Placental abnormalities eg praevia, abruption, vasa praevia

Question 1

What is placenta praevia?

Answer 1

• where the placenta is attached in the lower portion of the uterus, lower than the presenting part of the fetus
• Placenta praevia occurs in around 1% of pregnancies. It is a notable cause of antepartum haemorrhage.

Question 2

What is the difference between low-lying placenta and placenta praevia?

Answer 2

• Low-lying placenta is used when the placenta is within 20mm of the internal cervical os
• Placenta praevia is used only when the placenta is over the internal cervical os

Question 3

What are the causes of antepartum haemorrhage?

Answer 3

• placenta praevia
• placental abruption
• vasa praevia

Question 4

What are the risks associated with placenta praevia?

Answer 4

• Antepartum haemorrhage
• Emergency caesarean section
• Emergency hysterectomy
• Maternal anaemia and transfusions
• Preterm birth and low birth weight
• Stillbirth

Question 5

What are the risk factors for placenta praevia?

Answer 5

• Previous caesarean sections
• Previous placenta praevia
• Older maternal age
• Maternal smoking
• Structural uterine abnormalities (e.g. fibroids)
• Assisted reproduction (e.g. IVF)

Question 6

How is placenta praevia diagnosed?

Answer 6

-The 20-week anomaly scan is used to assess the position of the placenta and diagnose placenta praevia.

Question 7

What are the symptoms of placenta praevia?

Answer 7

• Many women with placenta praevia are asymptomatic
• may present with painless vaginal bleeding in pregnancy (antepartum haemorrhage)
• Bleeding usually occurs later in pregnancy (around or after 36 weeks)

Question 8

What is the management for placenta praevia?

Answer 8

• repeat transvaginal US scan at 32 and 36 weeks (if present on the 32 week scan)
• Corticosteroids are given between 24 and 37+ weeks gestation to mature the fetal lungs, given the risk of preterm delivery
• Planned caesarian delivery is considered between 36 and 37 weeks gestation (to reduce risk of SVB & bleeding: If the placenta covers all or part of the cervix, a vaginal delivery can cause severe bleeding. This can be deadly to both the mother and baby therefore avoid vaginal delivery )

Question 9

Why is planned delivery early in placenta praevia?

Answer 9

• planned early to reduce the risk of spontaneous labour and bleeding
• Planned cesarean section is required with placenta praevia and low-lying placenta (<20mm from the internal os
• Emergency caesarean section may be required with premature labour or antenatal bleeding

Question 10

What is the main complication of placenta praevia and how is it managed?

Answer 10

haemorrhage before, during and after delivery.When this occurs, urgent management is required and may involve:

• Emergency caesarean section
• Blood transfusions
• Intrauterine balloon tamponade
• Uterine artery occlusion
• Emergency hysterectomy

Question 11

A 35 year old woman presents to the early pregnancy unit with an episode of vaginal bleeding which is bright red and fresh in nature. She is 15 weeks pregnant and the pregnancy has been uncomplicated so far. She has one other child who was born via elective caesarean section at 37 weeks because of malpresentation. Her booking bloods were normal and she is rhesus positive. She feels well and reports no abdominal pain. On speculum examination there is a small amount of vaginal blood visible and the cervical os is closed.

Which is the most appropriate investigation?
A. Abdominal USS
B. Kleihauer test
C. TVUSS
D. Digital vaginal examination
E. Amniocentesis

Answer 11

C: TVUSS ( investigation of choice for placenta praevia)
not B: she’s already known to be rhesus positive so this is not necessary

Question 12

RFs for placental abruption

Answer 12

-Previous placental abruption
-Pre-eclampsia
-Bleeding early in pregnancy
-Trauma (consider domestic violence, assault, road traffic accident, iatrogenic)
-Multiple pregnancy
-Fetal growth restriction
-Multigravida
-Increased maternal age (>35)
-Smoking
-Cocaine or amphetamine use
shortened umbilical cord
-polyhydramnios
-Existing coagulation disorders
-IVF? (both praevia & abruption)

Question 13

what is the pain character in placental abruption:

Answer 13

sudden onset severe abdominal pain that is continuous (associated with woody contracted uterus)

Question 14

USS findings in placental abruption

Answer 14

often it is normal
-TVUSS & TAUSS can be done to confirm diagnosis, assess extent of abruption and also assess foetal wellbeing (in absence of foetal & maternal compromise, not done in emergency as emergency c-section needed for definitive management)

Question 15

A 29-year-old G3P2 female presents to maternity triage after her membranes ruptured. She is 34 weeks’ pregnant. She reports heavy vaginal bleeding since. Her pregnancy has so far been uncomplicated. Her 20-week scan showed a placenta lying 5 cm from the cervical os. On examination, the patient appears well. The abdomen is non-tender. There is a large volume of red blood in the vagina on speculum examination. Given the likely diagnosis, which of the following is a likely complication of this condition?

A. Foetal death

B. Low birthweight

C. Sepsis

D. Large birthweight

E. Maternal death

Answer 15

A. Foetal death

This patient most likely has vasa praevia. This occurs when the foetal blood vessels cross the cervical os. Vasa praevia often presents with painless vaginal bleeding during the third trimester or vaginal bleeding after membrane rupture. The blood loss is from the foetal vessels and so foetal blood loss and foetal death are the most important complications to be aware of.

Not: C: sepsis

Vasa praevia is not associated with an increased risk of sepsis.

Not E: maternal death

This patient most likely has vasa praevia. This occurs when the foetal blood vessels cross the cervical os. Vasa praevia often presents with painless vaginal bleeding during the third trimester or vaginal bleeding after membrane rupture. Blood loss is from the foetus, rather than the mother and so maternal death is less likely.

Not B: low birthweight

Low birthweight is a foetal complication associated with obstetric conditions such as pre-eclampsia and substance abuse.

Not D: Large birthweight

Large birthweight (macrosomia) is a foetal complication associated with gestational diabetes.

Question 16

triad of vasa praevia:

Answer 16

1. Painless vaginal bleeding
2. Rupture of membranes
3. Foetal bradycardia (or resulting foetal death)

Question 17

Management of vasa praevia:

Answer 17

Management is with elective caesarean section prior to rupture of membranes. This can be difficult to predict and so is usually arranged at 35-36 weeks gestation.

1. Corticosteroids, given from 32 weeks gestation to mature the fetal lungs
2. Elective caesarean section, planned for 34 – 36 weeks gestation

If the mother does however rupture her membranes or go into labour then emergency caesarean section should be carried out immediately.

Question 18

vasa praevia types:

Answer 18

There are two instances when the fetal vessels can be exposed, outside the protection of the umbilical cord or placenta:

Velamentous umbilical cord is where the umbilical cord inserts into the chorioamniotic membranes, and the fetal vessels travel unprotected through the membranes before joining the placenta (type 1)

An accessory lobe of the placenta (also known as a succenturiate lobe) is connected by fetal vessels that travel through the chorioamniotic membranes between the placental lobes (type 2)

Question 19

RFs of vasa praevia:

Answer 19

1.mLow lying placenta
2. IVF pregnancy
3. Multiple pregnancy

Question 20

Definition and pathophysiology of vasa praevia:

Answer 20

Vasa praevia is a condition where the fetal vessels are within the fetal membranes (chorioamniotic membranes) and travel across the internal cervical os. The fetal membranes surround the amniotic cavity and developing fetus. The fetal vessels consist of the two umbilical arteries and single umbilical vein.

Under normal circumstances, the umbilical cord containing the fetal vessels (umbilical arteries and vein) inserts directly into the placenta. The fetal vessels are always protected, either by the umbilical cord or by the placenta. The umbilical cord contains Wharton’s jelly. Wharton’s jelly is a layer of soft connective tissue that surrounds the blood vessels in the umbilical cord, offering protection.

In vasa praevia, the fetal vessels are exposed, outside the protection of the umbilical cord or the placenta. The fetal vessels travel through the chorioamniotic membranes, and pass across the internal cervical os (the inner opening of the cervix). These exposed vessels are prone to bleeding, particularly when the membranes are ruptured during labour and at birth. This can lead to dramatic fetal blood loss and death.

Question 21

management of placental abruption:

Answer 21

Placental abruption is an obstetric emergency. The urgency depends on the amount of placental separation, extent of bleeding, haemodynamic stability of the mother and condition of the fetus. It is important to consider concealed haemorrhage, where the vaginal bleeding may be disproportionate to the uterine bleeding.

The initial steps with major or massive haemorrhage are (A–> E approach_:

1. Urgent involvement of a senior obstetrician, midwife and anaesthetist
2. 2 x grey cannula
3. Bloods include FBC, UE, LFT and coagulation studies and G & S
4. Crossmatch 4 units of blood
5. Fluid and blood resuscitation as required
6. CTG monitoring of the fetus
7. Close monitoring of the mother
8. Ultrasound can be useful in excluding placenta praevia as a cause for antepartum haemorrhage, but is not very good at diagnosing or assessing abruption.
9. Antenatal steroids are offered between 24 and 34 + 6 weeks gestation to mature the fetal lungs in anticipation of preterm delivery.
10. Rhesus-D negative women require anti-D prophylaxis when bleeding occurs. A Kleihauer test is used to quantify how much fetal blood is mixed with the maternal blood, to determine the dose of anti-D that is required.
11. Emergency caesarean section may be required where the mother is unstable, or there is fetal distress (Generally after 34 weeks of pregnancy, if the placental abruption seems minimal, a closely monitored vaginal delivery might be possible. Induction of labour (IOL) with the aim of
    achieving a vaginal delivery should be considere. If the abruption worsens or jeopardizes your or your baby’s health, you’ll need an immediate delivery — usually by C-section)
12. There is an increased risk of postpartum haemorrhage after delivery in women with placental abruption. Active management of the third stage is recommended.

Question 22

placental abruption summary

Answer 22

Question 23

typical presentation of placental abruption

Answer 23

1. Sudden onset severe abdominal pain that is continuous
2. Vaginal bleeding (antepartum haemorrhage)
3. Shock (hypotension and tachycardia)
4. Abnormalities on the CTG indicating fetal distress
5. Characteristic “woody” abdomen on palpation, suggesting a large haemorrhage

Question 24

different types of abruption:

Answer 24

Concealed abruption is where the cervical os remains closed, and any bleeding that occurs remains within the uterine cavity. The severity of bleeding can be significantly underestimated with concealed haemorrhage.

Concealed abruption is opposed to revealed abruption, where the blood loss is observed via the vagina.

Question 25

3 layers of uterine wall and their components

Answer 25

1. Endometrium, the inner layer that contains connective tissue (stroma), epithelial cells and blood vessels
2. Myometrium, the middle layer that contains smooth muscle
3. Perimetrium, the outer layer, which is a serous membrane similar to the peritoneum (also known as serosa)

Question 26

3 types of placental insertion (other than endometrium)/mnemonic:

Answer 26

AIP

1. Superficial placenta accreta is where the placenta implants in the surface of the myometrium, but not beyond
2. Placenta increta is where the placenta attaches deeply into the myometrium
3. Placenta percreta is where the placenta invades past the myometrium and perimetrium, potentially reaching other organs such as the bladder

Question 27

RFs for placenta accreta:

Answer 27

1. Previous placenta accreta
   2 Previous endometrial curettage procedures (e.g. for miscarriage or abortion)
2. Previous caesarean section
3. Multigravida
4. Increased maternal age
5. Low-lying placenta or placenta praevia

Question 28

presentation of placenta accreta:

Answer 28

Placenta accreta does not typically cause any symptoms during pregnancy. It can present with bleeding (antepartum haemorrhage) in the third trimester.

It may be diagnosed on antenatal ultrasound scans, and particular attention is given to women with a previous placenta accreta or caesarean during scanning.

It may be diagnosed at birth, when it becomes difficult to deliver the placenta. It is a cause of significant postpartum haemorrhage.

Question 29

management for placenta accreta:

Answer 29

Ideally, placenta accreta is diagnosed antenatally by ultrasound. This allows planning for birth.

MRI scans may be used to assess the depth and width of the invasion.

A specialist MDT should manage women with placenta accreta. Patients may require additional management at birth due to the risk of bleeding and difficulty separating the placenta. This may include:

Complex uterine surgery
Blood transfusions
Intensive care for the mother
Neonatal intensive care

Delivery is planned between 35 to 36 + 6 weeks gestation to reduce the risk of spontaneous labour and delivery. Antenatal steroids are given to mature the fetal lungs before delivery.

The options during caesarean are:

Hysterectomy with the placenta remaining in the uterus (recommended)
Uterus preserving surgery, with resection of part of the myometrium along with the placenta

Expectant management, leaving the placenta in place to be reabsorbed over time

Expectant management comes with significant risks, particularly bleeding and infection.

The RCOG guideline (2018) suggests that if placenta accreta is seen when opening the abdomen for an elective caesarean section, the abdomen can be closed and delivery delayed whilst specialist services are put in place. If placenta accreta is discovered after delivery of the baby, a hysterectomy is recommended.

Question 30

what is expectant management in placenta accreta:

Answer 30

Expectant management, leaving the placenta in place to be reabsorbed over time

Expectant management comes with significant risks, particularly bleeding and infection. (Expectant management is defined as leaving the placenta either partially or fully in situ, and waiting for its spontaneous resorption or expulsion.)

The RCOG guideline (2018) suggests that if placenta accreta is seen when opening the abdomen for an elective caesarean section, the abdomen can be closed and delivery delayed whilst specialist services are put in place.

If placenta accreta is discovered after delivery of the baby, a hysterectomy is recommended.