What Is a Vacuum-Assisted Vaginal Delivery?
During vaginal delivery, your doctor may use a vacuum to help remove your baby from the birth canal. This procedure makes delivery more rapid. It may be needed to avoid injury to the baby and to avoid cesarean section.
Prerequisites for Vacuum-Assisted Vaginal Delivery
Several criteria must be met to safely perform a vacuum extraction. Prior to considering a vacuum procedure, your doctor will confirm the following:
The cervix is completely dilated
If your doctor attempts vacuum extraction when your cervix is not fully dilated, there’s a significant chance of injuring or tearing your cervix. Cervical injury requires surgical repair and may lead to problems in future pregnancies.
The exact position of your baby’s head must be known
The vacuum should never be placed on your baby’s face or brow. The ideal position for the vacuum cup is directly over the midline on top of your baby’s head. Vacuum delivery is less likely to succeed if your baby is facing straight up when you’re lying on your back.
Your baby’s head must be engaged within the birth canal
The position of your baby’s head in your birth canal is measured in relation to the narrowest point of the birth canal, called the ischial spines. These spines are part of the pelvic bone and can be felt during a vaginal exam. When the top of your baby's head is even with the spines, your baby is said to be at “zero station.” This means their head has descended well into your pelvis.
Before a vacuum extraction is attempted, the top of your baby's head must be at least even with the ischial spines. Preferably, your baby’s head has descended one to two centimeters below the spines. If so, the chances for a successful vacuum delivery increase. They also increase when your baby’s head can be seen at the vaginal opening during pushing.
The membranes must be ruptured
To apply the vacuum cup to your baby’s head, the amniotic membranes must be ruptured. This usually occurs well before a vacuum extraction is considered.
Your doctor must believe your baby will fit through the birth canal
There are times when your baby is too big or your birth canal is too small for a successful delivery. Attempting a vacuum extraction in these situations will not only be unsuccessful but may result in serious complications.
The pregnancy must be term or near term
The risks of vacuum extraction are increased in premature infants. Therefore, it should not be performed before 34 weeks into your pregnancy. Forceps may be used to assist in the delivery of preterm infants.
Normal labor is divided into two stages. The first stage of labor begins with the onset of regular contractions and ends when the cervix is completely dilated. It may last between 12 and 20 hours for a woman having her first baby. If a woman has had a previous vaginal delivery, it can be considerably shorter, lasting only seven to ten hours.
The second stage of labor begins when the cervix is fully dilated and ends with the delivery of the baby. During the second stage, uterine contractions and your pushing cause the baby to descend through your cervix and birth canal. For woman having her first baby, the second stage of labor may last as long as one to two hours. Women who’ve had previous vaginal births may deliver after less than one hour of pushing.
The length of the second stage may be affected by several factors including:
- the use of epidural anesthesia
- the size and position of the baby
- the size of the birth canal
Maternal exhaustion may also prolong the second stage of labor. This exhaustion occurs when you’re unable to push because of strong anesthesia. During this stage, your doctor will assess the progress of the labor by frequently checking the position of your baby’s head in your birth canal. As long as your baby continues to descend and is not experiencing problems, pushing may continue. However, when descent is delayed or when the second stage has been greatly prolonged (usually over two hours), your doctor may consider performing a vacuum-assisted vaginal delivery.
The effort required for effective pushing can be exhausting. Once pushing has continued for more than an hour, you may lose the strength to successfully deliver. In this situation, your doctor may provide some extra help to avoid complications. A vacuum extractor allows your doctor to pull while you continue to push, and your combined forces are usually sufficient to deliver your baby.
Dense Epidural Anesthesia
Epidural anesthesia is commonly used to relieve pain during labor. An epidural consists of placing a thin plastic tube, or catheter, just outside your spinal cord, in your lower back. Medication injected through this catheter bathes your nerves entering and leaving your spinal cord, relieving pain during labor. This epidural catheter is usually left in place throughout the entire labor and delivery. Additional medication may be injected as needed.
Epidurals are useful in labor because they block nerve fibers that relay pain signals. However, nerves that are necessary for movement and pushing aren’t affected as much. In an ideal situation, you will have the benefit of pain relief while still maintaining the ability to move and push effectively. Sometimes, you may need larger doses of medication, inhibiting your ability to push. In this case, your physician may use a vacuum extractor to provide additional force to help deliver your baby.
Maternal Medical Conditions
Some medical conditions may be aggravated by the efforts of pushing during labor. They can also make effective pushing impossible. During the act of pushing, your blood pressure and the pressure in your brain increase. Women with certain conditions can experience complications from pushing during the second stage of labor. These conditions include:
- extremely high blood pressure
- certain heart conditions, such as pulmonary hypertension or Eisenmenger's syndrome
- a history of aneurysm or stroke
- neuromuscular disorders
In these instances, your doctor may use a vacuum extractor to shorten the second stage of labor. Or they may prefer to use forceps because maternal effort is not as essential for their use.
Evidence of Fetal Problems
Throughout labor, every effort is made to stay up-to-date on the well-being of your baby. Most doctors use continuous fetal heart rate monitoring. This records your baby’s heart patterns and the contractions of your uterus to determine your baby’s condition during labor. Subtle changes in their heart rate pattern may signal fetal compromise. If your baby experiences a prolonged drop in heart rate and fails to return to a normal baseline, a rapid delivery is required. This will prevent irreversible damage to your baby. Under the appropriate conditions, a vacuum-assisted delivery can be used to deliver your baby quickly.
Abnormal Position of Your Baby’s Head
If your labor is delayed or prolonged, your baby’s head may be positioned abnormally.
During a normal delivery, a baby’s chin rests against their chest. This allows the very tip of their skull to come through the birth canal first. The baby should be facing toward the mother’s tailbone. In this position, the smallest diameter of the baby’s head passes through the birth canal.
The baby’s position is considered abnormal if their head is:
- slightly tilted to one side
- facing to the side
- facing front when the mother is lying on her back
In these cases, the second stage of labor may be delayed and a vacuum or forceps may be used to correct the baby’s position to achieve delivery. Forceps are preferred when attempting to rotate or turn the baby’s head to a more favorable position. Although the vacuum is not typically used for this, it can aid in auto-rotation. This occurs when the baby’s head turns by itself as gentle traction is applied.
Vacuum-assisted delivery is an option for deliveries that have gone on too long or need to happen quickly. However, it does create more of a risk of complications for the birth and potentially for later pregnancies. Be sure you are aware of these risks and speak to your physician about any concerns you have.