26. Abnormalities of the placenta ,membranes and umbilical cord. Flashcards
what are the causes for hydroaminos ?
anencephaly - brainstem and cerebella spared
open spina bifida
esophageal atresia - cannot swallow
less common -
Hydramnios is more common in monozygotic twins, usually affecting the second sac.
In TTTS the recipient twin develops polydramnios
Rh disease- hydrops fetalis and fetal ascites
maternal diabetes
Chorioangioma of the placenta-
what is the pathoetiology of hydro aminos in anencephaly ?
anencephaly / spinabifida
= transudation of fluid
excessive urination caused by stimulation cerebrospinal centres
impaired ADH release
absence of fetal swallowing
definition of polyhydroaminos / hydroaminos ?
Anatomically -liquor amnii exceeds 2,000 mL
Clinical definition-
excessive liquor amnii causing discomfort to the patient and/or when imaging help is needed for clinical diagnosis of the lie and presentation of the foetus
what are the signs and symptoms of hydro aminos ?
over distenstion of uterus - dyspnea
palpitation
edema of legs and varicosities , haemorrhoids
Fetal heart sound is not heard distinctly
definition of oligohydroaminos ?
less than 200 mL at term. Sonographically, it is defined when the maximum vertical pocket of liquor is less than <2 cm or when amniotic fluid index (AFI) is less than 5 cm
what is the diagnosis of hydro aminos ?
US -amniotic fluid index (AFI) is more than 24 cm and a deepest vertical pocket (DVP) is more than 8 cm
Amniotic fluid: Estimation of alpha fetoprotein - markedly elevated in open neural tube defect.
what is the management of hydro aminos ?
minor degrees and moderate - rarely require treatmnet
DVP: ≥16 cm or if dyspnea and abdominal pain or difficult to walk and move around -
bed rest , diuretics , water and salt restriction are INEFFECTIVE.
COX-2 inhibitor / INDOMETHACIN = reduces fetal urine output
amniocentesis
less than 37 wks = slow decompression, chance of accidental hemorrhage is less
amniotomy
complications of hydroaminos ?
Preeclampsia (25%)
Malpresentation
Premature rupture of the membranes
during labour :Cord prolapse
Uterine inertia
postpartum hemorrhage
Puerperium: Subinvolution
etiology of oligohydroaminos occur?
fetal
chromosomal and congenital anomalies
pregnancy that continues beyond term
there is a 25 percent decrease in amniotic fluid volume beyond 41 weeks
obstruction of fetal urinary tract
renal agenesis
drugs :
prostaglandin synthase inhibitors
ACE use
maternal
uteroplascental insufficiency
hypertension
what is the fetal prognosis on oligohydroaminos ?
fetal outcome poor in early onset oligohydroaminos
pulmonary hypoplasia is common
what is the management of oligohydroaminos
c section or
Oral administration of water
amnioinfusion
complication of oligohydroaminos ?
Abortion
Deformity - due to intra-amniotic adhesions or due to compression. The deformities include alteration in shape of the skull
Fetal pulmonary hypoplasia (may be the cause or effect)
Cord compression
Less fetal movements
Malpresentation
(breech) is common
what complications of short umbilical cord ?
fetal growth restriction intrapartum distress placental abruption prevent of fetal descend cannot do external version
what is associated with long cords ?
cord prolapse
what is the normal morphology of the umbilical cord ?
2 umbilical arteries
and 1 umbilical vein - both have a spiral course they twist around each other
umbilical vein carries oxygenated blood from the placenta towards the heart of
the fetus
umbilical arteries carry deoxygenated blood from the baby body away towards
the placenta
what are the abnormalities of cord insertion ?
furcate insertion -umbilical vessel separate from the cord before their insertion into the placenta
these vessels are prone to twisting and thrombosis
battledore placental / marginal insertion - insertion of the umbilical cord in the margin of the placenta
velamentous insertion - Normally the umbilical cord inserts into the middle of
In velamentous cord insertion, the umbilical cord inserts
between the fetal membranes (choriamniotic membranes), then travels within the
membranes to the placenta (between the amnion
and the chorion). The exposed
vessels are not protected by Wharton’s jelly hence are
vulnerable to rupture
and inserts marginally
what are the cord abnormalities capable of impending blow flow ?
False knots:
result a lot of wharton jelly leading to kinking of the vessels
true knots:
result from active fetal movements
even with true knot vessels are protected by wharton jelly
Loops: The cord frequently becomes coiled around portions of the fetus, usually the
neck. This is more likely with longer cords. Fortunately, coiling of the cord around the
neck is uncommon cause of antepartum fetal death or neurological damage
Torsion of the cord is rare. It results from fetal movements during which the cord normally becomes twisted
Cord stricture is more serious, and most infants with this finding are stillborn.The stricture is associated with an extreme focal deficiency in Wharton jelly
monoamnionic twinning, a significant fraction of the high perinatal mortality rate is attributed to entwining of the umbilical cords
what other abnormalities are found within the cord ?
Cord cysts occasionally are found along the course of the cord and are designated true and false
True cysts are quite small and may be derived from remnants of the umbilical vesicle or the allantois
False cysts, which may attain considerable size, result from liquefaction of Wharton jelly
measurements of all cord types ?
long cord more than 70cm
normal( 55-60)
less than 35 cm
single umbilical artery are most commonly found in ?
twins
diabetic mother
epilepsy
preeclampsia
single umbilical artery is frequently associated with ?
congenital malformation of the fetus
renal and genital anomalies
trisomy 18
oligohydroamnis
what are the abnormalities of the placenta ?
bilobed placenta
placental previa
placenta accreta
placenta succenturiate
placenta extrachorialis : circumvallate placenta
and placenta marginal
what is the morphology of placenta succenturiata ?
One (usual) or more small lobes of placenta, size of a cotyledon, placed at varying distances from the main placental margin.
Vessels connecting the main to the accessory lobe traverse through the membrane
absence of communicating blood vessels, it is called placenta spuria
how do you diagnose placenta succenturiata ?
inspection of the placenta after its expulsion
With missing lobe:
(a) there is a gap in the chorion and (b) torn ends of blood vessels are found on the margin of the gap
what is the clinical significance of placenta succenturiata
succenturiate lobe is retained it may lead to
Postpartum hemorrhage which may be primary or secondary
Subinvolution
Uterine sepsis
what is the treatment of placenta succenturiata?
Whenever the diagnosis of missing lobe is made, exploration of the uterus and removal of the lobe under general anesthesia is to be done
what causes placenta extrachorialis?
smaller chorionic plate (amnion and chorion) than the basal plate (decidua) and recurrent marginal hemorrhage diagnosed on US is thought to the the cause
what is the morphology of placenta extrachorialis ?
the chorionic plate smaller than the basal plate of the Decidua
parts of chorionic villi not covered by the chorionic plate
so the fetal membrane - amnion and chorion rolls back in on itself to form a ring on the fetal surface
what is the morphologial difference between circumvallate placenta and placenta marginata ?
circumvallate -thickened white ring which is usually complete
ring is situated at varying distance from the margin of the placenta
vessels radiate from the cord insertion as far as the ring and then disappear
marginata - thin fibrous ring where the fetal vessels terminate
clinical significance of
placenta extrachorialis?
Hydrorrhea gravidarum (excessive watery vaginal discharge)
Antepartum hemorrhage
iugr
as placental abruption,
oligohydramnios, abnormal
cardiotocography,
preterm birth,
miscarriage
what is clinically assessed of the fetal membranes ?
thickness
colour
bleeding
what is the normal fetal membrane anatomy ?
consist of two different layers- the layer facing amniotic cavity called amnion and facing the placenta called the chorion - when pulled apart - the membranes should be translucent without any discolouration
what does thickening of the fetal membranes suggest ?
chorioamnionitis
what type of bleeding is present in the fetal membrane ?
subchorionic hemorrhage - bleeding o blood clots between uterus and fetal membrane /chorion membrane
what is significant about the staining of the fetal membrane ?
should not be yellow or green - meconium
what does the normal maternal side of the placenta look like ?
red colour , 2-4 cm thick , and the surfaces divided into lobules called cotyledons
what do we ensure in the placenta of the maternal side
no gaps for any missing cotyledons
membrane should be inspected at the peripheral of the placental edge
calcification of placenta- third trimester is normal - however second trimester abnormal - leading to fetal growth restriction and distress
if any missing cotyledons what can it cause ?
postpartum hemorrage and infectio
