Can the sonar accurately differentiate between a premature and a postmature fetus? an improved approach

ABSTRACT

When the last menstrual period is not known and the pregnant woman comes for examination in the last trimester, the sonologist faces the problem of dating that pregnancy. During that period the classic growth diameters [biparietal, femur, or abdominal diameters] can not accurately differentiate between a premature fetus and a post-mature one suffering from being small for dates. This study tried to find an answer for that problem. It included 120 pregnant women in the third trimester. The classic ultrasonic examination was done for each. In addition, three parameters [the distal femoral epiphysis [DFE], the proximal tibial epiphysis [PTE], and the grade of fetal intestinal maturity] were evaluated. It was found that when the DFE is more than 5 mm and the PTE is more than 4 mm with a grade 4 colonic maturity, that fetus is definitely not premature and his lung is mature with a corresponding L/S ratio more than 2. The accuracy of that combination gave a sensitivity and a specificity of 100% with no false positive or negative results. It was concluded that measurement of the distal femoral and proximal tibial epiphysis besides determination of the fetal colonic maturity are of value in estimating fetal lung maturity and could aid the decision of pregnancy termination if dating is not available. It should be routine measurements in fetal ultrasonic examination