Abstract：
:The mechanisms responsible for twinning and disorders of twin gestations have been the subject of considerable interest by physicians and scientists, and cases of atypical twinning have called for a reexamination of the fundamental theories invoked to explain twin gestations. This article presents a review of the literature focusing on twinning and atypical twinning with an emphasis on the phenomena of chimeric twins, phenotypically discordant monozygotic twins, mirror-image twins, polar body twins, complete hydatidiform mole with a coexistent twin, vanishing twins, fetus papyraceus, fetus in fetu, superfetation, and superfecundation. The traditional models attributing monozygotic twinning to a fission event, and more recent models describing monozygotic twinning as a fusion event, are critically reviewed. Ethical restrictions on scientific experimentation with human embryos and the rarity of cases of atypical twinning have limited opportunities to elucidate the exact mechanisms by which these phenomena occur. Refinements in the modeling of early embryonic development in twin pregnancies may have significant clinical implications. The article includes a series of figures to illustrate the phenomena described.
journal_name
Am J Obstet Gynecoljournal_title
American journal of obstetrics and gynecologyauthors
McNamara HC,Kane SC,Craig JM,Short RV,Umstad MPdoi
10.1016/j.ajog.2015.10.930subject
Has Abstractpub_date
2016-02-01 00:00:00pages
172-191issue
2eissn
0002-9378issn
1097-6868pii
S0002-9378(15)02235-8journal_volume
214pub_type
杂志文章,评审abstract：OBJECTIVE:The study was conducted to systematically investigate previous anecdotal reports of memory decline during pregnancy. STUDY DESIGN:We used a longitudinal design to investigate memory in women throughout pregnancy and in the postpartum period. Closely matched, nonpregnant women were similarly studied at equiva...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/s0002-9378(98)70073-0
更新日期：1998-09-01 00:00:00
abstract：OBJECTIVE:Our purpose was to evaluate the role of testing for intermediate- and high-risk human papillomavirus by use of a hybrid capture technique for predicting which patients with abnormal Papanicolaou smears are most likely to have squamous intraepithelial lesions or cancer. STUDY DESIGN:Cervical cytologic studies...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/0002-9378(95)91473-0
更新日期：1995-04-01 00:00:00
abstract：:Based on ultrasonographic mensuration, a number of equations have previously been devised for the purpose of estimating fetal weights. The objective of this study was to develop a mathematical equation that is simple, accurate, and easy to use when applied to preterm or low-birth weight fetuses (less than 2,500 gm). R...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/0002-9378(83)91195-x
更新日期：1983-03-01 00:00:00
abstract：BACKGROUND:Pregnancy-related deaths in the United States are increasing. Medical, social, economic, and cultural issues have all been implicated in this trend, but few data exist to differentiate the relative contributions of these various factors. OBJECTIVE:The objective of the study was to examine trends in US pregn...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/j.ajog.2020.02.020
更新日期：2020-05-01 00:00:00
abstract：OBJECTIVE:We sought to determine the impact of geographic location on advanced-stage ovarian cancer mortality in relation to adherence to National Comprehensive Cancer Network (NCCN) treatment guidelines and hospital case volume. STUDY DESIGN:This was a retrospective observational cohort study of patients diagnosed wi...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/j.ajog.2015.01.045
更新日期：2015-07-01 00:00:00
abstract：OBJECTIVE:The purpose of this study was to determine whether changes in vaginal dimensions after transvaginal reconstructive pelvic surgeries affect the risk for postoperative dyspareunia. STUDY DESIGN:Charts of all sexually active patients who underwent transvaginal reconstructive pelvic surgeries in our institution ...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/j.ajog.2004.10.628
更新日期：2005-05-01 00:00:00
abstract：OBJECTIVE:The purpose of this study was to determine the effect of discordant fetal growth on subsequent perinatal and neonatal outcome for different degrees of birth weight discordance in preterm twin gestations. STUDY DESIGN:One hundred twenty-two live born twin sets delivered between 25 and 34 completed weeks' gest...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/0002-9378(95)90027-6
更新日期：1995-03-01 00:00:00
abstract：OBJECTIVE:This study was undertaken to develop, implement, and evaluate a program designed to improve residents' teaching skills. STUDY DESIGN:A training program to improve the teaching skills of obstetrics and gynecology residents was developed and implemented. All residents completed a survey of their teaching skill...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1067/s0002-9378(03)00879-2
更新日期：2003-09-01 00:00:00
abstract：:Micromanipulative techniques, such as subzonal insemination and direct intracytoplasmic sperm injection, are used when standard in vitro fertilization techniques have failed. These new approaches are currently under investigation in a variety of centers across the country. The projected results and the strengths and w...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章,评审
doi：10.1016/0002-9378(95)90152-3
更新日期：1995-02-01 00:00:00
abstract：:This essay presents a brief review of the history advocating a restructuring of residency training to increase the flexibility of the experience. The advantages for both the general obstetrician-gynecologist and the subspecialist are reviewed. ...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章,评审
doi：10.1016/s0002-9378(99)70246-2
更新日期：1999-03-01 00:00:00
abstract：OBJECTIVE:The purpose of this study was to determine whether thickness, fiber count, and density of urethral circular smooth muscle (CSM) differ in young and old women. STUDY DESIGN:Mid urethral hemiaxial sections from female cadavers aged 20-39 years (n = 12) and 70-89 years (n = 16) were stained for smooth muscle al...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/j.ajog.2008.03.009
更新日期：2008-05-01 00:00:00
abstract：:We report a case of splenic rupture after cesarean delivery for abruptio placentae. The diagnosis was not suspected until a laparotomy was performed. Diagnosis and management were complicated by disseminated intravascular coagulation and renal failure. The importance of early diagnosis and management modalities are di...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/0002-9378(95)90199-x
更新日期：1995-07-01 00:00:00
abstract：:The role of fetal prolactin (PRL) as a fetal adrenotropic hormone was investigated in eight chronically catheterized fetal lambs. Catheters were placed for measurement of plasma prolactin (PRL), cortisol (F), dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEA-S), and androstenedione (A). Daily (9 AM) ...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/0002-9378(81)90320-3
更新日期：1981-02-15 00:00:00
abstract：:Intrauterine 17 beta-estradiol pellets can induce an up-regulation of guinea pig myometrial beta-adrenergic receptor density and l-isoproterenol-dependent adenylate cyclase activity. Does 17 beta-estradiol influence the ability of beta-adrenergic receptors to form a "high affinity" state with l-isoproterenol, which is...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/0002-9378(89)90939-3
更新日期：1989-12-01 00:00:00
abstract：:Either Actinomyces israeli, A. naeslundii, or Arachnia propionica was found, by immunofluorescence studies, in cervicovaginal mucus from 36% of 50 women. One or more of these organisms were found in a surprising 27% of those with neither intrauterine contraceptive devices (IUDs) nor intravaginal foreign bodies. The on...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/0002-9378(81)90078-8
更新日期：1981-08-15 00:00:00
abstract：:We describe the preparation and usage of positive and negative quality control standards for the proline aminopeptidase assay of vaginal secretions as an indicator of bacterial vaginosis. ...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/s0002-9378(89)80075-4
更新日期：1989-03-01 00:00:00
abstract：OBJECTIVE:We sought to determine whether small-for-gestational age (SGA) and large-for-gestational age (LGA) birthweights increase autism risk. STUDY DESIGN:This was a retrospective cohort analysis comparing children with autism (n = 20,206) within a birth cohort (n = 5,979,605). Stratification by sex and birthweight ...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/j.ajog.2012.01.044
更新日期：2012-04-01 00:00:00
abstract：OBJECTIVE:We evaluated four oral combinations of conjugated estrogens (Premarin) and medroxyprogesterone acetate in preventing endometrial hyperplasia, which can occur with conjugated estrogens alone. STUDY DESIGN:This was a 1-year prospective, double-blind, randomized, multicenter study in 1724 postmenopausal women. ...
journal_title：American journal of obstetrics and gynecology
pub_type： 临床试验,杂志文章,多中心研究,随机对照试验
doi：10.1016/s0002-9378(94)70129-6
更新日期：1994-05-01 00:00:00
abstract：BACKGROUND:After initiating a new contraceptive method, the provider has little control of how or whether that method is used. OBJECTIVE:We sought to compare unintended pregnancy rates by the initial chosen contraceptive method after counseling to traditional contraceptive effectiveness in the same study population. ...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/j.ajog.2016.01.162
更新日期：2016-07-01 00:00:00
abstract：:We report a case of sigmoid perforation, peritonitis, and adult respiratory distress syndrome after a loop excision procedure for carcinoma in situ of the cervix and dysplasia of the vagina. Treatment of vaginal dysplasia with loop excision is potentially dangerous. Safer methods of management include carbon dioxide l...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1067/mob.2000.102701
更新日期：2000-03-01 00:00:00
abstract：:Chromosomal microarray analysis is a high-resolution, whole-genome technique used to identify chromosomal abnormalities, including those detected by conventional cytogenetic techniques, as well as small submicroscopic deletions and duplications referred to as copy number variants. Because chromosomal microarray analys...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/j.ajog.2016.07.016
更新日期：2016-10-01 00:00:00
abstract：:Vasoactive intestinal polypeptide, a neuropeptide with wide distribution in the central and peripheral nervous system, has a broad spectrum of biologic actions. The demonstration of vasoactive intestinal polypeptide containing nerve fibers within the female and male genital tract 17 years ago indicated a putative role...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章,评审
doi：10.1016/0002-9378(95)90506-5
更新日期：1995-05-01 00:00:00
abstract：:In a double-blind controlled multicentric study involving 94 patients with an intrauterine fetal death, we investigated the efficacy and tolerance of mifepristone (RU 486), a steroid compound that antagonizes progesterone action at the receptor level. Success of treatment was defined as the occurrence of fetal expulsi...
journal_title：American journal of obstetrics and gynecology
pub_type： 临床试验,杂志文章,多中心研究
doi：10.1016/0002-9378(90)91193-g
更新日期：1990-08-01 00:00:00
abstract：OBJECTIVE:Our purpose was to study the distribution of symptoms and disorders of urinary incontinence or prolapse among white and Hispanic women. STUDY DESIGN:Data were collected for all new patients referred to the urogynecology clinic over a 2-year period. One hundred twenty-one Hispanic and 50 white women consecuti...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/s0002-9378(96)70443-x
更新日期：1996-02-01 00:00:00
abstract：OBJECTIVE:The purpose of this study was to determine the accuracy of live-birth certificates and hospital discharge data that reported of pre-existing maternal medical conditions and complications of pregnancy. STUDY DESIGN:We conducted a population-based validation study in 19 non-federal short-stay hospitals in Wash...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/j.ajog.2005.02.096
更新日期：2005-07-01 00:00:00
abstract：OBJECTIVE:Our purpose was to analyze 3 obstetric outcomes according to the various forms of congenital uterine malformation after in vitro fertilization and embryo transfer. STUDY DESIGN:We conducted a retrospective analysis of data from 24 patients with the following types of congenital uterine malformation: 6 unicom...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/s0002-9378(96)70255-7
更新日期：1996-07-01 00:00:00
abstract：:The choroid plexus cyst is one of many malformations of the central nervous system that can be detected in utero by ultrasonography. Choroid plexus cysts occur in 2.3% of fetuses. Because previous reports have shown an association between choroid plexus cysts and chromosomal anomalies, we analyzed 82 prenatally diagno...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/0002-9378(89)90192-0
更新日期：1989-05-01 00:00:00
abstract：BACKGROUND:Uterine inflammatory processes trigger prolabor pathways and orchestrate on-time labor onset. Although essential for successful labor, inflammation needs to be regulated to avoid uncontrolled amplification and resolve postpartum. During labor, myometrial smooth muscle cells generate ATP mainly via anaerobic ...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/j.ajog.2016.09.072
更新日期：2017-01-01 00:00:00
abstract：:Primary prevention of sexually transmitted diseases has received little emphasis in control programs. To evaluate the effectiveness of prevention strategies, we reviewed the world's literature on this topic. Use of condoms and spermicides greatly reduces the risk of gonorrhea, and barrier methods are practical and acc...
journal_title：American journal of obstetrics and gynecology
pub_type： 临床试验,杂志文章,评审
doi：10.1016/0002-9378(86)90108-0
更新日期：1986-07-01 00:00:00
abstract：:We report the effect of high glucose infusion on vascular resistance in isolated human placental cotyledons perfused with Krebs-Ringer-bicarbonate solution containing 80 mg/dl (4.4 mmol/L), 160 mg/dl (8.8 mmol/L), or 320 mg/dl (17.6 mmol/L) D-glucose (n = 6). Placental vascular resistance remained constant during 25-m...
journal_title：American journal of obstetrics and gynecology
pub_type： 杂志文章
doi：10.1016/0002-9378(90)90758-y
更新日期：1990-12-01 00:00:00
