Placenta, Membranes, Amniotic Fluid Flashcards
What is the extra-embryonic membrane that, in early development, forms the outer wall of the blastocyst; from it develops the chorionic villi, which establish an intimate connection with the endometrium, giving rise to the placenta.
The Chorion
What is chorion frondosum?
The outer surface of the chorion whose villi contact the decidua basalis; the placental portion of the chorion.
What is chorion laeve?
The smooth, nonvillous portion of the chorion.
What is syncytiotrophoblast?
The outer layer of cells covering the chorionic villi of the placenta that are in contact with the maternal blood or decidua.
What is cytotrophoblast?
The thin inner layer of the trophoblast composed of cuboidal cells.
What is decidua capsularis?
The part of the decidua that surrounds the chorionic sac.
What is decidua basalis?
The part of the uterine decidua that unites with the chorion to form the placenta.
What is decidua parietalis (vera)?
The endometrium during pregnancy, except at the site of the implanted blastocyst.
What is the amnion?
The innermost fetal membrane; a thin, transparent sac that holds the fetus suspended in the amniotic fluid; it grows rapidly at the expense of the extra-embryonic coelom; by the end of the 3rd month, it fuses with the chorion, forming the amniochorionic sac, commonly called the ‘bag of waters.’
What is the primary function of the placenta?
Serves as fetal lungs, liver, and kidneys until birth, while growing and maintaining the conceptus in a balanced, healthy environment.
What do human trophoblasts produce?
Human trophoblasts produce more diverse steroid and protein hormones in greater amounts than any endocrine tissue in all of mammalian physiology.
What is the role of Estradiol-17B?
Estradiol-17B is responsible for the growth of the uterus, fallopian tubes, vagina, and mammary development.
What is Estriol?
Estriol is an estrogen metabolite excreted by the placenta during pregnancy; found in the urine of pregnant people.
What is the function of Progesterone?
Progesterone is secreted by the corpus luteum; essential in preparing the uterus for implantation of the fertilized ovum and maintaining the pregnancy.
What does Aldosterone regulate?
Aldosterone is responsible for the regulation of the body’s salt and water balance.
What role does Cortisol play?
Cortisol plays a role in the metabolism of fats, glucose, and proteins.
What is Human placental lactogen (hPL)?
hPL is a placental hormone that inhibits maternal insulin activity during pregnancy; decreases to undetectable levels soon after delivery of the placenta.
What is the function of Human chorionic gonadotropin (hCG)?
hCG is a hormone secreted by the placenta to help maintain corpus luteum function and production of progesterone; found in serum and urine assays of pregnant persons as early as a week after conception.
What does Placental adrenocorticotropin hormone (ACTH) regulate?
ACTH plays a role in the regulation of the secretion of glucocorticoids.
What is Pro-opiomelanocortin?
Pro-opiomelanocortin is a precursor polypeptide.
What is Chorionic thyrotropin?
Chorionic thyrotropin is a type of hormone similar to thyroid-stimulating hormone (TSH) that can increase metabolism.
What is the role of Growth hormone variant?
Growth hormone variant plays a vital role in growth control.
What is Parathyroid hormone-related protein (PTH-rP)?
PTH-rP is essential for bone differentiation and formation and development of mammary gland.
What does Calcitonin regulate?
Calcitonin is the hormone responsible for calcium balance.
What is Relaxin?
Relaxin is produced in the placenta and corpus luteum; believed to help with relaxing the uterine myometrium during pregnancy.
What are hypothalamic-like releasing and inhibiting hormones?
Hypothalamic-like releasing and inhibiting hormones are involved in the regulation of various physiological processes.
What is the function of Thyrotropin-releasing hormone (TRH)?
Responsible for the regulation of TSH.
What does Gonadotropin-releasing hormone (GnRH) control?
Essential in controlling the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
What is the role of Corticotropin-releasing hormone (CRH)?
Works with vasopressin hormone to regulate the release of ACTH.
What does Somatostatin inhibit?
Responsible for inhibiting the release of growth hormone, prolactin, and thyrotropin.
How does blood flow regulation occur in the placenta?
Maternal blood traverses the placenta randomly without preformed channels and enters the intervillous spaces in spurts, propelled by the maternal arterial pressure.
What is the placental ‘barrier’?
The placenta does not maintain absolute integrity between maternal and fetal circulations, as indicated by the presence of fetal blood cells in maternal circulation and the development of erythroblastosis fetalis.
How are oxygen and glucose transported across the placenta?
Transported via facilitated diffusion.
What are the vessels in the umbilical cord?
Two arteries carry fetal deoxygenated blood to the placenta; one vein carries oxygenated blood from the placenta to the fetus.
What are the measurements of the umbilical cord?
0.8-2 cm in diameter; average length of 55 cm, with a range of 30-100 cm.
What is Wharton’s jelly?
Extracellular matrix consisting of specialized connective tissue that serves as protection for the umbilical cord.
What influences the length of the umbilical cord?
Positively influenced by amniotic fluid volume (AFV) and fetal mobility.
What are the associations of an extremely short umbilical cord?
Associated with abruptio placentae or uterine inversion; the latter is rare.
What are the associations of an abnormally long umbilical cord?
Associated with vascular occlusion by thrombi and true knots.
How is amniotic fluid produced?
Produced by amniotic epithelium; water transfers across amnion and through fetal skin.
What happens to amniotic fluid in the second trimester?
The fetus starts to swallow, urinate, and inspire amniotic fluid.
What is polyhydramnios?
Polyhydramnios, or hydramnios, is an excess of amniotic fluid in a singleton pregnancy, defined as an amniotic fluid index (AFI) of ~24 cm or a maximum deepest vertical pocket of ~8 cm.
What is the incidence of polyhydramnios?
The incidence of polyhydramnios is approximately 1% of all pregnancies.
What are the common etiologies of polyhydramnios?
Approximately 50% to 60% of cases are idiopathic; it is also associated with fetal anomalies, fetal infection, twin-to-twin transfusion syndrome, alloimmunization, or multiple gestation.
What are the signs and symptoms of polyhydramnios?
Signs and symptoms include uterine size larger than expected for gestational age (GA), difficulty auscultating fetal heart rate (FHR) and palpating fetal parts, and mechanical pressure exerted by the large uterus, leading to dyspnea, edema, heartburn, and nausea.
What physical finding warrants an ultrasound in the diagnosis of polyhydramnios?
A fundal height measurement that is 3-4 cm greater than the normal height warrants an ultrasound to determine the reason for the enlarged uterus. Palpation of fetal parts and auscultation of fetal heartbeat may be difficult.
What ultrasonography measurements confirm a diagnosis of polyhydramnios?
An Amniotic Fluid Index (AFI) >24 cm or a single deepest vertical pocket ~8 cm confirms the diagnosis of polyhydramnios. Ultrasound may also identify an associated fetal anomaly.
What are some pregnancy outcomes associated with polyhydramnios?
Polyhydramnios has been linked to fetal macrosomia, higher perinatal mortality, increased preterm labor, higher risk for postpartum hemorrhage (PPH), increased risk for cord prolapse with rupture of membranes, and is associated with erythroblastosis.
When should polyhydramnios be treated?
Polyhydramnios should be treated only if symptomatic and if benefits outweigh risks. Antenatal monitoring is not required for mild idiopathic polyhydramnios alone, but serial antenatal testing may be indicated in the presence of additional perinatal or fetal complications.
What is amnioreduction and when is it indicated?
Amnioreduction via amniocentesis is indicated to reduce fluid volume if polyhydramnios is severe (AFI >35 cm), if there is severe maternal discomfort, and/or dyspnea. Amniotic fluid can be tested for fetal lung maturity and sent for chromosomal studies.
Why should indomethacin not be used in cases of polyhydramnios?
Indomethacin should not be used to decrease amniotic fluid due to findings of neonatal complications and absence of data to support improved perinatal or neonatal outcomes.
Where is birth recommended for individuals with severe polyhydramnios?
Birth at a tertiary center is recommended for birthing people with severe polyhydramnios given the high probability of fetal anomalies.
What is oligohydramnios?
Decreased amniotic fluid volume (AFV), defined as an amniotic fluid index (AFI) of 5 cm or a maximum deepest vertical pocket of fluid <2 cm.
What are fetal conditions associated with oligohydramnios?
Fetal urinary tract obstruction or renal agenesis, chromosomal abnormalities, congenital anomalies, growth restriction, demise, postterm pregnancy, and ruptured membranes (PROM).
What placental conditions are associated with oligohydramnios?
Abruption and twin-to-twin transfusion syndrome.
What perinatal conditions are associated with oligohydramnios?
Uteroplacental insufficiency, hypertensive disorders (chronic, gestational, superimposed), and diabetes.
What drugs are associated with oligohydramnios?
Prostaglandin synthesis inhibitors and angiotensin-converting enzyme inhibitors.
What is the prognosis for oligohydramnios due to early-onset diabetes?
Poor outcomes with an increased risk of pulmonary hypoplasia; if due to early PROM, the risk of stillbirth is increased.
What is the prognosis for oligohydramnios due to late pregnancy onset?
Leads to more cesarean sections for fetal distress.
What is the management for oligohydramnios?
Ultrasonographic evaluation for fetal anomalies and growth restriction, and amnioinfusion in the intrapartum period for the treatment of repetitive variable decelerations.
