Antenatal diagnosis of chorioamnionitis: A review of the potential role of fetal and placental imaging

Placental multimodal MRI prior to spontaneous preterm birth <32 weeks' gestation: An observational study

OBJECTIVE

To utilise combined diffusion-relaxation MRI techniques to interrogate antenatal changes in the placenta prior to extreme preterm birth among both women with PPROM and membranes intact, and compare this to a control group who subsequently delivered at term.

DESIGN

Observational study.

SETTING

Tertiary Obstetric Unit, London, UK.

POPULATION

Cases: pregnant women who subsequently spontaneously delivered a singleton pregnancy prior to 32 weeks' gestation without any other obstetric complications.

CONTROLS

pregnant women who delivered an uncomplicated pregnancy at term.

METHODS

All women consented to an MRI examination. A combined diffusion-relaxation MRI of the placenta was undertaken and analysed using fractional anisotropy, a combined T2*-apparent diffusion coefficient model and a combined T2*-intravoxel incoherent motion model, in order to provide a detailed placental phenotype associated with preterm birth. Subgroup analyses based on whether women in the case group had PPROM or intact membranes at time of scan, and on latency to delivery were performed.

MAIN OUTCOME MEASURES

Fractional anisotropy, apparent diffusion coefficients and T2* placental values, from two models including a combined T2*-IVIM model separating fast- and slow-flowing (perfusing and diffusing) compartments.

RESULTS

This study included 23 women who delivered preterm and 52 women who delivered at term. Placental T2* was lower in the T2*-apparent diffusion coefficient model (p < 0.001) and in the fast- and slow-flowing compartments (p = 0.001 and p < 0.001) of the T2*-IVIM model. This reached a higher level of significance in the preterm prelabour rupture of the membranes group than in the membranes intact group. There was a reduced perfusion fraction among the cases with impending delivery.

CONCLUSIONS

Placental diffusion-relaxation reveals significant changes in the placenta prior to preterm birth with greater effect noted in cases of preterm prelabour rupture of the membranes. Application of this technique may allow clinically valuable interrogation of histopathological changes before preterm birth. In turn, this could facilitate more accurate antenatal prediction of preterm chorioamnionitis and so aid decisions around the safest time of delivery. Furthermore, this technique provides a research tool to improve understanding of the pathological mechanisms associated with preterm birth in vivo.

Fetal inflammatory response syndrome predicts early-onset sepsis and cystic periventricular leukomalacia in preterm neonates: A retrospective study

BACKGROUND

Fetal inflammatory response syndrome (FIRS), the fetal equivalent of chorioamnionitis, is associated with poorer neonatal outcomes. FIRS is diagnosed through placental histology, namely by the identification of funisitis (inflammation of the umbilical cord) and chorionic vasculitis (inflammation of fetal vessels within the chorionic plate). The aim of this study was to identify and evaluate associations between FIRS and neonatal outcomes in preterm neonates.

METHODS

We performed a retrospective cohort study at a level III neonatal intensive care unit (NICU), from January 1st 2008 to December 31st 2022, involving all inborn neonates with a gestational age below 30 weeks. We compared preterm neonates based on whether their placental histology described funisitis with chorionic vasculitis (FCV) or not.

RESULTS

The study included 113 preterms, 27 (23.9%) of those had FCV and 86 (76.1%) did not. After adjusting to gestational age, prolonged rupture of membranes and preeclampsia, FCV was independently associated with the development of early-onset sepsis (OR = 7.3, p = 0.021) and cystic periventricular leukomalacia (OR = 4.6, p = 0.004).

CONCLUSION

The authors identified an association between FIRS and the development of early-onset sepsis and cystic periventricular leukomalacia, highlighting the importance of early detection and management of this condition in order to improve long-term neonatal outcomes.

Predicting Preterm Birth Using Cell-Free Ribonucleic Acid

Spontaneous preterm birth (sPTB) is a complex and clinically heterogeneous condition that remains incompletely understood, leading to insufficient interventions to effectively prevent it from occurring. Cell-free ribonucleic acid signatures in the maternal circulation have the potential to identify biologically relevant subtypes of sPTB. These could one day be used to predict and prevent sPTB in asymptomatic individuals, and to aid in prognosis and management for individuals presenting with threatened preterm labor and preterm prelabor rupture of membranes.

Risk of adverse perinatal outcomes among women with clinical and subclinical histopathological chorioamnionitis

Introduction

Histologic chorioamnionitis (HCA) is a placental inflammatory condition associated with adverse perinatal outcomes (APOs). This historical cohort study explores the risk of APOs in pregnant women with HCA and compares the impact of clinical chorioamnionitis (CCA) with subclinical chorioamnionitis (SCCA).

Methodology

Placentas were evaluated by a perinatal pathologist tand all women with HCA were included. Two groups were integrated: (1) women with clinical chorioamnionitis (CCA) and (2) women with subclinical chorioamnionitis (SCCA). Additionally, we conducted a secondary analysis to compare the prevalence of APOs among stage 1, 2 and 3 of HCA and the risk of APOs between grades 1 and 2 of HCA. The APOs analyzed were preterm birth, stillbirth, neonatal weight < 1,500 g, neonatal sepsis. Relative risk with 95% confidence interval was calculated.

Results

The study included 41 cases of CCA and 270 cases of SCCA. The mean gestational age at diagnosis and birth was 30.2 ± 5.4 weeks and 32.5 ± 5.1 weeks, for group 1 and 2, respectively. The study also found that women with HCA stage 3 and grade 2 had a higher prevalence and risk of adverse perinatal outcomes.

Discussion

The findings of this study suggest the importance of placental histological study to excluded SCCA, which represents a significant risk to both maternal and neonatal health, contributing to high morbidity and mortality.

Amniotic fluid sludge is associated with earlier preterm delivery and raised cervicovaginal interleukin 8 concentrations

BACKGROUND

Preterm birth is the leading cause of global neonatal mortality. Amniotic fluid sludge, thought to indicate intra-amniotic infection, may have potential as a clinical biomarker of preterm birth risk.

OBJECTIVE

This study aimed to analyze whether the presence of amniotic fluid sludge in pregnant participants with a known short cervical length can help improve the understanding of the etiology and guide management choice.

STUDY DESIGN

This was a retrospective cohort study analyzing the effects of amniotic fluid sludge presence on the risk of preterm birth in high-risk asymptomatic pregnant participants with a short cervical length (<25 mm) at a large tertiary referral maternity center in London. Amniotic fluid sludge was detected on a routine transvaginal ultrasound scan.

RESULTS

Overall, 147 pregnant participants with a short cervical length were identified, 54 of whom had amniotic fluid sludge. Compared with pregnant participants without amniotic fluid sludge, pregnant participants with amniotic fluid sludge were more likely to have a short cervical length (19 vs 14 mm, respectively; P<.0001) and increased cervicovaginal fetal fibronectin concentrations at diagnosis (125 vs 45 ng/mL, respectively; P=.0006). Pregnant participants with amniotic fluid sludge were at increased risk of midtrimester loss and delivery before 24 weeks of gestation (relative risk, 3.4; 95% confidence interval, 1.2-10.3). Furthermore, this study showed that pregnant participants with amniotic fluid sludge have increased cervicovaginal interleukin 8 concentrations, supporting the concept of amniotic fluid sludge as an indicator of an inflammatory response to microbial invasion (P=.03). Neonatal outcomes were similar between the 2 groups.

CONCLUSION

In our cohort of high-risk asymptomatic pregnant participants with a short cervical length, the presence of amniotic fluid sludge is associated with an increased risk of delivery before 24 weeks of gestation. Moreover, pregnant participants with amniotic fluid sludge were more likely to have raised fetal fibronectin levels and inflammatory cytokines, particularly interleukin 8, in the cervicovaginal fluid, supporting the concept that amniotic fluid sludge is associated with an infective or inflammatory process. Future research should aim to further establish the clinical significance of amniotic fluid sludge presence and guide subsequent management.

Chorioamnionitis: An Update on Diagnostic Evaluation

Chorioamnionitis remains a major cause of preterm birth and maternal and neonatal morbidity. We reviewed the current evidence for the diagnostic tests of chorioamnionitis and how this relates to clinical practice today. A comprehensive literature search and review was conducted on chorioamnionitis and intra-uterine inflammation. Data from randomized control trials and systematic reviews were prioritized. This review highlights that sterile inflammation plays an important role in chorioamnionitis and that the current tests for chorioamnionitis including clinical criteria, maternal plasma and vaginal biomarkers lack diagnostic accuracy. Concerningly, these tests often rely on detecting an inflammatory response after damage has occurred to the fetus. Care should be taken when interpreting current investigations for the diagnosis of chorioamnionitis and how they guide obstetric/neonatal management. There is an urgent need for further validation of current diagnostic tests and the development of novel, accurate, minimally invasive tests that detect subclinical intra-uterine inflammation.

The neutrophil-to-lymphocyte ratio: A low-cost antenatal indicator of placental chorioamnionitis in women who deliver preterm without clinical signs and symptoms of infection

Chorioamnionitis is present in up to 70% of spontaneous preterm births and is associated with poor maternal, fetal and neonatal outcomes.

OBJECTIVE

To explore the relationship between the neutrophil-to-lymphocyte ratio and histological chorioamnionitis in women who delivered preterm with no clinical signs or symptoms of infection.

STUDY DESIGN

This was a retrospective analysis of a cohort of women who delivered spontaneously between 16 and 36⁺⁶ weeks at a tertiary UK hospital. Only women with placental histology and no signs of clinical infection were included. The neutrophil-to-lymphocyte ratio was calculated from a full blood count sample taken routinely within 24 h of delivery. The neutrophil-to-lymphocyte ratio was also calculated from first trimester booking bloods (<13 + 6 weeks) in a subgroup. Placental histopathology was categorised as either inflammatory (i.e. histologic chorioamnionitis, with or without evidence of fetal inflammatory response) or non-inflammatory (vascular pathology or a normal placenta).

RESULTS

169 women had available placental pathology and were included in the analysis. 70 % (118/169) had confirmed placental inflammation. The mean neutrophil-to-lymphocyte ratio was significantly raised in this group compared to those with normal (n = 24) or vascular (n = 27) pathology (inflammatory neutrophil-to-lymphocyte ratio 9.81 vs non-inflammatory neutrophil-to-lymphocyte ratio 6.53, p = 0.002. The delivery neutrophil-to-lymphocyte ratio had an area under the receiver operating characteristic curve of 0.69 (0.60 to 0.78) for predicting placental inflammation. A raised neutrophil-to-lymphocyte ratio (>6) was associated with an odds ratio of 5.2 (95 % CI 2.55 to 10.56) for histological chorioamnionitis, with a sensitivity of 80 % and negative predictive value of 86 %. A higher cut-off of 9 had a negative predictive value of 79 % for fetal inflammatory response.

CONCLUSIONS

A raised neutrophil-to-lymphocyte ratio is associated with a 5-fold increased risk of histological chorioamnionitis in women who delivered early without signs or symptoms of infection. It was also raised at the time of preterm labour compared to the first trimester. A full blood count is an almost universal investigation in women admitted in preterm labour, often repeated, making this inexpensive and non-invasive ratio a useful additional antenatal biomarker in women admitted in spontaneous preterm labour at risk of subclinical chorioamnionitis and its associated poor outcomes.

Blood products transfusion and retinopathy of prematurity: A cohort study

AIM

The aim of the study was to assess the influence of blood product transfusions on the development and severity of retinopathy of prematurity (ROP).

METHODS

A retrospective cohort study was conducted of very low birth weight (VLBW) newborns with less than 32 weeks gestational age (GA) admitted to the neonatal unit of a tertiary care hospital during the period from 1 January 2008 to 31 December 2021. Data on the degree of ROP and the transfusions received were obtained and analysed. Both univariate and multivariate analyses were performed, by logistic regression.

RESULTS

A total of 565 VLBW newborns were recruited, of whom 263 received a red blood cell transfusion prior to 36 weeks corrected GA. The newborns with ROP received significantly more red blood cell transfusions than those not presenting this condition. After adjusting for oxygen therapy and GA, the risk of ROP was found to be 2.77 times higher (95% CI 1.31-5.88) after receiving three or more transfusions, with a 3.95 times higher risk (95% CI 1.40-11.1) of developing severe ROP. Having received the first red blood cell transfusion before 32 weeks corrected GA is associated with an increased risk of ROP (OR 2.18; 95% CI: 1.09-4.36).

CONCLUSION

In VLBW neonates, the number of red blood cell transfusions and their administration before 32 weeks corrected GA are important risk factors for ROP.