Roberts A B, Mitchell J M, McCowan L M, Barker S
Department of Obstetrics and Gynaecology, National Women's Hospital, Auckland, New Zealand.
Am J Obstet Gynecol. 1999 Mar;180(3 Pt 1):634-8. doi: 10.1016/s0002-9378(99)70266-8.
Our purpose was to measure fetal liver size in small-for-gestational-age fetuses diagnosed by ultrasonography and to determine whether the small abdominal circumference used to diagnose small for gestational age is the result of a small liver.
Ninety-eight pregnant women who were diagnosed as having a fetus that was small for gestational age were included. All had a fetal ultrasonographic measurement of abdominal circumference <10th percentile for gestational age. Measurements were made of the length of the right lobe of the fetal liver within 2 weeks of delivery. The liver length measurements were compared with data collected from a normal population that had been previously published by the authors. The group of fetuses with liver length measurements <10th percentile for gestational age were compared with those with liver length measurements within normal limits.
Liver length measurements were >10th percentile in 80 fetuses (82%). Eighteen fetuses (18%) had small liver lengths, and this group had significantly smaller antenatal ultrasonographic measurements of head, abdomen, and femur. They were smaller at birth with smaller placentas and they had a higher perinatal mortality rate.
The small abdominal circumference measurement that is the mainstay of ultrasonographic diagnosis of small for gestational age is thought to be a reflection of fetal liver size. This study questions that assumption. The majority of small-for-gestational-age fetuses in this small study did not have small liver lengths. The small abdominal circumference measurement may reflect a reduction in size of other intra-abdominal organs, reduced amounts of fat, or possibly an elevated diaphragm because of poor lung growth.
