Placenta praevia: Causes, Symptoms, Management & More

Placenta praevia: Bleeding in late pregnancy (antepartum haemorrhage) is a disheartening condition that threatens the wellbeing of both mother and fetus. This bleeding condition that occurs during the lasts two trimesters of pregnancy may be due to may be due to placenta previa or placenta abruptio

What is placenta praevia?

Placenta praevia refers to the placenta situated/ implanted wholly or partially in the lower uterine segment on either anterior or posterior wall which causes unavoidable bleeding from the genital tract. Bleeding from placenta praevia is said to be unavoidable and inevitable because the placenta will definitely separates and haemorrhage must follow as the uterus stretches and dilates in the late pregnancy and early labour.

Signs and symptoms of placenta praevia

  • History of amenorrhea which suggests pregnancy.
  • Painless, recurrent vaginal bleeding occurring at rest or after sexual intercourse
  • The causes of the bleeding are not always known
  • Spotting as the gestational age increases
  • There may not be passage of blood clots in slight bleeding. But clots follow heavy bleeding especially in type III and IV placenta praevia

Patient’s condition depends on the amount of blood loss. If the bleeding is slight, your blood pressure, respiratory rate and pulse rate tend to be normal. But if there is severe haemorrhage, hypotension and rapid pulse may be present — suggestive of shock.

What are classic signs of placenta praevia?

The only sign is vaginal bleeding that is painless. Other signs that will cause a midwife to suspect placenta previa in addition to bleeding are presenting part remains above the pelvis and unstable lie.

Causes of placenta praevia

The main aetiology of placenta previa is unknown but is associated with the following condition:

  • Uterine fibroids
  • Past caesarean births
  • Repeated abortion
  • Past uterine curettage
  • Multifetal pregnancy
  • Unhealthy endometrium/multiparity

Note: Multiparous women are more likely to suffer placenta praevia than primiparous women. This is because, in a new pregnancy, the placenta tends to look for a fresh surface to implant avoiding the previous placenta site scan. This may then result in implantation of the placenta in the lower uterus.

Who are at higher risk of placental praevia?

  • Those with increased maternal age
  • Women who smoke
  • Women with previous caesarian section
  • Women who had placenta previa before had 4-8% recurrent rate.

How common is placenta praevia?

Placenta previa occurs 2.8 per 1,000 in every singleton pregnancy and 3.6 per 1,000 in multiple pregnancies.

Placenta praevia Diagnosis

The degree of shock is associated with amount of bleeding. If there is shock other signs may be present such as rapid respiration (air hunger).  The mother is pale with cold clammy skin. There may be loss of consciousness in a torrential bleeding.

General Examination: Check the woman’s general appearance. The woman may be apprehensive due to bleeding. Check the vital signs: If the haemorrhage is slight blood pressure, pulse, respiration may be normal. In severe bleeding there may be hypotension, rapid pulse indicating shock.

Abdominal examination: The midwife finds that the fundal height usually corresponds with the gestational age. The consistency of uterus is also normal with no tenderness and no pain. The fetal heart is also heard on auscultation. The fetal lie may be oblique or transverse. No engagement: the fetal head will still be very high near term in a primigravida.

Obstetric ultrasonography:  The confirmatory diagnosis of placenta praevia is ultrasonic scanning because it determines its location.  However, X-ray (soft tissue placentography) carried out in the third trimester (after 34th week’s gestation) will show soft tissue radiography and outlining a low-lying placenta. Currently, obstetric ultrasonography is recommended for detecting the placental site.

Midwife’s Assessment

This would be divided into maternal and fetal assessment:

Assessment of mother’s condition:

Assess amount of vaginal blood loss. Take history of bleeding which is variable, some may have repeated small bleeding at interval, some may have repeated small bleeding at interval while some may experience sudden single episode after 20th week.

Severe bleeding may occur after 34th week and is usually associated with the following which the midwife must take note of:

  • Painless
  • May be mild, moderate or severe.
  • Does not occur with any particular activity and may occur when she is out rest.
  • The colour of the blood is bright red.
  • Bleeding is unimpeded and does not have retroplacental clot.

Assessment of fetal condition:

  • Get history of fetal activity whether normal less or cessation (this occur if there is severe hypoxia). Ask if there is increase in movement which is an indicator of fetal distress due to hypoxia.
  • Midwife should use cardio-tocograph, ultra sound fetal monitor or sonicaid. If these are not available, she should use pinard stethoscope.
  • Fetal distress (due to hypoxia) is a severe emergency and obstetrician should be sent for.

What are differences between placenta praevia and abruptio placenta?

S/NPlacental previaAbruptio placenta
1.Warning bleeding presentAbsent
2.Usually there is an abnormal lie or malpresentationUsually normal lie and presentation
3.Abdomen not likely to be tenderAbdomen is likely to be tender
4.No associated abdominal painThere is associated abdominal pain
5.Blood is usually bright redBlood  may be dark or bright red
6.Mother is usually compromisedFetus is usually compromised
7.Uterus is soft on palpationUterus is woody-hard on palpation
8.No particular association with pre-eclampsiaMay be associated with pre-eclampsia
9.No coagulation defect initiallycoagulation defect occurs early
10.Presenting part is high(unengaged)Presenting part may be  high or engaged

Types of Placenta Previa

Placenta praevia is classified into four degrees as follow:

Type I placenta praevia:

This occurs when the whole or majority of your placenta is situated in the upper uterine segment. There may be vaginal bleeding but blood loss is usually mild. Mother and fetus are in good condition and vaginal delivery is possible.

Type II placenta praevia:

 Thisis also called marginal placenta praevia. Marginal placenta praevia occurs when the placenta is partially situated or located in the lower uterine segment near the internal cervical os. 

Blood loss is often moderate but the conditions of both mother and fetus may vary.  Fetal hypoxia is far more likely to present than maternal shock. Vaginal birth is possible only when your placenta is positioned anteriorly because posterior position impedes the fetal descent.

Type III placenta praevia:

This occurs when placenta is situated over the internal os but not centrally. The patient is far more likely to experience severe bleeding especially when the lower uterine segment stretches and the cervix starts to efface and dilate in the late pregnancy. You can’t have vaginal birth because the placenta precedes the fetus (i.e. the placenta lies before the fetus)

Type IV placenta praevia:

This is also called Central placenta praevia, which occurs your placenta is located centrally over the internal cervical os.

Vaginal delivery is NOT possible because torrential haemorrhage is very likely to occur. Caesarean section is the only way to save your life and that of your baby.

Pathophysiology of bleeding in placenta praevia

Bleeding with placenta praevia happens when the lower uterine segment starts to grow progressively after 12th weeks and also differentiates from the upper uterine segment during late pregnancy (at about 30 weeks gestation) while the cervix begins to dilate.

Bleeding occurs due to placenta’s inability to stretch in order to accommodate the difference in as of the lower uterine segment or the cervix.

That is, placenta that is lowly situated begins to separate as lower uterine segment continues to grow and stretch. This allows escape of blood unimpeded without retroplacental clot. Due to non-formation of retroplacental clot, it is not usually without pain.

The bleeding that follows placenta praevia are usually abrupt, painless, bright red and sudden enough to frighten you.  Placenta praevia bleeding is not associated with increased activity or participation in sports.

The bleeding from placenta praevia may stop abruptly as it began. So that by the time you are seen at hospital, you are no longer bleeding.  Or it may slow down after the initial haemorrhage but continues as spotting and your fetus tends to lie transversely or breech in most cases. There may be history of slight repeated bleeding from 20th week or single episode of severe bleeding. Severe bleeding mostly occurs after 34th week of pregnancy.

Management of placenta praevia

Management or treatment of placenta praevia is of two types which are:

  1. Conservative (passive) management
  2. Active management

However, the placenta praevia management depends on these four conditions:

  1. The amount or severity of bleeding
  2. The stage of pregnancy
  3. The condition of mother
  4. The condition of fetus
  5. The location of the placenta

Conservative Management (Expectant Management)

Placenta praevia is managed conservatively if the bleeding is slight while both mother and fetus remain in good condition.  The woman is admitted in the hospital for bed rest. She remains on complete bed rest in hospital until bleeding stops. The hospital must be fully equipped and have facility for blood transfusion and emergency caesarian section. The aim of this management is to prolong the pregnancy to the age that fetal survival is ensured, usually:

  • Placental function is monitored through fetal kick count chart and use of cardiotocograph. Ultrasound is done at intervals to check position of the placenta in relation to cervical os as lower segment enlarges.
  • Fetal growth is also monitored because placental perfusion is less efficient than fundally situated placenta resulting to uterine growth retardation is some cases.
  • If haemorrhage was severe the mother is transfused in expectant management. Tocolytic drugs are used to inhibit premature labour.
  • Steroids are given to help the lungs mature to reduce perinatal mortality.

If haemorrhage occur after 37th week of pregnancy, it is better to deliver the baby in Type I and Type II, vaginal delivery is possible. The labour can be induced after 37 weeks if labour does not start on its own.  Remember, vaginal birth is only possible in type I and II placenta praevia should the placenta lies anterior.

The doctor performs gentle palpation on the vaginal fornices and should the placenta be felt, then immediate surgery is carried out. However, when the placenta could not be felt, artificial rupture of membranes is performed and labour induced with oxytocin infusion.

When the woman is having heavy bleeding or when fetus (baby) matures, vaginal examination is performed under general anaesthesia while she is already prepared for immediate caesarean section delivery.

The midwife should be aware that the woman may be in danger of post-partum haemorrhage even if vaginal birth is possible. This is because placenta has been localized at lower uterine segment where the oblique muscles are not well developed like at the fundal region, therefore nature’s living ligature is poor.

NOTE: If the bleeding is much or severe and pregnancy is not near term or at term, termination of the pregnancy can be the right decision.

Active management of placenta praevia

Active management of is required when the woman is experiencing severe vaginal bleeding. Immediately Caeserean section is done to save both the life of mother and baby. This will take place in a facility with newborn special care unit to manage preterm baby

Paediatrician and neonatal unit (special baby care unit) are usually informed prior to the surgery. Her blood is collected, grouped and cross-matched in order to purchase right blood which is to be made readily available within the hospital blood bank for emergency purpose.

Involve anaesthetist in assessment of the woman, to take decision on the amount of fluid needed and decision about type of anaesthesia (general or regional).  The midwife gives pre-operative care for the woman. The mother is extremely anxious and the midwife must comfort her and give her all the necessary comfort and encourage. Also, there is need to support the partner.

.The healthcare team should anticipate postpartum haemorrhage whether vaginal birth or caesarean section because the placenta has been located in the lower uterine segment where there is no enough oblique muscle fibres — making the action of living ligatures less effective or poor.

Note:  If bleeding fails to stop after delivery despite use of uterotonics, ligation of the iliac arteries or even hysterectomy may be done.

Examination under Anaesthesia

If ultrasound result is inconclusive and the condition of the woman worsens, there is need to carry out examination in theatre. Prior to this procedure, the examination take place in the theatre with full preparation for caesarian section, blood is available, instrument and personnel for C/S ready should the procedure lead to torrential haemorrhage.

Complications of placenta praevia

  • Anaemia
  • Prematurity
  • Air embolism
  • Postpartum haemorrhage
  • Maternal shock (consequence of blood loss and hypovolaemia)
  • Risk of anaesthesia and respiratory collapse
  • Fetal anoxia or hypoxia
  • Fetal death
  • Maternal death

Prevention of placenta praevia

There are no specific ways you can prevent placental praevia. But embracing healthy lifestyles such as quitting smoking, alcoholics and use of illegal drugs like cocaine; following therapeutic regimen prescribed by your healthcare provider in managing and monitoring high blood pressure can help lower the incidence of placenta praevia,

The prophylactic use of aspirin (≥100 mg from ≤16 weeks of gestation) reduces the risk of preeclampsia and small-for-gestational-age neonates.  Invariably, reduction in incidence of preeclampsia would lower the risk of placental praevia and antepartum hemorrhage.

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