2. ABNORMALITIES OF PLACENTA AND CORD
• ABNORMALITIES OF PLACENTA AND CORD
• There is a marked variation in the morphology including size,
shape and weight of the placenta. Variation of the cord is also
quite common. Only those of clinical importance are described.
3.
4. PLACENTA SUCCENTURIATA
• Morphology: One (usual) or more small lobes of placenta, size of a
cotyledon, may be placed at varying distances from the main
placental margin.
• A leash of vessels connecting the main to the small lobe traverse
through the membranes.
• The accessory lobe is developed from the activated villi on the
chorionic laeve. In cases of absence of communicating blood
vessels, it is called placenta spuria. The incidence of placenta
succenturiata is about 3%.
6. (E) = maternal surface; (F) = fetal surface with communicating vessels (see arrow).
E F
7. Diagnosis
• Diagnosis is made following inspection of the placenta after its
expulsion.
• (1) With intact lobe—the features have already been described
• (2) 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.
8. Clinical significance
• If the succenturiate lobe is retained, following birth of the
placenta, it may lead to:
• (1) Postpartum hemorrhage which may be primary or secondary
• (2) Subinvolution
• (3) Uterine sepsis
• (4) Polyp formation.
9. TREATMENT
• Whenever the diagnosis of missing lobe is made, exploration of
the uterus and removal of the lobe under general anesthesia is to
be done.
11. Development
• The placenta of such type is due to the smaller chorionic plate
than the basal plate. Recurrent marginal hemorrhage as
diagnosed on serial ultrasound is thought to be the cause.
• The chorionic plate does not extend to the placental margin. The
membranes (amnion and chorion) are folded, rolled back upon
itself to form a ring which is reflected centrally. This leaves a rim
of bare placental tissue.
12. Morphology
• Circumvallate placenta —
• (1) The fetal surface is divided into a central depressed zone
surrounded by a thickened white ring which is usually complete.
The ring is situated at varying distances from the margin of the
placenta. The ring is composed of a double fold of amnion and
chorion with degenerated decidua (vera) and fibrin in between.
• (2) Vessels radiate from the cord insertion as far as the ring and
then disappear from view
• (3) The peripheral zone outside the ring is thicker and the edge is
elevated and rounded.
13. Placenta marginata
• Placenta marginata—A thin fibrous ring is present at the margin of
the chorionic plate where the fetal vessels appear to terminate.
14. Clinical significance
• There is increased chance of:
• (1) Abortion
• (2) Hydrorrhea gravidarum (excessive watery vaginal discharge)
• (3) Antepartum hemorrhage
• (4) Growth retardation of the baby
• (5) Preterm delivery
• (6) Retained placenta or membranes.
15. PLACENTA MEMBRANECEA
• The placenta is unduly large and thin. The placenta not only
develops from the chorion frondosum but also from the chorion
laeve so that the whole of the ovum is practically covered by the
placenta.
16. Clinical significance:
• (1) Encroachment of some part over the lower segment leads to
placenta previa.
• (2) Imperfect separation in the third stage leads to postpartum
hemorrhage.
• (3) Chance of retained placenta is more and manual removal
becomes difficult.
18. BATTLEDORE PLACENTA
• The cord is attached to the margin of the placenta. If associated
with low implantation of the placenta, there is chance of cord
compression in vaginal delivery leading to fetal anoxia or even
death; otherwise, it has got little clinical significance.
19. VELAMENTOUS PLACENTA
• The cord is attached to the membranes. The branching vessels
traverse between the membranes for a varying distance before
they reach and supply the placenta.
• If the leash of blood vessels happens to traverse through the
membranes overlying the internal os, in front of the presenting
part, the condition is called vasa previa.
• Rupture of the membranes involving the overlying vessels leads to
vaginal bleeding.
• As it is entirely fetal blood, this may result in fetal exsanguination
and even death.
20. MANAGEMENT
• In the presence of fetal bleeding, urgent delivery is essential
either vaginally or by cesarean section.
• The infant’s hemoglobin should be estimated and if necessary,
blood transfusion be carried out. If the baby is dead, vaginal
delivery is awaited.
21. ABNORMAL LENGTH
• The cord may be unduly long (300 cm) or absent (acordia).
• Short cord: The short cord may be true (less than 20 cm or 8") or
commonly relative due to entanglement of the cord round any
fetal part.
• In exceptional circumstances, the cord may be absent and the
placenta may be attached to the liver as in exomphalos.
22. Clinical significance
• In either variety, it may cause:
• (1) Failure of external version
• (2) Prevent descent of the presenting part especially during labor
• (3) Separation of a normally situated placenta
• (4) Favor malpresentation
• (5) Fetal distress in labor.
23. Long cord
• The clinical significance due to the presence of a long cord is that
there is an increased chance of:
• (1) Cord prolapse.
• (2) Cord entanglement round the neck or the body. The condition
may produce sufficient compression on the cord vessels so as to
produce fetal distress or rarely death.
• (3) True knot is rare. Even with true knot the fetal vessels are
protected from compression, by the Wharton’s jelly. False knots
are the result of accumulation of Wharton’s jelly or due to
varices.
24. SINGLE UMBILICAL ARTERY
• Single umbilical artery is present in about 1–2% of cases. It may be due
to failure of development of one artery or due to its atrophy in later
months.
• It is more common in twins and in babies born of women with diabetes,
epilepsy, oligohydramnios, hydramnios, preeclampsia and antepartum
hemorrhage.
• It is frequently associated with congenital malformation of the fetus
(20–25%).
• Renal and genital anomalies, Trisomy 18 are common. There is
increased chance of abortion, fetal aneuploidy, prematurity, IUGR and
increased perinatal mortality.
