P1130047

1.3.3.3.2 Ribs, trunk and stornach

In order to determine the increase in the size of the transverse sections through the ribs, one must obtain a horizontal sonographic piane through the chest thereby making it will be pośsible to count the number of ribs and intercostal spaces per unit length (Fig. 1.93). In order to reduce the errors in measurements to a minimum, several ribs and their intercostal spaces (3 to 5) should be used for this assessment. The distance be-tween the edges on the same side of the cross sections of two distant ribs is determined. When this distance is di-vided by the number of rib cross sections included, the result will be the length of one rib cross section with its adjoining intercostal space.

The size of the stornach can be measured by orien-tating the ultrasound probe to show the image with the greatcst length of the stornach. Now the largest inner diameter óf the hypoechoic lumen of the słoniach can be measured.

The largest diameter of the trunk is determmcd at the level of the stornach and liver. The direct distance between the opposing body walls on a sonographic piane that is vertically oriented to the trunk is measured (Fig. 1.94). On average, the diameter of the trunk grows from 25 mm on Day 60 to 80 to 100 mm on about Day 150 (Fig. 1.91). During the Month 6 the size of the trunk exceeds the penetration depth of the ultrasound probe and can no longer be used for fetometrical pur-poses. Until the 5th month of gestation there is normal-ly vety little variation in the trunk diameter of different fetuses, making this a reliable parameter for the assess-ment of fetal development.