Description and Official Rationale
Amniotomy is frequently performed on women who labor in hospitals for
the purpose of speeding up their labors, or for insertion of the internal
electronic fetal monitor; occasionally it is performed so that the
physician can take fetal blood samples, and/or ascertain whether or
not there is evidence of meconium staining (fetal bowel movement), which
under the technocratic model is considered to be indicative of fetal
distress. The procedure is simple: a hospital attendant inserts an
instrument like a crochet hook through the cervix, and snags and breaks
the amniotic sac.
In a review of the literature, McKay and Mahan find that, if amniotomy
is not performed and membranes are allowed to rupture spontaneously,
most women will have intact membranes until they are either in very
active labor or reach complete cervical dilation (1983:173). Although
amniotomy does indeed often result in speedier labors (if performed
once active labor is well-established), it also increases the danger
of fetal infection from vaginal exams and/or inserted instruments.
(Such infections can of course be cured with antibiotics, but that
process can mean considerable discomfort and many extra days in the
hospital, as several of the women in my study discovered.) Should false
labor be mistaken for real labor, and amniotomy be performed too early,
the 24-hour rule will be invoked, and pitocin induction with all its
attendant hazards will be required (this particular complication can
be avoided if amniotomy is performed only after 5-6 centimeters dilation
is reached).
A further hazard of amniotomy is that without the protective
cushion of the amniotic fluid the baby's head is subject to greater pressure
during contractions, and the umbilical cord is more likely to become
compressed, resulting in oxygen deprivation and consequent respiratory
distress. Cord prolapse is also more common after amniotomy (Pritchard
and MacDonald 1985:289). Moreover, unruptured membranes often cushion
not only the fetal head but also the mother's perineum, allowing for
more gentle stretching and reducing the likelihood of tears. The
combination of rupture of the cushioning bag with pitocin-augmented
contractions often leads to more rapid and forced stretching of the
perineum and so to more tears (Brigitte Jordan, personal communication).