What Is External Cephalic Version (ECV)?

A Procedure to Turn a Breech Fetus

External cephalic version (ECV) is a positioning procedure to turn a fetus that is in the breech position (with their bottom facing down the birth canal) or side-lying position into a head-down (vertex) position before labor starts. 

There are several types of breech positions, including:

  • Complete breech (bottom first)
  • Breech with knees bent
  • Frank breech (the fetus is positioned to be born buttocks-first with their legs stretched up toward their head)
  • Footling breech (one or both legs are positioned to be delivered first)

When ECV is successful in turning the fetus, it means that delivery can proceed vaginally. If an ECV is unsuccessful, a cesarean section (C-section) might be necessary.

An ECV procedure is usually performed at around week 37 of pregnancy. However, an ECV might also be performed during labor, before the person's water breaks (rupture of the amniotic sac).

A doctor in a white coat with their hands on the abdomen of an unseen pregnant person

JGI/Jamie Grill/Getty Images

What Is ECV?

ECV is also called a version procedure. It is a maneuver that is intended to reposition a breech fetus. There are several steps that a healthcare provider will take to perform an ECV, including:

  1. Administering a medication (such as terbutaline sulfate injection) that helps relax the uterus and prevent contractions
  2. Placing both hands on the surface of the pregnant person's abdomen
  3. Positioning one hand by the fetus’s head and the other by the fetus's buttocks
  4. Manually pushing and rolling the fetus from a breech position to a head-down position 

A person may experience discomfort during the ECV procedure, particularly if the maneuver causes the uterus to contract.

During the procedure, the fetal heart rate is closely monitored with an electronic fetal heart rate monitor. There will usually be an increase in heart rate with fetal movement.

If the fetal heart rate does not respond normally to activity—such as when the heart rate drops and fetal distress is detected—the version procedure is stopped and other measures, such as a C-section, might need to happen next.

If an ECV is unsuccessful on the first try, a second attempt might be made. During the second try, epidural anesthesia might be used to promote relaxation and relieve pain. Research has shown that epidural anesthesia may actually improve the success rate of repeated ECV procedures.

An ECV procedure should only be performed in a hospital where there is quick access to emergency interventions. While rare, serious complications of a version procedure can occur.

Ultrasound

Fetal monitoring

Close fetal monitoring is necessary during a version procedure because while it is rare, there can be complications.

When the procedure is started, fetal monitoring is used to confirm the position of the fetus, locate the position of the placenta, and find out how much amniotic fluid is present. 

Throughout the version procedure, fetal monitoring will:

  • Watch the movement of the fetus to confirm whether the repositioning technique is successful
  • Monitor the fetal heart rate and observe for signs of fetal distress

Fetal monitoring will also continue for a short time after the procedure is done to ensure that all is well.

ECV Criteria

There are several criteria that must be met before an ECV will be performed. The first is that a pregnant person is at about 37 weeks gestation. Before 36 weeks gestation, a fetus may turn back to the head-down position on its own.

Some experts argue that an ECV procedure is more likely to be successful when it's done as soon as possible after the 36-week mark. At this stage in development, the fetus is smaller and there is more amniotic fluid surrounding it, which allows more space for it to move.

Before an ECV can be performed, several other criteria need to be met, including:

  • The pregnant person is carrying just one fetus.
  • The fetus has not yet engaged (descending into the pelvis). It would be difficult to move a fetus that is engaged.
  • There is sufficient amniotic fluid surrounding the fetus. If a condition called oligohydramnios is present, it means that there is not enough amniotic fluid. In this case, the fetus is more likely to sustain injuries secondary to the ECV procedure. Usually, an ECV will not be performed if oligohydramnios is present.
  • It is not a person's first pregnancy. Although a version procedure can be performed during a first pregnancy, the walls of the uterus are more flexible and easier to stretch if a person has been pregnant before.
  • The fetus is in a complete breech, frank breech, or footling breech position.

Contraindications

A contraindication is when a treatment, medication, or procedure is not given or performed because of the potential to cause harm. 

Contraindications for an ECV procedure include:

  • The amniotic fluid sac has ruptured (water has broken).
  • A pregnant person cannot take medications (such as tocolytic medications to prevent uterine contractions) because they have a medical condition (such as a cardiac condition).
  • A condition that warrants a C-section is present (e.g., placenta previa or placenta abruption).
  • There is fetal distress (as evidenced by fetal monitoring).
  • There is hyperextension of the fetal head (e.g., the neck is not in the normal position with the head bent forward and chin tucked into the chest).
  • There is a possible birth defect.
  • The pregnancy involves multiples (such as twins or triplets).
  • The uterus is abnormally shaped.

Risk Factors

The overall risk of harm to the fetus and pregnant person is considered very low as long as fetal monitoring is used during the version procedure. Certain complications can be looked for during the ECV, including:

  • Reduction of blood flow and/or oxygen to the fetus because the umbilical cord is twisted
  • Premature rupture of the membranes (PROM)
  • Placental abruption
  • Damage to the umbilical cord

ECV complications are considered rare. If they do occur, an emergency C-section might be needed to safely deliver the fetus.

Frequently Asked Questions

How often does ECV lead to a pregnant person starting labor?

According to researchers in Australia, in approximately 1 in 1,000 ECV procedures, the pregnant person will go into labor. Of those people, nearly 1 in 200 require an emergency C-section.

How late in pregnancy can an ECV be done?

An ECV can be performed from 34 to 37 weeks gestation, or even during labor. However, experts do not agree about when the procedure is most effective.

Some experts state that doing an ECV as soon as possible after 36 weeks provides the best odds of success. Others believe that the procedure should not be done before 37 weeks gestation (full-term). That way, should rare complications occur and a C-section is necessary, the fetus will not be premature.

Experts do agree that once engagement has occurred, an ECV should not be performed. In first pregnancies, engagement can occur between weeks 34 and 38; in subsequent pregnancies, engagement may not occur until labor has started.

How much amniotic fluid is needed for an ECV?

Having lower levels of amniotic fluid has been linked to unsuccessful ECVs, compared with the success of an ECV when amniotic fluid levels are normal.

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Article Sources
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