الفهرس 
Anatomy of the placentaOnly 14 pages are availabe for public view
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Abstract
PA is a significant cause of maternal morbidity and mortality and is now
the most common reason for emergent postpartum hysterectomy.
Placenta previa and previous cesarean section are the two most important
known risk factors for PA. Accurate prenatal identification of affected pregnancies allows optimal
obstetric management.
Ultrasonography (US) remains the diagnostic standard, and routine US
examination at 18–20 weeks gestation affords an ideal opportunity to screen for the
disorder. This modality has enjoyed great popularity because it is widely available,
patient friendly, and relatively inexpensive.
In recent years, there has been increased interest in magnetic resonance
(MR) imaging for the evaluation of PA, since it can provide information on depth
of invasion and more clearly depict posterior placentas. It can be used as
complementary imaging modality and problem solving method especially with
equivocal ultrasound or Doppler examination and when further characterization is
require.
MRI may rule out or confirm a diagnosis, for example, the presence of
parametrial invasion in cases of placental adherence which results in modifications
of surgical techniques, allowing a reduction in historical morbidity and a
significant increase in conservative surgeries.
PA is a clinical and diagnostic challenge that is being encountered with
increasing frequency. Clinicians should be aware of the clinical issues, risk factors,
and imaging findings associated with PA to facilitate optimal case management.
Magnetic resonance imaging hand in hand with ultrasound is important for
the accurate diagnosis of placenta previa and the serious co-existing placenta
accreta. Co-operation of both modalities may provide more diagnostic information.
Inclusion of MR imaging in the routine evaluation of patients with placenta previa
may reduce hospital stays and unnecessary interventions with favorable outcome.