ABSTRACT
In various stressful conditions, the thymus subjected to incidental involution, mostly due to the thymocytolytic effect of secreted glucocorticosteroids. The thymus gland play a key role in the body's defense against infection. this study aimed at assessing the variations of thymic size by ultrasonography in normal and diseased neonates with proven sepsis and to find whether there is a significant correlation between thymic index [Ti] and several variables. Study design: This cross-sectional, case-control study included 30 neonates with sepsis, 17 males and 13 females. Their mean gestational age was [38.93 +/- 1.91] weeks and their mean weight was [2.93 +/- 0.55] kg. Thirty cases of healthy neonates, 16 males and 14 females, their mean gestational age was [39.6 +/- 1.23] weeks and their mean weight was [3.25 +/- 0.55] kg., Served as controls. Every case underwent complete history taking and thorough physical examination with special emphasis on anthropometric measurements and a full evaluation for sepsis including complete blood count [CBC], C-reactive protein [CRP] and blood culture.Thymic sonography was done for every case to detect the thymic index [Ti] which indicates the size of thymus as a volume estimate. The results of this study showed a significantly lower value of Ti [P<0.001] and significantly higher level of CRP [P<0.001], in patients compared to controls. Also, the value of Ti was positively correlated with birth weight of healthy controls [P<0.05]. Ti showed positive predictive value of 87%, while that of CRP was 66%. A highly significantly increase was found, regarding Hb, platelet, immature neutrophils and I/T ratio, [p<0.001], and significantly increase as regards RBCs, [p<0.05], in patients compared to controls. While, no significant difference was found between the two groups as regard absolute neutrophils count [ANC] and total leucocytic count [TLC]. Also, there was no significant correlation between Ti and gestational age, body length, head circumference and different blood indices in both groups. We concluded that sonographic estimate of the thymus in infants less than one month of age seems to be an easy, reliable and safe diagnostic modality for assessment of thymic size. Thymic index could be considered as a sensitive predictor of neonatal sepsis and reflects the immune competence status of infants