Chapter 5 Antepartum Hemorrhage Flashcards
placenta previa
abnormal implantation of placenta over internal cervical os.
partial previa
placenta covers a portion of the internal os
marginal previa
edge of placenta reaches margin of the os
low lying placenta
implanted in lower uterine segment in close proximity but not extending to the internal os.
vasa previa
fetal vessel lying over the cervix.
with progression of pregnancy, more than 90% of low lying placentas identified early in pregnancy will appear to move away from the cervix and out of lower uterine segment.
true
placental migration
placenta does not actually move. most likely due to development of lower uterine segment. additionally, it may be that placenta grows preferentially toward a better vascularized fundus (trophotropism), whereas placenta overlying the less well-vascularized cervix may undergo atrophy.
placenta accreta
defined as superficial attachment of the placenta to the uterine myometrium.
increta occurs:
when placenta invades the myometrium
percreta
occurs when placenta invades through myometrium to the uterine serosa.
predisposing factors for placenta previa
- prior CS and uterine surgery
- multiparity
- multiple gestation
- erythroblastosis
- smoking
- history of placenta previa
- increasing maternal age.
patients with placenta previa present with sudden and profuse
painless vaginal bleeding.
is it ok to do vaginal exam in placenta previa?
NO. CONTRAINDICATED. digital exam can cause further separation of the placenta and trigger catastrophic hemorrhage.
US exam can diagnose placenta previa.
true. sensitivity is > 95%.
predisposing factors for Placenta abruption
- Hypertension
- Previous placental Abruption
- AMA
- Multiparity
- Uterine distension
- Multiple pregnancy
- Polyhydramnios
- Vascular deficiency
- Diabetes Mellitus
- Collagen vascular disease
- Cocaine use
- Methamphetamine use
- cigarette smoking
- alcohol use (>14drinks/week)
- circumvallate placenta
- short umbilical cord.
most common factor associated with increased incidence of abruption is
hypertension
in cases of abruptions that are severe enough to cause fetal death, 50% are due to hypertension, 25% of these are from chronic htn, and 25% are from preeclampsia.
true
historically taught that __ uterine bleeding signifies placental abruption, whereas __ uterine bleeding is indicative of placenta previa
painful, painless.
diagnosis of placental abruption is primarily clinical.
only 2-25% of abruptions are diagnosed by ultrasound.
negative findings on US exam do NOT exclude
placental abruption.
diagnosis of abruption may be confirmed by inspection of the placenta at deliery. presence of a ___ with overlying placental destruction confirms the dx.
retroplacental clot.
if a patient’s placenta previa persists into the 3rd trimester, she is at most risk for ___ in the presence of an anterior placenta previa and hx of 2 previous c/s.
placenta accreta
if placenta previa persists, it can be complicated by an associated
placenta accreta.
patients with a complete / partial previa to have complete pelvic rest which means
no intercourse, in order to preveng significant bleeding.
the special precautions regarding placenta previa are
- complete pelvic rest
2. close observation.
what further imaging may be helpful in dx of placenta accreta?
MRI is imaging modality of choice to evaluate myometrial and/or bladder invasion of the placenta, particularly when it is not clear on US.
what does a sinusoidal pattern on continuous fetal heart rate monitoring indicate?
fetal anemia.
when there is a true sinusoidal pattern, prompt emergent delivery
true
late decelerations are the typical fetal tracing when ___ occurs
uteroplacental insufficiency
