Fetal Portal System Flowmetry and Intra-Amniotic Inflammation in Preterm Prelabor Rupture of Membranes

The safety, acceptability, and success rates of amniocentesis in the context of preterm prelabor rupture of membranes and threatened preterm labor: a systematic review and meta-analysis

INTRODUCTION

Preterm birth, defined as birth before 37 weeks of gestation, is the leading cause of death of children under the age of five years worldwide. Globally there has been no change in the preterm birth rate between 2010 and 2020, when rates were calculated to be 9.8% and 9.9% of all livebirths, respectively. The analysis of amniotic fluid has been advocated by many to identify the mechanisms driving threatened preterm labor. Amniocentesis is largely considered to be safe, but care provider concerns about complications in the setting of threatened preterm labor (tPTL) exist. This systematic review will critically review the data regarding safety and outcomes of amniocentesis in cases of PPROM and tPTL and help in the counseling and clinical decision-making of patients and care providers alike.

METHODS

This systematic review was conducted in accordance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA). All English language, peer-reviewed human studies where amniocentesis was used to sample the amniotic fluid of patients presenting with tPTL or PPROM and published between January 1990 and March 2022 were included. Data on the uptake rates, success rates, and safety profile associated with amniocentesis in this context of tPTL or PPROM were analyzed as part of the systematic review. Included studies compromised of randomized control trials, cohort studies, and case-control studies. Conference abstracts and abstracts with no full text were excluded.

RESULTS

10,215 studies were returned after searches were conducted in MEDLINE, EMBASE, EMCARE, Web of Science, and SCOPUS databases using free text and Medical Subject Headings (MESH). 399 studies were assessed for eligibility with 15 studies being included in the final review. The main reason for exclusion from the review was an absence of safety data. Four studies gave information on uptake rates of amniocentesis in cases of PPROM and tPTL, with a range of 55% in an observational study to >99% in centers offering it as part of routine care. Eleven studies detailed success rates of amniocentesis, with all centers reporting >90% success rates. However, in some centers, a "successful" amniocentesis was deemed to be a retrieval of >0.5 ml. Three studies reported risks associated with amniocentesis. There were four reported complications (all transitory) in a series of 1119 cases (0.35%).

DISCUSSION

This systematic review found that amniocentesis in cases of PPROM or threatened preterm labor is a safe and feasible procedure. These data should give care providers confidence to counsel patients appropriately.

The Fetal Spleen in Low-Risk Pregnancies and prior to Preterm Birth: Observational Study of the Role of Anatomical and Functional Magnetic Resonance Imaging

INTRODUCTION

Spontaneous preterm birth complicates ∼7% of pregnancies and causes morbidity and mortality. Although infection is a common etiology, our understanding of the fetal immune system in vivo is limited. This study aimed to utilize T2-weighted imaging and T2* relaxometry (which is a proxy of tissue oxygenation) of the fetal spleen in uncomplicated pregnancies and in fetuses that were subsequently delivered spontaneously prior to 32 weeks.

METHODS

Women underwent imaging including T2-weighted fetal body images and multi-eco gradient echo single-shot echo planar sequences on a Phillips Achieva 3T system. Previously described postprocessing techniques were applied to obtain T2- and T2*-weighted imaging of the fetal spleen and T2-weighted fetal body volumes.

RESULTS

Among 55 women with uncomplicated pregnancies, an increase in fetal splenic volume, splenic:body volume, and a decrease in splenic T2* signal intensity was demonstrated across gestation. Compared to controls, fetuses who were subsequently delivered prior to 32 weeks' gestation (n = 19) had a larger spleen when controlled for the overall size of the fetus (p = 0.027), but T2* was consistent (p = 0.76).

CONCLUSION

These findings provide evidence of a replicable method of studying the fetal immune system and give novel results on the impact of impending preterm birth on the spleen. While T2* decreases prior to preterm birth in other organs, preservation demonstrated here suggests preferential sparing of the spleen.

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

Chorioamnionitis is present in up to 70% of spontaneous preterm births. It is defined as an acute inflammation of the chorion, with or without involvement of the amnion, and is evidence of a maternal immunological response to infection. A fetal inflammatory response can coexist and is diagnosed on placental histopathology postnatally. Fetal inflammatory response syndrome (FIRS) is associated with poorer fetal and neonatal outcomes. The only antenatal diagnostic test is amniocentesis which carries risks of miscarriage or preterm birth. Imaging of the fetal immune system, in particular the thymus and the spleen, and the placenta may give valuable information antenatally regarding the diagnosis of fetal inflammatory response. While ultrasound is largely limited to structural information, MRI can complement this with functional information that may provide insight into the metabolic activities of the fetal immune system and placenta. This review discusses fetal and placental imaging in pregnancies complicated by chorioamnionitis and their potential future use in achieving non-invasive antenatal diagnosis. This article is protected by copyright. All rights reserved.