Cervical insufficiency, amniotic fluid sludge, intra-amniotic infection, and maternal bacteremia: the need for a point-of-care test to assess inflammation and bacteria in amniotic fluid

Maternal Morbidity Associated with Early Preterm Birth in Low-Risk Singleton Pregnancies

Background/Objectives: While neonatal morbidities associated with early preterm birth are known, the risks of maternal morbidities in these births remain unclear. Thus, we set out to assess the risk of maternal morbidities associated with early preterm births. Methods: Retrospective cohort study utilizing the United States (US) Natality Live Birth database from the Centers for Disease Control and Prevention (2016-2021). Low-risk singleton pregnancies were included. High-risk conditions such as out-of-hospital births, fetal anomalies, pregestational and gestational diabetes, and hypertensive disorders of pregnancy were excluded. The rates of several maternal morbidities were compared among three gestational age at birth groups: 23 0/7-27 6/7 (i.e., extreme preterm), 28 0/7-33 6/7 (i.e., early preterm), and 37 0/7-41 6/7 (i.e., term, reference group) weeks. Multivariable logistic regression was used to adjust outcomes for potential confounders. Data were presented as adjusted odds ratios (aORs) with a 95% confidence interval (CI). Results: 18,797,394 live births were analyzed. Extreme and early preterm birth were associated with increased odds of maternal transfusion (aOR 3.32, 95% CI 3.13-3.53 and aOR 2.96, 95% CI 2.86-3.07), uterine rupture (aOR 3.75, 95% CI 3.14-4.48 and aOR 4.13, 95% CI 3.76-4.54), unplanned hysterectomy (aOR 5.60, 95% CI 4.85-6.48 and aOR 5.92, 95% CI 5.47-6.40), and maternal admission to the intensive care unit (ICU, aOR 10.58, 95% CI 9.97-11.54 and aOR 10.13, 95% CI 9.77-10.50) compared to term birth. The odds of third- or fourth-degree perineal lacerations were decreased in both preterm birth groups compared to term birth. Conclusions: In addition to the known prematurity-related neonatal morbidities, extreme and early preterm births also impose a risk for maternal morbidities. Higher odds of maternal transfusion, uterine rupture, unplanned hysterectomy, and maternal admission to the ICU were detected in our cohort. These data should be taken into consideration when caring for patients with preterm births.

A Review of the Literature: Amniotic Fluid "Sludge"-Clinical Significance and Perinatal Outcomes

Introduction: This paper seeks to report and emphasize the most important aspects from the scientific literature about the diagnostic accuracy of the amniotic fluid "sludge" (AFS), its characterization, its treatment, and its association with premature birth. AFS is defined as a floating freely hyperechogenic material within the amniotic cavity in the proximity of the internal os. Materials and Methods: We conducted a search on Pubmed and Google Scholar for relevant articles on the subject of amniotic fluid "sludge" published until January 2024. Searches were focused on articles about diagnosis, treatment, maternal and neonatal outcomes, risk of preterm birth, and case reports. The full-text reading stage resulted in the inclusion of 51 studies. Results: AFS is independently associated with chorioamnionitis, preterm delivery, short cervix, increased risk of neonatal morbidity, and cervical insufficiency. This hyperechogenic free-floating material is linked with preterm birth before 32 weeks of gestation, especially when it is associated with short cervical length. Discussion: Present studies identify some controversial benefits of antibiotics in reducing the incidence of preterm birth in women with AFS. Nevertheless, in this review, we can conclude that the presence of AFS in pregnancy is a marker for the microbial invasion of the amniotic cavity, as it is associated with preterm birth. Further studies on a larger group of patients are necessary to clarify and exactly define the terms of managing these cases.

Meconium-stained amniotic fluid

Green-stained amniotic fluid, often referred to as meconium-stained amniotic fluid, is present in 5% to 20% of patients in labor and is considered an obstetric hazard. The condition has been attributed to the passage of fetal colonic content (meconium), intraamniotic bleeding with the presence of heme catabolic products, or both. The frequency of green-stained amniotic fluid increases as a function of gestational age, reaching approximately 27% in post-term gestation. Green-stained amniotic fluid during labor has been associated with fetal acidemia (umbilical artery pH <7.00), neonatal respiratory distress, and seizures as well as cerebral palsy. Hypoxia is widely considered a mechanism responsible for fetal defecation and meconium-stained amniotic fluid; however, most fetuses with meconium-stained amniotic fluid do not have fetal acidemia. Intraamniotic infection/inflammation has emerged as an important factor in meconium-stained amniotic fluid in term and preterm gestations, as patients with these conditions have a higher rate of clinical chorioamnionitis and neonatal sepsis. The precise mechanisms linking intraamniotic inflammation to green-stained amniotic fluid have not been determined, but the effects of oxidative stress in heme catabolism have been implicated. Two randomized clinical trials suggest that antibiotic administration decreases the rate of clinical chorioamnionitis in patients with meconium-stained amniotic fluid. A serious complication of meconium-stained amniotic fluid is meconium aspiration syndrome. This condition develops in 5% of cases presenting with meconium-stained amniotic fluid and is a severe complication typical of term newborns. Meconium aspiration syndrome is attributed to the mechanical and chemical effects of aspirated meconium coupled with local and systemic fetal inflammation. Routine naso/oropharyngeal suctioning and tracheal intubation in cases of meconium-stained amniotic fluid have not been shown to be beneficial and are no longer recommended in obstetrical practice. A systematic review of randomized controlled trials suggested that amnioinfusion may decrease the rate of meconium aspiration syndrome. Histologic examination of the fetal membranes for meconium has been invoked in medical legal litigation to time the occurrence of fetal injury. However, inferences have been largely based on the results of in vitro experiments, and extrapolation of such findings to the clinical setting warrants caution. Fetal defecation throughout gestation appears to be a physiologic phenomenon based on ultrasound as well as in observations in animals.

Management of Pregnancy with Cervical Shortening: Real-Life Clinical Challenges

Background and Objectives: Preterm birth is the leading cause of neonatal mortality worldwide and may be responsible for lifelong morbidities in the survivors. Cervical shortening is one of the common pathways to preterm birth associated with its own diagnostic and management challenges. The preventive modalities that have been tested include progesterone supplementation and cervical cerclage and pessaries. The study aimed to assess the management strategies and outcomes in a group of patients with a short cervix during pregnancy or cervical insufficiency. Materials and Methods: Seventy patients from the Riga Maternity Hospital in Riga, Latvia, were included in the prospective longitudinal cohort study between 2017 and 2021. Patients were treated with progesterone, cerclage, and/or pessaries. The signs of intra-amniotic infection/inflammation were assessed, and antibacterial therapy was given when the signs were positive. Results: The rates of PTB were 43.6% (n = 17), 45.5% (n = 5), 61.1% (n = 11), and 50.0% (n = 1) in progesterone only, cerclage, pessary, and cerclage plus pesssary groups, respectively. The progesterone therapy was associated with a reduced preterm birth risk (x2(1) = 6.937, p = 0.008)), whereas positive signs of intra-amniotic infection/inflammation significantly predicted the risk of preterm birth (p = 0.005, OR = 3.82, 95% [CI 1.31–11.11]). Conclusions: A short cervix and bulging membranes, both indicators of intra-amniotic infection/inflammation, are the key risk factors in preterm birth risk predictions. Progesterone supplementation should remain at the forefront of preterm birth prevention. Among patients with a short cervix and especially complex anamnesis, the preterm rates remain high. The successful management of patients with cervical shortening lies between the consensus-based approach for screening, follow-up, and treatment on the one side and personalising medical therapy on the other.

Bacteria in the amniotic fluid without inflammation: early colonization vs. contamination

OBJECTIVES

Intra-amniotic infection, defined by the presence of microorganisms in the amniotic cavity, is often accompanied by intra-amniotic inflammation. Occasionally, laboratories report the growth of bacteria or the presence of microbial nucleic acids in amniotic fluid in the absence of intra-amniotic inflammation. This study was conducted to determine the clinical significance of the presence of bacteria in amniotic fluid samples in the absence of intra-amniotic inflammation.

METHODS

A retrospective cross-sectional study included 360 patients with preterm labor and intact membranes who underwent transabdominal amniocentesis for evaluation of the microbial state of the amniotic cavity as well as intra-amniotic inflammation. Cultivation techniques were used to isolate microorganisms, and broad-range polymerase chain reaction coupled with electrospray ionization mass spectrometry (PCR/ESI-MS) was utilized to detect the nucleic acids of bacteria, viruses, and fungi.

RESULTS

Patients whose amniotic fluid samples evinced microorganisms but did not indicate inflammation had a similar perinatal outcome to those without microorganisms or inflammation [amniocentesis-to-delivery interval (p=0.31), spontaneous preterm birth before 34 weeks (p=0.83), acute placental inflammatory lesions (p=1), and composite neonatal morbidity (p=0.8)].

CONCLUSIONS

The isolation of microorganisms from a sample of amniotic fluid in the absence of intra-amniotic inflammation is indicative of a benign condition, which most likely represents contamination of the specimen during the collection procedure or laboratory processing rather than early colonization or infection.