A 29-gauge atraumatic needle for amniocentesis.

OBJECTIVE: To compare perforation characteristics of standard 22 G (0.7 mm) to 29 G needle (0.34 mm) for amniocentesis. METHODS: Seventeen human chorio-amnion membranes were perforated immediately after cesarean section using 22 G needle for spinal anesthesia and 29 G "pencil-point" needles for amniocentesis under in-vitro conditions. Area of perforation was determined using a microscope and volume of fluid leakage was measured over a period of 5 min. RESULTS: Membrane perforation with the 22 G needle resulted in a mean damaged area of 225,147.4 µm(2), a hole with a mean area of 50,154 µm(2) and amniotic fluid volume passage of 17.5 mL/5 min, whereas the 29 G needle generated a mean damaged area of 114,812.4 µm(2), a hole with an average area of 1382.5 µm(2) and volume passage of 0.28 mL/5 min. These differences were significant. CONCLUSION: The hole formed by membrane perforation with 29 G "pencil-point" needle for amniocentesis is 36 times smaller, and the amniotic fluid loss is 61 times less than that measured with the 22 G standard needle for spinal anesthesia. Significant reduction of complications following amniocentesis is expected with the 29 G needle.

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.

A histological study of fetoscopic membrane defects to document membrane healing.

OBJECTIVE: To evaluate the rate of spontaneous healing in human fetal membranes after fetoscopy. STUDY DESIGN: Membranes from patients that had undergone fetoscopic interventions and delivered in one of the two treatment centers were included in the study. The membranes were examined macroscopically for any remaining defects and if present, the size of the defect in chorion and amnion was measured. Subsequently, the defect was excised and stained with HE for histological evaluation. Additional immunohistochemical staining was performed with Ki-67, cytokeratin and vimentin. The proliferation index (percentage of proliferating cells) was calculated in amnion and chorion. RESULTS: Nineteen membrane defects were included in the study. The median time interval between invasive procedures and delivery was 60 days (range 3-112). All fetoscopic defects (n=19) could be identified in the gestational sac and in none spontaneous closure had occurred. Proliferation indices as measured by inmunohistochemistry were very low (median 2.8%, range 0-7%) in the chorion and 0% in the amnion. CONCLUSION: No evidence of spontaneous membrane healing was found after fetoscopic procedures, suggesting that the membrane defect normally persists until delivery. Absence of amniotic fluid leakage after invasive procedures may be based on mechanisms other than histologic membrane repair.

Chorioamniotic membrane separation following open fetal surgery: pregnancy outcome.

OBJECTIVE: To review the incidence of posthysterotomy chorioamniotic membrane separation and delivery outcome following open fetal surgery [myelomeningocele (MMC); cystic adenomatoid malformation (CCAM); congenital diaphragmatic hernia (CDH); sacrococcygeal teratoma (SCT)]. STUDY DESIGN: Retrospective review of a maternal population undergoing open fetal surgery at a single tertiary level program (1998-2001) following the initiation of close postoperative ultrasound follow-up for membrane separation. Onset of membrane separation was coded as not present (NP), immediate (<2 weeks) or delayed (>2 weeks) from day of surgery. RESULTS: Fifty-three charts were reviewed: MMC 43, CCAM 7, CDH 1, and SCT 2. In the MMC group there were 26 NP, 8 immediate, and 9 delayed. Preterm labor occurred in 4 patients with only 2 having had membrane separation. Risk of membrane separation is increased for surgery done at less than 23 weeks gestation (p < 0.005). Delay from MMC surgery to delivery was 11.0, 9.8, 12.0 weeks for NP, immediate, and delay, respectively. In the MMC group, there were 3 neonatal deaths (NND) at 9, 9, and 21 days post surgery (PROM/PTL; chorioamnionitis, PROM/PTL, respectively). No membrane separation was present in the CCAM, CDH, and SCT cases. CONCLUSIONS: (1) Membrane separation was significantly more likely to occur if surgery was performed prior to 23 weeks. (2) Membrane separation post hysterotomy (17/50 = 34%) may be associated with an increased risk of PROM but not delivery before 30 weeks gestation. (3) Delivery prior to 33 weeks gestation for MMC groups was 12/43 (28%) with 3 NND (7%). (4) Elective delivery at 36-37 weeks gestation was possible for 43% of the fetal surgery population.

Chorioamniotic membrane separation following fetal surgery.

OBJECTIVE: As the volume of fetal surgery cases has steadily increased, an increasing incidence of chorioamniotic membrane separation (CMS) has been noted. Due to the potential adverse consequences from this abnormality, we reviewed the last decade of experience with fetal intervention at our institution and examined the incidence and outcomes of fetuses given this diagnosis. STUDY DESIGN: A retrospective chart review of 75 fetal surgery cases at our institution was performed. Variables analyzed included preoperative, operative, and outcome data. Postoperative ultrasounds were evaluated for the presence of CMS. RESULTS: Excluding operative deaths, the incidence of CMS was 47%. There were significant differences (p<0.05) in time to delivery (7 vs 5 weeks), cases using a perfusion pump (80% vs 60%), and number of trocars (2.13 vs 1.54) in cases of CMS versus those without. Ultrasounds showed normal to high levels of amniotic fluid in 97% of cases. There was an increased incidence of premature rupture of membranes (63% vs 45%), preterm labor (57% vs 38%), and chorioamnionitis (29% vs 15%) with CMS, but no difference in mortality rate. CONCLUSION: CMS is a frequent finding following fetal surgery. It is associated with significant morbidity but is manageable with close follow-up in a hospital setting. Following fetal surgery, the finding of CMS can be a life-threatening complication that warrants further study to understand its etiology and prevention.

Sorting of murine vascular smooth muscle cells during wound healing in the chicken chorioallantoic membrane.

The vascular wall is built up of a heterogeneous population of smooth muscle cells, which exhibit not only morphological distinctions but also important differences in the composition of their structural and contractile proteins. "Epithelioid" smooth muscle cells correspond to an intimal-like type and display features associated with immaturity, whereas "spindle-shaped" cells closely resemble the more typical medial smooth muscle population. We have investigated the integration of these two cell types into the vascular architecture of an in vivo wound-healing model. Stably transfected with the beta-galactosidase gene, intima- and media-like cells were injected intravenously into the chicken chorioallantoic membrane, within which superficial foci of granulation tissue had been created by thermal or chemical injury. At 24 to 72 h after injection, cells had honed in on the lesion sites and were observed in juxtaposition to the endothelial lining of the capillaries. They began to deposit laminin, thereby indicating an impending role in the formation of the vascular wall. Intima- and media-like smooth muscle cells did not differ in their capacity to associate with capillaries, and, in so doing, their biochemical lineage characteristics became indistinguishable from one another. However, intima-like cells also penetrated the adventitial and medial layers of arteries. These findings reveal vascular smooth muscle cells to possess an extraordinary degree of plasticity, being able to adapt flexibly to changes in functional demands.

Efficacy of fibrin glue for in vitro sealing of human chorioamniotic membranes.

OBJECTIVE: To assess the changes in tensile strength properties of artificially punctured chorioamniotic membranes after sealing the defect with fibrin glue, a tissue sealant. STUDY DESIGN: Chorioamniotic membranes were obtained from 30 term, uncomplicated pregnancies immediately after delivery. Adjacent, same-sized strips were cut from each membrane sample. After baseline tensile strength properties were obtained, identical size holes were made on each strip, and fibrin glue was applied onto half the specimens. Following adequate stabilization of fibrin, tensile strength properties--rupture tension, strain to rupture and work to rupture--were measured. RESULTS: Membrane puncture decreased the tensile strength characteristics, indicating weakening of the chorioamniotic membranes: Rupture tension (g/cm) dropped from 153.1 +/- 12.3 to 76.8 +/- 15.7; strain to rupture (%) from 193.9 +/- 29.9 to 152.6 +/- 36.8; and work to rupture (g x cm) from 560.8 +/- 51.8 to 239.0 +/- 65.5 (P < .05). Significant increases were noted in rupture tension (116.0 +/- 19.6), strain to rupture (173.5 +/- 30.8) and work to rupture (394.3 +/- 91.3) after application of fibrin glue; however, all three measurements remained less than prepuncture values (P < .05). CONCLUSION: Fibrin glue effectively improved the structural integrity of artificially punctured chorioamniotic membranes.

Chorioamniotic separation after second-trimester genetic amniocentesis: importance and frequency.

PURPOSE: To determine the frequency and importance of chorioamniotic separation (CAS) after second-trimester genetic amniocentesis. MATERIALS AND METHODS: In part 1 of the study, ultrasonography (US) databases were reviewed for cases of CAS. In part 2, a study population of 388 women undergoing amniocentesis underwent directed US examination for assessment of CAS 15 minutes and/or 2 weeks after amniocentesis. CAS, when present, was graded. A control population consisted of 363 women undergoing amniocentesis in whom the membranes were not assessed. RESULTS: In part 1, a review of 23,883 records revealed seven cases of complete CAS, with three deaths, two preterm deliveries, and one emergency cesarean section delivery due to fetal distress. In two of these cases, there were extremity deformities at birth. In part 2, CAS was present in 98 (25%) of 388 women at some point. There was no association between CAS and procedural variables. There was no substantial difference in morbidity between patients with and those without CAS, between patients with different grades of CAS, or between the study and control populations. CONCLUSION: Small degrees of CAS are frequently present after amniocentesis but are not detected because the membranes are not specifically evaluated. Complete CAS is less frequent.

Brief communication: sliding displacement of amnion and chorion following controlled laser wounding suggests a mechanism for short-term sealing of ruptured membranes.

The Erbium-YAG laser was used to produce narrow wounds of defined depth in term amniochorion. The charring effect of the laser meant that sites could be readily localized in histological sections. During brief post-wounding incubations, sliding displacement of the amnion relative to the chorion occurred through the plane of the spongy layer. This suggests a possible short-term mechanism whereby a spontaneous rupture could be sealed in vivo.