Placenta, Membranes, Amniotic Fluid

Question 1

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.

Answer 1

The Chorion

Question 2

What is chorion frondosum?

Answer 2

The outer surface of the chorion whose villi contact the decidua basalis; the placental portion of the chorion.

Question 3

What is chorion laeve?

Answer 3

The smooth, nonvillous portion of the chorion.

Question 4

What is syncytiotrophoblast?

Answer 4

The outer layer of cells covering the chorionic villi of the placenta that are in contact with the maternal blood or decidua.

Question 5

What is cytotrophoblast?

Answer 5

The thin inner layer of the trophoblast composed of cuboidal cells.

Question 6

What is decidua capsularis?

Answer 6

The part of the decidua that surrounds the chorionic sac.

Question 7

What is decidua basalis?

Answer 7

The part of the uterine decidua that unites with the chorion to form the placenta.

Question 8

What is decidua parietalis (vera)?

Answer 8

The endometrium during pregnancy, except at the site of the implanted blastocyst.

Question 9

What is the amnion?

Answer 9

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.’

Question 10

What is the primary function of the placenta?

Answer 10

Serves as fetal lungs, liver, and kidneys until birth, while growing and maintaining the conceptus in a balanced, healthy environment.

Question 11

What do human trophoblasts produce?

Answer 11

Human trophoblasts produce more diverse steroid and protein hormones in greater amounts than any endocrine tissue in all of mammalian physiology.

Question 12

What is the role of Estradiol-17B?

Answer 12

Estradiol-17B is responsible for the growth of the uterus, fallopian tubes, vagina, and mammary development.

Question 13

What is Estriol?

Answer 13

Estriol is an estrogen metabolite excreted by the placenta during pregnancy; found in the urine of pregnant people.

Question 14

What is the function of Progesterone?

Answer 14

Progesterone is secreted by the corpus luteum; essential in preparing the uterus for implantation of the fertilized ovum and maintaining the pregnancy.

Question 15

What does Aldosterone regulate?

Answer 15

Aldosterone is responsible for the regulation of the body’s salt and water balance.

Question 16

What role does Cortisol play?

Answer 16

Cortisol plays a role in the metabolism of fats, glucose, and proteins.

Question 17

What is Human placental lactogen (hPL)?

Answer 17

hPL is a placental hormone that inhibits maternal insulin activity during pregnancy; decreases to undetectable levels soon after delivery of the placenta.

Question 18

What is the function of Human chorionic gonadotropin (hCG)?

Answer 18

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.

Question 19

What does Placental adrenocorticotropin hormone (ACTH) regulate?

Answer 19

ACTH plays a role in the regulation of the secretion of glucocorticoids.

Question 20

What is Pro-opiomelanocortin?

Answer 20

Pro-opiomelanocortin is a precursor polypeptide.

Question 21

What is Chorionic thyrotropin?

Answer 21

Chorionic thyrotropin is a type of hormone similar to thyroid-stimulating hormone (TSH) that can increase metabolism.

Question 22

What is the role of Growth hormone variant?

Answer 22

Growth hormone variant plays a vital role in growth control.

Question 23

What is Parathyroid hormone-related protein (PTH-rP)?

Answer 23

PTH-rP is essential for bone differentiation and formation and development of mammary gland.

Question 24

What does Calcitonin regulate?

Answer 24

Calcitonin is the hormone responsible for calcium balance.

Question 25

What is Relaxin?

Answer 25

Relaxin is produced in the placenta and corpus luteum; believed to help with relaxing the uterine myometrium during pregnancy.

Question 26

What are hypothalamic-like releasing and inhibiting hormones?

Answer 26

Hypothalamic-like releasing and inhibiting hormones are involved in the regulation of various physiological processes.

Question 27

What is the function of Thyrotropin-releasing hormone (TRH)?

Answer 27

Responsible for the regulation of TSH.

Question 28

What does Gonadotropin-releasing hormone (GnRH) control?

Answer 28

Essential in controlling the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH).

Question 29

What is the role of Corticotropin-releasing hormone (CRH)?

Answer 29

Works with vasopressin hormone to regulate the release of ACTH.

Question 30

What does Somatostatin inhibit?

Answer 30

Responsible for inhibiting the release of growth hormone, prolactin, and thyrotropin.

Question 31

How does blood flow regulation occur in the placenta?

Answer 31

Maternal blood traverses the placenta randomly without preformed channels and enters the intervillous spaces in spurts, propelled by the maternal arterial pressure.

Question 32

What is the placental 'barrier'?

Answer 32

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.

Question 33

How are oxygen and glucose transported across the placenta?

Answer 33

Transported via facilitated diffusion.

Question 34

What are the vessels in the umbilical cord?

Answer 34

Two arteries carry fetal deoxygenated blood to the placenta; one vein carries oxygenated blood from the placenta to the fetus.

Question 35

What are the measurements of the umbilical cord?

Answer 35

0.8-2 cm in diameter; average length of 55 cm, with a range of 30-100 cm.

Question 36

What is Wharton's jelly?

Answer 36

Extracellular matrix consisting of specialized connective tissue that serves as protection for the umbilical cord.

Question 37

What influences the length of the umbilical cord?

Answer 37

Positively influenced by amniotic fluid volume (AFV) and fetal mobility.

Question 38

What are the associations of an extremely short umbilical cord?

Answer 38

Associated with abruptio placentae or uterine inversion; the latter is rare.

Question 39

What are the associations of an abnormally long umbilical cord?

Answer 39

Associated with vascular occlusion by thrombi and true knots.

Question 40

How is amniotic fluid produced?

Answer 40

Produced by amniotic epithelium; water transfers across amnion and through fetal skin.

Question 41

What happens to amniotic fluid in the second trimester?

Answer 41

The fetus starts to swallow, urinate, and inspire amniotic fluid.

Question 42

What is polyhydramnios?

Answer 42

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.

Question 43

What is the incidence of polyhydramnios?

Answer 43

The incidence of polyhydramnios is approximately 1% of all pregnancies.

Question 44

What are the common etiologies of polyhydramnios?

Answer 44

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.

Question 45

What are the signs and symptoms of polyhydramnios?

Answer 45

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.

Question 46

What physical finding warrants an ultrasound in the diagnosis of polyhydramnios?

Answer 46

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.

Question 47

What ultrasonography measurements confirm a diagnosis of polyhydramnios?

Answer 47

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.

Question 48

What are some pregnancy outcomes associated with polyhydramnios?

Answer 48

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.

Question 49

When should polyhydramnios be treated?

Answer 49

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.

Question 50

What is amnioreduction and when is it indicated?

Answer 50

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.

Question 51

Why should indomethacin not be used in cases of polyhydramnios?

Answer 51

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.

Question 52

Where is birth recommended for individuals with severe polyhydramnios?

Answer 52

Birth at a tertiary center is recommended for birthing people with severe polyhydramnios given the high probability of fetal anomalies.

Question 53

What is oligohydramnios?

Answer 53

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.

Question 54

What are fetal conditions associated with oligohydramnios?

Answer 54

Fetal urinary tract obstruction or renal agenesis, chromosomal abnormalities, congenital anomalies, growth restriction, demise, postterm pregnancy, and ruptured membranes (PROM).

Question 55

What placental conditions are associated with oligohydramnios?

Answer 55

Abruption and twin-to-twin transfusion syndrome.

Question 56

What perinatal conditions are associated with oligohydramnios?

Answer 56

Uteroplacental insufficiency, hypertensive disorders (chronic, gestational, superimposed), and diabetes.

Question 57

What drugs are associated with oligohydramnios?

Answer 57

Prostaglandin synthesis inhibitors and angiotensin-converting enzyme inhibitors.

Question 58

What is the prognosis for oligohydramnios due to early-onset diabetes?

Answer 58

Poor outcomes with an increased risk of pulmonary hypoplasia; if due to early PROM, the risk of stillbirth is increased.

Question 59

What is the prognosis for oligohydramnios due to late pregnancy onset?

Answer 59

Leads to more cesarean sections for fetal distress.

Question 60

What is the management for oligohydramnios?

Answer 60

Ultrasonographic evaluation for fetal anomalies and growth restriction, and amnioinfusion in the intrapartum period for the treatment of repetitive variable decelerations.