Placenta and umbilical cord registry review Flashcards
Normal placenta
-2 to 4cm thick
-Normal function as excretory organ
-Exchange gas and waste with nutrients and oxygen
-Means of nutrition and respiration
Maternal side of placenta
Decidua basalis or basal plate. Maternal vessels enter intervillous spaces where the exchanges occur
Fetal side of placenta
Chorion frondosum or chorionic plate which contains extensions called chorionic villi
Functional unit of placenta
Lobes of chorionic villi termed cotyledons
Bilobed placental variant
2 discs of equal size joined together by an isthmus of placental tissue (connects 2 lobes)
Accessory lobe/succenturiate lobe variant
Additional small lobe separate from main placental mass but connect by vascular connections
*NO placental tissue connection
Circumvallate variant
Curled up placental contour appearing as a shelf. Curled edges, do not lay flat or smooth along wall
-Increased risk of abnormal placental development and future abruption
Venous lakes/maternal lakes/placental lakes/lacunae variant
Pools of maternal venous blood. Sonolucent areas within placental mass
-Won’t fill with color
-“Swirling” in B mode
Placental grading
Placenta should be age appropriate
-Advance maturation indicates maternal complications leading to insufficiency and asymmetrical IUGR
Grade 0 placenta
Homogenous, smooth echotexture. No indentations in chorionic plate, smooth borders
-1st trimester to early 2nd trimester
Grade 1 placenta
Subtle indentations in chorionic plate, small random hyperechoic foci
-2nd to early 3rd trimester
*normal for anatomy scan
Grade 2 placenta
Large comma-like indentations alter chorionic plate, larger calcifications in basal plate
-Late 3rd trimester
Grade 3 placenta
Complete indentations chorionic to basal plate. Irregular calcifications with shadowing. Related to drug abuse and preeclampsia. May cause IUGR in early gestation
-Post dates/advanced
Asymmetrical IUGR
Poor placental health. Fetus isn’t getting enough oxygen, nutrients and growth will be affected. Brain will shunt more blood to itself
Dopplers
The arteries feeding the placenta may have increased resistance patterns. Includes uterine and umbilical artery
Placenta previa
Placenta is implanted within the LUS and covers or is near the internal os
-Increased risk with advanced maternal age, hx of c section, multiparty
-ONLY diagnosed 20 weeks+ due to possible migration
*MOST likely cause of painless vaginal bleeding in 2nd/3rd trimester
May result in false positive placenta previa
Overly distended bladder or LUS contraction
*Best to scan with empty bladder or soft touch TV
Complete previa
Internal os is completely covered by placental tissue
Marginal previa
Edge of placenta touches internal os
Low-lying placenta
edge of placenta is within 2cm of internal os
Accreta
Abnormal adherence of placenta to myometrium
Increased risk of accreta
Hx of multiple c sections and/or uterine surgery
-Scarring causes the disruption of the basal plate, special LUS placental location with a hx of multiple c sections
Sonographic appearance of placenta accreta
Loss of basal plate or myometrial/serous layer, multiple placental lacunae, and increased peripheral vascularity
Placenta accreta
Adhered to wall
*MOST common
Placenta increta
Invades myometrium
Placenta percreta
Penetrates through uterus and breach serosal layer
Placental abruption
Premature separation of placenta from uterine wall
-High risk of fetal death
*CRITICAL FINDING
Risk factors of placental abruption
Hypertension, preeclampsia, drug/alcohol abuse, smoking, poor maternal health/nutrition
Clinical findings of placenta abruption
Bleeding, pain, tenderness, trauma, decreased hematocrit
Sonographic appearance of placental abruption
Hypo or anechoic region between placenta and uterine wall at level of basal plate
Complete placental abruption
Most severe, entire retroplacental hematoma
Partial placental abruption
Few centimeters of separation
Marginal placental abruption
Placental edge, lifting the chorionic membrane from wall
Chorioangioma
Vascular tumor, most common location is adjacent to umbilical cord insertion at placenta.
*most common placental tumor
Umbilical cord
-2 arteries, 1 vein
-surrounded by Wharton’s jelly
What does the umbilical cord develop from?
Yolk sac and vitelline duct
Umbilical vein
Carries oxygenated blood to fetus
Umbilical arteries
Carries deoxygenated blood back to placenta
Placental cord insertion (PCI)
-Normally at central part of placenta
-Free floating cord attachment into the placenta helps locate
Marginal PCI
Within 2 cm of edge of placenta
-AKA battledore placenta
Velamentous/membraneous cord
Insertion into the membranes beyond the placental edge and insert into side of UTERINE wall. Vessels must travel to insert into placenta.
Vasa previa
Vessels implanted across the internal os
-May rupture if cervix dilates, can lead to exsanguination of fetus
Exsanguination
The loss of blood from the body’s circulatory system, usually resulting in death
Allantoic cyst
Cyst of cord, adjacent to vessels (may look like bubble)
-Near placenta
Omphalomesenteric cyst
Cyst of cord near fetal abdomen (at level of fetal CI)
Hemangioma
Solid, hyperechoic mass near placenta
*most common tumor of cord
Single umbilical artery (2 vessel cord)
1 umbilical artery and 1 umbilical vein. Most likely associated with congenital anomalies
Umbilical dopplers
-Resistance determined by demand of organ
-More volume flow (blood)=lower resistance
-Less volume flow (blood)=higher resistance
Measuring resistance in umbilical dopplers
Evaluate change in diastolic flow
Uterine arteries
-Supplies uterus and placenta
*gravida uterus requires HIGH volume flow aka LOW RESISTANCE
When to doppler uterine arteries
-Preeclampsia
-At risk for placental complications/insufficiency
Abnormal uterine artery doppler
Increased resistance/ decreased EDV
Umbilical artery
Evaluates placental resistance AND fetal well being
-Increased placental resistance indicates insufficiency which leads to FETAL consequences (IUGR/hypoxia)
Normal umbilical artery doppler
-Low resistance, HIGH diastolic flow
-S/D ratio < 3.0
-Resistance decreases with gestational age
Abnormal umbilical artery doppler
-Increased resistance, DECREASED diastolic flow
-Diastolic flow REVERSAL
-S/D ratio > 3.0
(a lot of PEAKS, not hills)
Intrauterine growth restriction (IUGR)
-EFW below 10th percentile
-Biometry measures 2 weeks below expected gestational age
-AC used to evaluate
Symmetric IUGR
Entire fetus is evenly small. Usually starts earlier and related to fetal syndrome
Asymmetric IUGR
Head biometry may be WNL
-ABNORMAL AC/HC ratio
-Usually presents in 2nd trimester
-Related to maternal complications, placental insufficiency and abnormal dopplers
*IMPORTANT to check MCA for intracranial shunting
Middle cerebral artery (MCA)
Normal = high resistance
Abnormal = lower resistance
Intracranial shunting
Fetal brain takes priority and shunts increased volume of blood to the head to “spare” the brain
-Decreasing resistance = increasing volume
*increasing blood supply to brain = head keeps growing therefore asymmetrical growth
Anemia
Reduces hemoglobin, making blood thinner.
-Thin blood flows faster therefore increasing PSV of MCA
Umbilical vein
-Steady, minimally phasic with constant flow to fetus
-Placenta –> fetus
-Flow is forward and constant
Ductus venosus
More pulsatile waveform (closer to heart), reflects arterial contractions
Abnormal flow of ductus venosus
Increased fetal resistance, abnormal flow patterns
-Causes: CHF, hydrops, pulmonary hypoplasia
