Unique Considerations: Preterm Prelabor Rupture of Membranes in the Setting of Fetal Surgery and Higher Order Pregnancies

Evidence-based Diagnosis and Treatment of Vasa Previa

Vasa previa is an abnormality of the umbilical cord and fetal membranes that affects ∼1 in 1300 pregnancies. The diagnosis is made by visualization of velamentous fetal vessels coursing within the membranes over the cervix unprotected by Wharton jelly or placenta. When it is not diagnosed prenatally, it is associated with a high risk of fetal death. Prenatal diagnosis of vasa previa using ultrasound, followed by close surveillance, and appropriately timed late preterm delivery by cesarean is associated with intact survival in >95% of cases. In this review, we review epidemiology, risk factors, diagnosis, and management of patients with vasa previa.

Fetoscopic Endoluminal Tracheal Occlusion-Synergic Therapies in the Prenatal Treatment of Congenital Diaphragmatic Hernia

Congenital diaphragmatic hernia (CDH) is a relatively rare and severe developmental disease. Even with the most recent multidisciplinary therapies, the risk for neonatal mortality and morbidity remains high. Recent advancements in prenatal treatments, alongside experimental and clinical data, suggest that fetoscopic endoluminal tracheal occlusion (FETO) promotes lung development and offers a promising strategy against lung hypoplasia and pulmonary hypertension. It is the only existing direct mechanical therapy that intervenes in the regulation of pulmonary pressure. Its influence on lung development also interferes with tissue homeostasis and cell differentiation; it also enhances inflammation and apoptosis. Its physiopathology on cellular and molecular levels is still poorly understood. Unfortunately, the procedure also carries significant pregnancy-, maternal-, and fetus-related risks. Assessing a multifaceted intervention requires a collective view of all aspects. This scoping review uncovers potential materno-fetal procedure-related risks and highlights innovative solutions. Future research on lung development therapies in CDH may focus on the "dual hit" mechanism, combining molecular-targeting drugs and regenerative medicine with the mechanical nature of FETO for synergistic effects.

Management of Acute Saddle Pulmonary Embolism in Pregnancy Following Fetal Surgery

A 33-year-old gravidity three parity three (G3P3) woman at 34 weeks of pregnancy underwent fetal surgery to repair an open lumbosacral myelomeningocele at 22 weeks gestation and experienced preterm premature rupture of membranes as a result. She developed a saddle pulmonary embolus with signs of right heart strain while on prolonged bed rest. She was treated emergently with aspiration thrombectomy and suprarenal inferior vena cava (IVC) filter placement, followed by an uncomplicated cesarean delivery thereafter.

Creation of a novel synthetic amniotic fluid for use in fetal therapy with in vitro testing on human amniotic membranes

BACKGROUND

Normal saline or lactated Ringer's solutions are usually infused at the time of fetal interventions; however, the effect of these fluids on the amniotic membranes has never been assessed. Given both the significant differences between the composition of normal saline solution, lactated Ringer's solution, and amniotic fluid and the significant risk of prematurity after fetal interventions, an investigation is warranted.

OBJECTIVE

This study aimed to evaluate the effect of current amnioinfusion fluids on the human amnion compared with a novel synthetic amniotic fluid.

STUDY DESIGN

Amniotic epithelial cells from term placentas were isolated and cultured per protocol. A synthetic amniotic fluid was created with similar electrolyte, pH, albumin, and glucose concentrations to human amniotic fluid, termed "Amnio-well." The cultured human amniotic epithelium was exposed to normal saline solution, lactated Ringer's solution, and Amnio-well. As a control, 1 group of cells remained in culture media. Cells were evaluated for apoptosis and necrosis. A second analysis to examine if cells could be "rescued" was performed, wherein the cells were allowed to remain in the culture media for an additional 48 hours after amnioinfusion. Subsequently, tissue testing with human amniotic membrane explants was evaluated similarly. Immunofluorescent intensity studies were undertaken to evaluate reactive oxygen species-mediated cell damage. Real-time quantitative polymerase chain reaction was used to evaluate gene expression in apoptotic pathways.

RESULTS

With simulated amnioinfusion, 44%, 52%, and 89% of amniotic epithelial cells were alive after exposure to normal saline solution, lactated Ringer's solution, and Amnio-well, respectively, compared with 85% in control (P<.001). After amnioinfusion and attempted cell rescue, 21%, 44%, 94%, and 88% of cells were alive after exposure to normal saline solution, lactated Ringer's solution, Amnio-well, and control, respectively (P<.001). In simulated amnioinfusion with full-thickness tissue explants, 68%, 80%, 93%, and 96% of cells were viable in normal saline solution, lactated Ringer's solution, Amnio-well, and control, respectively (P<.001). In culture, reactive oxygen species production was higher in normal saline solution, lactated Ringer's solution, and Amnio-well than in control (4.9-, 6.6-, and 1.8-fold higher, respectively, P<.001); however, this could be mitigated in Amnio-well by adding ulin-A-statin and ascorbic acid. Gene expression data revealed abnormal signaling in the p21 and BCL2/BAX pathways with normal saline solution compared with control (P=.006 and P=.041); changes were not seen with Amnio-well.

CONCLUSION

In vitro, normal saline and lactated Ringer's solutions caused increased amniotic membrane reactive oxygen species and cell death. The use of a novel fluid similar to human amniotic fluid led to the normalization of cellular signaling and less cell death.

Association of amnioinfusion volume at the time of surgery for twin-twin transfusion syndrome and latency to delivery

OBJECTIVE

To evaluate the impact of amnioinfusion and other peri-operative factors on pregnancy outcomes in the setting of Twin-twin transfusion syndrome (TTTS) treated via fetoscopic laser photocoagulation (FLP).

METHODS

Retrospective study of TTTS treated via FLP from 2010 to 2019. Pregnancies were grouped by amnioinfusion volume during FLP (<1 L vs. ≥1 L). The primary outcome was latency from surgery to delivery. An amnioinfusion statistic (AIstat) was created for each surgery based on the volume of fluid infused and removed and the preoperative deepest vertical pocket. Regression analysis was planned to assess the association of AIstat with latency.

RESULTS

Patients with amnioinfusion of ≥1 L at the time of FLP had decreased latency from surgery to delivery (61 ± 29.4 vs. 73 ± 28.8 days with amnioinfusion <1 L, p < 0.001) and increased preterm prelabor rupture of membranes (PPROM) <34 weeks (44.7% vs. 33.5%, p = 0.042). Amnioinfusion ≥1 L was associated with an increased risk of delivery <32 weeks (aRR 2.6, 95% CI 1.5-4.5), 30 weeks (aRR 2.4, 95% CI 1.5-3.8), and 28 weeks (aRR 1.9, 95% CI 1.1-2.3). Cox-proportional regression revealed that AIstat was inversely associated with latency (HR 1.1, 95% CI 1.1-1.2).

CONCLUSION

Amnioinfusion ≥1 L during FLP was associated with decreased latency after surgery and increased PPROM <34 weeks.

Pathophysiological Implication of Pattern Recognition Receptors in Fetal Membranes Rupture: RAGE and NLRP Inflammasome

Preterm prelabor ruptures of fetal membranes (pPROM) are a pregnancy complication responsible for 30% of all preterm births. This pathology currently appears more as a consequence of early and uncontrolled process runaway activation, which is usually implicated in the physiologic rupture at term: inflammation. This phenomenon can be septic but also sterile. In this latter case, the inflammation depends on some specific molecules called “alarmins” or “damage-associated molecular patterns” (DAMPs) that are recognized by pattern recognition receptors (PRRs), leading to a microbial-free inflammatory response. Recent data clarify how this activation works and which receptor translates this inflammatory signaling into fetal membranes (FM) to manage a successful rupture after 37 weeks of gestation. In this context, this review focused on two PRRs: the receptor for advanced glycation end-products (RAGE) and the NLRP7 inflammasome.