Placental weight, birth weight and fetal:placental weight ratio in dichorionic and monochorionic twin gestations in function of gestational age, cord insertion type and placental partition.

INTRODUCTION: We established reference values for placental weight, birth weight, and fetal:placental weight ratio (FPR) (a possible index of placental functional efficiency) in monochorionic and dichorionic twin gestations. METHODS: Placental weight, birth weight, and FPR in function of gestational age, cord insertion type and placental sharing were determined in 151 dye-injected diamniotic-monochorionic and 198 double-disc diamniotic-dichorionic twin placentas (25-39 weeks' gestation). RESULTS: As expected, FPR values increased with gestational age in both groups. Birth weights and placental weights of monochorionic twins >28 weeks' gestation were significantly lower than those of age-matched dichorionic twins. When stratified per placental weight, the birth weights and FPR values of monochorionic twins were overall lower than those of dichorionic twins within the same placental weight category. However, in the subset of monochorionic twins with small share in unevenly partitioned placentas, birth weights and FPR values per placental weight were similar to those of dichorionic twins, and significantly higher than those of monochorionic twins with larger share or even placental sharing. Cord insertion type did not correlate with birth weight or FPR values per placental weight in either twin type. DISCUSSION: Reference values were generated for placental weight, birth weight and FPR in monochorionic and double-disc dichorionic twins. The generally lower FPR per placental weight in monochorionic twins compared with dichorionic twins is suggestive of inherently lower placental functional efficiency in monochorionic gestations. The mechanisms and clinical implications of the apparent differential modulation of FPR/efficiency in monochorionic twins according to placental partitioning remain to be determined.

Correlation between cord insertion type and superficial choriovasculature in diamniotic-monochorionic twin placentas.

BACKGROUND: Non-central cord insertion has been associated with diminished chorionic vascular distribution in singleton placentas. The choriovascular correlates of peripheral cord insertion in diamniotic-monochorionic twin placentas remain undetermined. AIM: To study the association between type of cord insertion and choriovascular distribution of both twin territories in diamniotic-monochorionic twin placentas. DESIGN: A prospective cohort of 138 monochorionic placentas was examined at Women and Infants Hospital between 2009 and early 2011. Thirty-five cases (25%), including disrupted placentas, placentas from higher order multiples and placentas from pregnancies complicated by twin-to-twin transfusion syndrome, were excluded. The correlation between cord insertion type and superficial choriovascular distribution was studied in the remaining 103 dye-injected diamniotic-monochorionic placentas. Cord insertion was categorized as paracentral, marginal or velamentous. The choriovascular distribution of each individual twin territory was assessed by analysis of number and density (number per surface area) of perforating chorionic arteries (PCA). RESULTS: In contrast with singleton placentas, there was no correlation between cord insertion type and a twin's own choriovascular distribution in diamniotic-monochorionic placentas. However, a strong correlation was found between the choriovascular distribution of one twin and the cord insertion type of the opposite twin. For a twin with paracentral or marginal cord insertion, the PCA density was significantly higher if the co-twin had a velamentous cord insertion than if the co-twin had a paracentral cord insertion (P < 0.001 and P < 0.05, respectively). Similarly, the PCA density of a twin with velamentous cord insertion tended to be higher if the co-twin had a velamentous, rather than paracentral cord insertion (P = 0.09). CONCLUSIONS: This is the first study to suggest that in diamniotic-monochorionic twin gestations, the choriovascular architecture correlates with the cord insertion type of the co-twin. In general, velamentous cord insertion is associated with expanded choriovascular distribution in the opposite twin territory. Our observations may reflect novel manifestations of twin interdependence in monochorionic pregnancies.

Blast injuries--and the pivotal role of trauma surgeons.

An explosion is the sudden release of energy and its radial propagation through air, solid structures and living tissue. Treatment of blast injuries is complex and combines the principles of penetrating and blunt trauma, chemical or thermal burns and disaster and mass casualty management. Primary blast injuries are a direct result of the explosion itself. The sudden release of energy is translated into a shock wave that travels at supersonic speed (5000 metres/second). There is a sudden and short-lived rise in pressure, followed by a prolonged negative pressure, or vacuum, responsible for additional injury. The organs most at risk for primary blast injuries are the lungs, the ears and the gastrointestinal tract. The explosion also sets solid objects in motion; these act as projectiles, and can travel over far greater distances (secondary blast injuries), and their management is no different from penetrating or blunt trauma from other causes. The explosion may cause not only "projectiles," but the body itself to be displaced: These tertiary blast injuries include traumatic amputations and crush injuries following land mine explosions. Finally, quaternary blast injuries comprise other forms of associated trauma, such as burns, asphyxia or poisoning from release of noxious substances by the blast. These injuries can be particularly taxing for rescue teams because of their tendency to affect large amounts of patients and the risk they pose to the rescuers themselves. Individual management of the blast injury victim requires a multidisciplinary team; terrorist or wartime bombings also require expertise in disaster management and triage.

Placental characteristics of selective birth weight discordance in diamniotic-monochorionic twin gestations.

Up to 21% of diamniotic-monochorionic twin pregnancies are complicated by severe birth weight discordance in the absence of twin-to-twin transfusion syndrome, a serious condition termed 'selective' birth weight discordance. While its pathogenesis remains incompletely understood, the development of selective intertwin growth discordance, related to fetal growth restriction of one twin, is generally attributed to aberrant placental characteristics. The aim of this study was to characterize the placental markers of selective birth weight discordance, with special emphasis on the choriovascular architecture. A prospective cohort of 319 consecutive diamniotic/monochorionic twin placentas was examined at Women and Infants Hospital between 2001 and 2009. After exclusion of placentas from pregnancies complicated by twin-to-twin transfusion syndrome (TTTS), monoamniotic, multiple and disrupted placentas, 216 placentas (36 birth weight (BW)-discordant and 180 BW-concordant) formed the subject of this study. Following dye injection, the anatomic characteristics and choriovascular anastomotic patterns of BW-discordant and BW-concordant placentas were compared. The BW-discordant placentas showed significantly higher frequencies of velamentous cord insertion (22% versus 8%, P < 0.001) and uneven placental sharing (56% versus 19%, P < 0.0001) compared with BW-concordant placentas. The frequencies of intertwin AA, VV and AV anastomoses, the net number of AV anastomoses, and the net cross-sectional area of AV anastomoses were similar in both groups. There was no correlation between the frequency of velamentous cord insertion and degree of placental sharing or patterns of choriovascular anastomoses in either group. In conclusion, velamentous cord insertion and uneven placental sharing are the two major placental determinants of selective birth weight discordance in diamniotic-monochorionic twins. The role of the intertwin anastomoses, even when unbalanced, is likely negligible. Elucidation of the mechanisms whereby velamentous cord insertion affects fetal growth may lead to more focused and effective therapeutic strategies for twin and singleton pregnancies complicated by dysregulated fetal growth.

Placental markers of twin-to-twin transfusion syndrome in diamniotic-monochorionic twins: A morphometric analysis of deep artery-to-vein anastomoses.

Twin-to-twin transfusion syndrome (TTTS) is a multifactorial disorder that develops in 9-15% of diamniotic-monochorionic twin gestations. While the pathogenesis of TTTS remains poorly understood, unbalanced deep artery-to-vein (AV) anastomoses have traditionally been implicated in the gradual shift of blood from donor to recipient. The aim of this study was to define the placental markers of twin-to-twin transfusion syndrome, with special emphasis on the deep AV anastomoses. A prospective cohort of 284 consecutive diamniotic/monochorionic twin placentas was examined at Women and Infants Hospital between 2001 and 2008. Following exclusion of monoamniotic, multiple, disrupted and laser-treated placentas, 218 twin placentas (21 TTTS and 197 non-TTTS controls) formed the subject of this study. Placentas were injected with color-coded dyes. Anatomic characteristics and choriovascular anastomotic patterns of TTTS placentas were compared with non-TTTS controls. The TTTS placentas showed significantly higher frequencies of velamentous cord insertion, magistral vascular distribution patterns, uneven placental sharing, absence of AA anastomoses and presence of VV anastomoses. Deep AV anastomoses were identified in >or=95% of TTTS and non-TTTS placentas and were overall more abundant than previously reported. The total and net numbers of AV anastomoses were similar in both groups. However, the net cross-sectional area of AV anastomoses, which also takes into account the caliber of the vessels, was significantly smaller in TTTS placentas. There was no correlation between the direction of the AV imbalance and the twin donor/recipient status. In conclusion, TTTS has distinct placental characteristics, warranting their routine inclusion in the diamniotic-monochorionic placental pathology report. Our findings suggest imbalance of AV anastomoses is not required for the development for TTTS, although their presence, whether balanced or unbalanced, may contribute to the creation or perpetuation of the syndrome. Elucidation of the role of the various placental determinants in diamniotic-monochorionic twin gestations may lead to further refinement of therapeutic strategies.

Open and laparoscopic appendectomy are equally safe and acceptable in children.

BACKGROUND: The aim of this study was to evaluate prospectively whether laparoscopic (LA) and open appendectomy (OA) are equally safe and feasible in the treatment of pediatric appendicitis. METHODS: A total of 517 children with acute appendicitis were randomly assigned to undergo LA or OA appendectomy, based on the schedule of the attending surgeon on call. Patient age, sex, postoperative diagnosis, operating time, level of training of surgical resident, length of postoperative hospitalization, and minor and major postoperative complications were recorded. Chi-square analysis and the Student t-test were used for statistical analysis. RESULTS: In all, 376 OA and 141 LA were performed. The two groups were comparable in terms of patient demographics and the incidence of perforated appendicitis. The operative time was also similar (47.3 +/- 19.7 vs 49.9 +/- 12.9 min). The overall incidence of minor or major complications was 11.2% in the OA group and 9.9% in the LA group. CONCLUSION: Pediatric patients with appendicitis can safely be offered laparoscopic appendectomy without incurring a greater risk for complications. Nevertheless, a higher (but not significantly higher) abscess rate was found in patients with perforated appendicitis who underwent laparoscopy.

Minimal-access fetal surgery for twin-to-twin transfusion syndrome.

BACKGROUND: Laser ablation of placental vessels effectively halts severe twin-to-twin transfusion syndrome (TTTS), but fetal surgery remains a dangerous approach. The authors present the technical aspects of endoscopic fetal surgery in their initial clinical experience. METHODS: Altogether, 11 women underwent endoscopic fetal surgery for severe TTTS. Access to the recipient's sac was obtained by the Seldinger technique via minilaparotomy. A 12-Fr peel-away introducer was used as a cannula to accommodate a custom-curved 9-Fr sheath containing a 1.9-mm semirigid fiber endoscope. Laser ablation was performed on all unpaired vessels crossing the intertwin membrane using a 400- micro m neodymium: yttrium-aluminum-garnet (Nd: YAG) fiber. The cannula was removed over a gelatin sponge plug. RESULTS: The median operating time was 65 min (range, 45-105 min). No patient experienced amniotic leak postoperatively. The length of hospital stay was 2.8 +/- 1.6 days. Immediate improvement of the TTTS was noted in all but two patients. Pneumonia developed, in one mother leading to premature labor. There were no other major surgical complications. Fetal survival at 2 weeks was 73%. CONCLUSIONS: The safety and efficacy of endoscopic fetal surgery for severe TTTS can be optimized with the application of current minimal-access techniques. The superiority of this approach over less invasive means is still being evaluated through prospective studies.

Experience with a multidisciplinary antenatal diagnosis and management model in fetal medicine.

BACKGROUND: Fetal medicine is a new and evolving specialty. Complex fetal conditions may require the multidisciplinary input of clinicians from many different specialties. METHODS: Referral of fetal patients was made to a multidisciplinary antenatal diagnosis and management (MADAM) board if more than one specialty (in addition to maternal-fetal medicine) needed to be intimately involved in the evaluation or care of the fetus; consultation would probably lead to alterations in fetal or perinatal management; or development or revision of management guidelines was anticipated. The case log of the MADAM conferences was reviewed retrospectively for number and type of fetal anomalies, and outcome of the presentation to the MADAM board. RESULTS: During a 5-year period, 1% of 25654 pregnant women who were evaluated required consultations with individual pediatric and pediatric surgical specialists. Of these, 114 patients were referred to one of 77 MADAM conferences for consensus recommendation. Of these 77 discussions, 32 (42%) led to an alteration in prenatal management, 14 (18%) led to co-ordination of postnatal management and 12 (16%) led to the establishment of a new treatment guideline, or the modification of an existing one. In all, perinatal management was altered in 75% of cases. CONCLUSION: The MADAM model functions as a forum for exchange of up-to-date scientific information, development of evidence-based treatment protocols and continuity of care through the pre-, peri- and postnatal periods.

Laparoscopic gastrostomy in infants and children.

Gastrostomy is a common procedure in children. Percutaneous endoscopic gastrostomy (PEG) is less traumatic than open surgery, but carries a higher risk in small children. We report our experience with laparoscopic gastrostomy, which appears to combine the advantages of the PEG and the safety of an open operation. Operative technique. An umbilical port (5 or 10 mm, depending on the patient's weight) and a left subcostal cannula (site of the future gastrostomy) are used. The stomach is pulled to the abdominal wall with two T-anchors, and the gastrostomy is performed using the Seldinger technique. A 17-Fr peel-away sheath is placed, through which a 5 mm endoscope is introduced to confirm its intragastric position. A 14-Fr balloon gastrostomy tube or button is then introduced. Results. Fifty-one children, aged 0 to 19 years (mean 4.4 +/- 6.4 years), underwent a total of 54 laparoscopic gastrostomies in a 42-month period. Thirty-three patients were younger than 2 years, and 22 weighed less than 5 kg. Thirty-three children had failure-to-thrive, 12 suffered from cerebral palsy and 8 from cystic fibrosis. Operative time was 33.6 +/- 14.3 minutes; in 18 cases, a concomitant Nissen fundoplication was performed (total operative time 76.5 +/- 58.7 minutes). In all cases, gastrostomy feedings were started the following day, and hospital stay in the gastrostomy-only group was 3.3 +/- 0.6 days. There were two (recognized) perforations of the back wall of the stomach, which were repaired laparoscopically, and two tube dislodgments, at 24 hours and at 4 months, requiring reoperation. Conclusions. Laparoscopy allows a quick and simple technique of gastrostomy placement under direct vision in even the smallest newborn and infant. It carries minimal operative risks and allows initiation of feedings within 24 hours.