Vacuum
extraction
Figure P-6 shows the essential components of the vacuum extractor.
Figure P-6
Vacuum extractor
- vertex presentation;
- term
fetus;
- cervix fully dilated;
- head at least at 0 station or no more than 2/5 above symphysis pubis.
Check all connections and test the vacuum on a gloved hand.
Provide emotional support and encouragement. If necessary,
use a pudendal block.
Assess the position of the fetal head by feeling the sagittal suture line and the
fontanelles.
Identify the posterior fontanelle (Fig
P-7).
Figure P-7
Landmarks of the fetal skull
Apply the largest cup that will fit, with the center of the cup over the flexion point, 1 cm anterior to the posterior
fontanelle. This placement will promote flexion, descent and
autorotation with traction (Fig P-8).
Figure P-8
Applying the Malmstrom cup
-
An episiotomy may be needed for proper placement at this time. If an
episiotomy is not necessary for placement, delay the episiotomy until the head stretches the
perineum or the perineum interferes with the axis of traction. This will avoid unnecessary blood loss.
Check the application. Ensure there is no maternal soft tissue (cervix or vagina) within the
rim
With the pump, create a vacuum of 0.2 kg/cm2 negative pressure and check the application.
Increase the vacuum to 0.8 kg/cm2 and check the application.
After maximum negative pressure, start traction in the line of the pelvic axis and perpendicular to the cup. If the
fetal head is tilted to one side or not flexed well, traction should be
directed in a line that will try to correct the tilt or deflexion of the head (i.e. to one side or the other, not necessarily in the midline).
With each contraction, apply traction in a line perpendicular to the plane of the cup rim (Fig P-9). Wearing high-level disinfected gloves, place a finger on the scalp next to the cup
during traction to assess potential slippage and descent of the vertex.
Figure P-9
Applying traction
• Between contractions check:
- fetal heart rate;
- application of the cup.
TIPS
Never use the cup to actively rotate the baby’s head. Rotation of the baby’s head will occur with traction.
-
The first pulls help to find the proper direction for pulling.
-
Do not continue to pull between contractions and expulsive efforts.
-
With progress, and in the absence of fetal distress, continue the “guiding” pulls for a maximum of 30 minutes.
FAILURE
- The head does not advance with each pull;
- The fetus is undelivered after three pulls with no descent, or after 30 minutes;
- The cup slips off the head twice at the proper direction of pull with a maximum negative pressure.
-
Every application should be considered a trial of vacuum extraction. Do not persist if there is no descent with every pull.
-
If
vacuum extraction fails, use vacuum extraction in combination with symphysiotomy (see below) or perform
caesarean section.
VACUUM EXTRACTION AND SYMPHYSIOTOMY
- the head is at least at -2 station or no more than 3/5 palpable above the symphysis pubis;
- caesarean section is not feasible or immediately available;
- the provider is experienced and proficient in
symphysiotomy;
- vacuum extraction alone has failed or is expected to fail;
- there is no major degree of disproportion.
COMPLICATIONS
Complications usually result from not observing the conditions of application or from continuing efforts beyond the time limits stated above.
FETAL COMPLICATIONS
-
Localized scalp oedema (artificial caput or chignon) under the vacuum cup is harmless and disappears in a few hours.
-
Cephalohaematoma requires observation and usually will clear in 3-4 weeks.
-
Scalp abrasions (common and harmless) and lacerations may occur. Clean and examine lacerations to determine if sutures are necessary. Necrosis is extremely rare.
-
Intracranial bleeding is extremely rare and requires immediate intensive neonatal care.
MATERNAL COMPLICATIONS
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