Volumetric growth of the lungs in human fetuses: an anatomical, hydrostatic and statistical study

Abstract

PurposeThe prenatal assessment of lung volume is becoming increasingly important in determining survival in both preterm infants and newborns affected by pulmonary hypoplasia. This study aimed to examine the lung volumes in the human fetus at varying gestational ages.Materials and methodsUsing anatomical, hydrostatic (water displacement according to Archimedes’ patent) and statistical methods (one-way ANOVA test for paired data and post-hoc Bonferroni test, Kolmogorov–Smirnov test, Levene’s test, Student’s t test, regression analysis), volumes of the right and left lungs were measured in 67 human fetuses of both sexes (35 males, 32 females) aged 16–25 weeks, derived from spontaneous abortions and stillbirths.ResultsNo male–female differences concerning the right and left pulmonary volumes were found. The mean volume of the right lung increased from 1.43 ± 0.25 to 8.45 ± 2.66 cm3, according to the cubic function y = –1.592 + 0.0007 × age3 ± 0.851 (R2 = 0.84). The volumetric growth of the left lung, from 1.24 ± 0.22 to 6.78 ± 3.03 cm3, followed the cubic model y = –1.110 + 0.0005 × age3 ± 0.794 (R2 = 0.78). The total pulmonary volume increased from 2.67 ± 0.47 to 15.22 ± 5.58 cm3, in accordance with the cubic model y = –2.729 + 0.0012 × age3 ± 1.598 (R2 = 0.83). The mean volumes of the right and left lungs accounted for 54.9 ± 2.0 and 45.1 ± 2.0 %, respectively, of the total lung volume.ConclusionsNo sex differences are found between the lung volumes in the fetus. The growth of fetal lung volume follows a three-degree polynomial function. Throughout the analyzed period the two lungs grow proportionately to each other, with the volumetric predominance of the right lung. The lung volumes in the fetus are of great relevance in the evaluation of the normal pulmonary growth and the diagnosis of pulmonary hypoplasia.

Quantitative anatomy of the liver visceral surface in the human fetus

“…According to the professional literature, shrinkage in formalin did not exceed 1% with reference to any linear dimension of the liver. [18][19][20][21][22][23][24][25][26][27] Furthermore, the size of the liver in situ was virtually unfettered by formalin solution, since some liver linear dimensions, i.e., height, as well as transverse and sagittal diameters, achieved in the present series, accurately corresponded with those obtained by Chang et al, when measuring in utero fetuses of the same age with the use of 3D-ultrasound. 3 Thirdly, in order to measure the liver parameters, an optimized digital image system (NIS-Elements AR 3.0.; Nikon) was used.…”

“…Fetal age determination was based on the crown-rump length (CRL), known date of the 1 st day of the maternal menstrual period, and the 5 fetal anthropometric measurements (head circumference, bi-parietal diameter, occipitofrontal diameter, abdominal circumference, and femur length) assessed by early 2 nd trimester ultrasound scans. [18][19][20][21][22][23][24][25][26] As a prerequisite, we excluded fetuses with chromosomal abnormalities or intrauterine growth restriction, as well as from multiple pregnancies, from diabetic mothers and those with severe infections.…”

Three-dimensional growth dynamics of the liver in the human fetus

“…In clinical practice, a reliable estimate of gestational age up to 14 weeks is confirmed by ultrasound measurement of fetal crump-rump length. As recommended by the Fetal Growth Longitudinal Study, part of the International Fetal and Newborn Growth Consortium for the 21st Century (INTERGROWTH-21st) Project, in women commencing antenatal care at less than 14 weeks and 0 days of gestation until birth, a combination of known values of the five fetal ultrasonic measurements: head circumference, bi-parietal diameter, occipitofrontal diameter, abdominal circumference, and femur length behooves estimation of accurate fetal ages [ 4 , 18 , 23 – 28 , 31 ]. The Fetal Growth Longitudinal Study prospectively assessed fetal growth from 14 to 42 weeks of gestation in 4,321 mothers who were at low risk of intrauterine growth restriction (optimal health and nutritional maternal wellbeing, satisfactory antenatal care, singletons without congenital malformations) in eight geographically diverse urban populations [ 18 ].…”

“…The study encompassed a group consisting of 69 autopsied human fetuses of both sexes (32 males, 37 females) aged 18–30 weeks of Caucasian origin (Table 1 ), derived from spontaneous abortions or stillbirths in the years 1989–1999. According to the INTERGROWTH-21st Project, the fetal ages in weeks were fine-tuned by the following criteria: the fetal crown-rump length (gestational age), known date of the beginning of the last maternal menstrual period (amenorrhea age), and known values of the five fetal anthropometric measurements: head circumference, bi-parietal diameter, occipitofrontal diameter, abdominal circumference, and femur length assessed by early second trimester ultrasound scan (ultrasound age) [ 4 , 18 , 23 – 28 , 31 ]. The crown-rump length was measured with the use of a flexible caliper from the top of the head (crown) to the bottom of the buttocks (rump) of the fetus in its natural C-shaped posture [ 16 ].…”

“…Legal and ethical considerations were approved by the University Research Ethics Committee (reference: KB 161/2013). After having been immersed in 10 % neutral buffered formalin solution for 12–24 months [ 4 , 11 , 16 , 23 – 28 ], the fetuses were anatomically dissected through median and transverse laparotomy under tenfold magnification using a stereoscope with Huygens ocular (Fig. 1 ).…”