Amniotomy is done to initiate and accelerate the labor
process by rupturing the sac to release the fluid.
It is however not a routine procedure but usually
there are medical reasons behind this induction method.
Amniotomy or artificial rupture of membranes (ARM)
is not a painful procedure because of the absence
of nerve endings in the amniotic sac. Some amount
of discomfort is possible largely due to hand movements
during the internal exams.
Reasons for Amniotomy
• By far the most common reason for amniotomy
is to induce labor or speed up contractions in prolonged
labors. Prostaglandin from the amniotic fluid is released
which strengthens and increases the frequency of uterine
contractions.
• To better scrutinize the fetal heartbeat by
placing strategically an internal fetal electronic
monitor on baby's scalp. This equipment will reliably
record baby's heartbeat.
• To check the presence of meconium in the fluid,
an indication of fetal distress, by observing the
color of the amniotic fluid. Immediate action can
be taken to suction the contents of baby's bowel should
it be necessary.
• Mostly the sac tends to break on its own during
the second stage of labor but infrequently baby can
be born with an intact sac which must be quickly broken
to allow baby to breathe.
Hazards of Amniotomy
• The possibility of confusion between false
and true labor can ring high and one sure way to avoid
unwarranted complication is to perform the procedure
only after the 5-6 cm dilation is reached.
• Infection is another potential complication.
The danger of fetal infection from vaginal exams and/or
inserted instruments makes this procedure dangerous
especially if the baby has been in the utero for more
than 24 hours. (A course of antibiotics will be prescribed
to cure the infection).
• Prolapse of the umbilical cord is a potential
cause of fetal distress. The cord may slip between
the head and the cervix. Rupturing membranes could
then cause prolapse, making way for an emergency cesarean.
The Procedure
Amniotomy is usually performed in the hospital because
fetal monitoring is necessary. A crochet-like long
handled hook is inserted inside the vagina to rupture
the sac during a pelvic exam. Next, the fluid will
gush out. If performed without contractions, an oxytocin
drip will be necessary. IV oxytocin is often used
in the start with the rupture of membranes possibly
being delayed until the mother is in more active labor.
The following criteria must be fulfilled before beginning
the procedure:
• The mother should be in active labor (five
or more cm dilated)
• The mother should be at term.
• Baby's head should be engaged (0 station or
more)
• Situation should warrant the procedure.
