CLINICAL CASE
Unit Two: Obstetrics
Section B: Abnormal Obstetrics
Objective 23: Third Trimester Bleeding
At the conclusion of this exercise, the student will be able to
1.
Describe the approach to the patient with third trimester bleeding
2.
Compare symptoms, physical findings and diagnostic methods to
differentiate between placenta previa, placental abruption and other
causes of 3rd trimester bleeding
3.
Describe immediate management of shock due to 3rd trimester bleeding
4.
Understand complications of placental abruption and placenta previa
Joanne is a 25-year-old G2P1 female at 32 weeks gestation. About an hour before
arrival in labor and delivery, she was watching television when she noted a sudden
gush of bright red blood vaginally. The bleeding was heavy and soaked through her
clothes, though it has decreased since then. She denies any cramps or abdominal pain.
She says that her last sexual intercourse was a week ago. A review of her prenatal
chart finds nothing remarkable other than a borderline high blood pressure from her
first prenatal visit that has not required medication. There is no mention of bleeding
prior to this episode. She had an ultrasound to confirm pregnancy at 14 weeks, but
none since.
Physical examination reveals a very anxious woman whose blood pressure is 138/90,
pulse 90, respirations 22, temperature 99 F. Her abdomen is soft without guarding or
rebound to palpation, and the uterus is nontender and firm, but not rigid. Fundal
height is 33cm. Fetal heart tones are in the 140s with good variability. The external
monitor reveals uterine irritability, but no discrete contractions are seen. There is a
small amount of dark blood on her underwear, but no active bleeding is seen. Vaginal
examination is deferred pending an ultrasound evaluation of placental location.
Electrolytes, liver enzymes and coagulation profile are all within normal range. CBC
reveals a hemoglobin of 8.0 gm/dl and a hematocrit of 24%; MCV, MCH and MCHC
are all low normal. White blood cell and platelet counts are normal. Type and Rh
confirm A negative blood type with negative antibody titer. Kleihauer-Betke test is
negative for fetal blood.
An ultrasound examination shows a singleton fetus in cephalic position. Biparietal
diameter, head circumference and femur length are all consistent with gestational age.
No gross anomalies are seen. Amniotic fluid volume is normal. The placenta is low
lying and extends to, but does not appear to cover, the cervical os.
Diagnosis
Third trimester bleeding with low-lying placenta
Assessment/plan
After being observed for several hours in labor and delivery, Joanne is admitted to the
antepartum floor for further observation. She is placed at strict bed rest with fetal
heart monitoring each nursing shift. She is instructed to report any further bleeding.
Blood has been typed and crossed for 4 units and a repeat CBC ordered for the
morning. Nursing orders are to notify you of any orthostatic changes or complaints of
dizziness or weakness.
After 24 hours, there has been no further bleeding and Joanne’s vital signs have
remained normal. She is discharged to home on iron replacement, to follow-up at the
next scheduled appointment next week. She is advised to avoid intercourse or
strenuous physical activities, though she may to continue to do her regular work as an
accountant.
Teaching points
1.
There are several causes of third trimester bleeding. Placental
abruption describes separation of the placenta from the uterine wall. It
occurs in about 20% of all third trimester bleeders and has a 25%
recurrence risk in a subsequent pregnancy. Risk factors for placental
abruption include chronic hypertension, cocaine use, abdominal
trauma, sudden uterine compression (as with rupture of membranes),
and high parity. Physical findings include frequent uterine contractions
or hypertonicity, vaginal bleeding (sometimes catastrophic), and fetal
distress. Disseminated intravascular coagulation occurs in 10% of cases,
in 30% if the bleeding is severe. If the fetal heart tracing is reassuring,
expectant management and vaginal delivery may be considered. If
there are signs of maternal or fetal deterioration, an immediate
cesarean delivery is required. Perinatal mortality approaches 50% in
severe cases.
2.
Placenta previa occurs when placental tissue covers the cervical os. A
central or total placenta previa covers the os completely; as its name
implies, a partial placenta previa partially covers the os. In a marginal
previa, the placental edge is at the margin of the internal os while, with
a low-lying placenta, the placenta approaches the os, but is not at its
edge. At 24 weeks, about 1 pregnancy in 20 will demonstrate
ultrasound evidence of a placenta previa, while, at 40 weeks, the
incidence decreases to 1 in 200. Risk factors include prior cesarean
delivery, history of myomectomy, previous abortion, increased parity,
multiple gestation, advanced maternal age and smoking. Bleeding is
usually painless and may occur after intercourse. Management includes
observation in labor and delivery, IV access, continuous fetal
monitoring and steroids for fetal lung maturation if needed. Cesarean
delivery is the method of choice with hysterectomy backup if
intraoperative bleeding cannot be controlled. Perinatal mortality can
read 40%
3.
Vasa previa is a rare condition where the fetal vessels of a velamentous
cord insertion cover the cervical os. The incidence is less than 1% of all
pregnancies, though it is increased in multiple gestations: up to 11% in
twins and up to 95% in triplets. The diagnosis is suggested by painless
vaginal bleeding in the absence of evidence of placenta previa or
abruption. Treatment is delivery by cesarean section.
4.
Other causes of 3rd trimester bleeding can be cervicitis, cervical
erosions, trauma, cervical cancer, foreign body or even bloody show.
5.
Shock from blood loss is a very real possibility in 3rd trimester bleeding
from any cause. Management includes 2 large bore IVs, crossmatch for
4 or more units of blood; 5% dextrose in lactated ringers or normal
saline should be infused rapidly. Urine output must be monitored and is
a gauge of renal failure from hypoperfusion. Serial CBC and platelet
counts, prothrombin time and partial thromboplastin time are all
followed. Transfusion products are given as needed: whole blood,
packed red blood cells, platelets, fresh frozen plasma and
cryoprecipitate.