Medical Quiz: Obstetrics

A 19-year-old mother of two rushes to her obstetrician’s office at 35 weeks’ gestation because of cramping abdominal pain and mild vaginal bleeding. Both cramps and bleeding started about two hours ago. Pain is constant, with intermittent episodes of severe cramping. Bleeding has been sufficient to soak through four to five pads within the past few hours. She denies a history of trauma or leakage of clear fluid. She does admit to using cocaine three times within the past month, most recently last night. She is afebrile, blood pressure is 155/95 mm Hg, and heart rate is 100/min. Bi-manual examination reveals tenderness over the fundus and a nondilated cervix. Ultrasound reveals a normally implanted placenta with no visible abnormalities. Foetal heart rate is in the 170-180/min range. Which of the following is the most likely diagnosis?

A Abruptio placentae
B Concealed abruption
C Labour
D Placenta accreta
E Placenta praevia
Check answer below:







Answer: A (Abruptio placentae)

Explanation:

 A Abruptio placentae
Abruptio placentae typically presents as bleeding along with uterine contractions and pain due to premature separation of the placenta from the uterus, despite its implantation in a normal location. It is caused most often by a rupture of defective maternal vessels in the decidua basalis. This patient is at high risk for abruptio placentae because of her known hypertension and cocaine use. Other risk factors include short umbilical cord, trauma, prior abruption, cigarette smoking, uterine fibroids, advanced age, sudden uterine decompression, preterm premature rupture of the membranes, and a bleeding diathesis. Whereas ultrasound can reveal abruptio placentae, it is not very sensitive and will be positive in only 25% of cases of abruption confirmed at delivery.

 B Concealed abruption
Concealed abruption refers to abruptio placentae that occurs near the center of the placenta. By definition, there is no external bleeding because the blood forms a haematoma that is hidden behind the placenta. Thus this case cannot represent a concealed abruption.

 C Labour
Labour is defined as regular uterine contractions that result in cervical change. This patient does not describe contractions at regular intervals, but rather a constant pain with intermittent cramping. In addition, her cervix remains closed, so she has not started labour.

 D Placenta accreta
Placenta accreta refers to the abnormally strong adherence of the placenta to the uterine wall. This happens because the placental villi attach directly to the myometrium as a result of a defect in the decidua basalis layer. Placenta accreta manifests as incomplete separation of the placenta after delivery and can result in severe postpartum hemorrhage. Risk factors include placenta praevia, prior caesarean delivery, and prior intrauterine manipulation or surgery. The most common setting for accreta involves a placenta praevia after a prior caesarean delivery.

 E Placenta praevia
Placenta praevia occurs when the placenta overlies the internal cervical os. The distinction between placenta praevia and abruptio placentae is classically made based on the presence (abruptio placentae) or absence (placenta praevia) of pain.