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International Birth Defects Information Systems
Placenta

International Birth Defects Information Systems



Placenta


Topics: | Intrauterine Growth Retardation ( IUGR ) | Placenta abruptio | Prenatal diagnosis | Placental Mosaicism | Small for Gestational Age | Triploidy, partial hydatiform mole | Trisomy 22 | Placenta | Umbilical cord |

Related Topics : | Disabilities | Birth Defects |

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Languages: | English | Ukrainian |

Prenatal Diagnosis
The Internet Pathology Laboratory, University of Utah
Visitor Comments [for Professionals mainly] [Illustrated]
Prenatal diagnosis employs a variety of techniques to determine the health and condition of an unborn fetus …
- Ultrasonography
- Amniocentesis
- Chorionic villus sampling
- Fetal blood cells in maternal blood
- Maternal serum beta-HCG
- Maternal serum estriol
Ultrasonography
Non - invasive procedure that is harmless to both the fetus and the mother …
Amniocentesis
Invasive procedure in which a needle is passed through the mother's lower abdomen into the amniotic cavity inside the uterus … For prenatal diagnosis, most amniocenteses are performed between 14 and 20 weeks gestation … Risks with amniocentesis are uncommon, but include fetal loss and maternal Rh sensitization. The increased risk for fetal mortality following amniocentesis is about 0.5% above what would normally be expected …
Chorionic Villus Sampling (CVS)
A catheter is passed via the vagina through the cervix and into the uterus to the developing placenta under ultrasound guidance. Alternative approaches are transvaginal and transabdominal … of the catheter allows sampling of cells from the placental chorionic villi … CVS has the disadvantage of being an invasive procedure … small but significant rate of morbidity for the fetus; this loss rate is about 0.5 to 1% …
Maternal blood sampling for fetal blood cells
Maternal serum alpha - fetoprotein (MSAFP)
Maternal serum beta - HCG
Maternal serum estriol
Techniques for Pathologic Examination
A variety of methods can be employed for analysis of fetal and placental tissues:
Gross Examination
Microscopic Examination
Microbiologic Culture
Karyotyping
FISH (performed on fresh tissue or paraffin blocks)
Biochemical Analysis
Flow Cytometry
Electron Microscopy
Overview of Fetal - Placental Abnormalities
Chromosomal Abnormalities
Trisomy 16: Seen in abortuses from first trimester. Never liveborn …
Hydrops Fetalis
There are many causes for fetal hydrops, and in about 25 to 30% of cases, no specific cause for hydrops can be identified. Multiple congenital anomalies can also be associated with hydrops, though the mechanism is obscure for everything except cardiac anomalies that produce heart failure. Hydrops can be classified as immune and non - immune. Immune causes such as Rh incompatibility between mother and fetus are now uncommon. Non - immune causes can include:
- Congenital infections
- Cardiac anomalies
- Chromosomal abnormalities
- Fetal neoplasms
- Twin pregnancy
- Fetal anemia
- Other anomalies (pulmonary, renal, gastrointestinal)
Disruptions
It is becoming increasingly recognized that many fetal abnormalities result from problems with embryogenesis early on … Such disruptions are generally asymmetric. Examples may include:
Limb - Body Wall Complex (amnionic band syndrome)
- Omphalocele
- Gastroschissis
- Amnionic bands
- Limb - body wall complex
Sirenomelia
Hydranencephaly
Renal Cystic Disease
Polycystic Kidney Disease
Multicystic Renal Dysplasia
Dominant Polycystic Kidney Disease (DPKD)
Congenital Neoplasms
Such tumors are uncommon, but those that are seen most frequently include:
Teratoma …
- Nasopharyngeal teratoma …
Hemangioma … lymphangiomas. Fibromatoses … Neuroblastoma …
Placental Abnormalities
Abruptio placenta … Placenta previa … Velamenous insertion … Long - short cord: Umbilical cord length is determined by the amount of fetal movement. More movement increases cord length. A long cord can become entangled with the baby or more easily prolapse.
- Nuchal cord
- True knot of umbilical cord ...

Triploidy, partial hydatiform mole (IUGR)
Ori M Avrech, MD, Assaf Harofeh Medical Center, Zerifin, Israel, thefetus.net
Visitor Comments [for Professionals mainly] [Illustrated]
Incomplete molar gestation, partial triploid mole …
Definition: Focal hydropic swelling of chorionic villi with trophoblastic hyperplasia and identifiable embryonic or fetal tissues.
Etiology: Abnormal fertilization
Virtually all partial moles are triploid, anomalies of all major systems have been found. They include anomalies of the CNS, the heart, lungs, skeleton and genitalia. All fetuses show intra - uterine growth retardation …
Introduction
Partial moles account for 0.001 - 0.01% of all pregnancies, and all have severe chromosomal anomalies …
Anomalies associated with partial moles and triploid fetuses
Relative macrocephaly … spina bifida … Cleft lip, low set ears … VSD, ASD, Hydrohephrosis … cryptorchidism, hypospadias ... Skeletal dysplasias, syndactyly … IUGR, cystic hygroma, omphalocele, hypoplasia of lungs …

Trisomy 22, placenta
Dominique Thomas, MD et al., Centre Hospitalier Etterbeck Ixelles … Bruxelles, Belgium
Visitor Comments [for Professionals mainly] [Illustrated]
Synonyms: Fetal - placental discrepancy …
Thick placenta, intrauterine growth retardation (IUGR) are associated with this case of placental aneuploidy ... Dombrowski et al. Studied thick placentas and found an incidence of 0.6% among ultrasound recordings of 18,827 viable pregnancies. In the group of pregnancies with a thick placenta, perinatal mortality, rate of abruptio placentae, neonatal intensive care unit admissions and abnormalities have significantly increased …

Umbilical cord, short umbilical cord syndrome
Luc De Catte, MD et al., Academic Hospital, Free University of Brussels, Belgium
Visitor Comments [for Professionals mainly] [Illustrated]
Synonyms: Body stalk anomaly, aplasia of the cord, cyllosomas.
Definition: Set of disruptive abnormalities, including lateral body wall defect involving thorax, abdomen or both, skeletal abnormalities of the spine, lower or upper limb reduction anomalies and a failure of umbilical …
Body stalk anomaly is a part of the Early amnion rupture sequence …

Examination of the Placenta
Joseph F. Yetter III, COL, MC, USA, Fort Lewis, Washington, American Family Physician, March 1998
A one - minute examination of the placenta performed in the delivery room provides information that may be important to the care of both mother and infant … size, shape, consistency and completeness of the placenta should be determined, … accessory lobes, placental infarcts, hemorrhage, tumors and nodules should be noted. The umbilical cord should be assessed for length, insertion, number of vessels, thromboses, knots and the presence of Wharton's jelly … luster and odor of the fetal membranes should be evaluated, … examined for the presence of large (velamentous) vessels …

The Placenta: A literature review by David Butlin
School of Animal and Microbial Sciences, The University of Reading
The types of Chlorioallantoic placentation.
The development and structure of the human placenta …
The endocrine role of the placenta …
Clinical testing during pregnancy …

Confined Placental Mosaicism
Richard M. Pauli, M.D., Ph.D., University of Wisconsin
When an individual has two or more different genetic contents of cells, then we speak of mosaicism … More than half of the human population is functionally mosaic: women have, randomly, one or the other of their X chromosomes inactivated early in development resulting in effective mosaicism for all of the genes that are located on the X chromosome … Somatic mosaicism, mosaicism not affecting the germ cells, is exceedingly common - simple nevi or moles of the skin probably arise because of mutation resulting in a different genetic makeup of the cell that gives rise to these moles … Germinal mosaicism … can result in abnormal offspring of the affected individual …
Confined Placental Mosaicism
A special kind of mosaicism was first recognized about 15 years ago (and became a hot topic with the development of chorionic villus sampling for prenatal diagnosis). Based on a few isolated instances in which chromosomal differences were seen when a baby and its placenta were both assessed, confined placental mosaicism was defined as any discrepancy in the chromosomal makeup of an embryo/fetus/infant compared with its placenta. This phenomenon was identified as a critical determinant of survival in some anueploid babies. It was discovered that in all liveborn babies with trisomy 13 or trisomy 18, there was, in the placental, a normal cell line. That is, survival beyond the fetal period and resultant live birth only arises in these conditions when a spontaneous reversion to a normal chromosome makeup occurs by chance in the cell lineages that give rise to the placenta ("rescue" in an otherwise uniformly lethal condition). This observation helped to explain why many babies with these trisomies are miscarried or are stillborn while others are born alive …
Confined Placental Mosaicism and Prenatal Diagnosis
A thorny problem arose related to confined placental mosaicism …
If the fetus is truly chromosomally normal … Confined placental mosaicism might cause the placenta itself to be poorly functional. This appears to be the most likely mechanism explaining intrauterine growth retardation in some instances of confined placental mosaicism … … nondisjunction in an egg or sperm results in a newly fertilized zygote with three copies of chromosome 7 instead of the usual two. Two of these would come from one parent (let's say for this example from the mother) and one from the other parent. Now let's "correct" this trisomy through a second chance event - loss of one of the three chromosome 7s. Two - thirds of the time one of the maternal 7s will be lost and everything will, presumably, be ok. However, one - third of the time the paternal 7 will be lost and what will remain are two maternal 7s … Uniparental disomy can have bad effects in two ways …
Placental mosaicism in spontaneous abortions or stillbirths … the data are very uncertain …

Placenta abruptio
Medline Plus, National Library of Medicine, November 8, 2006
Alternative names: ablatio placentae; abruptio placentae; accidental hemorrhage; premature separation of placenta
Definition: The separation of the placenta from the site of uterine implantation before delivery of the fetus.
It is frequently difficult to determine the exact causes of placenta abruptio. Definable, direct causes that trigger placenta abruptio are quite rare (1 to 5%) … Predisposing factors include the following risk factors: a past medical history of placenta abruptio (after 1 prior episode there is a 10 to 17% recurrence, after 2 prior episodes the incidence of recurrence exceeds 20%); hypertension or high blood pressure during pregnancy is associated with 2.5 to 17.9% incidence (however, approximately 50% of placenta abruptio cases severe enough to cause fetal death are associated with hypertension); increased maternal age; increased number of prior deliveries; increased uterine distention … abnormally large volume of amniotic fluid; diabetes mellitus … drinking alcohol during pregnancy …

Biological mechanisms of environmentally induced causes of IUGR
JA Prada and RC Tsang, Children’s Hospital Medical Center, Cincinnati, Ohio
The causes of intrauterine growth retardation (IUGR) are multiple … genetic determinants …
Hormonal regulation of fetal growth …
Nutrition and placental functions …
Maternal environment …
Maternal disorders …
Cigarette smoking …
Maternal nutrition …
Interaction factors …

IUGR: etiology
Yong H. Hahn, MD, Medical College of Wisconsin
UTEROPLACENTAL INSUFFICIENCY (80%)
Maternal causes
- deficient supply of nutrients: smoking, malnutrition, multiple …
- maternal vascular disease … severe diabetes Primary placental causes
- … placental infarctions … separation, placenta previa
PRIMARY FETAL CAUSES (20%)
- … intrinsic growth; symmetrical IUGR
- congenital heart disease, genitourinary anomalies, CNS anomalies, chromosomal abnormalities (trisomy 13, 18, 21) …

Intrauterine Growth Retardation Fact Sheet for Professionals
I.B.I.S. Birth Defects, February 6, 2002
Visitor Comments [Ukrainian]
What is IUGR ... Etiology ... Classification ... Clinical features ... Diagnosis ... Pathophysiology ... Prenatal diagnosis ... IUGR pregnancy follow up ... Management ... Prognosis

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Last Updated: 2007/08/20

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