Book of Medical Disorders in Pregnancy - Tintash

associated with advanced gestation (over
35 weeks), and the choice of imaging in
later pregnancy is more problematic. The
only published study on the use of CT
for appendicitis in pregnancy showed
100% accuracy in a small series of 7
patients, 2 of whom were found to have
appendicitis. More recently, there has
been some interest in the use of MRI to
diagnose appendicitis in pregnancy. In a
Dutch study of 12 suspected cases
between 7 and 35 weeks gestation (3
with subsequently proven appendicitis at
surgery), MRI correctly identified all 3
cases of acute appendicitis and correctly
identified 7 normal cases. The appendix
was not seen in two patients (at 17 and
35 weeks gestation). Our institutional
experience suggests all modalities (US,
CT, and MRI) become problematic in
later pregnancy (past 35 weeks
gestation) and consultation with on call
faculty may be appropriate in such
patients.
Ultrasound is the preferred modality for
imaging of suspected acute appendicitis
in pregnancy, except in later pregnancy
(> 35 weeks) when CT or MRI may be
required (consult with radiology
faculty).
Imaging of suspected renal colic in
pregnancy:
Obstructive urinary calculi complicate
approximately 1 in 3300 pregnancies.
Imaging is complicated by the normal
physiological hydronephrosis that occurs
in pregnancy. Despite this confounding
factor, ultrasound correctly visualized 21
of 35 (60%) stones in a retrospective
study. This suggests ultrasound remains
the initial study of choice, but that
additional imaging by non contrast spiral
CT or IVP may be required if ultrasound
224
is negative. Non contrast CT is probably
the more accurate modality, although the
radiation dose to the fetus is probably
higher. However, radiation dose comparisons
between CT and IVP are not
straightforward because both can be
performed with a wide range of techniques
that may or may not incorporate
dose-reducing approaches. Ultrasound is
the preferred modality for imaging of
suspected renal colic in pregnancy; if
negative, CT or MRI may be required
(consult with radiology faculty).
Imaging of trauma in pregnancy:
Trauma and accidental injuries complicate
6-7% of all pregnancies, and are
usually due to motor vehicle accidents,
domestic abuse or assaults, and falls.
Common adverse con sequences include
uterine contractions, preterm labour or
delivery, and placental abruption. Fetal
or maternal demise is rare. In many
cases, external fetal monitoring and
ultrasound may be adequate for
assessment, including detection of placental
abruption or uterine rupture (the
most serious complication) and documentation
of fetal well being. That said,
trauma to the pregnant patient must be
considered with the utmost seriousness
because even minor trauma can cause
fetal demise. The cardinal principle in
the management of trauma in pregnancy
is that there can be no fetal survival
without maternal survival, with the rare
exception of the gravely injured mother
late in pregnancy where urgent Cesarean
section may allow for fetal survival.
From an imaging perspective, ultrasound
is an excellent tool for initial evaluation
of the traumatized pregnant patient, but
CT is the preferred modality when
clinical or ultrasound findings suggest
visceral injuries unaccompanied by