Abnormalities of Placenta and Cord

PLACENTA SUCCENTURIATA:

• One (usual) or more small lobes of placenta, size of cotyledon, may be placed at varying distances from the placental margin
• In absence of communicating blood vessels, it is called placenta spuria. 
• Incidence: 3%

Clinical significance:

• If the succenturiate lobe is retained, following birth of the placenta, it may lead to: 
• Postpartum haemorrhage 
• Subinvolution
• Uterine sepsis
•  Polyp formation

Treatment:

• Missing lobe :exploration of the uterus and removal of the lobe under general anaesthesia

TYPES:

1.Circumvallate placenta:

• Development:due to smaller chorionic plate than the basal plate resulting from Recurrent marginal hemorrhage
• Morphology:
• Fetal surface is divided into a central depressed zone surrounded by a thickened white ring (complete)
  
• Vessels radiate from cord insertion as far as the ring and then disappear from view.
• The peripheral zone is thicker and the edge is elevated and rounded

2.Placenta marginata:

• Thin fibrous ring present at margin of chorionic plate where the fetal vessels appear to terminate.

PLACENTA MEMBRANECEA:

• Placenta is unduly large and thin
• Develops from  chorion frondosum & chorion laeve
• Clinical significance:
• Enroachment of some part over lower segment
•  Imperfect separation in third stage
• Chance of retained placenta 
• Manual removal difficult.

PLACENTA ACCRETA, INCRETA AND PERCETA:

• Abnormalities  in which trophoblastic tissues invade the myometrium to varying depths. 
• Much more likely with placenta previa or with implantation over  prior uterine incision or perforation.

CORD ABNORMALITIES:

SHORT CORD:

• Less than 20cm
• Due to entanglement of cord round any fetal part.
• Exceptionally: cord may be absent and placenta may be attached to liver as in exomphalus.
• Clinical significance:
• Prevent descent of presenting part 
• Separation of normally situated placenta 
• Favour malpresentation
• Acute inversion 
• Fetal growth restriction 
• Intrapartum distress 
• Failure of external version
• Two fold risk of fetal death

LONG CORD:

• Clinical Significance 
• Cord prolapse 
• Cord entanglement round the neck or the body 
• True knot 
• False knots

SINGLE UMBILICAL ARTERY:

Incidence : 

• 0.63 %in liveborns
• 1.92 % in perinatal deaths
• 3 %in twins.
• Common in twins and in babies born of diabetic mothers or in polyhydraminos.

Frequently association:

• Congenital malformation of fetus (10-20%).
• Renal and genital anomalies
•  Trisomy 18

Increased chance of :

• Abortion 
• Prematurity 
• FGR 
• Perinatal mortality

Diagnosis:

• Sonographic screening

BATTLEDORE PLACENTA:

• Cord attached to margin of the placenta
• If associated with low implantation of the placenta, chances of cord compression in vaginal delivery leading to fetal anoxia or even death.

VELAMENTOUS PLACENTA:

• Umbilical vessels spread within the membranes  distance from the placental margin
• They reach surrounded only by a fold of amnion.
• Risk of Fetal exsanguinations before labor
• Common in placenta previa and multifetal gestations

VASA PRAEVIA:

• Leash of blood vessels happen to traverse through the membranes overlying the internal os &  can be ruptured easily.
• Incidence is 1:1500
• Associated with low lying placenta

MANAGEMENT:

• Fetal bleeding: urgent delivery (vaginally or CS )
• The newborn’s haemoglobin is estimated and if necessary, blood transfusion be carried out.
• If the baby is dead, vaginal delivery is awaited.

BIPARTITE PLACENTA:

• Two complete and separate parts are present, each with cord leaving it. 
• The bipartite cord joins short distance from the two parts of the placenta
• Tripartite placenta is similar but with three distinct parts

CORD ABNORMALITIES CAPABLE OF IMPENDING BLOOD FLOW:

KNOTS:

False Knots

• Knobs protruding from cord surface and are focal redundancies of a vessel or Wharton jelly, with no clinical significance.

True Knots

• Active fetal movements create cord knotting
• Stillbirth risk

 Loops:

• Cord frequently becomes coiled around portions of fetus.
• Those looped around neck are termed nuchal cord(20 – 34% of deliveries)
• Two loops: 34% 
• Three loops: 0.2 – 0.5%

FUNIC PRESENTATION:

• Cord prolapse or fetal heart rate abnormalities is an associated labor finding.
• Diagnosis:Sonography and color flow Doppler.
• Treatment:During labor, cesarean delivery

UMBILICAL CORD STRICTURE:

• Focal narrowing of cord diameter 
• Develops in area of fetal umbilical insertion 
• Absence of Wharton jelly and stenosis or obliteration of cord vessels at the narrow segment 
• Most fetuses are stillborn

• The findings of a single umbilical artery on examination of the umbilical cord after delivery is An indicator of considerably increased incidence of major malformation of the fetus
• Velamentous insertion of the cord is associated with an increased risk for Fetal exsanguinations before labor
• Placenta in which vessels seperate before reaching margin is Velamentous placenta
• Fetal blood loss in abnormal cord insertion is seen in  Vasa previa
• Single umbilical artery is associated with diabetes in mother. 
• Failure of development of one artery in later months is implicated single umbilical artery case
• Vasa previa is Associated with low lying placenta
•  In vasa previa Incidence is 1:1500
• In  vasa previa Caesarian section is indicated
• Single umbilical artery is associated with Polyhydramnios, Fetal growth retardation & Increased incidence of fetal malformation
• Unilateral renal agenesis is associated with Single umbilical artery