Transfer of inflammatory cytokines across the placenta

OBJECTIVE

The purpose of this study was to determine whether the placental transfer of interleukin (IL)-1alpha, IL-6, and tumor necrosis factor-alpha (TNF-alpha) occurs.

METHODS

Four normal-term placentas were perfused for maternal-fetal transfer of the cytokines, 2 placentas for fetal-maternal transfer, and 4 additional placentas were used for an endogenous control. The ex vivo isolated cotyledon human placental perfusion model was used. The reference compound antipyrine was used to determine the transport fraction and clearance index of the cytokines. The cytokines were added to either the maternal or fetal circulations, and samples were collected for 1 hour in a constant-flow open circulation. Cytokine levels were compared between the study and control placentas. Concentrations of the cytokines were measured by sandwich enzyme immunoassay.

RESULTS

The clearance index for the maternal-fetal transfer of IL-1alpha and TNF-alpha was 0.001, suggesting minimal transfer to the fetal circulation. The clearance index for IL-6 was 0.30, indicating transfer to the fetal circulation. When the cytokines were added to the fetal circulation, the clearance index for IL-1alpha was 0.001, again indicating minimal transfer. The clearance index for TNF-alpha in the fetal-maternal study was not determined. IL-6 had a clearance index of 0.23, which was similar to that observed with maternal-fetal transfer. IL-6 concentrations in the study placentas were higher than the concentrations found in the controls.

CONCLUSION

There appears to be bidirectional transfer of IL-6 in the healthy-term human placental perfusion model.

LEVEL OF EVIDENCE

II-2

Single uterine axial fast acquisition magnetic resonance fetal survey: is it feasible?

OBJECTIVES

To determine which non-biometric components of the ultrasound fetal survey can routinely be seen on a single fast acquisition magnetic resonance (MR) sequence aligned axial to the maternal uterus.

STUDY DESIGN

The non-biometric components of the routine fetal ultrasound examination were applied retrospectively to the initial MR single-shot fast spin-echo acquisition aligned axial to the maternal uterus in the normal fetus to determine whether these parameters could be routinely evaluated. Nineteen women with anatomically normal fetuses had a total of 31 MR studies performed for fetal or maternal indications, either as part of an indicated examination or as part of a study protocol approved by the institutional review board. The images in these 31 MR studies were reviewed by two independent examiners who were blinded to the other's assessment; concordance was necessary for a component to be adequately assessed. The Wilcoxon rank sum test was used to determine the effect of gestational age and fetal lie on the ability to assess non-biometric parameters.

RESULTS

Assessment was possible in 85% of the non-biometric parameters. Cord insertion, external genitalia and the four-chamber view of the heart were most problematic. In only two cases was the four-chamber view of the heart identified. Longitudinal lie allowed significantly more parameters (82%) to be evaluated than transverse lie (45%) (p < 0.003). No difference based on gestational age was found.

CONCLUSION

A single fast acquisition axial MR sequence can evaluate 85% of the non-biometric components of the fetal ultrasound survey. Fetal lie is an important confounder in the ability to resolve fetal anatomy with a single MR axial uterine acquisition.

Comparison of magnetic resonance imaging to ultrasound in the estimation of birth weight at term

OBJECTIVE

This study was undertaken to compare magnetic resonance (MR) and ultrasound (US) fetal weight estimates obtained immediately before delivery with birth weight.

STUDY DESIGN

Eighty women scheduled for a cesarean delivery underwent a fast acquisition MR and US for fetal weight estimation within 3 hours of delivery. Prospective MR calculation was based on the equation 0.12+1.031 g/mLxfetal volume (mL)=MR weight (g). US fetal weight estimation was calculated by the formula by Hadlock et al. Estimations were compared with birth weight.

RESULTS

Correlation (95% CI) between birth weight and MR weight is 0.95 with a mean absolute error of 129 g (105-155) compared with the correlation between birth weight and US of 0.85 with a mean absolute error of 225 g (186-264). The correlation for birth weight and MR imaging is significantly greater than that of birth weight and US, P<.001.

CONCLUSION

Birth weight estimation is more accurate by MR imaging than by US in term infants.

Feasibility of the fetal anatomic and maternal pelvic survey by magnetic resonance imaging at term

OBJECTIVE

This study was undertaken to determine which nonbiometric components of the American College of Obstetricians and Gynecologists recommended ultrasound fetal anatomic and maternal pelvic survey can be evaluated by fast acquisition magnetic resonance (MR) imaging in the term fetus.

STUDY DESIGN

Nonbiometric components of the fetal survey were retrospectively evaluated by fast acquisition MR images. Thirteen components were assessed, including fetal number, presentation, placental location, qualitative assessment of amniotic fluid, and the maternal pelvis (n=5). The fetal anatomy included bilateral cerebral ventricles, spine, bilateral kidneys, stomach, bladder, cord insertion, sex, and four-chamber view of the heart (n=8). Studies were performed before delivery and neonatal outcomes were reviewed.

RESULTS

All 50 neonates were normal at follow-up. A total of 94% (702 of 750) of the components were assessed by MR imaging.

CONCLUSION

Fetal MR imaging can assess 94% of the American College of Obstetricians and Gynecologists recommended ultrasound fetal and pelvic anatomic survey. If the heart is excluded, this increases to 99%.