A dusty veil shading Betelgeuse during its Great Dimming.

Red supergiants are the most common final evolutionary stage of stars that have initial masses between 8 and 35 times that of the Sun1. During this stage, which lasts roughly 100,000 years1, red supergiants experience substantial mass loss. However, the mechanism for this mass loss is unknown2. Mass loss may affect the evolutionary path, collapse and future supernova light curve3 of a red supergiant, and its ultimate fate as either a neutron star or a black hole4. From November 2019 to March 2020, Betelgeuse-the second-closest red supergiant to Earth (roughly 220 parsecs, or 724 light years, away)5,6-experienced a historic dimming of its visible brightness. Usually having an apparent magnitude between 0.1 and 1.0, its visual brightness decreased to 1.614 ± 0.008 magnitudes around 7-13 February 20207-an event referred to as Betelgeuse's Great Dimming. Here we report high-angular-resolution observations showing that the southern hemisphere of Betelgeuse was ten times darker than usual in the visible spectrum during its Great Dimming. Observations and modelling support a scenario in which a dust clump formed recently in the vicinity of the star, owing to a local temperature decrease in a cool patch that appeared on the photosphere. The directly imaged brightness variations of Betelgeuse evolved on a timescale of weeks. Our findings suggest that a component of mass loss from red supergiants8 is inhomogeneous, linked to a very contrasted and rapidly changing photosphere.

Understanding the anatomy of dermoscopy of melanocytic skin tumours: Correlation in vivo with line-field optical coherence tomography.

BACKGROUND: Early melanoma detection is the main factor affecting prognosis and survival. For that reason, non-invasive technologies have been developed to provide a more accurate diagnosis. Recently, line-field confocal optical coherence tomography (LC-OCT) was developed to provide an in vivo, imaging device, with deep penetration and cellular resolution in three dimensions. Combining the advantages of conventional OCT and reflectance confocal microscopy, this tool seems to be particularly suitable for melanocytic lesions. OBJECTIVES: The objective of this study was to identify and describe the correlation between specific dermoscopic criteria and LC-OCT features in three dimensions associated with melanocytic lesions. METHODS: Dermoscopic and LC-OCT images of 126 melanocytic lesions were acquired in three different centres. The following dermoscopic criteria have been considered: reticular pattern, dots and globules, structureless areas, blue-whitish veil, regression structures, negative network, homogeneous pattern, streaks and blotches. RESULTS: 69 (55%) benign and 57 (45%) malignant lesions were analysed. A regular reticular pattern was found associated in the 75% of the cases with the presence of elongated rete ridges with pigmented cells along the basal layer, while atypical reticular pattern showed an irregular organization of rete ridges with melanocytic hyperplasia, broadened and fused ridges and elongated nests. Both typical and atypical dots and globules were found associated with melanocytic nests in the dermis or at the dermoepidermal junction (DEJ), as well as with keratin cysts/pseudocysts. Grey globules corresponded to the presence of melanin-containing dermal inflammatory cells (melanophages) within the papillae. Structureless brown/black areas correlated with alterations of the DEJ. We observed the same DEJ alterations, but with the presence of dermal melanophages, in 36% of the cases of blue/white/grey structureless areas. A description of each LC-OCT/dermoscopy correlation was made. CONCLUSIONS: LC-OCT permitted for the first time to perform an in vivo, 3D correlation between dermoscopic criteria and pathological-like features of melanocytic lesions.

No Sun-like dynamo on the active star ζ Andromedae from starspot asymmetry.

Sunspots are cool areas caused by strong surface magnetic fields that inhibit convection. Moreover, strong magnetic fields can alter the average atmospheric structure, degrading our ability to measure stellar masses and ages. Stars that are more active than the Sun have more and stronger dark spots than does the Sun, including on the rotational pole. Doppler imaging, which has so far produced the most detailed images of surface structures on other stars, cannot always distinguish the hemisphere in which the starspots are located, especially in the equatorial region and if the data quality is not optimal. This leads to problems in investigating the north-south distribution of starspot active latitudes (those latitudes with more starspot activity); this distribution is a crucial constraint of dynamo theory. Polar spots, whose existence is inferred from Doppler tomography, could plausibly be observational artefacts. Here we report imaging of the old, magnetically active star ζ Andromedae using long-baseline infrared interferometry. In our data, a dark polar spot is seen in each of two observation epochs, whereas lower-latitude spot structures in both hemispheres do not persist between observations, revealing global starspot asymmetries. The north-south symmetry of active latitudes observed on the Sun is absent on ζ And, which hosts global spot patterns that cannot be produced by solar-type dynamos.

Non-invasive, in vivo, characterization of cutaneous metastases using a novel multimodal RCM-OCT imaging device: a case-series.

BACKGROUND: Cutaneous metastases (CM) diagnosis is clinically challenging, requiring an invasive biopsy for confirmation. A novel, RCM-OCT device combines the advantage of horizontal high-resolution reflectance confocal microscopy (RCM) images and vertical deeper optical coherence tomography (OCT) images to aid in non-invasive diagnosis of CM from breast cancers. OBJECTIVE: Characterize CM from breast cancers using RCM-OCT device. METHODS: Seven patients suffering from breast cancers with suspicious CM were consented and imaged with RCM-OCT device. CM features were defined by comparing with histopathology. Tumour depths were measured on OCT and on H&E-images and correlated using statistical analysis Pearson test. 3D-OCT images were reconstructed to enhance tumour visualization. RESULTS: 6/7 lesions were CM from breast cancers, and one was vascular ectasia, on histopathology. CM appeared as greyish-darkish oval to round structures within the dermis on RCM and OCT-images. On RCM, individual tumour cells were seen, enabling identification of even small tumour foci; while, on OCT deeper tumours were detected. Inflammatory cells, dilated vessels and coarse collagen were identified in the dermis. Pearson correlation had an r2 of 0.38 and a significant P-value <0.004 for depth measurements. CM from breast cancers could be differentiated from ecstatic vessels on 3D-reconstructed OCT image. LIMITATION: Small sample size and lack of clinical mimickers. CONCLUSION: RCM-OCT can detect CM and has potential in aiding non-invasive diagnosis and management.

Line-field confocal optical coherence tomography of basal cell carcinoma: a descriptive study.

BACKGROUND: Early diagnosis and subtype classification of basal cell carcinoma (BCC) are crucial to reduce morbidity and optimize treatment. Good accuracy in differentiating BCC from clinical imitators has been achieved with existing diagnostic strategies but lower performance in discriminating BCC subtypes. Line-field confocal optical coherence tomography (LC-OCT) is a new technology able to combine the technical advantages of reflectance confocal microscopy and OCT. OBJECTIVES: To identify and describe LC-OCT criteria associated with BCC and explore their association with BCC subtypes. METHODS: Basal cell carcinoma were imaged with a handheld LC-OCT device before surgical excision. LC-OCT images were retrospectively evaluated by three observers for presence/absence of criteria for BCC. Multivariate logistic regression models were used to find independent predictors of BCC subtypes. RESULTS: Eighty-nine histopathologically proven BCCs were included, of which 66 (74.2%) were pure subtypes [superficial BCC (sBCC): 19/66 (28.8%); nodular BCC (nBCC): 31/66 (47.0%); infiltrative BCC (iBCC): 16/66 (24.2%)]. Lobules, blood vessels and small bright cells within epidermis/lobules were the most frequent criteria for BCC. LC-OCT criteria independently associated with sBCC were presence of hemispheric lobules, absence of lobule separation from the epidermis, absence of stretching of the stroma; with nBCC were presence of macrolobules, absence of lobule connection to the epidermis; and with iBCC were presence of branched lobules. CONCLUSIONS: This was the first study describing the characteristics of BCC under LC-OCT examination. We proposed morphologic criteria, which could be potentially useful for diagnosis and subtype classification of BCC, as well as for its therapeutic management. Future studies are needed to assess these hypotheses.

The expanding fireball of Nova Delphini 2013.

A classical nova occurs when material accreting onto the surface of a white dwarf in a close binary system ignites in a thermonuclear runaway. Complex structures observed in the ejecta at late stages could result from interactions with the companion during the common-envelope phase. Alternatively, the explosion could be intrinsically bipolar, resulting from a localized ignition on the surface of the white dwarf or as a consequence of rotational distortion. Studying the structure of novae during the earliest phases is challenging because of the high spatial resolution needed to measure their small sizes. Here we report near-infrared interferometric measurements of the angular size of Nova Delphini 2013, starting one day after the explosion and continuing with extensive time coverage during the first 43 days. Changes in the apparent expansion rate can be explained by an explosion model consisting of an optically thick core surrounded by a diffuse envelope. The optical depth of the ejected material changes as it expands. We detect an ellipticity in the light distribution, suggesting a prolate or bipolar structure that develops as early as the second day. Combining the angular expansion rate with radial velocity measurements, we derive a geometric distance to the nova of 4.54 ± 0.59 kiloparsecs from the Sun.

In vivo characterization of healthy human skin with a novel, non-invasive imaging technique: line-field confocal optical coherence tomography.

BACKGROUND: Line-field confocal optical coherence tomography (LC-OCT) is a non-invasive optical technique recently developed for skin examination in vivo. It provides real-time, high-resolution vertical images with an isotropic resolution of ~1 µm and a penetration depth of ~500 µm. OBJECTIVES: Study goals were to qualitatively/quantitatively characterize healthy skin at different body sites using LC-OCT. METHODS: The skin of young healthy volunteers was imaged with a handheld LC-OCT imaging device. Seven body sites (back of the hand, forehead, cheek, nose, chest, forearm and back) were investigated. An independent qualitative [cutaneous structures' description; visibility of keratinocytes' nuclei and dermal-epidermal junction (DEJ)] and quantitative [stratum corneum (SC)/epidermal thicknesses; height of dermal papillae] assessment of the LC-OCT images was performed. RESULTS: A total of 88 LC-OCT images were collected from 29 participants (20 females; nine males; mean age 25.9 years). Keratinocytes' nuclei and DEJ were visible in the totality of images. The different layers of the epidermis and the remaining cutaneous structures/findings were visualized. Body sites-related variability was detected for SC/epidermal thicknesses and height of dermal papillae. Inter-observer agreement was excellent (SC thickness), good-to-excellent (epidermal thickness) and moderate-to-good (papillae). CONCLUSIONS: Line-field confocal-OCT provides non-invasive, real-time imaging of the skin in vivo with deep penetration and high resolution, enabling the visualization of single cells. The histology-like vertical view provides an easy way to recognize/measure different cutaneous structures/findings. LC-OCT appears as a promising technique for the examination of physiological/pathological skin.

Effect of O2 on the adsorption of SO2 on carbon-supported Pt electrocatalysts.

Adsorption of SO(2) in the presence of O(2) on Pt/C catalysts often used as electrocatalysts has been investigated by temperature programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). The amounts of SO(2) adsorption on Pt/C in the presence of O(2) were much higher than those in the absence of O(2) (SO(2)-N(2)) and from the carbon support (Vulcan XC-72) alone. Adsorption is dependent on oxygen concentration over the range 0-20% but reaches saturation at 20% O(2). The spillover of SO(2) from Pt to the carbon support has been proposed for 10, 20, and 40% Pt loadings, characterized by desorption temperatures of approximately 150 and 260 °C for SO(2) adsorbed on Pt and carbon, respectively. Adsorbed Pt-S, C-S, C-SO(x), and Pt-SO(4) species were identified by XPS as S-containing species on both Pt and carbon. Both TPD and XPS indicate that the carbon support plays a major role in SO(2) adsorption, primarily as SO(x) (x = 3, 4). The bonding of S and SO(x) on the carbon support was strong enough that back diffusion to the Pt surface did not occur.

SO2 adsorption on carbon-supported Pt electrocatalysts.

Adsorption of SO2 on a Pt/C catalyst typically used in proton exchange- membrane fuel cells (PEMFCs) has been investigated by temperature programmed desorption (TPD). SO2 concentrations in N2 were varied from 5 ppm to 1% (vol) and adsorption isotherms were determined at 25, 50, and 80 °C. Oxygen assisted (O-assisted) desorption experiments (i.e., successive TPD experiments following exposure to room temperature O2 after the first TPD event) produced an additional SO2 peak at a temperature higher than the initial SO2 peak. These two types of SO2 adsorption were identified as weakly adsorbed SO2 species desorbed between 140 and 200 °C, depending on concentration, and a strongly adsorbed, dissociated species. For the strongly adsorbed, dissociative species, (18)O2 isotope introduction during O-assisted desorption yielded ratios of 50%, 36%, and 14% for SO2 masses of 64, 66, and 68, respectively. The activation energy and kinetic constant of desorption are reported for weakly adsorbed SO2 at 1% and 20 ppm SO2 using the Polanyi-Wigner equation.

Minimum instructional and program-specific administrative costs of educating residents in internal medicine.

BACKGROUND: The cost associated with education of residents is of interest from an educational as well as a political perspective. Most studies report a single institution's actual incurred costs, based on traditional cost accounting methods. We quantified the minimum instructional and program-specific administrative costs for residency training in internal medicine. METHODS: Using the Accreditation Council for Graduate Medical Education program requirements for internal medicine as minimum standards for teaching and administrative effort, we quantified the minimum instructional and administrative costs for sponsorship of an accredited residency program in internal medicine. We also analyzed the impact of resident complement and program curricular emphasis (outpatient, inpatient, or traditional) on the per-resident cost. The main outcome measure was the minimum annual per-resident cost of instruction and program-specific administration. RESULTS: Using the assumptions in this model, we estimated the annual cost per resident of implementing the program requirements to be $50,648, $35,477, $28,517, and $26,197 for inpatient intensive residency programs with resident complements of 21, 42, 84, and 126, respectively. For outpatient intensive residency programs of identical resident complements, we estimated the annual per-resident cost to be $58,025, $42,853, $35,894, and $33,574 for similar resident complements. Fixed costs mandated by the program requirements, which did not vary across program size or configuration, were estimated to be $640,737. CONCLUSIONS: There are fixed and variable costs associated with sponsorship of accredited internal medicine residency programs. The minimum cost per resident of education and departmental administration varies inversely with program size within the sizes examined.

Intravenous nitroglycerin for internal podalic version of the second twin in transverse lie.

OBJECTIVE: To report our experience with high doses (0.1-0.2 mg per 10 kg pregnant weight) of intravenous (IV) nitroglycerin as a uterine relaxing agent for managing internal podalic version of the second twin in transverse lie with unruptured membranes. METHODS: Between August 1994 and December 1997, we managed 22 cases of internal podalic version of the second twin with the administration of high doses of IV nitroglycerin. RESULTS: Twenty internal podalic versions were completed successfully, and two cases failed. One failure was considered not related to IV nitroglycerin because the patient had a panic attack, requiring general anesthesia for sedation. The internal podalic version then succeeded. The patient with true failure of IV nitroglycerin required emergency cesarean because of acute fetal bradycardia and a nonrelaxed uterus. This was the only nontransverse lie, but with a very high face presentation. One internal podalic version was complicated by hemorrhage (2000 mL). CONCLUSION: Intravenous nitroglycerin to induce uterine atonia, with epidural analgesia, avoids general anesthesia and makes internal podalic version easier. In 22 cases (with success in 20) of internal podalic version of the second twin in transverse lie with unruptured membranes, IV nitroglycerin induced transient and prompt uterine relaxation without affecting maternal and fetal outcomes.

Generalized anxiety disorder in women.

Women have a higher prevalence of GAD than do men. This ratio holds true in most clinical and general-population samples. Some variations exist, with evidence to suggest the strong impact of environment and life events. Women are sensitive to lifetime adversity and exacerbation of symptoms in conjunction with their menstrual cycle. Comorbidity is a crucial diagnostic factor when treating anyone with GAD, especially women. Most notably, high comorbidity with other anxiety disorders, MDD and alcohol-abuse disorder occurs for women. Overall, although the prevalence of women with GAD is greater than that of men with GAD, the course of illness and prognosis are not qualitatively different. Across varied methodology, data suggest gender-related differences in the metabolism and potentially in the effects and side effects of the various benzodiazepines and antidepressant psychopharmacologic treatments of GAD. Additional research is needed to better understand these differences.

Increased insulin sensitivity and basal insulin effectiveness in postprandial reactive hypoglycaemia.

Glucose clamp experiments have shown that patients with reactive postprandial hypoglycaemia (PRH) frequently have an increased glucose disposal, but the relative involvement of insulin sensitivity (SI) and glucose effectiveness (Sg) in this process remains unknown. The minimal model approach was used to compare 13 patients in whom moderate reactive hypoglycaemia ( < 3.3 mmol) had been previously diagnosed and 13 matched controls. The intravenous glucose tolerance test (IVGTT, 0.5 g/kg glucose IV) with 0.02 U/kg insulin given at the 19th min and frequent sampling over 180 min shows that PRH patients exhibit a higher glucose tolerance coefficient Kg (2.99 +/- 0.26 vs 2.19 +/- 0.12; P < 0.02), higher SI [22.9 +/- 6.4 vs 7.18 +/- 0.14 min-1/(microU/ml). 10(-4); P < 0.01] and higher Sg (3.84 +/- 0.35 vs 2.92 +/- 0.79 min-1. 10(-2); P < 0.05). The increase in Sg is explained by an increase in its component basal insulin effectiveness (BIE: 1.2 +/- 0.27 min-1.10(-2) in PRH subjects vs 0.58 +/- 0.07; P < 0.05) rather than an increase in Sg at zero insulin. The increase in BIE results from the high values of SI. In 4 PRH subjects SI and Sg were within the normal range, and the increase in Kg evidenced in the 9 others was explained by an increase in SI alone in 3 cases, in Sg alone in 1 case, and both SI and Sg in 5 cases. Thus, in sedentary subjects, the previously reported rise in tissue glucose assimilation is mainly explained by an increased insulin-mediated glucose disposal rather than non-insulin-mediated glucose disposal.

External radiotherapy and radioiodine in the treatment of 359 thyroid cancers.

Between 1943 and 1965, 359 patients with carcinoma of the thyroid were treated by external radiotherapy or radioiodine out of a total number of 560 patients treated during the same period. In 65 of these patients surgery had been satisfactory from a macroscopic point of view. Prophylactic post-operative irradiation was given to 55 and the survival rate was 91 per cent at five years and 85 per cent at ten years. Ten received radioiodine, eight were alive at five years and six at ten years. In 95 patients excision of the tumour had been macroscopically incomplete. Fifty-four were treated by external radiotherapy and the survival rates were 50 per cent at five years and 48 per cent at ten years. For the differentiated carcinoma of this group 68 per cent were surviving at five years and 58 per cent at ten years. Of 41 patients treated with radioiodine, 75 per cent were surviving at five years and 31 per cent at ten years. Eighty-five patients were inoperable. Sixty were treated by external radiotherapy, the survival rates were 17 per cent at five years and 8.5 per cent at ten years. For the differentiated carcinomas of this group the survival rates were 24 per cent and 18 per cent. Twenty-five were treated with radioiodine, 26 per cent were surviving at five years and 4.5 per cent at ten years. The patients treated by external radiotherapy can be divided into two subgroups according to the technique of treatment and dose used. Between 1943 and 1955, patients were treated with conventional X rays (mean applied dose 2,800 rads), between 1956 and 1965 the patients were treated with 60Co (mean applied dose 5,000 rads). For the 45 patients of the first group, the survival rates were 35 per cent at five years and 32 per cent at ten years. For the 124 of the second group the respective survival rates were significantly higher: 60.6 per cent and 53 per cent. The results of external radiotherapy were similar to those of radioiodine at five years and better at ten years. In conclusion, a dose of 5,000 to 6,000 rads delivered by megavoltage external radiotherapy in five to six weeks, is well tolerated and effective mostly in differentiated carcinomas and medullary carcinomas. The survival rates of 64 patients whose metastases were unable to pick up iodine is practically zero at five years. For 68 patients with uptake in their metastases the survival rates were 53 per cent at five years and 23 per cent at ten years. The survival rate in patients with pulmonary metastases was higher than in patients with bony metastases (75 per cent versus 44 per cent at five years and 42 per cent versus 8 per cent at ten years.

Pre-eclampsia: physiology and immunological aspects.

Pre-eclampsia is a frequent, unpredictable syndrome which is dangerous for both mother and foetus. The concept of placental ischemia has gained wide acceptance among the numerous theories put forward to explain the illness. The setting up of preeclampsia seems to be scheduled in two steps: (1) an absolute or relative placental ischemia due to vascular diseases or hypertrophic placenta, or most often secondary to implantation defect, particularly anomaly with the invasive trophoblast; (2) a diffuse endothelial disease. The connection between these two steps is incompletely disclosed. The authors demonstrate that the maternal immune system which is strongly stressed during all the stages of normal gestation is implicated in pre-eclampsia. Its role is probably not univocal. Foeto-trophoblastic antigens could be poorly recognised. This defect of recognition could lead to the abnormalities of trophoblastic invasion observed in pre-eclampsia. Pre-eclampsia does not seem to be accompanied by an immunological rejection of the foetus. Some genetically predisposed patients do not have a sufficiently competent immune system to neutralise one or more of the toxic products released by the ischemic placenta. Certain types of pre-eclampsia could be auto-immune, with the auto-antibodies directed against certain types of phospholipids or trophoblastic constituents. A disequilibrium between oxidation and anti-oxidation mechanisms involving neutrophils could lead to aggression of the endothelium which is observed in pre-eclampsia. Pre-eclampsia could represent a form of immuno-dystrophy, with the excessive production of adverse cytokines locally, directed against the trophoblast. Without directly implicating the immune system as the trigger of pre-eclampsia, it seems that its role is unclear. In some cases it develops protective mechanisms which, when overwhelmed or inadequate, allows pre-eclampsia to occur. In other cases it can form part of the cascade of aggressions leading to the abnormalities encountered. The integration of these abnormalities in the pathophysiological models, could help improve the classification of pre-eclampsia. This attempt will lead to a more adapted preventive and therapeutic management of pre-eclampsia.

Immunological aspects of ovarian function: role of the cytokines.

Interaction between the immune system and reproduction is multiple. Either directly or indirectly through their products, immune cells are associated with the regulation of every level of the hypothalamus-pituitary-ovarian axis. Immune cells are present in the ovaries and their numbers increase during the cycle. During the follicular development cytokines assist granulosa cell growth while inhibiting their differentiation. During the LH peak, an influx of immune cells occurs and several cytokines are released. The rupture of the follicle is considered as an inflammatory reaction. IL-1, TNF-alpha are the main cytokines involved in this process. During the luteal phase, the installation of the corpus luteum needs the setting up of neovascularization. Cytokines are probable candidates for this function, but they also promote cellular differentiation resulting in steroid synthesis. In the absence of pregnancy T lymphocytes and eosinophils are involved in corpus luteum regression. Their products are directly cytotoxic for the luteal cells. They attract macrophages which are locally activated to phagocytose the damaged luteal cells. They can induce apoptosis of endothelial and luteal cells through gene expression. Cytokines are members of a larger regulatory network residing in the ovary and involving hormones and growth factors. The various stages of ovarian cycle will be shown from an immunological point of view. Understanding the role of the cytokines should enable us to go beyond a purely descriptive stage, and allow us to envisage new ovulation induction therapy and treatment in certain cases of premature menopause.

Myotonic dystrophy and pregnancy. A report of two cases and a review of the literature.

Myotonic dystrophy is a rare disease (1/8000), that is rarely associated with pregnancy, due to the fact that parents carrying the disease often encounter hypogonadism. Myotonic dystrophy is a neuro-endocrinian 'heredo-degenerative' dystrophy, with dominant autosomic transmission. Its association with pregnancy can lead to several problems. The myotony is often aggravated which leads to obstetrical complications turning into fetal loss, premature term delivery, hydrops, in-utero death, difficulties in expulsion, haemorrhage during delivery and/or anaesthetic accidents. The following signs during the pregnancy can diagnose fetal damage: presence of a hydrops, rare active fetal movements, and low fetal cardiac rhythm. They signify serious fetal damage leading to a diagnosis of myotonic dystrophy. Personal and family antecedents as well as an important hypotony and respiratory distress discovered in the new born are equally evocative elements. In congenital cases (6-30% of the time) the prognosis of the child is pessimistic. For all of the above elements, transmission is of maternal origin. The diagnosis of the congenital form is difficult because the disease is often unknown by the mother. The appearance of molecular tools permits a diagnosis to be formed much more rapidly in a new-born suspected to carry the illness of neonatal Steinert. Two observations illustrate this pathology. The occurrence of congenital myotonic dystrophy in a new-born allows us to diagnose the disease within the mother.

Fetal macrosomia: risk factors and outcome. A study of the outcome concerning 100 cases >4500 g.

OBJECTIVE: Because difficult vaginal delivery is more frequent with macrosomic fetuses, some authors recommend routine caesarean section for the delivery of fetuses >4500 g. The purpose of this study was to evaluate the appropriateness of this recommendation, in particular, to analyze maternal and fetal complications according to the mode of delivery. METHOD: Maternal and neonatal records of 100 infants with weights of at least 4500 g were identified retrospectively from January 1991 to December 1996. Outcome variables included the mode of delivery and the incidence of maternal and perinatal complications. RESULTS: The study sample consisted of 100 infant and mother pairs. Macrosomic fetuses represented 0.95% of all deliveries during this period and only ten were >5000 g. Mean birth weight was 4730 g (maximum, 5780 g). Gestational diabetes was present in nineteen patients. Diabetes was present in three patients. A trial of labour was allowed in 87 women, and elective caesarean delivery was performed in thirteen patients. The overall cesarean rate, including elective caesarean delivery and failed trial of labour, was 36%. Of those undergoing a trial of labour, 73% (64/87) delivered vaginally. Shoulder dystocia occurred fourteen times (22% of vaginal deliveries) and it was the most frequent complication in our series. There were five cases of Erb's palsy, one of which was associated with humeral fracture, and four cases of clavicular fracture. By three months of age, all affected infants were without sequelae. There was no related perinatal mortality and only two cases of birth asphyxia. Maternal complications with vaginal delivery of macrosomic infants included a high incidence of lacerations requiring repair (eleven cases). No complications were noticed in the patients who had a caesarean section. CONCLUSION: Vaginal delivery is a reasonable alternative to elective cesarean section for infants with estimated birth weights of less than 5000 g and a trial of labour can be offered. For the fetuses with estimated birth weight >5000 g, an elective caesarean section should be recommended, especially in primiparous women.

Monoamniotic twin pregnancies. Review of the literature, and a case report with vaginal delivery.

OBJECTIVE: To specify the process of the sometimes difficult diagnosis of monoamniotic twin pregnancies, as well as the best practise for delivery of this type of pregnancy. METHOD: Using their personal observation (a patient with a monoamniotic twin pregnancy, which presented a vaginal delivery at 35 weeks of gestation, two girls, in cephalic presentation, without particular problem, despite an entanglement of the cord and the existence of a knot), the authors established a review of the literature on this subject. RESULTS: Monoamniotic twin pregnancies represent a rare possibility. The prognosis is traditionally somber: 40-60% mortality, mainly due to pathologies of the cord. The review of the recent literature shows that most authors remain in favour of weekly ultrasound supervision from the 23rd week and of caesarean section in principle at 34 weeks (or from fetal pulmonary maturation). CONCLUSION: In the absence of funicular compression signs by colour-doppler, and under the cover of flawless obstetrical conditions, vaginal delivery can only be authorized for cases when both presentations are cephalic.