Placenta, Umbilical Cord Flashcards
What abnormalities are associated with the Placenta, Umbilical Cord in pregnancies?
6 Chorioangioma Morbid Adherent Placenta Single Umbilical Artery Umbilical Cord Cyst Umbilical Cord Knot Vasa Praevia
Chorioangioma
Prevalence: 1 in 5,000 pregnancies.
Ultrasound: Hypo- or hyperechoic, well-circumscribed mass, which is usually located underneath the chorionic plate near the umbilical cord insertion, and often protrudes into the amniotic cavity.
Color Doppler demonstrates large vascular channels around and within the tumor.
Assoc Abnorms: Large tumours may result in fetal anemia and thrombocytopenia (due to sequestration of red blood cells and platelets by the tumor), fetal heart failure, hydrops and placentomegaly (due to a hyperdynamic circulation as a result of arteriovenous shunting), polyhydramnios (due to direct transudation into the amniotic fluid and due to fetal polyuria, secondary to the hyperdynamic circulation) and maternal mirror syndrome (generalized fluid overload and preeclampsia).
Follow-Up: Follow-up scans every 2 to 3 weeks to monitor growth of the tumor, heart function, MCA PSV and amniotic fluid volume.
Ultrasound guided laser coagulation of vessels within the tumor, fetal blood transfusions and amniodrainage may become necessary.
Prognosis: Symptomatic chorioangiomas carry a high risk of perinatal death. The neonate may have severe microangiopathic hemolytic anemia and thrombocytopenia.
Recurrence: No increased risk of recurrence.
Morbid Adherent Placenta
Prevalence: 1 in 400 pregnancies.
Placenta previa with history of previous cesarean section (CS): 3% for 1 CS, 10% for 2 CS, >50% for ≥3 CS.
A morbidly adherent placenta includes placenta accreta (chorionic villi attach to myometrium), increta (chorionic villi invade into the myometrium) and percreta (chorionic villi invade through the myometrium).
Ultrasound: Multiple vascular lacunae (spaces) within the placenta (‘Swiss cheese’ appearance) with turbulent flow (peak systolic velocity >15 cm/s),
Retroplacental myometrial thickness of <1 mm.
Loss of normal retroplacental hypoechogenic zone.
Blood vessels and placental tissue bridging uterine-placental margin, myometrial-bladder interface, or crossing uterine serosa. Exophytic masses invading the urinary bladder.
Irregular vascularization involving the whole uterine serosa–bladder junction, visualised with 3-dimensional power Doppler.
Assoc Abnorms: -
Follow-Up: Follow-up should be standard.
Prognosis: Maternal mortality 5-10%, morbidity 75%.
Early diagnosis reduces mortality and morbidity by 50%.
Recurrence: -
Single Umbilical Artery
Prevalence: 1 in 100 pregnancies.
Ultrasound: Visualization of only one artery around the fetal bladder.
Assoc Abnorms: Chromosomal abnormalities, mainly trisomy 18, 13 and triploidy, are found in 5% of cases.
Fetal growth restriction (<5th percentile) occurs in 10% of cases. Stillbirth, usually in association with growth restriction is twice as common as in the general population.
Abnormalities affecting cardiovascular, skeletal, gastrointestinal, genitourinary and central nervous systems, are found in 20% of cases.
Follow-Up: Serial scans at 28, 32 and 36 weeks’ gestation to assess fetal growth and well-being.
Prognosis: In isolated cases the prognosis is normal.
Recurrence: Isolated: no increased risk of recurrence.
Part of trisomies: 1%.
Umbilical Cord Cyst
Prevalence: 1 in 100 pregnancies.
Ultrasound: True cysts are derived from the embryological remnants of either the allantois or the omphalomesenteric duct and are typically located towards the fetal insertion of the cord.
Pseudocysts are more common than true cysts and are located anywhere along the cord. They have no epithelial lining and represent localized edema and liquefaction of Wharton’s jelly.
Assoc Abnorms: Single cysts are usually transient with no adverse effect.
Multiple cysts are associated with increased risk of miscarriage, trisomies 18 and 13, omphalocele, VACTREL association and fetal growth restriction.
Follow-Up: -
Prognosis: Isolated cases: normal prognosis.
Recurrence: Isolated cases: no increased risk of recurrence.
Part of trisomies: 1%.
Umbilical Cord Knot
Prevalence: 1 in 100 pregnancies.
Ultrasound: Visualisation of a transverse section of the umbilical cord surrounded by a loop of umbilical cord: ‘hanging noose sign’.
Predisposing factors include: long cord, small fetus, polyhydramnios, monoamniotic twins.
Assoc Abnorms: -
Follow-Up: The detection of an umbilical cord knot is not an indication for delivery unless associated with evidence of fetal compromise, such as abnormal fetal heart rate pattern.
Closer fetal surveillance by fetal Dopplers and cardiotocography should be considered.
Prognosis: Risk of stillbirth is increased by 5 times.
Recurrence: No increased risk of recurrence.
Vasa Praevia
Prevalence: 1 in 3,000 pregnancies.
Ultrasound: Umbilical vessels, unsupported by either the umbilical cord or placental tissue, traverse the fetal membranes of the lower segment above the cervix.
Use of transvaginal ultrasound and color Doppler are necessary to make the diagnosis.
Assoc Abnorms: Vasa previa usually occurs in association with velamentous cord insertion, bipartite placenta, or succenturiate lobe, where vessels run through the membranes to join the separate lobes.
Risk factors are multiple pregnancies, IVF conceptions (1 in 300) and low lying placenta in the second trimester.
Follow-Up: Serial scans every 2 weeks after 26 weeks to monitor cervical length. If there is cervical shortening (<25 mm) hospitalization should be considered.
Prognosis: Fetal death: >60% if not diagnosed prenatally and <3% if diagnosed prenatally.
Recurrence: No increased risk of recurrence.
