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Y4 - GOSH > Placenta Praevia / Abruption > Flashcards

Placenta Praevia / Abruption Flashcards

1
Q

What is placenta praevia?

A
  • occurs when the placenta is attached to the lower portion of the uterus
  • this is lower than the presenting part of the foetus
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2
Q

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

A

low-lying placenta:

  • when the placenta is within 20mm of the internal cervical os

placenta praevia:

  • used only when the placenta is OVER the internal cervical os
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3
Q

What is the major effect associated with placenta praevia?

A

it is associated with antepartum haemorrhage

placenta praevia occurs in around 1% of pregnancies

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4
Q

What are the differences in the causes of antepartum haemorrhage & minor bleeding in pregnancy?

A

antepartum haemorrhage:

  • placenta praevia
  • placental abruption
  • vasa praevia

minor bleeding in pregnancy:

  • cervical ectropion
  • infection
  • vaginal abrasions from intercourse / procedures
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5
Q

What are the risks associated with placenta praevia?

A
  • antepartum haemorrhage
  • emergency C-section / hysterectomy
  • maternal anaemia + transfusions
  • preterm birth + low birth weight
  • stillbirth
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6
Q

What are the risk factors for placenta praevia?

A
  • maternal smoking
  • previous C-section
  • previous placenta praevia
  • older maternal age
  • structural uterine abnormalities (e.g. fibroids)
  • assisted reproduction (e.g. IVF)
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7
Q

How is placenta praevia diagnosed?

A
  • it is identified on the 20-week anomaly scan
  • this is used to assess the position of the placenta
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8
Q

What are the symptoms of placenta praevia?

A
  • most women are asymptomatic
  • it can present with painless vaginal bleeding in pregnancy
  • bleeding usually occurs later in pregnancy (around 36 weeks)
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9
Q

What are the RCOG guidelines for repeating scans in placenta praevia?

A
  • placenta praevia should be diagnosed at the 20-week foetal anomaly scan
  • transvaginal US scan is repeated at 32 weeks gestation
  • and then again at 36 weeks gestation
  • the latter scan is used to guide decisions about delivery
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10
Q

What medication may be given to women with placenta praevia?

A

corticosteroids

  • these are given to mature the fetal lungs as there is a risk of preterm delivery
  • these are given between 34 and 35 + 6 weeks gestation
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11
Q

What plans are put in place for delivery in placenta praevia and why?

A
  • a planned C-section is considered between 36 and 37 weeks gestation
  • it is planned early to reduce the risk of spontaneous labour and bleeding

planned C-section is required for BOTH placenta praevia and low-lying placenta

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12
Q

How is a planned C-section different in placenta praevia?

A
  • US is used to determine the location of the placenta
  • different incisions may be made in the skin / uterus depending on the position of the foetus / placenta
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13
Q

When might emergency C-section be required in placenta praevia?

A
  • premature labour
  • antenatal bleeding
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14
Q

If haemorrhage occurs before, during or after delivery, what urgent management may be required?

A
  • emergency C-section
  • blood transfusions
  • intrauterine balloon tamponade
  • uterine artery occlusion
  • emergency hysterectomy
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15
Q

What is meant by vasa praevia?

A
  • the fetal vessels run through the free placental membranes (chorioamniotic membranes)
  • they pass over the internal cervical os

fetal vessels = 2 umbilical arteries + 1 umbilical vein

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16
Q

Where are the fetal vessels found normally?

A
  • the umbilical cord contains the fetal vessels
  • the umbilical cord inserts directly into the placenta
  • the fetal vessels are always protected - either by the placenta or umbilical cord

the umbilical cord contains Wharton’s jelly which gives protection to the fetal vessels

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17
Q

How is the protection of the fetal vessels different in vasa praevia?

A
  • the fetal vessels are exposed
  • they are outside of the protection from the umbilical cord or placenta
18
Q

What 2 situations can result in vasa praevia?

A
  • velamentous umbilical cord
  • multi-lobed placenta
19
Q

What is meant by a velamentous umbilical cord?

A
  • the umbilical cord inserts into the chorioamniotic membranes
  • the fetal vessels travel unprotected through the membranes before joining the placenta

the umbilical cord attaches to the membranes surrounding the placenta rather than the central mass

20
Q

How does a multi-lobed placenta result in vasa praevia?

A
  • the separate lobes of placenta are connected by fetal vessels
  • these vessels travel through the chorioamniotic membranes
21
Q

What is the major consequence associated with vasa praevia?

A
  • the fetal vessels travelling through the chorioamniotic membranes are unprotected

AND

  • they pass across the internal cervical os
  • these exposed vessels are prone to bleeding, especially when the membranes are ruptured during labour
22
Q

What are the 2 types of vasa praevia?

A

type I:

  • fetal vessels are exposed as a velamentous umbilical cord

type II:

  • fetal vessels are exposed as they travel to an accessory placental lobe
23
Q

What are the risk factors for vasa praevia?

A
  • low lying placenta
  • IVF pregnancy
  • multiple pregnancy
24
Q

How is vasa praevia diagnosed?

A
  • ideally, it is diagnosed via an US scan
  • sometimes it is not possible to diagnose antenatally
  • it may be detected by vaginal exam during labour - pulsating fetal vessels are seen in the membranes through the dilated cervix
25
Q

What are the symptoms associated with vasa praevia?

A
  • it may be asymptomatic
  • it may present with antepartum haemorrhage in the 2nd/3rd trimester
26
Q

How might vasa praevia be diagnosed during labour?

A
  • fetal distress + dark red bleeding occur following rupture of the membranes

this carries very high fetal mortality, even with emergency C-section

27
Q

What is the management for vasa praevia?

A
  • corticosteroids given from 32 weeks gestation to mature the fetal lungs
  • elective C-section planned from 34 to 36 weeks gestation

  • elective C-section reduces the risk of haemorrhage
  • if haemorrhage does occur, emergency C-section is required
28
Q

What is a placental abruption?

A
  • occurs when the placenta separates from the wall of the uterus during pregnancy
  • the site of attachment bleeds excessively after the placenta separates
  • it is a significant cause of antepartum haemorrhage
29
Q

What are the risk factors for placental abruption?

A
  • previous placental abruption
  • multiple pregnancy
  • multigravida
  • increased maternal age
  • smoking
  • trauma (think domestic abuse)
  • fetal growth restriction
  • pre-eclapmsia
  • cocaine or amphetamine use
30
Q

What is the typical presentation of placental abruption?

A
  • sudden onset severe abdominal pain that is continuous
  • a woody abdomen on palpation
  • shock (hypotension / tachycardia)
  • signs of fetal distress on CTG
  • vaginal bleeding

a “woody” abdomen is associated with large haemorrhage

31
Q

How can the severity of antepartum haemorrhage be divided into 4 categories?

A

spotting:

  • spots of blood noticed on the underwear

minor haemorrhage:

  • less than 50ml lost

major haemorrhage:

  • 50 - 1000ml lost

massive haemorhage:

  • more than 1000ml lost OR signs of shock
32
Q

What is meant by a concealed abruption?

A
  • the cervical os remains closed
  • the blood remains within the uterine cavity
  • the severity of bleeding can be significantly underestimated

this is opposed to revealed abruption in which there is blood loss via the vagina

33
Q

How is placental abruption diagnosed?

A
  • there are no tests for diagnosing placental abruption
  • it is a clinical diagnosis based on presentation
34
Q

What is the management for placental abruption?

A

it is an obstetric emergency !!

  • it should be treated as a major/massive haemorrhage
  • the urgency depends on:
  1. extent of bleeding
  2. haemodynamic stability of the mother
  3. condition of the fetus

always consider concealed haemorrhage where vaginal bleeding is disproportionate to uterine bleeding

35
Q

What is the role of US in placental abruption?

A
  • US CANNOT diagnose abruption
  • it can be used to exclude placenta praevia as a cause of bleeding
36
Q

What medications are given in placental abruption?

A

antenatal steroids:

  • offered between 24 and 34+6 weeks gestation to mature the fetal lungs

anti-D:

  • given to rhesus-D negative women
37
Q

What might be required if the mother is unstable due to placental abruption?

A

emergency C-section

38
Q

What extra blood tests are required if there are concerns about antepartum haemorrhage?

A
  • group & save
  • crossmatch
  • required when there has been >1L of blood lost
39
Q

How does vasa praevia typically present?

A
  • there is rupture of the membranes (clear fluid discharge be noticed)
  • followed IMMEDIATELY by continuous bright red vaginal bleeding
  • this is a result of rupture of the fetal vessels and subsequent fetal haemorrhage
40
Q

What is the triad of symptoms associated with vasa praevia?

A
  • fetal bradycardia (HR < 100bpm)
  • painless vaginal bleeding
  • rupture of the membranes

Y4 - GOSH (62 decks)

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