what-when-how
In Depth Tutorials and Information
with thus the assumption that the maternal pelvic
outlet is adequate to carry to term and deliver a term-
sized infant vaginally. The decision regarding adequate
size of the pelvic outlet is determined by an obstetri-
cian based on clinical findings such as pelvimetry prior
to labor or evidence of cephalopelvic disproportion
in labor. There are case reports of women with milder
types of OI having normal vaginal deliveries at term
and there does not appear to be an increased incidence
of preterm delivery in the literature.
38
There are three
case reports of uterine rupture in patients with milder
OI.
39-41
While uterine rupture in the third trimester is a
rare event (1/2000), it is difficult to assess whether these
three cases truly suggest an increased risk, but caregiv-
ers and patients should be made aware of this rare, but
life threatening complication, especially when consider-
ing a trial of labor after cesarean delivery.
Management of a patient with severe OI, especially
wheelchair dependent, is more complicated. As delin-
eated in the previous section, women with the severe
form of OI are at risk for cardiopulmonary complica-
tions and it is possible that the gravid uterus in some
women will worsen their cardiopulmonary status.
The goal is the same for pregnant OI as it is for non-OI
patients; provide an atraumatic delivery to the mother
and fetus, optimizing fetal gestation as close to term as
possible. Pregnant wheelchair bound women are at the-
oretical increased risk for thromboembolic events and
anticoagulants (heparin) have been prophylactically
employed. This is especially important if the patient,
in addition to having OI, is a carrier of a thrombo-
philia. Further complicating management is that hepa-
rin can adversely affects bone mass, even if used just
for the time period of a pregnancy, though controversy
exists.
42,43
It is not known whether heparin-induced
bone loss would be exacerbated in an OI patient.
The pregnant OI patient should be encouraged to
deliver as close to term as possible based on her level
of physical comfort (cardiopulmonary status). Though
limited data exist, most women with more severe
forms of OI deliver in the third trimester. However, in
a patient with severe kyphoscoliosis and contracted
pelvis, the normal late third trimester cephalic descent
of the fetus into the maternal pelvis may not occur; the
fetus then will further push up on the maternal dia-
phragm, making the patient very uncomfortable and
dyspneic. If the patient develops preterm labor, stan-
dardized obstetrical management is advised. For those
women who need to deliver prior to 34 weeks for
maternal or fetal indications, antenatal steroids should
be offered to minimize respiratory distress syndrome in
the neonate.
44
Severely affected women with OI tend to have con-
tracted pelvises due to pelvic fractures and kyphosco-
liosis, and vaginal delivery should not be considered
unless there are compelling reasons such as extreme
prematurity. Obstetricians should be made aware that
patients with OI frequently have bleeding diatheses
and fragile tissues at time of either vaginal or cesarean
delivery, increasing the risk of excessive blood loss.
45,46
Additionally, while a low transverse uterine incision
is the preferred approach due to less bleeding and less
risk for subsequent uterine rupture in future gesta-
tions, this may not always be an option. A patient with
a very contracted pelvis and spinal abnormalities may
have resultant malposition of the uterus, and access to
the lower uterine segment may be difficult. Thus the
vertical cesarean section is indicated. If a fetus is at risk
for OI based on dominant familial inheritance or estab-
lished molecular diagnosis, the obstetrician should be
aware that cephalic instrumentation using either for-
ceps or vacuum delivery is risky because the fetal cal-
varium is softer and places the fetus at increased risk
for complications (
Figure 26.1
).
Anesthesiology should meet the patient ideally prior
to delivery. Regional anesthesia is frequently used for
pain relief in patients attempting vaginal delivery, and
also for cesarean sections. Without any spinal hardware,
regional anesthesia can be employed in a laboring or
cesarean section OI patient.
47
There is controversy in the
anesthesia management of the more severe OI patient
particularly those with spinal rods and severe kypho-
scoliosis. General anesthesia is indicated in scoliosis
if it is the maternal preference, when there is severe
maternal cardiopulmonary disease and if there is dif-
ficulty in performing regional anesthesia. However,
severe scoliosis is associated with altered anatomy of
the airway, potentially causing difficulty in laryngos-
copy and intubation.
48
Difficult intubations potentiate
the risk of hyphypoxia, hypercapnea and acidosis, all
of which can adversely affect both mother and fetus.
Regional anesthesia has been used for cesarean sections
in patients with scoliosis and rods,
48
though the distri-
bution of anesthetic may vary causing either hypoten-
sion or inadequate anesthesia. Anesthesiologists caring
for, or attending severely affected patients should be
well acquainted with other potential complications in
OI, including necessary position, temperature regula-
tion and bleeding.
Postpartum management of an OI patient includes
any complications associated with delivery. The ques-
tion of whether the patient should breastfeed is a per-
sonal one. Most obstetricians and pediatricians would
support the benefits to the newborn from breastfeed-
ing. Lactation is associated with bone loss, but studies
suggest that in non-OI patients this is transient with
no long-term effect. However, transient osteoporosis
of the hip has been described in one OI patient dur-
ing lactation.
31
Patients with limited mobility may find
that breastfeeding is physically difficult, and lactation
