Placenta_Praevia_Flashcards
What is placenta praevia?
Placenta praevia describes a placenta lying wholly or partly in the lower uterine segment.
What is the grading for placenta previa?
Grade 1 (Low-lying placenta):
The placenta is located in the lower part of the uterus but does not cover the cervical opening.
Grade 2 (Marginal placenta previa):
The placenta reaches the edge of the cervix but does not cover it.
Grade 3 (Partial placenta previa):
The placenta partially covers the cervical opening.
Grade 4 (Complete placenta previa):
The placenta completely covers the cervical opening.
What should be done if a low-lying placenta is detected at the 20-week scan?
Rescan at 32 weeks. No need to limit activity or intercourse unless they bleed. If still present at 32 weeks and grade I/II, scan every 2 weeks. Final ultrasound at 36-37 weeks to determine the method of delivery.
What is the recommended method of delivery for grades III/IV placenta praevia?
Elective caesarean section between 37-38 weeks.
What is the recommended method of delivery for grade I placenta praevia?
A trial of vaginal delivery may be offered.
What should be done if a woman with known placenta praevia goes into labour before the elective caesarean section?
An emergency caesarean section should be performed due to the risk of post-partum haemorrhage.
What is the management of placenta praevia with bleeding?
Admit, use ABC approach to stabilise the woman. If not able to stabilise, perform emergency caesarean section. If in labour or term reached, perform emergency caesarean section.
What is the prognosis for placenta praevia?
Death is now extremely rare. The major cause of death in women with placenta praevia is now post-partum haemorrhage (PPH).
summarise
Placenta praevia: management and prognosis
Placenta praevia describes a placenta lying wholly or partly in the lower uterine segment.
If low-lying placenta at the 20-week scan:
rescan at 32 weeks
no need to limit activity or intercourse unless they bleed
if still present at 32 weeks and grade I/II then scan every 2 weeks
final ultrasound at 36-37 weeks to determine the method of delivery
elective caesarean section for grades III/IV between 37-38 weeks
if grade I then a trial of vaginal delivery may be offered
if a woman with known placenta praevia goes into labour prior to the elective caesarean section an emergency caesarean section should be performed due to the risk of post-partum haemorrhage
Placenta praevia with bleeding
admit
ABC approach to stabilise the woman
if not able to stabilise → emergency caesarean section
if in labour or term reached → emergency caesarean section
Prognosis
death is now extremely rare
major cause of death in women with placenta praevia is now PPH
A 32-year-old woman who is 30+2 weeks pregnant, G3 P2+0, presents to the maternity triage unit. Her past deliveries were both elective Caesarean sections. Her pregnancy has been uneventful up to this point but she presents to the maternity triage unit this morning with an episode of vaginal bleeding. She describes the amount as about a tablespoon. There is no associated pain.
What should be done next to determine the diagnosis?
Ultrasound scan
Full blood count to assess haemoglobin
Digital vaginal exam
Nothing as amount of blood loss not significant
Fetal blood monitoring to check for fetal distress
Ultrasound scan
This woman may have placenta praevia which is an important cause of antepartum haemorrhage. She is more likely to have a low-lying placenta due to her previous Caesarean sections, multiparity, and her presentation (minimal bleeding, no pain).
An ultrasound scan is used to determine the site of the placenta as this can be missed or mis-interpreted in earlier ultrasound scans. An ultrasound scan can diagnose placenta praevia and also determine grading. Any type of internal examination should be avoided initially as this can cause the placenta to bleed. The RCOG Green Top guidelines state:
If placenta praevia is a possible diagnosis (for example, a previous scan shows a low placenta, there is a high
presenting part on abdominal examination or the bleed has been painless), digital vaginal examination should
not be performed until an ultrasound has excluded placenta praevia.
Some clinicians may consider doing a speculum examination in this scenario to check for polyps/ectropion but this is not given as an option here and would not be diagnostic for placenta praevia.
A full blood count would not be helpful in determining the diagnosis. Any amount of blood loss during pregnancy should be investigated.
A 34-year-old primigravida woman at 36 weeks gestation presents to the emergency department with sudden onset abdominal pain. She describes the pain as constant and severe, located in the centre of her abdomen. There is no history of previous uterine surgery or trauma.
On examination, there is a small amount of vaginal bleeding. The uterus is tender and tense on palpation. Her blood pressure is 92/56 mmHg, and her heart rate is 129 bpm.
What is the most likely diagnosis?
Ectopic pregnancy
Placenta praevia
Placental abruption
Uterine rupture
Vasa praevia
Placental abruption
Placental abruption is characterised by constant pain, shock out of keeping with the visible loss, tender and tense uterus
Placental abruption is the correct answer. Placental abruption is where the placenta separates from the wall of the uterus before delivery, potentially leading to significant bleeding and complications for both the mother and the baby. Placental abruption is characterised by sudden onset of severe, constant abdominal pain, vaginal bleeding, and signs of shock that are disproportionate to the amount of bleeding. Additionally, a tender and tense uterus is commonly noted. These clinical findings are consistent with the clinical presentation described in the scenario.
Ectopic pregnancy is not the correct diagnosis. An ectopic pregnancy occurs when a fertilised egg implants and grows outside the uterus, typically in the fallopian tube, posing serious health risks to the mother. While an ectopic pregnancy may present with abdominal pain and vaginal bleeding, it typically causes unilateral lower abdominal pain and can be associated with signs of intra-abdominal bleeding such as shoulder tip pain or syncope. Ectopic pregnancies occur significantly earlier than 36 weeks gestation, with patients presenting with symptoms between 4-12 weeks of pregnancy. The presentation of constant central abdominal pain along with a tender and tense uterus does not correspond with an ectopic pregnancy.
Placenta praevia is also incorrect. Placenta praevia is a condition in pregnancy where the placenta implants low in the uterus, partially or completely covering the cervix, which can cause bleeding and complications during childbirth. This is characterised by painless vaginal bleeding that usually occurs in the third trimester. There is typically no associated abdominal pain or signs of shock.
Uterine rupture is incorrect. Uterine rupture is a serious obstetric complication where the muscular wall of the uterus tears, potentially endangering both maternal and fetal health. This may present with sudden onset abdominal pain and signs of shock; however, it is more frequently associated with a history of previous uterine surgery or trauma. Although a tender and tense uterus could indicate uterine rupture, the clinical presentation in this scenario leans more towards placental abruption.
Vasa praevia is not the correct answer. This is a rare condition in which fetal blood vessels cross the fetal membranes overlying the cervix. This can lead to painless vaginal bleeding if these vessels rupture. However, there are typically no accompanying symptoms of abdominal pain or signs of shock. Consequently, the described symptoms of constant severe abdominal pain and a tender and tense uterus do not fit with vasa praevia.
A 34 weeks pregnant woman, who is G2 P0, presents to the emergency department with vaginal bleeding. She had suffered from severe nausea and vomiting earlier in the pregnancy which has now resolved. She has no abdominal pain, no vaginal discharge, no headache, and no pruritus. On abdominal examination, purple striae were noted on the abdomen as well as a dark line running vertically down the middle of the abdomen. A transverse lie is noticed and there is no fetal engagement. The symphyseal-fundal height is 35cm.
What is the best gold standard investigation to do?
Cardiotocography
Digital vaginal examination
Hysteroscopy
Pelvic ultrasound
Transvaginal ultrasound scan
Transvaginal ultrasound scan
In suspected placenta praevia, digital vaginal examination should not be performed before an ultrasound as it may provoke a severe haemorrhage
Transvaginal ultrasound scan - this is the gold standard investigation to diagnose placenta praevia and determine the position of the placenta. The position of the placenta can affect the management. The purple lesions noted on the abdomen are the striae gravidarum and the dark line running vertically down the middle of the abdomen is the linea nigra.
Cardiotocography - although this is important as it will show any fetal distress, it does not diagnose placenta praevia.
Digital vaginal examination - a digital vaginal examination should be avoided in placenta praevia.
Hysteroscopy - this can be used to investigate causes of vaginal bleeding, such as endometrial cancer and uterine fibroids. It is not used in pregnant women.
Pelvic ultrasound - although this can be used to diagnose placenta praevia, a transvaginal ultrasound is more accurate and is the gold standard investigation for diagnosis.
A 32-week gestation woman attends for a repeat ultrasound scan after her 20-week scan showed a low lying placenta. The repeat ultrasound in the department shows a placenta that is partially covering the top of the cervix. She is counselled by the obstetric consultant on her mode of delivery. She has had 4 previous pregnancies which she delivered vaginally and has no other past medical or surgical history.
What is the appropriate offer she should be given regarding recommended mode of delivery?
Spontaneous vaginal delivery unless placenta descends to grade IV placenta praevia
Elective caesarean section at 37-38 weeks
Induction of labour at 37-38 weeks
Elective caesarean section at 39-40 weeks
Induction of labour at 39 weeks
Elective caesarean section at 37-38 weeks
Women with grade III/IV placenta praevia should be offered an elective caesarean section at 37-38 weeks
This patient has a low-lying placenta covering part of the cervix - a grade III placenta praevia. If the placenta is completely covering the cervix, this is known as a grade IV (or complete) placenta praevia. Spontaneous vaginal delivery carries a significant risk of haemorrhage in grade III and grade IV placenta praevia and the patient should be counselled about the risk of this. Management for grade III or IV placenta praevia is a scheduled elective caesarean section at 37-38 weeks. This is to prevent a massive obstetric haemorrhage which may occur if cervical ripening and dilatation occurs with the placenta overlying the cervical os.
Spontaneous vaginal delivery carries a significant risk of haemorrhage in grade III and grade IV placenta praevia, hence this should be avoided unless the patient refuses the other options.
Induction of labour at 37-38 weeks will lead to the patient potentially having a vaginal delivery and does not mitigate against the risk of haemorrhage. This is, therefore, incorrect as the recommended mode of delivery at any gestation for this patient.
Offering an elective caesarean section at 39 - 40 weeks is a possibility, however, there is a much greater risk of the patient going into spontaneous labour at this gestation and haemorrhaging. This is, therefore, incorrect as the ideal offer.
Induction of labour at 39 weeks will lead to the patient potentially having a vaginal delivery and does not mitigate against the risk of haemorrhage. This is, therefore, incorrect as the recommended mode of delivery at any gestation for this patient.
