Placenta Previa: A Potentially Serious Complication of Pregnancy
- Posted on- Oct 29, 2015
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With the excitement that surrounds a pregnancy, there also comes the need to address certain risks that the anatomy of a female is exposed to. During pregnancy, the body goes through a lot of changes that not only tip the balance of the hormones, but also cause stress on certain organs. Placenta Previa is one such condition. It is a condition, in which, the placenta lies unusually low in the uterus. The placenta, in this condition, lies adjacent to or covers the cervix. It is a problem that needs to be addressed and taken care of, during the early pregnancy stages, once diagnosed.
There are 4 types of placenta previa:
- Low-lying placenta: The lower edge of the placenta is within the lower uterine segment
- Partial or marginal placenta previa: The lower edge of the placenta reaches to within 2cm of the internal OS (internal cervical opening)
- Placenta previa: The lower edge of the placenta crosses the internal OS
- Major or complete placenta previa: The placenta has a central location within the lower segment and covers the cervix
Placenta previa can go away as the pregnancy progresses. The minor types of placenta previa that do not cross the internal OS (internal opening) of the cervix will appear to migrate upwards as the pregnancy advances. The reason for this is that as pregnancy progresses, the lower uterine segment gradually thins out and the cervix shortens, in association with Braxton-Hicks contractions (these are 'practice' contractions) that gradually increase in the third trimester. These practice contractions are normal and serve to gradually prepare the uterus and cervix for normal labour at term. During this apparent upward migration, the placenta remains attached to its original location.
Complications arising from placenta previa
Causes of placenta previa
- Caesarean delivery: Due to vaginal bleeding, abnormal lie transverse lie, or abnormal presentation (breech presentation) of the foetus.
- Antepartum haemorrhage (APH): When the placenta crosses over the internal OS, it is unable to 'move' with the uterine thinning process (the resultant stretching) in the upward direction, causing placental separation. Maternal blood is thus released through the cervix into the vagina. Classically, this bleeding is painless, in contrast to bleeding from a normally-located placenta (known as placental abruption).
- Preterm delivery: Most episodes of vaginal bleeding are mild and stop by their own, the bleeding is fresh, bright red, and causes alarm, thus prompting hospital assessment followed by admission until it has ceased. Occasionally, very heavy vaginal bleeding can occur that requires a blood transfusion. Unless such bleeding stops, delivery by Caesarean section is required in order to remove the placenta and stop the bleeding. Since the foetus may not be full term when this bleeding occurs, this may result in a preterm delivery.
There is no single cause of this condition. It has no underlying genetic factors. A woman’s risk is determined by the presence or absence of risk factors described below.
Signs and symptoms of placenta previa
Painless, bright red vaginal bleeding in the late second or third trimester is suggesting of placenta previa. The bleeding may range from light to heavy, and may be accompanied by uterine cramping, but is typically not associated with abdominal pain.
Diagnosis of placenta previa
In most cases, placenta previa is suspected at the time of the routine foetal anatomy exam
at 18-20 weeks. This examination is an abdominal (belly) ultrasound that is usually capable of making an accurate diagnosis of major or complete placenta previa. Intermediate types (partial/marginal placenta previa, and placenta previa, as described above) usually require a transvaginal ultrasound examination.
Risk factors associated with placenta previa
Treatment of placenta previa
- Previous Caesarean section
- Advanced maternal age
- Multiparity (more than one previous pregnancy)
- Multi-foetal pregnancy (more than one foetus in the current pregnancy)
- In-vitro fertilization (IVF)
- Previous uterine surgery such as myomectomy or septoplasty
Doctors will decide how to treat your placenta previa based on the amount of bleeding, the month of your pregnancy, the baby’s health, and the position of the placenta and the baby. The amount of bleeding, however, is the main consideration when a doctor is making a decision on how to treat the condition.
- Minimal to No Bleeding: For cases of placenta previa with minimal or no bleeding, your doctor will likely suggest bed rest, which means resting in bed as much as possible-only standing and sitting when absolutely necessary. You’ll also be asked to avoid sex and likely exercise as well. If bleeding occurs during this time, you should seek medical care as soon as possible.
- Heavy Bleeding: Cases of heavy bleeding may require hospital bed rest. Depending on the amount of blood lost, you may need blood transfusions. You may also need to take medicine to prevent prematurelabour. In the case of heavy bleeding, your doctor will advise a C-section be scheduled as soon as it is safe to deliver-preferably after 36 weeks. If the C-section needs to be scheduled sooner, your baby may be given corticosteroid injections to speed up his or her lung growth.
- Uncontrollable Bleeding: In the case of uncontrolled bleeding, an emergency C-section will have to be performed.