Intracervical fibrin sealants: a potential treatment for early preterm premature rupture of the membranes

Application of Tissue Engineering and Regenerative Medicine in Prelabor Rupture of Membranes: a Review of the Current Evidence

Preterm prelabor rupture of membranes (PPROM) is the main cause of preterm delivery, resulting in increased perinatal morbidity and mortality. Several techniques have been studied for the healing of ruptured membranes, with some success. Before new techniques using tissue/organ engineering are applied in clinical practice, these techniques must be validated in clinical trials. To address this issue, the objective of this study was to summarize the current literature on interventions to seal or heal the amniotic membranes after PPROM. An electronic search was conducted using the keywords "fetal membranes," "premature rupture," "amnion," "tissue engineering," "fibrin tissue adhesive," "regenerative medicine," "tissue adhesive," "wound healing," and "fetoscopy" through the MEDLINE, Embase, and Cochrane CENTRAL databases, with the limitation of English-language studies. Through a review of the identified studies, it was found that spontaneous healing of the fetal membrane has not been successful. Several efforts have been made to seal membranes before or after rupture using different methods, including amniopatches, collagen, tissue patches, fibrin sealant, mussel-mimetic sealant, engineered cell matrix, and immunological supplements. However, most studies have been conducted in ex vivo or in vivo settings, so the safety and applicability of these techniques to spontaneous rupture of membranes in clinical settings have not been sufficiently tested. Overall, the current evidence is limited regarding the safety and effectiveness of interventions against PPROM.

Intracervical elastomeric sealant in an ex vivo model

BACKGROUND

Premature rupture of membranes occurring in previable midtrimester patients is associated with perinatal mortality, and optimal therapeutic methods are yet to be established.

OBJECTIVE

This study's objective was to investigate whether an elastomeric sealant, which has been used as a hemostatic agent for arterial anastomosis, could plug the uterine endocervical canal to prevent leakage of intrauterine fluid in an ex vivo model.

METHODS

The elastomeric sealant or fibrin glue was applied to the cervix of uteri removed for benign gynecological disease (n = 4). Normal saline was administered into the ex vivo uterine cavity through a catheter using a pressure infusion bag. Intrauterine pressure was measured using a digital pressure gauge, and the pressure at which normal saline started leaking out of the uterine cervix was compared between both the sealants.

RESULTS

No fluid leakage was observed with the elastomeric sealant until the pressure exceeded 20 kPa (150 mmHg), while the leakage onset pressure with fibrin sealant was 6.6 ± 1.8 kPa (50 ± 14 mmHg). The threshold leak pressure where the onset of liquid flow was initiated was significantly different between both the sealants (p < .0001).

CONCLUSIONS

Intracervical elastomeric sealant exhibited powerful fluid leakage prevention in an ex vivo model. The sealant would have potential to prevent the leakage of amniotic fluid in pregnancies with previable premature rupture of membranes.

Sealing procedures for preterm prelabour rupture of membranes

BACKGROUND

Preterm prelabour rupture of the membranes (PPROM) complicates approximately 2% of pregnancies and can be either spontaneous or iatrogenic in nature. Complications of PPROM include prematurity, chorioamnionitis, neonatal sepsis, limb position defects, respiratory distress syndrome, pulmonary hypoplasia chronic lung disease, periventricular leukomalacia and intraventricular haemorrhage.A number of different sealing techniques have been employed which aim to restore a physical barrier against infection and encourage the re-accumulation of amniotic fluid. Routine use of sealants is currently not recommended due to a lack of sufficient evidence to support the safety and effectiveness of such interventions.

OBJECTIVES

To assess the effects of sealing techniques following PPROM against each other, or versus standard care (including no sealant), on maternal and neonatal outcomes.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 May 2016) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing different techniques for sealing preterm prelabour ruptured membranes. Cluster-randomised trials and trials using a cross-over design were not eligible for inclusion in this review. We planned to include abstracts when sufficient information was provided.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and assessed trial quality. Two review authors independently extracted data. Data were checked for accuracy.

MAIN RESULTS

We included two studies (involving 141 women - with data from 124 women). We considered both studies as being at high risk of bias. Meta-analysis was not possible because the included studies examined different interventions (both in comparison with standard care) and reported on few, but different, outcomes. One study compared cervical adapter (mechanical sealing), and the other study examined an immunological membrane sealant. Neither of the included studies reported on this review's primary outcome of interest - perinatal mortality. Similarly, data were not reported for the majority of this review's secondary infant and maternal outcomes. Cervical adapter (mechanical sealing) versus standard care (one study, data from 35 participants)No data were reported for this review's primary outcome - perinatal mortality. Data were reported for few of this review's infant or maternal secondary outcomes.There was no clear difference between the mechanical sealing group and the standard care control in relation to the incidence of neonatal sepsis (risk ratio (RR) 1.19, 95% confidence interval (CI) 0.28 to 5.09 (very low-quality evidence)) or chorioamnionitis (RR 1.19, 95% CI 0.28 to 5.09 (very low-quality evidence)). Oral immunological membrane sealant versus standard care (one study, data from 94 participants)No data were available for perinatal mortality (this review's primary outcome) or for the majority of this review's infant and maternal secondary outcomes. Compared to standard care, the immunological membrane sealant was associated with a reduction in preterm birth less than 37 weeks (RR 0.48, 95% CI 0.34 to 0.68 (very low-quality evidence)) and a reduction in neonatal death (RR 0.38, 95% CI 0.19 to 0.75 (very low-quality evidence)). However, there was no clear difference between groups in terms of neonatal sepsis (RR 0.64, 95% CI 0.28 to 1.46 (very low-quality evidence)) or respiratory distress syndrome (RR 0.64, 95% CI 0.28 to 1.46 (very low-quality evidence)).

AUTHORS' CONCLUSIONS

There is insufficient evidence to evaluate sealing procedures for PPROM. There were no data relating to this review's primary outcome (perinatal mortality) and the majority of our infant and maternal secondary outcomes were not reported in the two included studies.There was limited evidence to suggest that an immunological membrane sealant was associated with a reduction in preterm birth at less than 37 weeks and neonatal death, but these results should be interpreted with caution as this is based on one small study, with a high risk of bias, and the intervention has not been tested in other studies.Although midtrimester PPROM is not a rare occurrence, there are only a small amount of published data addressing the benefits and risks of sealing procedures. Most of these studies are retrospective and cohort based and could therefore not be included in our data-analysis.This review highlights the paucity of prospective randomised trials in this area. Current evidence provides limited information both on effectiveness and safety for the interventions described. Given the paucity of high-quality data, we recommend that future research efforts focus on the conduct of randomised trials assessing the effect of promising interventions that have been only evaluated to date in cohort studies (e.g. amniopatch). Future trials should address outcomes including perinatal mortality, preterm birth, neonatal death, respiratory distress syndrome, neonatal sepsis and developmental delay. They should also evaluate maternal outcomes including sepsis, mode of delivery, length of hospital stay and emotional well-being.

Severe midtrimester oligohydramnios: treatment strategies

PURPOSE OF REVIEW

Nearly 1% of pregnancies are affected by some type of midtrimester oligohydramnios. Evidence is currently accumulating that suggests the better efficacy of the new therapeutic procedures relative to conventional management. This review summarizes the available evidence.

RECENT FINDINGS

The prolongation of the period between the diagnosis of oligohydramnios and delivery following amnioinfusion and amniopatch techniques appears to be strongly associated with the gestational age and whether the situation was based on rupture of the membranes or not. Case series reveal that amnioinfusion significantly improves the perinatal outcome and prolongs the pregnancy in severe second-trimester oligohydramnios in both idiopathic cases and those involving rupture of the amniotic membranes [preterm prelabor rupture of the membranes (PPROM)]. There is clear evidence of a lower frequency of perinatal complications and successfully prolonged gestation in iatrogenic PPROM after the amniopatch technique relative to population controls.

SUMMARY

Identification of potentially modifiable risk factors for the successful prolongation of pregnancy complicated with midtrimester oligohydramnios, and previable PPROM is needed for the improvement of treatment strategies and prognosis. Randomized trials are needed to determine whether amniotic fluid-replenishing strategies can improve pregnancy outcomes.

Transabdominal amnioinfusion for preterm premature rupture of membranes: a systematic review and metaanalysis of randomized and observational studies

OBJECTIVE

The purpose of this study was to review systematically the efficacy of transabdominal amnioinfusion (TA) in early preterm premature rupture of membranes (PPROM).

STUDY DESIGN

We conducted a literature search of EMBASE, MEDLINE, and ClinicalTrials.gov databases and identified studies in which TA was used in cases of proven PPROM and oligohydramnios. Risk of bias was assessed for observational studies and randomized controlled trials. Primary outcomes were latency period and perinatal mortality rates.

RESULTS

Four observational studies (n = 147) and 3 randomized controlled trials (n = 165) were eligible. Pooled latency period was 14.4 (range, 8.2-20.6) and 11.41 (range -3.4 to 26.2) days longer in the TA group in the observational and the randomized controlled trials, respectively. Perinatal mortality rates were reduced among the treatment groups in both the observational studies (odds ratio, 0.12; 95% confidence interval, 0.02-0.61) and the randomized controlled trials (odds ratio, 0.33; 95% confidence interval, 0.10-1.12).

CONCLUSION

Serial TA for early PPROM may improve early PPROM-associated morbidity and mortality rates. Additional adequately powered randomized control trials are needed.

Pulmonary effects of prolonged oligohydramnios following mid-trimester rupture of the membranes--antenatal and postnatal management

Mid-trimester, preterm prelabour rupture of the membranes (PPROM) with prolonged oligohydramnios remains a challenge for both obstetricians and neonatologists. Although survival rates have improved, morbidity remains common particularly due to pulmonary insufficiency and pulmonary hypertension. The aetiology of abnormal lung development is unknown but may depend critically on pulmonary vascular development. Antenatal evaluation of at-risk foetuses by three-dimensional ultrasound and MRI is possible but the techniques need to be further assessed. Antenatal corticosteroids given in cases of PPROM reduce the incidence of neonatal death, respiratory distress syndrome, intraventricular haemorrhage and necrotising enterocolitis without increasing maternal or neonatal infection. The true risk-benefit ratio of antibiotics, tocolysis and strategies to normalise amniotic fluid volume remains less clear. There is no consensus regarding the optimal ventilation strategy to support infants with pulmonary insufficiency following PPROM, and further work is required to determine whether and which pulmonary vasodilators improve long-term outcome in these infants.

Management of oligohydramnios in pregnancy

The finding of oligohydramnios in pregnancy is problematic. The various mechanisms that control amniotic fluid, the inability to precisely measure and quantify the amount, and the relevance of a "decreased" amount of fluid make the management of this finding unclear. Given the limited amount of data, the single deepest vertical pocket may be a better method than the amniotic fluid index to define oligohydramnios. A large prospective study is needed to develop the most optimal management recommendations, especially for idiopathic oligohydramnios at or near term.

Laser therapy for twin-to-twin transfusion syndrome (TTTS)

Monochorionic twins are subjected to specific complications which originate in either imbalance or abnormality of the single placenta serving two twins including twin-to-twin transfusion syndrome. The diagnosis is well established in overt clinical forms with the association of polyuric polyhydramnios and oliguric oligohydramnios. The best treatment of cases presenting before 26 weeks of gestion is fetoscopic laser ablation of the intertwin anastomoses on the chorionic plate. Although subjected to subtle variations, the core technique follows robust guidelines which could help understanding and acquiring the required skills and experience to perform this procedure. However appropriate and tailored hands-on training and appropriate perinatal set-up are critical not only for surgical management but also for the follow-up and management of related complications.

Amniopatch for iatrogenic rupture of the fetal membranes

With the increased use of invasive fetal procedures, the number of women facing post-procedure membrane rupture is increasing. Here we review the use of platelets and fresh frozen plasma for sealing iatrogenic fetal membrane defects by describing the mechanisms of action of the amniopatch procedure as well as published experience. In cases of iatrogenic preterm pre-labour rupture of the membranes, amniopatch effectively seals the fetal membranes in over two-thirds of cases. There is a risk of 16% of in utero fetal death, which may occur at varying intervals from the procedure and often for unknown reasons. Amniopatch has also been used as a treatment of chorionic membrane separation. In summary, current experience suggests that in cases of early onset but persistent amniotic fluid leakage following an invasive fetal procedure, amniopatch is an option.

[Amniopatch to treat iatrogenic rupture of the fetal membranes]

OBJECTIVE

With the increased use of invasive fetal procedures, the number of patients facing postprocedure membrane rupture is increasing. We aimed to describe the use of platelets and fresh frozen plasma for sealing iatrogenic fetal membrane defects.

PATIENTS AND METHODS

We describe the mechanisms of action of the amniopatch procedure as well as published experience.

RESULTS

Amniopatch effectively sealed the fetal membranes in over two thirds of published cases (n=44). There is a risk of 17% of in utero fetal death, which may occur remotely from the procedure and is often unexplained.

DISCUSSION AND CONCLUSION

In case of early onset but persistent amniotic fluid leakage following an invasive fetal procedure, amniopatch may be offered.

Mussel-mimetic tissue adhesive for fetal membrane repair: a standardized ex vivo evaluation using elastomeric membranes

OBJECTIVE

Iatrogenic preterm premature rupture of membranes (iPPROM), the main complication of invasive interventions in the prenatal period, seriously limits the benefit of diagnostic or surgical prenatal procedures. This study aimed to evaluate preventive plugging of punctured fetal membranes in an ex vivo situation using a new mussel-mimetic tissue adhesive (mussel glue) to inhibit leakage.

METHODS

A novel biomechanical test device that tests the closure of injured membranes under near-physiological conditions was used. Mussel glue, a poly(ethylene glycol)-based hydrogel, was used to seal membrane defects of up to 3 mm in mechanically well-defined elastomeric membranes with three different degrees of stiffness.

RESULTS

Elastomeric test membranes were successfully employed for testing mussel glue under well-defined conditions. Mussel glue plugs were distended by up to 94%, which translated to an improved sealing efficiency on elastomeric membranes with high stiffness. For the stiffest membrane tested, a critical burst pressure of 48 mbar (36 mmHg) was accomplished in this ex vivo setting.

CONCLUSIONS

Mussel glue appears to efficiently seal membrane defects under well-standardized ex vivo conditions. As repaired membranes resist pressures measured in amniotic cavities, mussel glue might represent a novel sealing method for iatrogenic membrane defects.

Precipitated egg white as a sealant for iatrogenic preterm premature rupture of the membranes

OBJECTIVE

The objective of the study was to investigate whether precipitated egg white could be used as a sealant for iatrogenic injury to fetal membranes.

STUDY DESIGN

Membranes were collected, washed, and affixed to the bottom of glass cylinders filled with second-trimester amniotic fluid. An iatrogenic defect with an 8-gauge needle was created in the test column, and precipitated egg white was added. Fluid levels in test and control columns were compared over a 14 day period. The amount of fluid added to columns was compared using the Wilcoxon rank sum test; P < .05 was considered significant.

RESULTS

Test columns (20/21) maintained seal integrity for 14 days and required less amniotic fluid to be added as compared with controls: median: 55.1 mL (range, 20-137 mL) vs 61.6 mL (range, 22-159 mL), respectively (P < .01).

CONCLUSION

Precipitated egg white has the potential to seal iatrogenic membrane defects for up to 14 days' duration.

A new fibrin sealant from Crotalus durissus terrificus venom: applications in medicine

Fibrin sealant, a widely available tissue adhesive, has been used since 1940 in a variety of clinical applications. Commercially available fibrin sealant products are synthesized from bovine thrombin and human fibrinogen, which may transmit infectious diseases, and recipients may also develop antibodies against bovine thrombin. Bearing these disadvantages in mind, a new fibrin sealant was developed in 1989 by a group of researchers from the Center for the Study of Venoms and Venomous Animals, in Sao Paulo State, Brazil. The main purpose was to produce an adhesive fibrin without using human blood, to avoid transmitting infectious diseases. The components of this novel sealant were extracted from large animals and a serine proteinase extracted from Crotalus durissus terrificus snake venom. The applicability of this sealant was tested in animals and humans with beneficial results. The new fibrin sealant can be a useful tool clinically due to its flexibility and diversity of applications. This sealant is a biological and biodegradable product that (1) does not produce adverse reactions, (1) contains no human blood, (3) has a good adhesive capacity, (4) gives no transmission of infectious diseases, and (5) may be used as an adjuvant in conventional suture procedures. The effectiveness of this new fibrin sealant is reviewed and its development and employment are described.

The management of preterm premature rupture of the membranes near the limit of fetal viability

Preterm premature rupture of the membranes near the limit of fetal viability is an uncommon complication of pregnancy, affecting approximately 4 in 1000 gravidas. However, maternal, fetal, and neonatal complications resulting from this condition are significant and include chorioamnionitis, pulmonary hypoplasia, restriction deformities, fetal loss, and complications of extreme prematurity among surviving infants. In this article, we review the literature regarding pregnancy outcomes after preterm premature rupture of the membranes near the limit of viability, and the data on traditional and nontraditional interventions to improve outcomes. An approach to patients who present with preterm premature rupture of the membranes near the limit of viability will be proposed.

Treatment with amniopatch of premature rupture of membranes after first-trimester chorionic villus sampling

OBJECTIVE

To assess the amniopatch procedure when premature rupture of membranes occurs after first-trimester chorionic villus sampling (CVS).

STUDY DESIGN

From May 2001 to June 2004, the amniopatch procedure was offered in cases of premature rupture of membranes after CVS when severe oligohydramnios was present (largest vertical pocket < 2 cm) and persistent (more than 1 week).

RESULTS

The amniopatch was placed in five pregnancies at 12-18 weeks of gestation, resulting in amniotic fluid restoration in all but one pregnancy. In three pregnancies, fetal demise was observed at 1, 2 and 36 days after the procedure. The last procedure resulted in a healthy newborn.

CONCLUSION

Although the amniopatch restored normal amniotic fluid levels in all cases, 4 of the 5 cases resulted in fetal demise.

Manufacture of a Cell-free Amnion Matrix Scaffold that Supports Amnion Cell Outgrowth In Vitro

We manufactured a cell-free extracellular matrix scaffolds in order to obtain a support material for amnion cell outgrowth, eventually being used for repair of prematurely ruptured fetal membrane. Human preterm or term amnion tissue was separated into its collagenous extracellular matrix and cell components. The acellular scaffold was explored for its capacity to support regrowth of isolated human amnion epithelial or mesenchymal cells in vitro. The outgrowth of amnion cells on and in the scaffold was investigated by scanning and transmission electron microscopy, and confocal laser scanning microscopy. Cell-free amnion matrix scaffolds demonstrated a porous collagen fiber network similar as in native amnion. Inoculation of acellular amnion scaffolds with human amnion cells revealed that its property to support amnion cell outgrowth was retained. Amnion epithelial and mesenchymal cells were found to grow into dense layers on the surface of the scaffold within 3-4 days and 7-8 days, respectively, and to some extent, invaded the scaffold during the culture period. Manufactured acellular amnion matrix retains structural and functional properties required for cell outgrowth in vitro. It may become useful to repair prematurely ruptured fetal membranes.

Fetal membrane healing after spontaneous and iatrogenic membrane rupture: a review of current evidence

In view of the important protective role of the fetal membranes, wound sealing, tissue regeneration, or wound healing could be life saving in cases of preterm premature rupture of the membranes. Although many investigators are studying the causes of preterm premature rupture of membranes, the emphasis has not been on the wound healing capacity of the fetal membranes. In this review, the relevant literature on the pathophysiologic condition that leads to preterm premature rupture of membranes will be summarized to emphasize a continuum of events between rupture and repair. We will present the current knowledge on fetal membrane wound healing and discuss the clinical implications of these findings. We will critically discuss recent experimental interventions in women to seal or heal the fetal membranes after preterm premature rupture of membranes.

Premature rupture of membranes at 20 weeks: report of a successful outcome after transcervical application of fibrin glue

A 30-year-old primigravida was admitted to hospital at 20 weeks of gestation because of premature rupture of membranes and oligohydramnios. The patient was maintained in bed rest and given intravenous ampicillin. Forty-eight hours later, after documenting the absence of infection and maintenance of the oligohydramnios, fibrin glue was applied transcervically under ultrasound control. There was subjective improvement in amniotic fluid volume after treatment, but always within the criteria of oligohydramnios. Fibrin glue application was repeated twice due to reported increase in fluid loss and diminished amniotic fluid volume on ultrasound. Amoxicillin per os was started at 23 weeks, and clavulanic acid was added at 26 weeks due to the isolation of an Escherichia coli on cervical-vaginal cultures. No signs of infection ensued until 34 weeks, when an axillary temperature of 39.5 degrees C was detected together with a non-reassuring cardiotocographic pattern, the latter leading to the performance of an urgent cesarean section. The newborn had an Apgar score of 9/10/10, umbilical artery pH of 7.32, and no external deformities. He showed no signs of lung hypoplasia and required no oxygen supplementation. Oropharyngeal and blood cultures revealed an E. coli infection and antibiotic treatment was started. No further complications occurred and he was discharged home on the 8th day of life. At 12 months, the child reveals a normal development. The mother had a mild and short-lasting wound infection and was discharged on the 8th postoperative day.

Predictors of perinatal survival in a cohort of pregnancies with severe oligohydramnios due to premature rupture of membranes at <26 weeks managed with serial amnioinfusions

OBJECTIVE

To evaluate whether successful amnioinfusion is an independent predictor of perinatal survival in a cohort of cases with extreme and persistent oligohydramnios due to preterm premature rupture of membranes (pPROM) who reached viability and were managed with serial amnioinfusions.

STUDY DESIGN

We included all consecutive singleton pregnancies with pPROM at <26 weeks and oligohydramnios lasting >4 days between 1/1991 and 12/2001 and who consented to undergo amnioinfusion (n=77). Women received serial transabdominal amnioinfusions in an attempt to maintain a pocket of fluid >2 cm. The procedure was deemed successful if the median deepest pocket of fluid during the latency period was >2 cm. Excluded were miscarriages (n=10), fetal deaths before viability (24 weeks) (n=15), and cases that did not develop oligohydramnios (n=17). Prenatal predictors of outcome were compared between cases who survived the perinatal period and those who did not using Wilcoxon rank-sum test, Fisher's exact test and stepwise logistic regression analysis, with a two-tailed P<0.05 considered significant.

RESULTS

Of the 35 patients fulfilling the study criteria, 20 (57%) survived the perinatal period. Perinatal survivors had similar gestational age at pPROM (P=0.68) and at first amnioinfusion (P=0.53) as those who died in the perinatal period, but longer latency (P=0.013). Consequently, median gestational age at delivery [29.2 (25.4-35.3) weeks versus 26.1 (24.0-34.0) weeks, P<0.001] and median birth weight [1220 (650-2240) g versus 863 (520-2200) g, P=0.001] were significantly greater among survivors than among those who died. Significant predictors of survival at univariate analysis were entered into a stepwise logistic regression analysis in the chronological order in which they normally occur. The analysis demonstrated that successful amnioinfusion (OR=6.9, 95% CI 1.2-40.4) and administration of steroids (OR=14.6, 95% CI 1.5-144.1) were independent and significant predictors of perinatal survival.

CONCLUSION

In a cohort of women with pPROM at <26 weeks and severe oligohydramnios managed with serial amnioinfusions, successful procedures and prenatal administration of corticosteroids are the only independent predictors of perinatal survival.

Intracervical application of synthetic hydrogel sealant for preterm prelabor rupture of membranes: a case report

We report a case of prelabor rupture of membranes at 20 weeks' gestation where a hydrogel sealant was applied to the cervical canal in order to maintain an adequate liquor volume in the second trimester. The use of this agent for the purpose of creating plug has not been reported to date.

Human preterm amnion cells cultured in 3-dimensional collagen I and fibrin matrices for tissue engineering purposes

OBJECTIVE

In this study, human preterm amnion cells were investigated in 3-dimensional (3D) cell-matrix culture systems in an attempt to design therapeutic strategies for preterm premature rupture of the membranes.

STUDY DESIGN

Three-dimensional collagen I and fibrin cell-containing biomatrices were created to mimic the architecture of native amnion. Amnion mesenchymal cells were embedded in 3D matrices, and epithelial cells were placed on top of these matrices. Cell viability and morphology were visualized by DiI-ac-LDL, F-actin, and nuclear staining. Proteolytic activity of matrix metalloproteinases (MMPs) was investigated using gelatine zymography.

RESULTS

Preterm amnion epithelial and mesenchymal cells cultured in collagen I and fibrin matrices assume cell morphologies similar to those observed in vivo. Mesenchymal cells were capable of remodelling collagen I, as seen by extensive volume contraction, by 40% at day 1 and 80% at day 5. Matrix contraction was independent of the presence of epithelial cells, and could not be inhibited by GM6001 and/or aprotinin. No contraction was observed in fibrin matrices over 8 days. The migratory response of mesenchymal cells cultured in 3D fibrin matrices supplemented with fibronectin was associated with specific activated MMP-9.

CONCLUSION

Three-dimensional fibrin matrices might be useful in amnion cell tissue engineering, including cell-matrix transplantation.

Preterm premature rupture of the membranes: current approaches to evaluation and management

Preterm premature rupture of the membranes (PROM) complicates 3% of pregnancies and is responsible for approximately one third of all preterm births. Because preterm PROM presents a clinical situation where early delivery is to be anticipated and prenatal and neonatal complications are common, the physician caring for women with this common obstetric complication has an opportunity to intervene in a manner that can improve perinatal outcome. This article addresses clinically relevant questions regarding the evaluation and management of preterm PROM.

Preterm premature rupture of the membranes: diagnosis and management

Preterm premature rupture of the membranes (preterm PROM) is a common and significant cause of preterm birth and perinatal morbidity and mortality. The obstetric caregiver has the opportunity significantly to alter pregnancy and perinatal outcome for women suffering from this complication. Although management is often predetermined by the presence of clinical infection, vaginal bleeding, labor, or nonreassuring fetal heart-rate pattern on admission, a gestational age-based approach to the management of the stable patient with preterm PROM offers the potential to reduce perinatal infectious and gestational age-dependent morbidity for patients who are amenable to conservative management.

Successful patching of iatrogenic rupture of the fetal membranes

Rupture of the fetal membranes is a common, but potentially serious complication of invasive fetal procedures. Quintero described a technique to seal the fetal membrane defect by means of a bloodpatch, usually called 'amniopatch' in this application. The successful use in two consecutive patients with ruptured membranes after a fetoscopic intervention at respectively 17 and 22 weeks' gestational age is described, together with a literature review of published experience.

In vitro lesion repair by human amnion epithelial and mesenchymal cells

OBJECTIVE

The purpose of this study was to compare wound healing by human amnion epithelial and mesenchymal cells from preterm and term placenta with the use of an in vitro lesion repair assay.

STUDY DESIGN

Lesions were created in confluent monolayers of amnion epithelial and mesenchymal cells from preterm and term placentas. The repair was monitored by the measurement of the lesion area and the response to potential stimulants (platelet-derived growth factor, tumor necrosis factor-alpha, fibrinogen, and phorbol myristate acetate). Cell proliferation was detected with 5-bromodeoxyuridine staining.

RESULTS

Lesion repair was complete within 40 hours in control epithelial cultures from preterm and term placenta but incomplete in mesenchymal cultures (preterm cells, 80%; term cells, 40%). Platelet-derived growth factor, tumor necrosis factor-alpha, fibrinogen, and phorbol myristate acetate did not accelerate repair in either cell type.

CONCLUSION

An in vitro lesion repair assay revealed the differences in lesion repair capacity between amnion epithelial and mesenchymal cells and between mesenchymal cells from preterm and term placenta.

Test amnioinfusion to determine suitability for serial therapeutic amnioinfusion in midtrimester premature rupture of membranes

OBJECTIVE

To evaluate whether a test amnioinfusion procedure is useful in selecting cases of midtrimester preterm premature rupture of membranes (PPROM) which may benefit from serial amnioinfusions if the initial fluid is retained.

STUDY DESIGN

The Centre for Fetal Care database between 1992 and 2000 was reviewed for women with PPROM <26 weeks who had undergone amnioinfusion. Amniotic fluid index (AFI) was assessed before and after a test amnioinfusion procedure. Those who retained fluid > or =48 h underwent serial AFI assessment with a view to serial amnioinfusion when oligohydramnios recurred.

RESULTS

Eighty-five amnioinfusion procedures were performed in 60 women with oligohydramnios. Nineteen of these women presented with confirmed PPROM at a median gestation of 19 (range 15-22) weeks and severe olighohydramnios (median AFI 1, range 0-3 cm), in whom 20 test amnioinfusions were carried out. Two amnioinfusions were abandoned during the procedure because of fetal bradycardia and both mothers opted for termination of pregnancy. Only 4 women retained fluid during the test amnioinfusion, 1 of whom miscarried at 19 weeks before serial amnioinfusion could be started. The remaining 3 underwent a median of 4 (range 1-6) serial amnioinfusion procedures; none had evidence of pulmonary hypoplasia. Thirteen (68%) leaked fluid within 48 h; within this group there was 1 subsequent miscarriage and 9 pregnancy terminations. The remaining 3 pregnancies resulted in livebirths 2 of which had pulmonary hypoplasia with 1 early neonatal death. Overall survival was poor (4/19), largely attributed to the high incidence of terminations in the presence of persistent severe oligohydramnios. In continuing pregnancies reaching viability survival was 67% (4 of 6).

CONCLUSION

Three quarters of women with mid-trimester PPROM lose fluid at test amnioinfusion and therefore would not be suitable candidates for serial amnioinfusion. However, if infused fluid is retained, this allows subsequent serial amnioinfusion and prolongation of pregnancy in about 75%, with an attendant decrease in the risk of pulmonary hypoplasia. However, even successful serial amnioinfusion remains associated with procedure-related complications (i.e. chorioamnionitis, placental abruption) which themselves may predispose to preterm delivery.

An aggressive interventional protocol for early midtrimester premature rupture of the membranes using gelatin sponge for cervical plugging

OBJECTIVE

This study was performed to evaluate a protocol for treatment of previable premature rupture of membranes (PROM) that includes the administration of gelatin sponge to retard the loss of fluid from the amniotic cavity.

STUDY DESIGN

Women with PROM at <or=21 weeks' gestation with a structurally normal singleton; having no evidence of infection, active bleeding, or labor; and a maximum vertical fluid pocket of less than 1.5 cm were candidates. Interventions included hospital admission, amnioinfusion, cervical cerclage, administration of gelatin sponge (Gelfoam) into the amniotic cavity, antibiotic administration, and perioperative tocolysis. Weekly assessment of fluid status was performed and if oligohydramnios returned, patients were offered repeat amnioinfusion.

RESULTS

Fifteen women with PROM at 17.9 +/- 2.2 weeks' gestation (range 13-21 weeks) underwent this protocol. Spontaneous PROM was diagnosed in 14 patients and one had iatrogenic PROM after fetoscopy. Eight fetuses reached a viable gestational age (>or=24 weeks, 53%), with six of these newborn infants surviving to hospital discharge (30%) and two suffering intrauterine death. The average gestational age of delivery for survivors was 31.8 +/- 4.3 weeks, range 25 to 36 weeks. Talipes equivarus was observed in three survivors (50%). Bilateral hip dysplasia and torticollis were also diagnosed in two infants. Respiratory distress syndrome was diagnosed in all cases delivered at less than 32 weeks but was not observed thereafter. No adverse sequelae have been attributed to gelatin sponge exposure.

CONCLUSION

The observed survival rate with this interventional approach in a population at highest risk for pregnancy loss justifies further study of this treatment strategy. This protocol may not reduce the rate of musculoskeletal abnormalities.

An in vitro model and case report that used gelatin sponge to restore amniotic fluid volume after spontaneous premature rupture of the membranes

OBJECTIVE

The purpose of this project was to study an in vitro model for plugging membrane defects with gelatin sponge and to develop a method with which to use this material to treat premature rupture of the membranes.

STUDY DESIGN

Fetal membranes were fixed over the opening of a flask that was filled with saline solution and gelatin sponge. Defects of various sizes were created, and the usefulness of differing sizes of gelatin sponge to obstruct the defects was observed. This technique was then applied to a case of previable, spontaneous premature rupture of the membranes.

RESULTS

Fifteen amniotomies were performed in the in vitro model. The gelatin sponge obstructed all defects less than 7 mm in length, when pieces up to 1 x 1 cm in dimension (n = 8 amniotomies) were used. For larger defects or those defects with a complex shape (such as cruciate), gelatin sponge was not effective at arresting fluid loss (n = 4 amniotomies). An inspection of larger gelatin sponge pieces, after instillation through a 12-gauge angiocatheter, revealed 36% (15 of 42 pieces) of 1 x 1 - cm pieces remained intact. A case of spontaneous, previable premature rupture of the membranes was treated with this material. A favorable outcome was observed.

CONCLUSION

Gelatin sponge is successful at arresting the egress of fluid through membrane defects when smaller defects are present. Complex or larger linear defects may not be treated by this method alone and necessitate adjuvant therapies. This therapeutic strategy can be applied to cases of previable, spontaneous premature rupture of the membranes.

In vitro sealing of punctured fetal membranes: potential treatment for midtrimester premature rupture of membranes

OBJECTIVE

Midtrimester premature rupture of membranes causes significant perinatal morbidity and death. No effective treatment exists. We investigated (1) whether a needle puncture in the fetal membranes could be sealed in vitro and (2) the optimal composition of the sealant to be used.

STUDY DESIGN

Membranes from second trimester pregnancies (16-24 weeks of gestation) were stretched over a modified syringe with a 2.5-cm open diameter. The syringe was filled with 20 mL of second trimester amniotic fluid, and the membrane was punctured with a 20-gauge needle. Sealants were injected into the amniotic fluid. The primary outcome variable was time for leakage of amniotic fluid. Median times for leakage for the formulations were compared by Wilcoxon exact rank sum test.

RESULTS

Platelets alone failed to seal the puncture site. All other formulations stopped leakage temporarily. Tisseel (Baxter Corp, Glendale, Calif) and cryoprecipitate/thrombin preparations led to more prolonged sealing of punctured amniotic membranes than platelets (P <.01) and were not significantly different from each other.

CONCLUSION

Of the sealants tested in vitro, amniotic membranes are best sealed by a fibrin/thrombin-based sealant.