Reference ranges of fetal adrenal gland and fetal zone volumes between 24 and 37 + 6 weeks of gestation by three-dimensional ultrasound

Anatomical and functional changes of the fetal adrenal gland in intrauterine growth restriction

OBJECTIVE

The aim of this study was to demonstrate the establishment of adrenal sparing in intrauterine growth restricted (IUGR) human fetuses. IUGR fetuses are a subgroup of small for gestational age (SGA) fetuses that are unable to reach their own growth potential because of chronic hypoxia and undernutrition. We hypothesized that in IUGR fetuses the adrenal gland is relatively larger and secretion of noradrenaline (NA), adrenaline (A), and cortisol is increased.

STUDY DESIGN

This is a prospective observational study including 65 singleton pregnancies (42 IUGR and 23 controls). Using two-dimensional ultrasound, we measured fetal adrenal diameters and adrenal/abdominal circumference (AD/AC) ratio between 25 and 37 weeks. We considered only one measurement per fetus. In 21 pregnancies we also measured NA, A, and cortisol levels in arterial and venous fetal cord blood collected at the time of delivery.

RESULTS

The AD/AC ratio was significantly higher in IUGR fetuses than in controls. Cord NA and A levels were significantly higher in IUGR fetuses than in controls. An increase in cortisol secretion in IUGR fetuses was observed but the difference was not statistically significant.

CONCLUSIONS

Adrenal sparing correlates with a relative increase in adrenal measurements and function.

Adrenal volumes in fetuses delivering prior to 32 weeks' gestation: An MRI pilot study

INTRODUCTION

Spontaneous preterm birth prior to 32 weeks' gestation accounts for 1% of all deliveries and is associated with high rates of morbidity and mortality. A total of 70% are associated with chorioamnionitis which increases the incidence of morbidity, but for which there is no noninvasive antenatal test. Fetal adrenal glands produce cortisol and dehydroepiandosterone-sulphate which upregulate prior to spontaneous preterm birth. Ultrasound suggests that adrenal volumes may increase prior to preterm birth, but studies are limited. This study aimed to: (i) demonstrate reproducibility of magnetic resonance imaging (MRI) derived adrenal volumetry; (ii) derive normal ranges of total adrenal volumes, and adrenal: body volume for normal; (iii) compare with those who have spontaneous very preterm birth; and (iv) correlate with histopathological chorioamnionitis.

MATERIAL AND METHODS

Patients at high risk of preterm birth prior to 32 weeks were prospectively recruited, and included if they did deliver prior to 32 weeks; a control group who delivered an uncomplicated pregnancy at term was also recruited. T2 weighted images of the entire uterus were obtained, and a deformable slice-to-volume method was used to reconstruct the fetal abdomen. Adrenal and body volumes were obtained via manual segmentation, and adrenal: body volume ratios generated. Normal ranges were created using control data. Differences between groups were investigated accounting for the effect of gestation by use of regression analysis. Placental histopathology was reviewed for pregnancies delivering preterm.

RESULTS

A total of 56 controls and 26 cases were included in the analysis. Volumetry was consistent between observers. Adrenal volumes were not higher in the case group (p = 0.2); adrenal: body volume ratios were higher (p = 0.011), persisting in the presence of chorioamnionitis (p = 0.017). A cluster of three pairs of adrenal glands below the fifth centile were noted among the cases all of whom had a protracted period at risk of preterm birth prior to MRI.

CONCLUSIONS

Adrenal: body volume ratios are significantly larger in fetuses who go on to deliver preterm than those delivering at term. Adrenal volumes were not significantly larger, we hypothesize that this could be due to an adrenal atrophy in fetuses with fulminating chorioamnionitis. A straightforward relationship of adrenal size being increased prior to preterm birth should not be assumed.

Fetal adrenal gland size and umbilical artery Doppler in growth-restricted fetuses

OBJECTIVES

In fetal growth restriction (FGR), Doppler ultrasound is the most important method for the detection and management. However, additional parameters are needed to improve the distinction between constitutionally small fetuses and fetuses affected by FGR.

METHODS

A total of 445 singleton pregnancies between 23 and 40 weeks of gestation were included in our retrospective study, of which 67 with FGR and 378 normal fetuses. A 2D-plane of the fetal adrenal gland was obtained and the adrenal gland ratio was measured. Spearman's correlation coefficient was calculated to assess the association of fetal Doppler and adrenal gland ratio with outcome parameters. Logistic regression analysis was performed to assess the statistical significance of "PI of the umbilical artery" and "adrenal gland ratio" as prognostic factors for intrauterine growth restriction (IUGR).

RESULTS

PI of the umbilical artery was shown to correlate with outcome parameters (WG_Delivery: r=-0.125, p=0.008; birth weight: r=-0.268, p<0.001; birth weight centile: r=-0.248, p<0.001; APGAR at 5 min: r=-0.117, p=0.014). Adrenal gland ratio showed no correlation with any of the outcome parameters. In logistic regression however, both PI of the umbilical artery and the adrenal ratio were shown to be significantly associated with fetal IUGR. When combining the two parameters, predictive value was superior to the predictive value of each individual parameter (AUC 0.738 [95% CI 0.670; 0.806]).

CONCLUSIONS

The adrenal gland ratio can be a useful addition to Doppler ultrasound when it comes to the detection of fetal FGR. Prospective studies are needed to establish references ranges and cut-off values for clinical decision-making.

Longitudinal adrenal gland measurements and growth trajectories as risk markers for late preterm delivery

BACKGROUND

The fetal adrenal gland receives rising awareness as a predictor of spontaneous preterm birth. We hereby provide longitudinal growth assessments of the fetal adrenal gland in a low risk population with an additional focus on trajectories in fetuses born preterm.

METHODS

Fetal adrenal gland was assessed via transabdominal ultrasound at gestational weeks (gw) 24-26, 28-30, and 34-36 in a low-risk pregnancy cohort. Longitudinal trajectories of the total gland and the mark (so called fetal zone) as well as ratio of fetal zone width/ total widths (w/W) were analyzed using repeated ANOVA analyses. To compare trajectories of the ratio w/W for preterm and term fetuses respectively, as well as women with and without clinical signs of preterm labor, the propensity score method was applied.

RESULTS

Fetal zone width increased over the course of pregnancy (p < 0.0001), while the ratio w/W decreased (p < 0.0001) (n = 327). Comparing the trajectories of the ratio w/W in fetuses born preterm (n = 11) with propensity-score matched term born fetuses (n = 22), a decrease between gw 24-26 and 28-30 was observed in both groups, which continued to decrease for the term born fetuses. However, in preterm born fetuses, the ratio increased above the term born values at gw 34-36.

CONCLUSION

Our study provides for the first time longitudinal growth data on the fetal adrenal gland and supports the hypothesis that fetal zone enlargement is associated with preterm birth which could play an important role in risk-prediction.

Normal size of the fetal adrenal gland on prenatal magnetic resonance imaging

BACKGROUND

The adrenal gland plays a vital role in fetal growth. Many disease states such as congenital adrenal hyperplasia, hemorrhage and tumors can lead to morphological changes in the gland. Ultrasound measurements of normal adrenal sizes in the fetus reported in the literature have shown a trend of increasing size with gestational age. There is no literature available on standard fetal adrenal sizes or detailed appearance by fetal MRI.

OBJECTIVE

The purpose of this study was to provide MR data on the size and signal characteristics of the fetal adrenal gland throughout the second and third trimesters.

MATERIALS AND METHODS

In this retrospective review, we selected 185 prenatal MRIs obtained from Jan. 1, 2014, to May 31, 2017, with normal abdominal findings for inclusion. The adrenal glands were identified in coronal, sagittal or axial T2-W planes and coronal T1-W plane when available. We measured the length and thickness of the medial and lateral limbs of the right and left adrenal glands and recorded signal intensity on T1-W and T2-W sequences, gender and gestational age in each case.

RESULTS

The gestational age (GA) ranged 18-37 weeks. Visibility of the adrenal glands on T2-W images was high (90.3-97.2%) up to 30 weeks of GA but declined afterward (47.5-62.2% at 31-37 weeks). Visibility on T1-W images increased with GA, ranging from 21.4% visibility at 18-22 weeks and increasing to 40% at 35-37 weeks. Mean lengths of the adrenal gland limbs steadily increased from 8.2 mm at 18-22 weeks to 11.0 mm at 35-37 weeks. In the second trimester, adrenal glands were low in signal intensity on T2-W images and were surrounded by hyperintense perirenal fatty tissue. In the third trimester, the glands became less distinct, with increasing signal and obliteration of perirenal tissue. The glands were moderately hyperintense on T1-W images throughout pregnancy, with increasing visibility as pregnancy progressed.

CONCLUSION

Normal sizes and signal intensities for adrenal glands are reported. Visibility of adrenal glands on T2-W images was 90.3-97.2% up to 30 weeks but declined thereafter. Visibility on T1-W images increased in the third trimester. Adrenal gland sizes increased with gestational age.

Adrenal gland size in growth restricted fetuses

Objective To compare the adrenal gland size of fetal growth restricted (FGR) and normal control fetuses. Study design In this prospective study the adrenal gland size of 63 FGR fetuses and 343 normal controls was measured between 20 and 41 weeks of gestation. The total width and the medulla width were measured in a new standardized transversal plane. The cortex width and a calculated ratio of the total and medulla width (adrenal gland ratio) were compared between both groups. Results The mean cortex width and the adrenal gland ratio in FGR fetuses were higher in comparison to the controls (P<0.001; P=0.036, respectively). The cortex width correlated positively with the gestational age (control group: P<0.001; FGR group: P=0.089) whilst the adrenal gland ratio showed no association with the gestational age (control group: P=0.153; FGR group: P=0.314). Conclusion The adrenal gland cortex width and the adrenal gland ratio were increased in FGR fetuses compared to normal fetuses.

Ultrasound measurement of fetal adrenal gland in fetuses with intrauterine growth restriction, an early predictive method for adverse outcomes

OBJECTIVES

Comparing the sonographic measurements of fetal adrenal gland in pregnancies with intrauterine growth restriction (IUGR) versus healthy controls and to assess whether the changes in adrenal gland measurements could predict adverse pregnancy outcomes in IUGR fetuses.

METHODS

This prospective cohort study evaluated 97 pregnant women (48 with IUGR pregnancies and 49 healthy controls) during their third gestational trimester. All mothers underwent two dimensional ultrasonography of the fetal adrenal gland, and the fetal zone in transverse, sagittal, and coronal planes. Adrenal gland volume (AGV) and fetal zone volume (FZV) were calculated and corrected (c) for fetal weight. The mothers were then followed until delivery.

RESULTS

Fetuses in the IUGR group had larger corrected adrenal gland volume (c_AGV) and smaller corrected fetal zone volume (c_FZV) compared to the fetuses in the control groups (p < .001). In the IUGR group, significantly smaller c_AGV and higher fetal/adrenal were detected in IUGR fetuses who had nonreassuring fetal status before delivery, preterm birth, very low birth weight delivery, and also those who required neonatal intensive care unit admission (p < .01 for all).

CONCLUSIONS

Third trimester fetal adrenal gland sonography could potentially be used as an easy noninvasive method for identifying those IUGR fetuses who might have poorer outcomes.

Assessment of neonatal adrenal size using high resolution 2D ultrasound and its correlation with birth demographics and clinical outcomes

OBJECTIVE

Assessment of adrenal function in a sick neonate remains a challenge in spite of major advances in neonatal care. We used 2D ultrasound of adrenal glands to assess maturity of adrenal glands in extremely preterm infants and sick term and near term infants.

STUDY DESIGN

We collected demographics details of 99 mother-infants pairs (24-41 weeks) and obtained 2D ultrasound scans of adrenal glands in first week of life to measure adrenal volume, fetal zone size, and adrenal to kidney ratios. Relationship between adrenal measurements, antenatal factors, and postnatal outcomes were studied.

RESULTS

We reported normative adrenal gland volume data during gestation from 80 appropriate for gestational age (AGA) infants. In a binary analysis, adrenal size was significantly related to gender, race, intrauterine growth restriction (IUGR), maternal chorioamnionitis, and maternal hypertension. Linear regression analysis showed that fetal zone is significantly related to not only gestational age but also chorioamnionitis and later development of intraventricular hemorrhage (IVH). Adrenal volume likewise is also related to gestational age, preeclampsia, and IVH.

CONCLUSIONS

Antenatal maternal factors and uterine environment affects adrenal growth and development thus postnatal high resolution 2D US scan of adrenal glands can provide useful information to predict outcomes. This information can complement hormone and adrenocorticotrophic hormone (ACTH) stimulation assays.

Kisspeptin Is a Novel Regulator of Human Fetal Adrenocortical Development and Function: A Finding With Important Implications for the Human Fetoplacental Unit

CONTEXT

The human fetal adrenal (HFA) is an integral component of the fetoplacental unit and important for the maintenance of pregnancy. Low kisspeptin levels during pregnancy are associated with miscarriage, and kisspeptin and its receptor are expressed in the HFA. However, the role of kisspeptin in fetal adrenal function remains unknown.

OBJECTIVE

To determine the role of kisspeptin in the developing HFA.

DESIGN

Experiments using H295R and primary HFA cells as in vitro models of the fetal adrenal. Association of plasma kisspeptin levels with HFA size in a longitudinal clinical study.

SETTING

Academic research center and tertiary fetal medicine unit.

PARTICIPANTS

Thirty-three healthy pregnant women were recruited at their 12-week routine antenatal ultrasound scan.

MAIN OUTCOME MEASURES

The spatiotemporal expression of Kiss1R in the HFA. The production of dehydroepiandrosterone sulfate (DHEAS) from HFA cells after kisspeptin treatment, alone or in combination with adrenocorticotropic hormone or corticotropin-releasing hormone. Fetal adrenal volume (FAV) and kisspeptin levels at four antenatal visits (∼20, 28, 34, and 38 weeks' gestation).

RESULTS

Expression of Kiss1R was present in the HFA from 8 weeks after conception to term and was shown in the inner fetal zone. Kisspeptin significantly increased DHEAS production in H295R and second-trimester HFA cells. Serial measurements of kisspeptin confirmed a correlation with FAV growth in the second trimester, independent of sex or estimated fetal weight.

CONCLUSIONS

Kisspeptin plays a key role in the regulation of the HFA and thus the fetoplacental unit, particularly in the second trimester of pregnancy.