One of the most frequent concerns of the researches is sample size calculation. There are many equations to calculate sample size one should be selected correctly based on the type of the study and data type. Any mistake can mislead the researcher and so the study results. Even an overestimation can cause waste of cost, time and material. Either statisticians or other researchers frequently use online advice on sample size calculation. Online sample size calculators have been searched, reviewed and checked for the calculated results based on known formulas for common research objectives. Considering the most common types of health study objectives regarding sample size calculation (estimating proportion or mean, comparison of two proportions or two means), from 60 website or software, only 5(8.3%) provided all four types of calculations. Overall exact calculation rate was 8.3% and 16.1% per calculation and per site, respectively. Many of the sites just calculate sample size for estimating proportions and most of the results lack the accuracy in calculation.

Background: Tetralogy of Fallot (TOF) is considered as the most frequent cyanotic congenital heart disorder. Right ventricular (RV) dysfunction is possible to be observed in patients with repaired TOF. Delayed enhancement (DE) is one of the recommended findings for RV dysfunction. Objectives: This study aimed at investigating the DE and its probable relationship with RV function through cardiac magnetic resonance (CMR). Patients and Methods:In this cross-sectional study, the values of cardiovascular magnetic resonance of 110 symptomatic patients, who had repaired TOF for 35 years, were gathered. We compared cardiac function indices (CFI) in patients with and without DE. Results:The patients had an average age of 21.93 ± 6.94 years (59.12% were male and 40.94% were female). 93.66% of the subjects showed DE and 6.44% of them did not have DE. 78.61% of the samples had DE of the right ventricular outflow tract (RVOT); whereas, 21.39% showed DE of the other sites. The differences between mean regurgitation fraction, average RV end-diastolic volume (RVEDV), average RV end systolic volume (ESV), and average RV ejection fraction in DE positive and negative patients were statistically significant (P values = 0.01, 0.04, 0.04, and 0.01, respectively.) Conclusion: DE commonly occurs as a complication of surgery to repair TOF and could be used as a factor for impaired RV function and other complications. Using CMR imaging for follow up of these patients could lead to diagnosis of these complications.

BACKGROUND Pancreatitis is an inflammation of the pancreatic tissue. Gallstones are known to be the most common cause of acute pancreatitis, especially in eastern countries, including Iran. Pancreatitis, in its course, can cause complications for the patient. Different systems have been identified as predictors of the severity of acute pancreatitis. As a result, we decided to examine the factors influencing the severity of biliary pancreatitis and their relationship with the complications in Iranian society. METHODS The present study is a cross-sectional, analytical study that was performed retrospectively on 160 patients with biliary pancreatitis. The main and dependent variable in this study is the severity of pancreatitis, which is divided into two groups of complications (local complications and systemic complications) and without complications. The necessary information was extracted from the patients' files and evaluated with SPSS software version 22. RESULTS Based on the results of single-variable analysis, there was a significant relationship between the patient's age, sex, Ranson and CRP criteria, and complication of the disease. In the univariate analysis, no significant statistical relationship was found between patients' BMI(Body Mass Index), CBD (common bile duct) size, serum alkaline phosphatase level, gallstone size, and FBS(Fasting blood sugar), and the complications of the disease, based on the multivariate analysis results. CONCLUSION The results of this study showed that four variables of the female sex, stone size, CRP, and high score of Ranson criteria act as independent risk factors in the development of complicating biliary pancreatitis.

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is now a global threat. Various papers have addressed the pulmonary symptoms of this viral disease. Also, thrombotic complications have been highly prevalent among COVID-19 patients. Reports on rare presentations of COVID-19 can help fast diagnosis and management. In this study, a COVID-19 patient is presented who developed mesenteric ischemia.