You are called to the obstetric suite to help care for a patient in her third trimester of pregnancy who is presenting with painless vaginal bleeding. Which of the following diagnoses is MOST likely?

  • □ (A) Placenta previa

  • □ (B) Placenta accreta

  • □ (C) Placental abruption

The classic presentation of placenta previa (Figure) is a patient in her second or third trimester of pregnancy with painless vaginal bleeding that is not associated with labor or any other inciting event. Diagnosis is best made by transvaginal ultrasound, measuring the distance from the uterine os to the edge of the placenta. If this distance is greater than 1 cm and bleeding is minimal, a trial of labor may be offered. Otherwise, cesarean delivery is usually recommended.

Figure:

Placenta previa. ©2019 American Society of Anesthesiologists.

Figure:

Placenta previa. ©2019 American Society of Anesthesiologists.

Uterine rupture has a variable presentation, but classically presents as sudden and severe maternal abdominal pain, hypotension, or shock with profound fetal bradycardia.

Placenta accreta causes postpartum hemorrhage, not antenatal vaginal bleeding. In placenta accreta, the placenta invades and becomes abnormally adherent to the uterine wall. It is usually diagnosed after delivery or in the antenatal period by ultrasound or MRI.

Placental abruption classically presents as painful vaginal bleeding, uterine irritability, and fetal distress. Abruption occurs when the placenta detaches (partially or completely) with the fetus in utero. In some cases, the abruption may be contained such that no vaginal bleeding is observed.

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Bibliography:

Bibliography:
Chestnut
DH
,
Wong
CA
,
Tsen
LC
,
Ngan Kee
WD
,
Beilin
Y
,
Mhyre
JM, eds
.
Chestnut's Obstetric Anesthesia: Principles and Practice
. 5th ed.
Philadelphia, PA
:
Elsevier Saunders
;
2014
:
882
8
, 893-4.

Answer: A