Ultrasound estimates of gestational age among perinatally demised: a population-based study

Development of fetal intestinal length during 2nd-trimester in normal and pathologic pregnancies

Linear growth of the human fetal gastrointestinal tract is not often discussed in the literature, and little is known about the effects of chromosomal abnormalities and intrauterine growth restriction (IUGR) on intestinal length, especially during the 2nd trimester. Accurate evaluation of intestinal length and knowledge of normal and reference values are of clinical importance. For example, intestinal resection may be necessary in preterm infants with necrotizing enterocolitis or mid-gut volvulus, and the surgeon should use data to be judicious in the amount removed. Linear measurements are essential in evaluating fetal development ultrasonographically and are an integral part of the postmortem examination. The intestinal lengths of 203 2nd-trimester fetuses and premature infants were measured. Small intestine length (SIL), colon length (CL), total bowel length (TBL; TBL  =  SIL + CL), and the length of the appendix (AL) increased with gestational age. No differences between the genders were observed. Colon length increased secondary to maceration, but no such effects were shown on SIL, TBL, or AL. No differences were shown in relation to IUGR. Small intestine length, CL, and TBL, but not AL, were shorter in fetuses with trisomy 21. Appendix length was not affected by any of the studied factors. We propose that the measurement of the length of the appendix may be used as an additional parameter for the postmortem evaluation of gestational age. Furthermore, its assessment may have potential as an ultrasonographic indicator of gestational age, particularly for the 2nd trimester.

Comparison of gestational age at birth based on last menstrual period and ultrasound during the first trimester

Reported last menstrual period (LMP) is commonly used to estimate gestational age (GA) but may be unreliable. Ultrasound in the first trimester is generally considered a highly accurate method of pregnancy dating. The authors compared first trimester report of LMP and first trimester ultrasound for estimating GA at birth and examined whether disagreement between estimates varied by maternal and infant characteristics. Analyses included 1867 singleton livebirths to women enrolled in a prospective pregnancy cohort. The authors computed the difference between LMP and ultrasound GA estimates (GA difference) and examined the proportion of births within categories of GA difference stratified by maternal and infant characteristics. The proportion of births classified as preterm, term and post-term by pregnancy dating methods was also examined. LMP-based estimates were 0.8 days (standard deviation = 8.0, median = 0) longer on average than ultrasound estimates. LMP classified more births as post-term than ultrasound (4.0% vs. 0.7%). GA difference was greater among young women, non-Hispanic Black and Hispanic women, women of non-optimal body weight and mothers of low-birthweight infants. Results indicate first trimester report of LMP reasonably approximates gestational age obtained from first trimester ultrasound, but the degree of discrepancy between estimates varies by important maternal characteristics.