AMERICAN JOURNAL OF PERINATOLOGY/VOLUME 9, NUMBER 5/6
ULTRASONOGRAPHIC ASSESSMENT OF FETAL AND NEONATAL SPLEEN Showa Aoki, M.D., Toshiyuki Hata, M.D., Ph.D., and Manabu Kitao, M.D., Ph.D.
There have been only two reports on the growth of the fetal spleen measured by ultrasonography between 18 weeks, menstrual age, and term,1-2 and the number of observations reported in both studies has been rather small. In the first investigation,1 mathematical functions were not presented and the second investigation2 was a mixed study without descriptive statistics. The spleen is a reservoir of blood and a contractile organ. 34 Splenic contraction is caused by the adrenergic alpha-receptor stimulation induced by catecholamine released by exercise or stress.5 During delivery, the stress to the fetus has been reported to induce the elevation of catecholamine concentrations in umbilical cord plasma,6-7 and the level of catecholamines has been shown to be significantly lower in a cesarean section group than in a (spontaneous) vaginal delivery group.8 Therefore it is of interest to know the degree to which the fetal spleen can contract during delivery in the case of vaginal delivery and in the case of cesarean section. In an experimental study, Hibino5 reported that the spleen has the function of storing blood in a concentrated state and releasing it into the circulation with a chemical hemolytic substance, lysolecithin, during continuous stress caused by the injection of epinephrine to the dog's spleen. Therefore values of hematologic and biochemical laboratory findings of umbilical cord blood become an indirect
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To assess the growth and function of the fetal spleen, ultrasonographic examinations were performed on 229 normal fetuses, ranging from 20 to 41 weeks, menstrual age. Curvilinear relationships were found between the menstrual age and splenic length (R2 = 92.7%), circumference (R2 = 93.9%), and area (R2 = 95.2%). A normal range of splenic length, circumference, and area measurements for estimating the growth of the fetal spleen during normal pregnancy was generated. Splenic parameter values just after delivery were significantly lower than those measured within 7 days before delivery, and returned to former sizes 24 hours later, in both vaginal delivery and cesarean section groups. Splenic parameter values in the vaginal delivery group were also significantly lower than those in the cesarean section group, just after delivery. Moreover, neonatal splenic length showed negative correlations with lactate dehydrogenase (p