarial such as chloroquine is indicated perioperatively in all patients undergoing splenectomy; prophylaxis is then necessary for life in malarious regions to reduce the risk of fatal malaria. Asplenic patients from malaria-free countries should be warned against travel to malarious areas even with appropriate chemoprophylaxis.

The incidence of overwhelming bacterial sepsis after splenectomy may be greater in the tropics than temperate zones, and the mortality rate also seems higher, perhaps due to delays and deficiencies in treatment. The relative incidence of the different causative organisms in the tropics is not known. Pneumococcal vaccines may offer partial protection, but are no substitute for preservation of at least a portion of normally perfused spleen whenever technically possible.

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