Splenic Infarction in Patients with Philadelphia-negative Myeloproliferative Neoplasms.

Objective We retrospectively analyzed the prevalence and clinical features of splenic infarctions in patients with Philadelphia chromosome-negative myeloproliferative neoplasms (Ph- MPNs). Patients Patients diagnosed with essential thrombocythemia (ET), polycythemia vera (PV), prefibrotic/early primary myelofibrosis (pre-PMF), or PMF from January 1996 to October 2020 in Chungnam National University Hospital, Daejeon, Korea, were reviewed. Results A total of 347 patients (143 ET, 129 PV, 44 pre-PMF, and 31 PMF patients; 201 men and 146 women) with a median age of 64 (range 15-91) years old were followed up for a median of 4.7 (range 0.1-26.5) years. Fifteen (4.3%) patients exhibited splenic infarctions at the diagnosis. These were most common in PMF patients (12.9%), followed by pre-PMF (9.1%) and PV (5.4%) patients. Multifocal infarcts (60.0%) were most common, followed by solitary (33.3%) and extensive infarcts (6.7%). The cumulative incidence of thrombosis in patients with splenic infarctions tended to be higher than in those lacking infarctions (10-year incidence 46.7% vs. 21.0% in PV; p=0.215; 33.3% vs. 17.9% in pre-PMF; p=0.473) patients, but statistical significance was lacking. Palpable splenomegaly (hazard ratio 14.89; 95% confidence interval 4.00-55.35; p<0.001) was the only independent risk factor for splenic infarction. During follow-up, 5 (1.4%) patients developed splenic infarctions. Conservative treatment adequately controlled the symptoms; no serious complications were noted in any patient. Conclusion Splenic infarctions occurred most frequently in patients with PMF; it was rare in patients with ET. The clinical courses were generally mild.

Risk assessment and prognostic analysis of patients with splenic infarction in emergency department: a multicenter retrospective study.

Splenic infarction is a thromboembolic disease that is frequently missed in acute settings. Previous reviews were rarely presented from a clinical perspective. We aimed to evaluate the clinical characteristics, risk factors with diagnostic value, and prognostic factors using large cohort data and a matched case-control study method. A retrospective medical record review of six hospitals in Taiwan from January 1, 2005, to August 31, 2020, was conducted. All patients who underwent contrast CT with confirmed the diagnosis of splenic infarction were included. Their characteristics were presented and compared to a matched control group with similar presenting characteristics. Prognostic factors were also analyzed. A total of 130 cases were included, two-thirds of whom presented with abdominal pain. Atrial fibrillation was the most common associated predisposing condition, followed by hematologic disease. A higher proportion of tachycardia, positive qSOFA score, history of hypertension or atrial fibrillation, leukocytosis, and thrombocytopenia were found in splenic infarction patients compared to their counterparts. An underlying etiology of infective endocarditis was associated with a higher proportion of ICU admission. Splenic infarction patients often presented with left upper abdominal pain and tachycardia. A history of hypertension, atrial fibrillation, a laboratory result of leukocytosis or thrombocytopenia may provide a clue for clinicians to include splenic infarction in the differential list. Among the patients diagnosed with splenic infarction, those with an underlying etiology of infectious endocarditis may be prone to deterioration or ICU admission.

Splenic infarction and infectious diseases in Korea.

BACKGROUND: The spleen contains immune cells and exhibits a pattern of infarction different from other organs; as such, splenic infarction (SI) may provide important clues to infection. However, the nature of the relationship between SI and infectious disease(s) is not well understood. Accordingly, this retrospective study investigated the relationship between SI and infection. METHODS: Hospital records of patients with SI, who visited Inha University Hospital (Incheon, Republic of Korea) between January 2008 and December 2018, were reviewed. Patient data regarding clinical presentation, causative pathogens, risk factors, and radiological findings were collected and analyzed. RESULTS: Of 353 patients with SI, 101 with infectious conditions were enrolled in this study, and their data were analyzed to identify associations between SI and infection. Ten patients were diagnosed with infective endocarditis (IE), and 26 exhibited bacteremia without IE. Twenty-seven patients experienced systemic infection due to miscellaneous causes (negative result on conventional automated blood culture), including the following intracellular organisms: parasites (malaria [n = 12], babesiosis [n = 1]); bacteria (scrub typhus [n = 5]); viruses (Epstein-Barr [n = 1], cytomegalovirus [n = 1]); and unidentified pathogen[s] (n = 7). Splenomegaly was more common among patients with miscellaneous systemic infection; infarction involving other organs was rare. Thirty-eight patients had localized infections (e.g., respiratory, intra-abdominal, or skin and soft tissue infection), and most (35 of 38) had other risk factors for SI. CONCLUSIONS: In this study, various infectious conditions were found to be associated with SI, and intracellular organisms were the most common causative pathogens. Further studies are needed to examine other possible etiologies and the underlying pathophysiological mechanisms.

Bevacizumab Does Not Influence the Efficacy of Partial Splenic Embolization in the Management of Chemotherapy-Induced Hypersplenism.

BACKGROUND: Antiangiogenics attenuate chemotherapy-related hepatotoxicity and portal hypertension. The potential impact of bevacizumab on the efficacy and safety of partial splenic embolization (PSE) in the management of chemotherapy-induced hypersplenism (CIH) has never been investigated. PATIENTS AND METHODS: We conducted a retrospective study with gastrointestinal cancer patients who have undergone PSE for the treatment of thrombocytopenia resulting from hypersplenism. Pre- and post-PSE platelet count (PC), the percentage of patients who resumed systemic therapy, and complication rates were compared between patients exposed and not exposed to bevacizumab. RESULTS: A total of 110 patients were eligible. Colorectal cancer was the predominant neoplasm (60%), and 5-fluorouracil, oxaliplatin, and bevacizumab were the most commonly provided drugs (70%, 65%, and 65% of patients, respectively). After PSE, 80% of patients recovered PC ≥ 100 × 109/L (100K). Systemic therapy was resumed in 81% of patients. Seventy-one patients exposed to bevacizumab had a median PC before PSE of 77.5K and after PSE of 167.0K, with a mean difference of 108K (P < .0001). Thirty-nine patients not exposed to bevacizumab had a median PC of pre-PSE of 73.0K and post-PSE of 187.0K, with a mean difference of 117.7K (P < .0001). Both groups had similar values of percentages of patients with PC post-PSE ≥ 100K (83% vs. 74%; P = .463), resumption of systemic therapy (85% vs. 74%; P = .213), and complication rates. A linear association between splenic infarction rate and increment in PC was found (P < .0001). CONCLUSION: PSE is a safe and effective procedure in the management of CIH, regardless of the provision of bevacizumab. Splenic infarction rate should be optimized to enhance patient outcomes.

Splenic Infarction in Plasmodium vivax Infection in South Korea.

Splenic infarction caused by malaria can be fatal, but its incidence and clinical presentation are not well-known. Thus, we investigated the prevalence and characteristics of splenic complications in patients with vivax malaria from 2005 to 2017 in a university hospital. Among 273 patients who were diagnosed with Plasmodium vivax infection by blood smear, 92 underwent abdominal computed tomography or ultrasonography. Twelve patients had splenic infarction. All patients with splenic infarction recovered after treatment with antimalarial drugs, without surgery and intervention. Although anemia and prolonged fever may be risk factors for splenic infarction, the incidence of these events was insufficient for a detailed analysis.

Association of Vegetation Size With Embolic Risk in Patients With Infective Endocarditis: A Systematic Review and Meta-analysis.

Importance: Infective endocarditis is a life-threating condition with annual mortality of as much as 40% and is associated with embolic events in as many as 80% of cases. These embolic events have notable prognostic implications and have been linked to increased length of stay in intensive care units and mortality. A vegetation size greater than 10 mm has often been suggested as an optimal cutoff to estimate the risk of embolism, but the evidence is based largely on small observational studies. Objective: To study the association of vegetation size greater than 10 mm with embolic events using meta-analytic techniques. Data Sources: A computerized literature search of all publications in the PubMed and EMBASE databases from inception to May 1, 2017, was performed with search terms including varying combinations of infective endocarditis, emboli, vegetation size, pulmonary infarct, stroke, splenic emboli, renal emboli, retinal emboli, and mesenteric emboli. This search was last assessed as being up to date on May 1, 2017. Study Selection: Observational studies or randomized clinical trials that evaluated the association of vegetation size greater than 10 mm with embolic events in adult patients with infective endocarditis were included. Conference abstracts and non-English language literature were excluded. The search was conducted by 2 independent reviewers blinded to the other's work. Data Extraction and Synthesis: Following PRISMA guidelines, the 2 reviewers independently extracted data; disputes were resolved with consensus or by a third investigator. Categorical dichotomous data were summarized across treatment arms using Mantel-Haenszel odds ratios (ORs) with 95% CIs. Heterogeneity of effects was evaluated using the Higgins I2 statistic. Results: The search yielded 21 unique studies published from 1983 to 2016 with a total of 6646 unique patients with infective endocarditis and 5116 vegetations with available dimensions. Patients with a vegetation size greater than 10 mm had increased odds of embolic events (OR, 2.28; 95% CI, 1.71-3.05; P < .001) and mortality (OR, 1.63; 95% CI, 1.13-2.35; P = .009) compared with those with a vegetation size less than 10 mm. Conclusions and Relevance: In this meta-analysis of 21 studies, patients with vegetation size greater than 10 mm had significantly increased odds of embolism and mortality. Understanding the risk of embolization will allow clinicians to adequately risk stratify patients and will also help facilitate discussions regarding surgery in patients with a vegetation size greater than 10 mm.

A single-center experience with the laparoscopic Warshaw technique in 122 consecutive patients.

BACKGROUND: Preservation of the spleen in distal pancreatectomy has recently attracted considerable attention. Our current study aimed in the first instance to define the safety of lap-WT in relation to the capacity of this technique to achieve preservation of the spleen and secondly to investigate the effectiveness of a planned lap-WT procedure or early conversion to lap-WT in selected patients with a large tumor attached to the splenic vessels. METHODS: Among 1056 patients who underwent a laparoscopic distal pancreatectomy between January 2005 and December 2014 at our hospital, 122 (24.6 %) underwent lap-WT which were analyzed. The 122 patients were categorized into two groups chronologically (early group: 2005-2012, late group: 2013-2014). RESULTS: The median follow-up was 35 months, and the median operation time was 181 min. The median postoperative hospital stay was 7 days, and the median estimated blood loss was 316 ml. Postoperative complications occurred in 9 patients (7.3 %), including 4 patients (3.2 %) with major pancreatic fistula (ISGPF grade B, C). A reoperation to address postoperative bleeding was needed in one patient. During a median follow-up of 35 months, there were no clinical significant splenic infarctions or gastric varices in any case. All patients were observed conservatively. In patients in the late group who underwent the lap-WT, the mean operating time (171 vs. 205 min, p = 0.001) and mean estimated blood loss (232.1 vs. 370.0 ml, p = 0.017) were significantly less than the early group cases who received lap-WT. CONCLUSIONS: A lap-WT is a safe treatment strategy in select cases when used as a way of preserving the spleen. When splenic vessel preservation is technically challenging, for example when the tumor is enlarged or is attached to the splenic vessels, planned lap-WT or early conversion to lap-WT may be a feasible option.

Acute Splenic Infarction at an Academic General Hospital Over 10 Years: Presentation, Etiology, and Outcome.

Few case series provide a current, comprehensive, and detailed description of splenic infarction (SI), an uncommon condition.Retrospective chart review complemented by imaging evaluation and patient follow-up.All adult patients with a confirmed diagnosis of acute SI discharged over 10 years from a single academic center were studied. A systematic literature review was done to compile a complete list of SI etiologies.SI was found in 32 patients, 0.016% of admissions. Ages ranged from 18 to 86 (median 64) years. Cardiogenic emboli were the predominant etiology (20/32, 62.5%) and atrial fibrillation was frequent. Other patients had autoimmune disease (12.5%), associated infection (12.5%), or hematological malignancy (6%). Nine of the patients (28%) had been previously healthy or with no recognized morbidity predisposing to SI. In 5 of 9 hitherto silent antiphospholipid syndrome or mitral valve disease had been identified. Two remained cryptogenic. Most patients presented with abdominal pain (84%), often felt in the left upper quadrant or epigastrium. Associated symptoms, leukocytosis or increased serum lactate dehydrogenase occurred inconsistently (∼25% each). Chest X-ray showed suggestive Lt. supra-diaphragmatic findings in 22%. Thus, the typical predisposing factors and/or clinical presentation should suggest SI to the clinician and be followed by early imaging by computed tomography (CT), highly useful also in atypical presentations. Complications were rare and patients were discharged after 6.5 days (median) on anticoagulant treatment. The systematic literature review revealed an extensive list of conditions underlying SI. In some, SI may be the first and presenting manifestation.SI is a rare event but should be considered in predisposed patients or those with any combination of suggestive clinical features, especially abdominal pain CT evaluation is diagnostic and the outcome is good.

A case of functional asplenia and pneumococcal sepsis.

Asplenia may refer to the spleen's surgical removal, functional impairment, or congenital absence. It is a risk factor for the development of severe bacterial infection. Functional asplenia is likely the most common presentation of this entity and has many etiologies. Those that are previously undiagnosed may present completely well until an episode of overt sepsis develops. The true incidence of mortality secondary to functional asplenia remains elusive. As lifetime mortality remains exceedingly high in the asplenic population regardless of etiology, markers of hyposplenism are important to detect. The present report describes an infant with trisomy 21 and previously undiagnosed functional asplenia who ultimately experienced overwhelming pneumococcal sepsis with features of Waterhouse-Friderichsen syndrome and died within 12 hours of initial presentation. It is a poignant reminder of what features to be cognizant of on peripheral blood smear in a previously well child, who may be at risk for a devastating consequence.

The significance of pseudoaneurysms in the nonoperative management of pediatric blunt splenic trauma.

PURPOSE: Nonoperative management is the standard of care for hemodynamically stable pediatric and adult blunt splenic injuries. In adults, most centers follow a well-defined protocol involving repeated imaging at 24 to 48 hours, with embolization of splenic pseudoaneurysms (SAPs). In children, the significance of radiologically detected SAP has yet to be clarified. METHODS: A systematic review of the medical literature was conducted to analyze the outcomes of documented posttraumatic SAP in the pediatric population. RESULTS: Sixteen articles, including 1 prospective study, 4 retrospective reviews, and 11 case reports were reviewed. Forty-five SAPs were reported. Ninety-six percent of children were reported as stable. Yet, 82% underwent splenectomy, splenorrhaphy, or embolization. The fear of delayed complications owing to SAP was often cited as the reason for intervention in otherwise stable children. Only one child with a documented pseudoaneurysm experienced a delayed splenic rupture while under observation. No deaths were reported. CONCLUSIONS: There is no evidence to support or dispute the routine use of follow-up imaging and embolization of posttraumatic SAP in the pediatric population. At present, the decision to treat SAP in stable children is at the discretion of the treating physician. A prospective study is needed to clarify this issue.

Clinical implications of sleeve gastrectomy as a source of spleen infarction or ischemia.

Splenic arterial demarcation has been observed during laparoscopic sleeve gastrectomy (LSG). The present study aims to detect its actual incidence during LSG and clarify its clinical significance. This is a prospective observational study of 287 consecutive patients that underwent LSG by the same surgical team over 3 years. In all patients, the gastric fundus was mobilized using a standard technique. Before withdrawal of the pneumoperitoneum, the spleen was exposed and carefully inspected for evidence of arterial demarcation. Patients with a clear demarcation were followed with Doppler ultrasound. Computed tomography scan with oral contrast was performed to rule out septic complications. Median preoperative body mass index was 46 kg/m(2) (range 35.1-78). Median operative time was 58 min (range 42-185), median hospital stay was 3 days (range 3-45), and overall morbidity rate was 8.6%. Intraoperative demarcation of the upper splenic pole was evident in 12 patients (4.1%). Eleven patients had uneventful postoperative course. One patient raised temperature of 38.5°C at the 7th postoperative day and was readmitted for further treatment. Once afebrile, the patient was discharged on the 10th postoperative day and continued on prophylactic low molecular weight heparin (tinzaparin, 7,500 U sc.) for 20 days. Splenic discoloration following LSG is an uncommon complication with minimal clinical significance, which could be related to hematoma, venous congestion, or ischemia. The possibility of a late splenic abscess cannot be ruled out. No risk factors can be identified preoperatively.

Splenic syndrome: a rare indication for splenectomy.

Splenic infarction due to sickle cell trait and high-altitude stress has been reported in the literature. Contributing factors leading to infarction are degree of altitude stress and status of physical condition. Medical therapy, which consists of evacuation from high altitude, intravenous fluids, supplemental oxygen, and pain control, has been the mainstay of treatment. However, some patients require surgical intervention. We describe six patients with sickle cell trait who sustained splenic infarctions due to high-altitude stress; two of these patients required splenectomy for near-total splenic necrosis and intractable pain. A review of the literature demonstrates that the common indications for splenectomy are splenic rupture, extensive splenic necrosis, or persistent abdominal pain.

[Vascular complications of infective endocarditis: a retrospective analysis of 18 cases]. / Les complications vasculaires de l'endocardite infectieuse.

OBJECTIVES: Among 82 patients hospitalized for infective endocarditis between June 1995 and June 2001 at the cardiology B unit of the Rabat University Hospital Morocco, 18 (22%) had one or more vascular complications. We present here a retrospective analysis. PATIENTS AND METHODS: The cohort included 12 men and 6 women, mean age 22 years. Infective endocarditis had grafted on a pre-existing cardiopathy among 17 patients: rheumatic heart disease (n=14), mechanical prosthetic valve (n=2), congenital heart disease (n=1). RESULTS: For 12 patients, vascular disease was the only complication, 1 had two complications and 4 three complications. This gave 26 lesions: 11 neurological complications, 10 arterial diseases involving the limbs including 5 mycotic aneurysms, 2 acute myocardial infarcts, 2 splenic infarcts, and 1 recurrent septic pulmonary embolism. Vascular disease was the inaugural manifestation in 9 patients and 54% of the complications occurred before the end of the second week of antibiotic treatment. Blood cultures were positive in 7 patients (40%). Oral streptococcus was isolated in 5 cases, Gram-negative bacillus in 1 case and Staphylococcus aureus in 1. Echography revealed valvular vegetations in the 16 cases of infective endocarditis on native valves: mitral (n=9), aortic (n=5), mitroaortic (n=1), tricuspid (n=1). Short term outcome was marked by 4 deaths including 3 directly related to the vascular complication. DISCUSSION: We emphasize the variable and diverse features of vascular complications of infective endocarditis. Prevention and early diagnosis are essential to institute optimal management of infective endocarditis.

Wandering spleen presenting as a right hypochondrial mass and intestinal obstruction.

This is a case report of a 23 year old multiparous woman who presented with intestinal obstruction and a right hypochondrial mass. Laparatomy revealed an infarcted 1.4 Kg spleen in the right lumbar region compressing the ascending colon. There was also ileal volvulus around the splenic pedicle. This is probably the first documented case of wandering spleen in the right hypochondrium, presenting as right large bowel obstruction, to be reported in our region. Wandering spleen is a rare condition, often asymptomatic, but may present as an acute abdomen. Pre-operative diagnosis is difficult and rarely made. Laboratory tests are seldom useful, but imaging studies do assist. Up to 1971 only 350 cases had been reported in the western literature. Review of English literature from 1900 to 1991 reported only 51 cases in children. In our region 11 cases were reported in Uganda between 1968 and 1971. No other literature is available from our region. Clinical presentation, aetiology, investigation, and management of wandering spleen is discussed.

Complications of laparoscopic adrenalectomy: results of 169 consecutive procedures.

Laparoscopic adrenalectomy (LA) has become the gold standard for adrenalectomy. Review of the literature indicates that the rate of intra- and postoperative complications is not negligible. The aim of this study was to evaluate the complications observed in a series of 169 consecutive LAs performed at a same center for a variety of endocrine disorders. Between June 1994 and December 1998 a series of 169 LAs were performed in 159 patients: 149 unilateral LAs and 10 bilateral LAs. There were 98 women and 61 men with a mean age of 49. 7 years (range 22-76 years). There were patients with 61 Conn syndrome, 41 with Cushing syndrome, 1 androgen-producing tumor, 29 pheochromocytomas, and 37 nonfunctioning tumors. Mean tumor size was 32 mm (range 7-110 mm). LA was performed by a transperitoneal flank approach in the lateral decubitus position. Mean operating time was 129 minutes (range 48-300 minutes) for unilateral LA and 228 minutes (range 175-275 minutes) for bilateral LA. There was no mortality. Twelve patients had a significant complication (7.5%): three peritoneal hematomas requiring (in two cases) laparotomy and (in one case) transfusion; one parietal hematoma; three intraoperative bleeding episodes without need for transfusion; one partial infarction of the spleen; one pneumothorax; one capsular effraction of the tumor; and two deep venous thromboses. Eight tumors were malignant at final histology (4.7%), of which four were completely removed laparoscopically. Conversion to open surgery was required in eight cases (5%): for malignancy in four cases, difficulty of dissection in three cases, and pneumothorax in one case. With a mean follow-up of 26.58 months (range 6-60 months) all patients are disease-free. We conclude that LA is a safe procedure. With increasing experience the morbidity becomes minor. To avoid complications LA should be converted to open surgery if local invasion is suspected or if there is difficulty with the dissection.

Management of the wandering spleen.

A case of torsion of a wandering spleen in an 8 year old girl is reported. The authors discuss the aetiology and management of this rare condition and review the literature. Wandering spleen is relatively more common in children than in adults. Under the age of 10 the sex distribution is even; over 10, females outnumber males by seven to one. In 66 children under 10 years, 50% of wandering spleens were lost through acute ischaemia. The authors recommend that early splenopexy replace conservative management.

Splenic septic emboli in endocarditis.

The significance of septic emboli to the spleen is inferred by the frequency of septic emboli in general seen in patients with left-sided infective endocarditis who are referred for valve replacement. To determine the proper management of splenic infarcts and abscess due to septic emboli, we retrospectively reviewed the records of 108 patients with left-sided endocarditis who underwent valvular surgery at the University of Illinois Hospital from 1980 through 1988. Intravenous drug abuse was the etiology in 68% (n = 73). The incidence of splenic infarcts and abscess was 19% (n = 20), but an incidental finding of splenic infarcts was found in 38% (n = 11) of 29 asymptomatic patients who had computed tomograms. Streptococci and staphylococci were the causative organisms in 85% (n = 17). Localized findings were absent in 90% of splenic infarcts and abscesses. Abdominal computed tomograms were diagnostic of the sequelae of splenic septic emboli in 100%. No patient had intra-abdominal bleeding complications associated with cardiopulmonary bypass. Splenectomy was performed in 50% (n = 10) of patients 3-24 days (mean, 11.2 days) after valve replacement. Indications for splenectomy included persistent sepsis in 60% (n = 6), large (greater than 2 cm) and peripheral lesions in 30% (n = 3), and splenic rupture in 10% (n = 1). Perioperative mortality of patients who underwent splenectomy was 30% (n = 3). The following conclusions can be drawn: 1) Splenic septic embolus is common in endocarditis. 2) Abdominal computed tomography should be performed for all patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Splenic infarction complicating pediatric liver transplantation: incidence and CT appearance.

In children it is often necessary to ligate the splenic artery and the main collateral supply to the spleen during liver transplantation. The complication of splenic infarction has been observed on postoperative CT in such patients. The purpose of our study was to determine the incidence and CT appearance of splenic infarction and to correlate its occurrence with a vascular cause related to the operative procedure. During a 2 year period, 26 of 94 (28%) children receiving liver transplants developed splenic infarction as shown by CT. Infarction generally occurred within 2 weeks of transplantation. Computed tomography demonstrated variable portions of splenic involvement with hypodense lesions. Twenty-two of 39 (56%) patients whose splenic artery was ligated developed splenic infarctions. Only 4 of 55 (7%) patients whose splenic artery was left intact had splenic infarctions on postoperative CT. We conclude that there is an increased incidence of splenic infarction in pediatric liver transplant recipients. The incidence of infarction is related to ligation of the splenic artery and collateral pathways.

Sickle cell trait revisited.

Variability in the clinical severity of sickle cell diseases is often genetically determined. Coexistent alpha-thalassemia decreases some, but not all, associated morbid complications. Polymorphisms within the beta-globin-like gene cluster influence disease severity by varying gamma-gene expression and the amount of Hb F within the cells. Few persons with the sickle cell trait experience adverse consequences attributable to the beta s gene. Is this also due to genetic factors? A literature search failed to answer this question. It is intriguing, however, that reported associations of sickle cell trait and splenic infarction have occurred exclusively in males and mostly in whites. Plausible but scanty data suggest that splenic infarction, hematuria, and reduced renal concentrating ability may be associated with higher amounts of Hb S. Therefore, alpha-thalassemia may be protective. No evidence was found that the amount of Hb S influenced the incidence of sudden death after exertion or that increased amounts of Hb F accounted for protection against any complications. More detailed reporting of biochemical and genetic evaluations of persons with sickle cell trait who experience related clinical events may lead to a better understanding of risks in subpopulations of persons carrying a single beta s gene.