Evaluation of Regenerative Efficacy of Amnion and Chorion Membrane in Treatment of Mandibular Molar Furcation Defects: A Clinico-radiographic Study.

AIM: Amnion and chorion membranes possess unique inherited biological properties that enhance wound healing and may accelerate periodontal regeneration. The present study aims to evaluate and compare the efficacy of amnion and chorion membranes in the treatment of furcation defects. MATERIALS AND METHODS: A total of 20 patients were selected and were randomly allocated to group I and group II with 10 subjects in each group. Amnion and chorion membranes are placental-derived membranes that accelerate regeneration by having natural growth factors with their antimicrobial and inflammation reduction properties. Group I was treated using bone grafting with decalcified freeze-dried bone allograft (DFDBA) and placement of amnion as a membrane for guided tissue regeneration (GTR) whereas group II was treated using bone grafting with DFDBA and placement of chorion as a membrane for GTR. The patients were followed for clinical and radiographic parameters and were evaluated between 3 and 6 months after surgery. RESULT: In intragroup comparison, a significant difference was evident in both the groups for all the clinical and radiographic parameters within the groups. (p = 0.01) This means both amnion and chorion membranes showed statistically significant regenerative efficacy. In intergroup comparison, the results show that all the clinical parameters and radiographic parameters show no significant difference between the groups. CONCLUSION: The amnion and chorion membranes had similar regenerative efficacy in combination with DFDBA in patients with buccal degree II furcation defects in mandibular molars. CLINICAL SIGNIFICANCE: The amnion and chorion membranes have shown significant improvement in clinical and radiographic parameters when used for the treatment of buccal degree II furcation defects in mandibular molars. How to cite this article: Mallapragda S, Gupta R, Gupta S, et al. Evaluation of Regenerative Efficacy of Amnion and Chorion Membrane in Treatment of Mandibular Molar Furcation Defects: A Clinico-radiographic Study. J Contemp Dent Pract 2024;25(2):160-167.

Periodontal Regeneration with Amnion-Chorion Membrane on Root Surface: A Retrospective Case Series.

This retrospective case series investigated the clinical and radiographic outcomes in 19 intrabony defects treated with periodontal regenerative therapy utilizing a combined approach. Placing an amnion-chorion membrane (ACM) as a biologic modifier on the root surface of the periodontally diseased tooth, combined with bone substitutes and an additional ACM as a barrier membrane, the treated sites were examined 8 to 24 months after the therapy. The preoperative (baseline) mean probing pocket depth (PPD) was 7.21 ± 1.08 mm, and the mean clinical attachment level (CAL) was 7.68 ± 1.49 mm. A mean PPD reduction of 4.05 ± 1.22 mm, CAL gain of 3.68 ± 1.34 mm, and 73.91% ± 22.02% of bone fill were recorded postoperatively. Without any adverse events, root-surface application of ACM as a biologic material in periodontal regenerative therapy could be a safe and cost-effective approach.

VISTA technique in combination with chorionic allograft for gingival recession coverage: a case series.

The vestibular incision subperiosteal tunnel access (VISTA) technique, a minimally invasive procedure, achieves multitooth recession coverage with only a single access incision. Use of fetal membranes such as the amnion and chorion has become increasingly popular in the field of dentistry due to their lack of immunogenicity and added advantage of growth factors. The present case series aimed to provide information regarding the potential advantage of placing a chorionic membrane in combination with the VISTA technique to achieve recession coverage. Eight healthy adult patients presenting with 24 Miller Class I multitooth gingival recession defects were surgically treated with the VISTA technique and a chorionic membrane. The clinical parameters measured at baseline and 1, 3, and 6 months postoperatively were probing depth, clinical attachment level, width of keratinized gingiva, thickness of attached gingiva, and height of gingival recession. A repeated-measures analysis of variance with a post hoc Bonferroni test was carried out to compare the baseline values with the 1-, 3-, and 6-month postoperative values. The mean (SD) height of gingival recession was significantly reduced from 2.04 (0.67) mm at baseline to 0.71 (0.71) mm at 6 months (P < 0.001). In addition, there were statistically significant gains in the clinical attachment level, width of keratinized gingiva, and thickness of attached gingiva from baseline to 6 months postoperatively (P < 0.001). The probing depth remained the same at all measurement times. The VISTA technique provided good results in terms of recession coverage. Although there was an improvement in the gingival biotype, the placement of a chorionic membrane did not provide any advantage in terms of percentage of root coverage.

US Evaluation of Twin Pregnancies: Importance of Chorionicity and Amnionicity.

The twin birth rate is increasing in the United States. Twin pregnancies can be dichorionic or monochorionic (MC). MC twins account for 20% of twin pregnancies but 30% of all-cause pregnancy-related complications. This article describes the imaging findings that establish chorionicity and amnionicity. Ideally, these are established in the first trimester when accuracy is high, but they can also be determined later in pregnancy. Complications unique to MC twin pregnancy include twin-twin transfusion syndrome, twin anemia polycythemia sequence, twin reversed arterial perfusion sequence, and selective fetal growth restriction. The US features, staging systems, and management of these complications are reviewed, and the consequences of MC twin demise are illustrated. Ongoing surveillance for these conditions starts at 16 weeks gestation. Monoamniotic (MA) twins are a small subset of MC twins. In addition to all of the MC complications, specific MA complications include cord entanglement and conjoined twinning. Radiologists must be able to determine chorionicity and amnionicity and should be aware of potential complications so that patients may be referred to appropriate regional specialized centers. A proposed algorithm for referral to specialized fetal treatment centers is outlined. Online supplemental material is available for this article. ©RSNA, 2019.

Isolated Ascites in a Monochorionic Twin after Fetoscopic Laser Ablation Is Not Necessarily Secondary to Recurrence or Anaemia: Bowel Complications in Twin-to-Twin Transfusion Syndrome after Fetoscopic Laser Ablation.

BACKGROUND/PURPOSE: We report a case study of jejunal atresia and the results of a systematic literature review of all reported cases of bowel complications occurring after fetoscopic laser ablation (FLA) for the treatment of twin-to-twin transfusion syndrome (TTTS). METHODS: A systematic literature review was performed of bowel complications after FLA for TTTS according to PRISMA guidelines. RESULTS: There are 11 published cases of small bowel atresia, 5 cases of necrotising enterocolitis (NEC), and 2 cases with foetal bowel perforations. Recipient twins were more likely to be affected by small bowel atresia (7 recipient and 4 donor cases) and NEC (3 recipient and 2 donor twins). Prenatal ultrasonographic abnormalities were demonstrated in 7 out of 9 cases with bowel atresia and in both cases of bowel perforation. The overall survival rate for neonates with bowel complications after FLA is 72%, but is much lower for co-twins at 22%. The survival rates for jejunoileal atresia and NEC are 91 and 40%, respectively. CONCLUSIONS: It is uncertain as to whether these bowel anomalies are due to bowel ischaemia associated with TTTS, the treatment with FLA, or a combination of both. Cases with prenatal abdominal ultrasonographic abnormalities after FLA should have close prenatal and postnatal assessment to detect bowel complications.

Diagnóstico genético preimplantacional de la enfermedad de Charcot-Marie-Tooth ligada al cromosoma X mediante análisis de ligamiento indirect / Preimplantation genetic diagnosis of X-linked Charcot-Marie-Tooth disease by indirect linkage analysis

Objetivo: Presentar un enfoque metodológico del diagnóstico genético preimplantacional (DGP) como opción para embarazos no afectados en parejas en edad reproductiva con riesgo genético de neuropatía periférica dominante por enfermedad de Charcot-Marie-Tooth tipo 1 ligada al cromosoma X. Pacientes y métodos: Llevamos a cabo el DGP de enfermedad de Charcot-Marie-Tooth tipo 1 ligada al cromosoma X utilizando un análisis de ligamiento indirecto/haplotificación, durante el cual logramos excluir los embriones portadores de un haplotipo de alto riesgo ligado a la mutación causal p.Leu9Phe en el gen GJB1. Resultados: Dentro del ciclo de DGP, examinamos 4 blastómeros biopsiados de los embriones en fase de división, y recomendamos la transferencia de 3 embriones. Dos embriones fueron implantados en el útero; sin embargo, el resultado fue un embarazo único con un descendiente varón. Transcurridos 3 años, la pareja regresó con un embarazo espontáneo. La biopsia coriónica de este embarazo reveló el sexo femenino y una inversión pericéntrica del cromosoma 5 en el 70% de las células fetales cultivadas. Conclusión: Utilizando el análisis de ligamiento indirecto, el DGP puede ayudar a identificar durante el cribado los defectos genéticos ligados al cromosoma X, eludiendo por tanto los problemas potenciales con el aborto (AU)

Objective: To present methodical approach of preimplantation genetic diagnosis (PGD) as an option for an unaffected pregnancy in reproductive-age couples who have a genetic risk of the X-linked dominant peripheral neuropathy Charcot-Marie-Tooth type 1 disease. Patients and methods: We performed PGD of X-linked Charcot-Marie-Tooth type 1 disease using haplotyping/indirect linkage analysis, when during analysis we reach to exclude embryos that carry a high-risk haplotype linked to the causal mutation p.Leu9Phe in the GJB1 gene. Results: Within the PGD cycle, we examined 4 blastomeres biopsied from cleavage-stage embryos and recommended 3 embryos for transfer. Two embryos were implanted into the uterus; however, it resulted in a singleton pregnancy with a male descendant. Three years later, the couple returned again with spontaneous gravidity. A chorionic biopsy examination of this gravidity ascertained the female sex and a pericentric inversion of chromosome 5 in 70% of the cultivated foetal cells. Conclusion: Using indirect linkage analysis, PGD may help to identify genetic X-linked defects within embryos during screening, thereby circumventing the potential problems with abortion (AU)

Preterm premature rupture of membranes is a collateral effect of improvement in perinatal outcomes following fetoscopic coagulation of chorionic vessels for twin-twin transfusion syndrome: a retrospective observational study of 1092 cases.

OBJECTIVES: Preterm premature rupture of membranes (PPROM) is a leading complication following fetoscopic laser coagulation (FLC) for twin-twin transfusion syndrome (TTTS). Our primary objective was to describe the impact of improvements in surgical technique on survival and rate of PPROM over time. The secondary objective was to assess potential risk factors for PPROM. DESIGN AND SETTING: Single-centre retrospective observational study. POPULATION: 1092 consecutive cases of TTTS operated by FLC between 2000 and 2016, with a 6.8% rate of loss to follow up. METHODS: The incidence of PPROM and potential risk factors were analysed using competing risks models. MAIN OUTCOME MEASURES: PPROM, neonatal survival and neurological damage at 28 days. RESULTS: PPROM <32 weeks increased from 15 to 40% between 2000 and 2016 along with an overall improvement of perinatal outcomes: dual survival rose from 42 to 66% whereas dual losses dropped two-fold, from 19 to 9%. Gestational age at surgery at <17 weeks was a significant risk-factor for PPROM, with an additional risk of 10% within the first week of surgery. Although early PPROM at <20 weeks carried a 56% risk of miscarriage, the occurrence of PPROM at >20 weeks did not affect survival, despite an increase in preterm birth at <32 weeks. CONCLUSIONS: With significant improvement in perinatal outcomes, possibly related to improvements in surgical technique, postoperative complications have shifted to non-lethal obstetric complications such as PPROM, with rather reassuring postnatal outcomes, despite an increase in preterm birth and, potentially, morbidity. Early surgeries (<17 weeks) are at higher risk of postoperative PPROM. TWEETABLE ABSTRACT: Following laser/TTTS, rates of PPROM increased with perinatal survival; surgeries at <17 weeks are at highest risk.

Expectant management and laser photocoagulation in isolated selective intra-uterine growth restriction: A single-center series.

INTRODUCTION: The objective was to report on a consecutive series of monochorionic diamniotic pregnancies complicated by selective Intra-Uterine Growth Restriction (sIUGR) and to describe perinatal outcomes based on whether or not there were umbilical Doppler findings, and specifically to study those pregnancies treated by laser. MATERIAL AND METHODS: This was a retrospective cohort study enrolling monochorionic diamniotic pregnancies presenting isolated sIUGR after 16 weeks' gestation (WG). RESULTS: Of the 25 cases of sIUGR, 16 were type I and 9 type II or III. Types II and III occurred earlier than type I (22.3 versus 24.3 WG), were more severe (discordance of 37% versus 23%), and delivered earlier (31.3 versus 33.9 WG). Survival was 12/18 (66.7%) for types II or III versus 32/32 (100%) for type I. Five laser photocoagulation procedures were attempted and allowed the survival of both twins in 2 cases. Overall survival after laser was 6/10 (60%). DISCUSSION: Isolated sIUGR is associated with high perinatal morbidity and mortality. Laser photocoagulation treatment is feasible and may enable survival of both twins in some cases, but may be technically difficult.

Endoscopic laser dichorionization of the placenta in the treatment of severe twin-twin transfusion syndrome.

OBJECTIVES: To describe the results of a technique of laser ablation of placental vessels in the treatment of severe twin-twin transfusion syndrome (TTTS), which is characterized by separation of the fetoplacental vascular territories and dichorionization of the placenta. PATIENTS AND METHODS: Descriptive analysis of TTTS cases treated with the endoscopic laser dichorionization of the placenta (ELDP) procedure. The variables evaluated were the occurrence of reversal of the donor-recipient phenotype, persistence of TTTS or twin anemia-polycythemia sequence (TAPS); gestational age at delivery; discharge from the hospital of at least 1 or 2 live neonates, and incidence of neurological alterations among survivors. RESULTS: 67 patients were treated with the ELDP procedure. There was no persistence of TTTS, reversal of the donor-recipient phenotype or TAPS. The median gestational age at delivery was 33.0 (23.6-37.7) weeks. The rate of discharge from the hospital of at least 1 or 2 live neonates was 88.2% (67/76) and 71.1% (54/76), respectively. Among survivors, 17 (17/121 = 14.0%) children presented with neurodevelopmental alterations during clinical follow-up. CONCLUSIONS: The major contribution of this study was the demonstration that the ELDP technique appears to be associated with a low risk of persistence or recurrence of TTTS and TAPS.

Bipolar cord coagulation for selective feticide in complicated monochorionic twin pregnancies: 118 consecutive cases at a single center.

OBJECTIVE: To review the experience of performing selective feticide with bipolar cord coagulation (BCC) in complicated monochorionic (MC) twin pregnancies at a single center. METHODS: This was a retrospective analysis of BCC performed using 3-mm bipolar forceps under ultrasound control in cases complicated by twin-to-twin transfusion syndrome, selective growth restriction, discordant anomaly or twin reversed arterial perfusion sequence. RESULTS: The series comprised 118 cases with a median gestational age at the time of the procedure of 22 (range, 16-30) weeks. There were 14 (12%) intrauterine deaths of the cotwin, eight (7%) miscarriages and one (1%) termination of pregnancy. When BCC was performed before 19 weeks of gestation, the rate of miscarriage was 45%, whereas it was 3% (P < 0.001) when BCC was performed after 19 weeks. Preterm prelabor rupture of membranes (PPROM) occurred in 45 (38%) cases. The median interval between BCC and PPROM was 4 (interquartile range, 2-9) weeks. In 15 (13%) cases, PPROM occurred within 2 weeks after the procedure. Median gestational age at delivery was 34 (range, 24-41) weeks. The median birth weight was 2103 (range, 480-3875) g. Neonatal death occurred in 11 (9%) cases, and two (2%) children had severe neurologic morbidity. The overall survival rate was 71% (84/118). CONCLUSION: BCC is an effective procedure in complicated MC twin pregnancies for selective feticide or when one fetus is severely jeopardized and delivery is not yet an option. Better outcomes can be achieved when this procedure is performed after 19 weeks.

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.

Dechorionation of medaka embryos and cell transplantation for the generation of chimeras.

Medaka is a small egg-laying freshwater fish that allows both genetic and embryological analyses and is one of the three vertebrate model organisms in which genome-wide phenotype-driven mutant screens were carried out (1). Divergence of functional overlap of related genes between medaka and zebrafish allows identification of novel phenotypes that are unidentifiable in a single species (2), thus medaka and zebrafish are complementary for genetic dissection of the vertebrate genome functions. Manipulation of medaka embryos, such as dechorionation, mounting embryos for imaging and cell transplantation, are key procedures to work on both medaka and zebrafish in a laboratory. Cell transplantation examines cell autonomy of medaka mutations. Chimeras are generated by transplanting labeled cells from donor embryos into unlabeled recipient embryos. Donor cells can be transplanted to specific areas of the recipient embryos based on the fate maps (3) so that clones from transplanted cells can be integrated in the tissue of interest during development. Due to the hard chorion and soft embryos, manipulation of medaka embryos is more involved than in zebrafish. In this video, we show detailed procedures to manipulate medaka embryos.

A definition of selectivity in laser coagulation of chorionic plate anastomoses in twin-to-twin transfusion syndrome and its relationship to perinatal outcome.

OBJECTIVE: This study was undertaken to correlate selectivity of surgery and perinatal outcome in twin-to-twin transfusion syndrome treated by endoscopic laser coagulation, using a quantitative definition of selectivity. STUDY DESIGN: 287 consecutive cases of severe twin-to-twin transfusion syndrome were reviewed. A selectivity index was built as the ratio of selective over nonselective coagulations per procedure. Outcome measures were survival at 28 days and failure of surgery as defined by recurrence of twin-to-twin transfusion syndrome or fetofetal hemorrhage. RESULTS: Two populations were identified: a high selectivity group (63.8%) and a low selectivity group (36.2%). Survival of at least one twin and survival of both twins were higher in the high-selectivity group (p = .007 and p = .04 respectively). Failure of surgery rates were similar in both groups. CONCLUSION: A quantitative definition of selectivity appears justified by the large variations found in the practice of a single center and by significant differences in outcome. Survival is significantly improved in highly selective procedures.

Transient chorioamniotic membrane separation after fetoscope guide laser therapy for twin-twin transfusion syndrome: a case report.

Chorioamniotic membrane separation (CMS) means that the close attachment of amniotic and chorionic membranes is disrupted, usually following the traumatic entry into the amniotic cavity including fetal therapy. We report a case of twin-twin transfusion syndrome receiving fetoscopic guide laser therapy at gestational age of 19 weeks with partial CMS detected at the fifth week (gestational age of 24 weeks) after surgery and resealed 1 week later. There was no more CMS noted till delivery at gestational age of 34 weeks 6 days. CMS after fetoscope surgery may reseal spontaneously.

Hypothetical role of prostaglandins in the onset of preterm labor after fetal surgery.

Preterm labor is one of the most important factors limiting the advancement of fetal surgery programs. While prostaglandins (PGs) have long been indicated as the key factor in the initiation of labor in humans, there is significant evidence showing that the chorionic membrane acts as a powerful barrier between the decidua/myometrium and amniotic PGs during normal pregnancy. After either open or endoscopic fetal surgery the imperfect, non-hermetical closure of the chorion permits leakage of PGs from the amnionic sac, allowing them to reach the decidua and myometrium. The surgical wound in the chorionic barrier could be the major factor involved in preterm labor and delivery after human fetal surgery.

Intertwin anastomoses in monochorionic placentas after fetoscopic laser coagulation for twin-to-twin transfusion syndrome: is there more than meets the eye?

OBJECTIVE: This study was undertaken to detect missed anastomoses on the chorionic surface as well as hidden connections in the depth of the cotyledons in placentas after laser coagulation for twin-to-twin transfusion syndrome (TTTS) and to correlate these findings to clinical outcome. STUDY DESIGN: All cord vessels were injected with dyed barium sulphate. A digital photograph of the chorionic surface angioarchitecture and single-shot digital X-ray (Rx) angiograms were made. The presence and diameter of any missed anastomoses on the chorionic surface and of any hidden angiographic connections were determined. RESULTS: Fifty placentas were analyzed, 7 of double intrauterine fetal death (IUFD) and 43 of double survivors. In 9 of 43 (21%) cases with double survival and in all 7 cases of double IUFD, missed anastomoses were identified that should have been ablated by laser coagulation (P < .001). There appeared to be a correlation between the type and diameter of missed anastomoses on the chorionic surface and the clinical outcome. Placentas with missed large arteriovenous/venoarterial anastomoses (AV/VA) (N = 8) were from cases with recurrent TTTS or double IUFD (unless compensated by a large arterioarterial anastomosis [AA]). Next, missed small AV/VA (N = 4) without AA resulted in isolated (ie, without TTTS) discordant hemoglobin levels requiring intrauterine transfusion. Finally, when there were no missed anastomoses (N = 34), TTTS had resolved in all cases and outcome was good, although 1 case had discordant hemoglobin values treated with a single intrauterine transfusion and 4 others had discordant hemoglobin at birth. On Rx angiography, potential hidden connections were present, all but 1 case. CONCLUSION: Coagulation of all anastomoses visible on the chorionic surface seems adequate to treat TTTS. However, hidden connections in the depth of the cotyledon could not be excluded and may be involved in lesser degrees of intertwin transfusion.

In vitro methods for studying vascularization of the murine allantois and allantoic union with the chorion.

Despite the importance of the definitive chorio-allantoic placenta in fetal survival, fetal development, and long-term health of the adult, little is known about how the placenta's individual components, the allantois and the chorion, proliferate and develop. In this chapter, two techniques will be described: (1) explanting murine allantoises for culture in isolation, and (2) grafting murine allantoises into living whole mouse embryos. Together, these will enable study of differentiation of allantoic mesoderm into the umbilical vasculature, and the mechanism(s) by which the allantois unites with the chorion to form the chorio-allantoic placenta.

Incidence and impact of perioperative complications in 175 fetoscopy-guided laser coagulations of chorionic plate anastomoses in fetofetal transfusion syndrome before 26 weeks of gestation.

OBJECTIVE: The purpose of this study was to evaluate the perioperative complications in fetoscopy-guided laser therapy in fetofetal transfusion syndrome. STUDY DESIGN: Details of fetofetal transfusion syndrome cases who were delivered between 1999 and 2004 in a single center were reviewed retrospectively. RESULTS: One hundred seventy-five procedures were performed percutaneously with the use of local anesthesia. Survival at 6 months of at least 1, 1, and 2 babies was 73%, 38%, and 35%, respectively. Placental abruption and miscarriage was diagnosed in 3 and 12 cases, respectively. Premature rupture of membranes occurred in 49 cases (28%) and including 12, 29, and 46 cases that occurred before 24, 28, and 34 weeks of gestation, respectively. The entry of the trocar was transplacental in 48 cases (27%), but it was not associated with miscarriage (P = .26), premature rupture of membranes (P = .58), or placental abruption (P = .37). CONCLUSION: Fetoscopic laser treatment of fetofetal transfusion syndrome can be performed percutaneously with local anesthesia without significant maternal morbidity. Transplacental entry was not associated with premature rupture of membranes or miscarriage.

The chick chorioallantoic membrane as a model tissue for surgical retinal research and simulation.

PURPOSE: We describe the use of chick chorioallantoic membrane (CAM) as a model system for the study of the precision and safety of vitreoretinal microsurgical instruments and techniques. METHODS: The CAM was prepared for experimentation with and without its inner shell membrane (ISM) attached for in vivo and in vitro experiments that simulated medical and surgical interventions on the retina. RESULTS: The CAM's ease of use, low cost, and anatomic structure make it a convenient model for surgical retinal and retinal vascular modeling. CONCLUSION: While CAM has been used extensively in the past for ocular angiogenesis studies, we describe the tissue as a useful tool for a variety of other applications, including (1) testing of novel surgical tools and techniques for cutting and coagulating retina and its vasculature, (2) testing vessel cannulation and injection techniques, (3) angiographic studies, and (4) endoscopic surgery.