Placenta, cord, and Cervical Abnormalities

Placental thickness is affected by

1. Gestational diabetes 2. Non-immune hydrops 3. Congenital abnormalities 4. Rh sensitization, immune hydrops 5. Multiple gestations

Long UC

1. Increased mobility 2. May prolapse into LUS and block exit point of baby 3. May cause nuchal cord 4. May form true knot

Short UC

1. Inhibited fetal movement 2. Fetal malformations like ABD wall defects

Compromised fetuses may show reduced diastolic flow with various clinical conditions

1. Maternal HTN 2. Diabetes mellitus 3. IUGR 4. Rh sensitization 5. Systemic lupus 6. Other vascular disease 7. Twin gestation 8. Fetal anomalies

Complications associated with Abruption

1. Maternal morbidity/mortality (rare) 2. Fetal death can result from acute hypoxia produced by placental detachment 3. Maternal hemorrhage 4. Premature delivery 5. IUGR

Most frequently affected organ system from SUA

1. Musculoskeletal 2. Genitourinary (most common) 3. Cardiovascular 4. Gastrointestinal 5. CNS Most subtle malformation is unilateral absence of kidney.

Abnormally thin placentas are seen in patients with

1. Preeclampsia 2. IUGR 3. Juvenile diabetes

Cervix dilates in 3 situations

1. Preterm delivery 2. Inevitable abortion (cervical funneling) 3. Incompetent cervix (when this is found in its early stages, a cerclage may be performed in order to suture and close the cervix until it is time to deliver. Avoided after 24wks)

Risk factors for Abruption

1. Previous history of abruption, perinatal death, or preterm delivery 2. Maternal HTN 3. Maternal vascular disease 4. Maternal smoking, drug use 5. Fibroid uterus 6. Trauma to mother 7. Fetal malformations

Placental Hemorrhage sites my include

1. Retroplacental (behind) 2. Subchorial (below) 3. Subamniotic (below amnion) 4. Intraplacental (within tissue) On US, presence of a retroplacental clot, echogenic area between basal placental region and uterine wall, as clot becomes more organized it gets more echopoor. Ill defined collection behind placenta. Presence of extramembranous clot (outside placenta). If separation is not seen on US it does not exclude abruption, this carries a better prognosis that if a clot is seen.

Placental Functions

1. Transfer of nourishment 2. Remove waste 3. Produce and transfer hormones like HCG essential for pregnancy Acts as intestinal tract, kidneys, and lungs for fetus, > 4cm at 2nd tri thickness is abnormal. Visual at 8wks as a thickened area. Amnion fuses with chorion at 16wks. Normal thickness increases until 33wks, 4.5cm. Placental surface area increases throughout pregnancy

Yolk Sac function

1. Transfer of nutrients 2. Hematopoesis (RBC production 3. Partial sex organ determination Disappears after 12wks

BhCG

1000BhCG = GS = <5wks 7200BhCG = GS and YS = 5-6wks 10000BhCG = GS and YS and Embryo = 6wks Will image about a week earlier with TV

Placenta Previa

Abnormal placement over internal os. Happens every 1/200. 2.0cm away from os or less is considered low lying. Preform TV to help rule out. Partial is when the placenta is partial covering the os. Marginal is when the placenta is adjacent to the cervix but not covering. Complete is when the placenta is completely covering the os. Don't consider doing c-section for placenta previa until 37wks

Placenta Accreta, Increta, and Percreta and US findings

Accreta: Abnormally adherent placenta where the chorionic villi grow directly into the myometrium Increta: Extends (invades) through the myometrium Precreta: Penetration of uterine serosa Absence of hypoechoic subplacental venous complex and myometrium beneath placenta. When we put color behind a placenta, we should see blood flow in order to r/o accretas.

Placenta Location

Can either be Anterior, Posterior, Fundal, Fundal Anterior, Fundal Posterior

UC Cysts

Can originate from remnants of either the omphalomesenteric or allantoid ductal systems. Seen on US. Other cystic appearances of the cord are focal accumulation of Wharton's jelly.

Types of Extrachorial Placentation

Circumvallate placenta: Diagnosed when placental margin is folded, thickened, or elevated with underlying fibrin and/or hemorrhage. Can be associated with bleeding and placental abruption. It's important because any debris can go under the folded parts and it can push away and cause placental tissue to pull from the basal plate which then doesn't allow for nutrients to get to the fetus as it should. Circummarginate placenta: Margin of placenta will not be distorted. We probably won't even recognize this

Umbilical Cord

Contains 2 arteries and 1 vein. Surrounded by a protective jelly called Wharton's jelly. We visualize 3 vessel cord during exam, we see 2 arteries wrapping around the bladder. Trans imaging shows a mickey mouse sign with the 2 arteries and 1 vein. PCI is cord going into placenta. ACI is cord going into ABD of fetus. Growth parallels embryo until 28wks at which it is 50-60cm long

Battledore Placenta

Cord insertion into the margin of the placenta

Cord presentation and Prolapse

Cord presentation (LUS), prolapse, and nuchal cord are potential causes of UC compression and fetal distress. First clue is abnormal fetal heart tracings. Prolapse of cord thru cervical os at delivery is 1/200. High perinatal mortality is due to cord compression with vaginal delivery. Most common cause is abnormal fetal presentation (breech, transverse, oblique). Cord presentation should be established when there is an abnormal presentation and vaginal deliver is anticipated.

Umbilical vein

Delivers oxygen, nutrients, and hormones to the fetus. There is only one

Umbilical Doppler

Evaluates placental circulation and resistance. Normal values of systolic-diastolic ratio vary with gestational age. Increasing end-diastolic flow is observed with advancing gestational age. The ratio should be less than 3:1 during 3rd Tri.

Placenta on US

Fine, granular, moderately echogenic. Thickness correlates with the gestational age. Echogenic interface = chorionic plate. Hypoechoic = basal plate (has both fetal and maternal components)

Placenta

Grading of 0 1 2 3. Braxton Hicks contraction (entire uterus contracts). Focal Myometrial contractions are localized contractions or myometrium. Succenturiate lobe: one or more accessory lobes. Lakes and thrombin deposits contain both fetal and maternal blood and develop in the mid placental region. Cysts are rare but occur and are found in contact with chorionic plate, are outside the placenta! Lakes fill with color when cysts don't.

Chorioangioma

Hemangioma, echogenic and well circumscribed. Most common tumor of placenta. Benign vascular malformation composed of tissue normally present in the placenta. Does not metastasize. Potential complications include polyhydramnios, premature labor, fetal hydrops, IUGR, fetal demise, msAFP may be elevated. US seen as well defined mass of varied appearances, more often hyperechoic, that protrudes from fetal surface of placenta and possibly UCI. Doppler may be helpful in distinguishing chorioangioma from hemorrhage. Chorioangiomas will have flow when a hemorrhage will not.

Complete breech

Hips flexed, knees flexed, feet above or at level of butt

Frank breech

Hips flexed, legs extended with feet above head

Incomplete breech

Hips flexed, one knee flexed, one knee extended with foot above head, one foot above or level with butt

Pregnancy test

IRP (International Reference Prep) SIS (Second or Third International Standard) Both of these are blood tests, IRP is twice SIS

False positive Previa

If maternal bladder is too full it can cause compression of the LUS and mimic a previa. Overfull bladder can distort the shape of the GS, mostly for the 1st tri. Post void images should be taken to ensure placenta location.

Velamentous Insertion

Insertion of cord into chorioamniotic membranes instead of placenta. Vessels in this position extend beyond placental parenchyma and run along the wall of the uterus. Carries risk of cord rupture.

Knee breech

Knee in maternal pelvis below fetal butt

Fetal component is comprised of chorionic plate and chorion frondosum

Maternal component is the decidua basalis.

Intervillous Thrombosis

May not be seen on US. Seen inside placenta once it is removed from patient after delivery. Pathological finding. Seen in 36% of term pregnancies. Results from intraplacental hemorrhage caused by breaks in villous capillaries. Considers to be of little risk to fetus, but has been associated with Rh sensitization (immune hydrops) and increased msAFP. US may be seen as intraplacental sonolucency (venous lakes).

Single Umbilical Artery

Most common UC abnormality. Higher in caucasians. Associated with major congenital anomalies, perinatal death, premature delivery, IUGR, chromosomal abnormalities like T18. 20-50% with SUA have congenital anomaly. Best seen in cross section, single artery is larger than normal, detection of malformation in addition to SUA usually predicts presence of additional non-detectable anomalies with risk of chromosomal abnormality. Patient may need amniocentesis. Seen in 2nd tri, only 1 vessel seen at 3VC view.

UC Hematoma and Thrombosis

Most commonly result from needle puncture during amniocentesis or other interventional procedures. Thrombus is likely to cause fetal demise

UC Enlargement

Normal cord is 1-2cm in diameter. Variations depend on amount of Wharton's jelly and size of vessels.

Chorioamniotic Separation

Normal finding until 16wks. After 16wks, amnion and chorion fuse and no separation should be seen. on US the membrane will appear thickened and can be followed by the placental margin

Extrachorial Placentation and US findings

Occurs when the chorionic plate from which the villi develop is smaller than basal plate, causing the choriol plate to fold over. Attachment of placental membranes to the fetal side of the placenta rather than margin of placenta (edge rolls up know as circumvallate). Difficult to distinguish circummarginate on US. Circumvallate will have elevation of placental margins or hemorrhage.

Footling breech

One or both feet in maternal pelvis below butt

Placental abnormalities and msAFP

Placental abnormalities have been suspected as a cause if elevated msAFP. Even small amounts of fetal-maternal hemorrhage can result in significant increase of msAFP.

Abruptio Placenta and symptoms

Placental abruption refers to premature separation of the placenta from the uterine attachment. Retroplacental and marginal hemorrhages are associated. Retroplacental abruption results from rupture of the spiral arteries and marginal is from tears in the marginal veins. Retro is worse than marginal. Patient can present with pain with or without vaginal bleeding. Severe abruption has knife-like pain, fetus may be still born, may or may not have bleeding or shock. Mild abruption can be just painless vaginal bleeding mimicking previa, blood can build up behind placenta.

Succenturiate Placenta

Presence of one or more placentas connected to the body of the placenta by blood vessels. Retention of the lobe at delivery may result in postpartum hemorrhage and/or infection (if doctor delivering baby is not aware of this extra lobe). US may appear as a discrete lobe separate from the body of the placenta. Bipartite Placenta: 2 placentas of same size

Amniotic Band Syndrome

Rare condition caused by rupture of the amnion during pregnancy. Common associated anomalies include craniofacial defects, asymmetric facial clefts, amputation of extremeties, ABD wall defects

Etiology of -cretas and increased risk

Result from underdeveloped decidualization of the endometrium. Can be secondary to placenta previa due to inadequate decidualization of LUS. The three conditions may require a hysterectomy because retained tissue after delivery will continue to bleed. We should have a barrier between the placenta and uterus, that's our vessels. Placenta has invaded the space of the myometrium. Risk of -cretas include history of prior C-section, uterine scar, and anterior placenta.

Placental Infarction

Results from the interruption of blood supply to a part of the placenta causing cells to die. Found pathologically in 25% or normal term pregnancies. Large infarcts usually associated with underlying maternal vascular disease, HTN and renal disease. US can appear similar in echo pattern to adjacent placenta making it difficult to ID.

Cervix

Should not measure less than 2.5cm otherwise it is considered incompetent. Full bladders can overdistended and cause a false enlargement of the cervix, always make sure the bladder is not too big. Normally a mucous plug fills the non-dilated endocervical canal giving it an echogenic appearance.

UC Hemangioma

Similar to hemangiomas of the placenta. Can be associated with fetal hydrops and elevated msAFP. Increased risk of cord compression. US as echogenic mas with possible cystic components

Trophoblast

Syncytiotrophoblast: outer layer, in contact with endometrium. Invades decidua after fertilization, spaces between become intervillous spaces, maternal spiral arteries enter establishing maternal blood supply Cytotrophoblast: inner cell layer Fetal and maternal blood do not mix in intervillous spaces. Major functioning unit is the chorionic villi (Villi that sprout from the chorion and provide max contact area with maternal blood, fetal portion of placenta)

Synichae vs ABS

Synichea is a broad based band that goes across the uterus, we get two compartments, a form of prior manipulation of the uterus. Patient maye have had a DNC, termination of pregnancy. It is not harmful itself as long as the fetus stays on one side of the band.

Etiology and Complications of Previa

Thought to be the possible low implantation of the fertilized ovum or possibly defective decidual vascularization. Poor vascularization can be caused by advanced maternal age, mutliparas, incision scars, and multiple pregnancies. Patients present with PAINLESS vaginal bleeding in the 2nd and 3rd tri. Complete previa is associated with transvers or breech lie since bulk of placenta prevents fetal head from entering pelvis (previa doesn't allow for baby to lie normally). IDing previa is important because the mother is in danger of hemorrhage if she goes into labor. Always put color in the lower uterine segment to make sure there are no vessels blocking the babies exit.

Cord Knots

True knots in cord less than 1%of cases. Associated with 1. Long cords 2. Polyhydramnios 3. Small fetuses 3. Monoamniotic twins Loose knots have no clinical significance. If tight, the knots can obstruct fetal circulation and cause fetal demise.

Chorionic Leave

Villi become atrophic resulting in a smooth chorion. Succenturiate lobe forms when the leave doesn't happen and the secondary lobe is attached to the main lobe. Cotyledons are a partitioning of villi into compartments, transmit fetal blood and allow for exchange of nutrients with maternal blood

Umbilical Artery

Waste and carbon dioxide are delivered from the fetus. There are 2 of these

Trophotropism

When a placenta moves, doesn't have to be previa

Nuchal cord

Wrapping of cord around neck of fetus. Associated with 1. Increased cord length 2. Polyhydramnios 3. Small fetuses 4. Vertex presentation Can produce signs of fetal distress. Best seen in trans view of C-Spine