Chorioamnion plugging and the risk of preterm premature rupture of membranes after laser surgery in twin–twin transfusion syndrome

Objective To examine the incidence of preterm premature rupture of membranes (PPROM) in pregnancies affected by twin–twin transfusion syndrome (TTTS) treated with laser photocoagulation where an absorbable gelatin sponge was used as a chorioamnion sealant of the fetoscopic access port. Method A retrospective review was undertaken of consecutive cases undergoing fetoscopic directed laser surgery for TTTS between October 2006 and November 2008 at Texas Children's Fetal Center, in which an absorbable gelatin sponge, used as a chorioamnion ‘plug’, was placed at the conclusion of the intervention as a possible prophylactic measure to prevent PPROM. We excluded cases that had a failure of plug placement and those in which it was not attempted. PPROM was defined as rupture of membranes before 34 weeks' gestation. A comparison was performed between the PPROM group and a no-PPROM group to determine risk factors and outcomes. Results Successful plug placement occurred in 79 of 84 cases (94%) in which it was attempted after laser surgery, with a rate of PPROM of 34% in these patients. PPROM occurred at an average gestational age of 26.5 ± 3.6 weeks, with an average procedure-to-PPROM interval of 5.2 ± 3.5 weeks. There were no statistically significant differences between the PPROM group and the no-PPROM group in maternal demographics or preoperative parameters including: amniotic fluid volumes in the recipient twin's gestational sac, volume of amnioreduction, and location of the placenta. The procedure-to-delivery interval for the total cohort (n = 79) was 9.2 ± 4.7 weeks, without a significant difference between the two groups (P = 0.08). However, after exclusion of one PPROM outlier, the PPROM group had an average procedure-to-delivery time 2 weeks shorter than the group with no PPROM (P = 0.03). The live birth rates were similar in the PPROM and no-PPROM groups, at 77 and 73%, respectively. However, the average recipient's weight in the PPROM group was significantly lower than in the no-PPROM group (1321 ± 493 vs. 1705 ± 576 g; P = 0.02). Conclusion The rate of PPROM and the mean gestational age at delivery in pregnancies in which an absorbable gelatin sponge was used as a sealant of the fetoscopic port following laser photocoagulation for TTTS were comparable to those that have been reported by other laser centers where membrane sealants were not used. A randomized controlled trial should be considered to evaluate the effect of chorioamnion plugging

Doctor of Philosophy

dissertationInspired by the Sandcastle Worm, biomimetic of the water-borne adhesive was developed by complex coacervation of the synthetic copolyelectrolytes, mimicking the chemistries of the worm glue. The developed underwater adhesive was designed for sealing fetal membranes after fetoscopic surgery in twin-to-twin transfusion syndrome (TTTS) and sealing neural tissue of a fetus in aminiotic sac for spina bifida condition. Complex coacervate with increased bond strength was created by entrapping polyethylene glycol diacrylate (PEG-dA) monomer within the cross-linked coacervate network. Maximum shear bond strength of ~ 1.2 MPa on aluminum substrates was reached. The monomer-filled coacervate had complex flow behavior, thickening at low shear rates and then thinning suddenly with a 16-fold drop in viscosity at shear rates near 6 s-1. The microscale structure of the complex coacervates resembled a three-dimensional porous network of interconnected tubules. This complex coacervate adhesive was used in vitro studies to mimic the uterine wall-fetal membrane interface using a water column with one end and sealed with human fetal membranes and poultry breast, and a defect was created with an 11 French trocar. The coacervate adhesive in conjunction with the multiphase adhesive was used to seal the defect. The sealant withstood an additional traction of 12 g for 30-60 minutes and turbulence of the water column without leakage of fluid or slippage. The adhesive is nontoxic when in direct contact with human fetal membranes in an organ culture setting

Mechanisms and Strategies for Fetal Membrane Weakening and Repair after Trauma

Preterm premature rupture of membranes (PPROM) is the rupture of fetal membranes prior to 37 weeks gestation, and before the onset of labour. PPROM complicates 40% of preterm births, which can result in lifelong disabilities such as respiratory, cardiac and neurological disorders. The causes of PPROM are multifactorial and not well understood. Iatrogenic PPROM is a major complication after invasive fetal interventions and occurs in 6-45% of cases. The high prevalence of iatrogenic PPROM after fetal surgery, due to the absent healing capacity of fetal membranes, reduces the effectiveness of interventions to treat fetal abnormalities demonstrating a need to design therapies with clinical potential. The present study demonstrates that connexin 43 (Cx43) is verexpressed in amniotic membrane (AM) after fetoscopic surgery and artificial in vitro trauma. Cx43 was preferentially distributed in mesenchymal cells compared to epithelial cells, with significant expression in the fibroblast layer compared to the epithelial layer. Polarisation of mesenchymal cell nuclei and collagen fibres at the wound edge is also reported. To investigate mechanotransduction AM weakening mechanisms we used an ex-vivo bioreactor system to study the effect of cyclic tensile strain. Changes in matrix composition (collagen, elastin and GAG), and pro-inflammatory factors (MMPs and PGE2) after 24 hours were studied. Cyclic tensile strain significantly increased GAG synthesis and release of MMPs and PGE2, with an associated reduction of collagen and elastin content, compared to unstrained AM. Furthermore, we demonstrate the reversal of these biochemical changes induced by cyclic tensile strain after AM exposure to pharmacological agents that target the broad group of PI3-kinases and selectively inhibit AKT-1/2 activity. Interestingly, addition of Cx43 and COX-2 inhibiting agents also reversed the biochemical response after cyclic tensile strain. It is suggested that alterations in the ECM composition affects AM integrity and leads to fetal membrane weakening following cyclic tensile strain. Finally, a novel sealing approach based on peptide amphiphile self-assembling gels in the presence of amniotic fluid is developed. By using peptide amphiphiles we were able to seal fetal membrane defects in vitro. This innovative approach provides a new avenue for a tissue engineering approach to prevent PPROM. The results obtained in this study contributes to our understanding on: (1) AM wound healing and repair capacity, the (2) mechanotransduction mechanisms behind AM weakening, and (3) a novel tissue engineering approach to seal fetal membrane defects using self-assembly of peptide amphiphiles for iatrogenic PPROM prevention

Premature rupture of membranes one fetus from a multiple pregnancy

Summary In multiple gestation, premature rupture of fetal membranes (PROM) is an important risk factor for premature delivery and intrauterine infection. The incidence of PROM in twin gestations is threefold of that in singleton pregnancies. The incidence in triplets occurs even more frequently, underlining the role of PROM as a leading cause of infant mortality and morbidity. Besides prematurity, the complications of PROM include umbilical cord compression due to oligohydramnios, cord prolapse, placental abruption, and chorioamnionitis. Together with PROM, chorioamnionitis is held responsible for significant maternal and neonatal morbidity, including endometritis and sepsis in the mother, and early-onset sepsis, respiratory distress syndrome, inborn pneumonia, bronchopulmonary dysplasia, intraventricular hemorrhage, and periventricular white matter injury in the neonate. Furthermore, in twin gestations, PROM remains an independent risk factor for long-term neonatal care. An uncommon situation develops when in multiple gestation PROM affects only one of the fetuses. In such cases, the co-existence in the uterine cavity of the properly developing fetus(es) can be a challenge for the process of medical decision-making. In the present work, limited world literature on the topic was critically reviewed in search of the best possible recommendations for clinical management

How do factors known to cause preterm premature rupture of the membranes affect the ultrastructure and integrity of the amnion?

Introduction: Preterm premature rupture of the fetal amniotic membrane (PPROM) is a cause of preterm birth and affects 2% of women worldwide. Causative factors such as uterine contractions and inflammatory mediators such as PGE2 weaken the fetal membrane due to a loss in biomechanical properties. This study investigated the influence of fibre orientation on the mechanical properties of the amniotic membrane (AM) and the effect of cyclical tensile strain (CTS) regimens on the fibre network within the AM as well as on PGE2 production. Methods: AM were collected from women undergoing term elective Caesarean Section at University College Hospital. AM from the cervix and placental regions were stained to identify fibre orientation. Specimens of AM were then subjected to a strain to failure regimen (Bionix 100, MTS). AM were also subjected to CTS using the Bose bioreactor (Bose Enduratec, UK). Assays for GAG, DNA, collagen, elastin and PGE2 were performed and compared to unstrained membrane. Results: The mechanical properties of the AM were dependent on fibre orientation with samples where fibres were strained in parallel being stronger than those strained perpendicular (p=0.0002 comparing the placental region using Student t test). Histological examination of the fibres revealed an abundance of elastin rather than collagen fibres within the AM. CTS reduced collagen and elastin synthesis within the AM, which was most marked in the cervical region (p=0.002, for elastin and p=0.02 for collagen, both in the cervical region). PGE2 production increased in strained specimens, again, most marked in the cervical region (p=0.00001). Conclusion: This study shows that fibre orientation is an important factor which influences the mechanical properties of the AM. Furthermore, elastin may have a larger contribution to membrane integrity than previously thought. CTS influenced the AM to cause weakening by decreasing the collagen and elastin content and increasing PGE2 production

Placental characteristics and complications in monochorionic twin pregnancies

Increasing body of evidence shows that perinatal outcomes in MC twins are strongly associated with the complications resulting from the unique angioarchitecture in MC placentas, in particular the placental vascular anastomoses. Due to the extensive application of prenatal ultrasound examination, an increasing number and types of complication dedicated for MC twins are being diagnosed. Delineation of the placental characteristics classified by specific complications may shed light on the pathophysiology of various complications in MC twins. One of the great successes in fetal therapy is the introduction of fetoscopic laser coagulation of vascular anastomoses for the treatment of twin–twin transfusion syndrome (TTTS). The investigation on postoperative complications in TTTS placentas is crucial for the further improvement of fetoscopic laser surgery and improvement of perinatal outcome. Since 2002, all MC placentas delivered at the Leiden University Medical Center (LUMC) are consecutively being examined and injected with colored dye. This large database of MC placentas (n=940 in 2016) allows detailed investigation of the pathogenesis and clinical outcome of these rare diseases.  China Scholarship CouncilLUMC / Geneeskund

Healing and repair mechanisms in fetal membrane defects after trauma, strain and fetal surgery

Iatrogenic preterm premature rupture of the fetal membranes (iPPROM) is a major complication after diagnostic or invasive fetal surgical interventions, often associated with adverse perinatal outcomes. Strategies to seal human FM defects with glues, collagen or fibrin plugs have failed to restore structural function of the FM and promote tissue regeneration and defect repair, and none are in routine clinical use. In this thesis, the mechanisms of human FM healing after iatrogenic rupture were investigated, to translate this to pregnancies affected by spontaneous PPROM. The concentration of the gap-junction protein Connexin 43 (Cx43) has been associated with poor wound healing mechanisms in skin models and its expression was increased in FM defect sites taken from fetoscopic interventions. The present study examined the healing mechanisms in amniotic membrane (AM) defects after trauma, cyclic tensile strain (CTS) and fetal surgery. There was evidence that Cx43 increased in expression in term AM following in vitro trauma concurrent with αSMA-expressing myofibroblast differentiation and collagen polarisation examined by SHG imaging. Both the wound healing marker TGFβ1 and Cx43 gene expression were significantly increased after trauma. To investigate mechanotransduction mechanisms, preterm AM was subjected to 2% CTS for 24 hours. Collagen fibres were polarised in the direction of strain concurrent with differential effects on markers for ECM (collagen, elastin, GAGs), inflammation (PGE2) and healing (Cx43 and TGFβ1) in a donor and tissue-dependent manner. Morphological changes in AM cell populations in iPPROM defects and spontaneous PPROM showed myofibroblast differentiation, changes in collagen alignment and lack of wound closure. The results obtained in this study contribute to our knowledge on AM wound healing and repair capabilities, mechanotransduction mechanisms in preterm AM and the influence of fetal surgical interventions on AM cell types and collagen integrity. Establishing how Cx43 regulates AM cell function and healing after trauma and CTS could be an approach to repair defects in FM

Cirugía fetal láser en síndrome de transfusión feto feto y restricción selectiva del crecimiento intrauterino

Introduction: The monochorionic biamniotic twin pregnancy (MCBA) corresponds to approximately 15% of all twin pregnancies and an estimate of 10-15% develop complications proper of these types of pregnancies, such as selective intrauterine fetal growth restriction (IUGRs) and feto-fetal transfusion syndrome (FFTS). Laser fetal surgery allows treatment of these hemodynamic alterations of MCBA by fulguration of placental anastomoses, and it is currently considered the first-choice therapy for FFTS and some IUGR cases. Objectives: To highlight the general aspects of laser fetal surgery and to describe current evidence of its efficacy and safety in FFTS and IUGRs. Methods: Review of articles published during the last five years in indexed journals from the following databases: PUBMED, MEDLINE, EMBASE and Cochrane Library. Review papers, original papers, and systemic reviews were included. Classic relevant papers on fetal surgery history were also included. Results: By means of this nonsystematic review of the literature, 43 articles were considered for the present paper. Conclusion: This review evidences that laser fetal surgery improves the prognosis of FFTS fetuses. The use of this therapy in IUGRs cases has not improved survival.Introducción. El embarazo gemelar monocorial biamniótico (MCBA) corresponde aproximadamente al 15% de los embarazos gemelares y, de estos, se estima que 10 a 15% desarrollan complicaciones propias de este tipo de embarazos, como la restricción selectiva del crecimiento intrauterino (RCIUS) y el síndrome de transfusión feto (STFF). La cirugía fetal láser permite tratar la causa de estas alteraciones hemodinámicas propias de los embarazos MCBA a través de la coagulación de las anastomosis placentarias, y es considerada actualmente la terapia de elección en el STFF y aplicable en algunos casos de RCIUS. Objetivos. Resaltar los aspectos generales de la cirugía fetal láser y describir la evidencia actual de la eficacia y seguridad de su uso en el STFF y la RCIUS. Metodología. Se realizó una búsqueda de la literatura de artículos publicados en revistas indexadas en las siguientes bases de datos: PUBMED, MEDLINE, EMBASE, Cochrane Library. Se incluyeron revisiones de tema, investigaciones originales y revisiones sistemáticas de la literatura, publicadas en los últimos 5 años. Además, se incluyen artículos clásicos relevantes en la historia de la cirugía fetal. Resultados. Producto de la revisión no sistemática de la literatura, se incluyeron 43 para la construcción de la presente revisión. Conclusiones. La presente revisión evidencia que la cirugía láser fetal mejora el pronóstico de los fetos con STFF. El uso de dicha terapia para los casos de restricción de crecimiento intrauterino selectivo no ha mejorado la sobrevida