Splenic Infarct As an Harbinger for Sickle Cell Traits in High Altitude

Background: Sickle cell trait (SCT) is a common genetic abnormality in the so called 'Sickle belts' in India. Splenic infarction often brings to medical attention an underlying SCT, when appropriately looked for. The hypoxic environment of high-altitude area (HAA) is conducive for developing a splenic infarct in an SCT individual. Soldiers get frequently exposed to extreme altitudes.

Aim & Objective: The objectives of the study were (a) To identify the incidence and etiology of splenic infarcts in HAA. (b) To identify the predisposing factors for splenic infarct with sickle cell trait from all patients managed at a tertiary care hospital at sea level.

Methodology: The study was done in two phases. Phase I of the study was conducted at an high altitude (HA) secondary care hospital. All patients admitted with splenic infarct (n-82) to this hospital over a period of 1.5y were evaluated for limited thrombophilia states (FVL mutation, PNH, Polycythemia, MTHFR mutation, JAK2 mutation) and sickle cell trait. Also, these patients were evaluated for portal vein thrombosis or concomitant thrombosis of any other sites. Phase II of the study was conducted at a tertiary care referral center of the armed forces, where all the patients with concomitant sickle cell trait and splenic infarct were evaluated for precipitating causes over a period of 04y (n-51).

Results: A total of 82 patients were admitted with splenic infarct to the HA secondary care hospital during the study period. The median age of the population was 28.4y (range: 23-42y) and all were males. They constituted 38.31% of all cases of thrombosis (214) admissions at HA in the given study period. They were second only to DVT (112, 52.33%) in the incidence of HA associated thrombosis, which were followed by CVT (16, 7.47%) and PTE (14, 6.54%) (Patients had variable combinations of DVT/ PTE/ CVT/ Splenic infarcts). Patients of splenic infarcts initially presented to surgeon in 85.3% instances (n-70) with pain abdomen (88%, n-72) or pleuritic pain (33%, n-27). Concurrent thrombosis at other sites were present in 33% (n-27) of the patients, of which 25.6% (n-21) had thrombosis of spleno-portal axis. High altitude illnesses were present in only 7.3% (n-6) of the patients. The mean duration to occurrence of the splenic infarct was 124.2 days (SD-31.8) after arrival to HA, but was less than 5.4 days (SD - 2.1) in patients with sickle cell trait (p<0.01). The etiology was mostly idiopathic (64.6%, n-53) followed by sickle cell trait in 24.4% (n-20) and other thrombophilia states in 10.9% (n-9) cases. Among the secondary causes, sickle cell trait was the commonest cause. Among the idiopathic cases few might have been secondary to protein C/ S or Antithrombin III deficiency which could not be evaluated during the acute phase. In patients with sickle cell trait, sickling at the time of splenic infarct at HA was seen in only 55% (n-11) though expected to be 100%. Family history was present in only 5% (n-1) of the patients with sickle cell trait of any sickling syndrome.

In phase II of the study, a total of 51 cases of sickle cell trait with splenic infarcts were admitted in the study period, who were evaluated. The median age of the study population was 29.6y (range: 21-48y). Of these, 82.4% (n-42) patients had developed the splenic infarct on exposure to HAA. Clinically splenomegaly was seen in 25.5% (n-13) patients with splenic infarct at presentation. The mean HbS was 37.34% in the SCT patients. A thrombus in the spleno-portal axis was demonstrated in 17.6% (n-9) of cases. The splenic rupture was a rare event, seen in only one patient. Splenectomy was done in only one patient due to non-resolving abscess. Of these patients 09 patients had sickle cell syndrome on exposure to severe exertion (n-8) / fever (n-1) at plains.

Conclusion: It is important to test for sickle cell trait in these otherwise healthy soldiers who develop splenic infarct at HA. The clinical importance of otherwise benign sickle cell trait in the form of splenic infarct by HA exposure or severe exertion is elucidated by this study.