A 34-year-old G4P3003 at 31 weeks’ gestation with a known placenta previa presents to the hospital with vaginal bleeding. On assessment, she has normal vital signs, a reactive fetal heart tracing, and no uterine contractions. Heavy vaginal bleeding is noted.
Which of the following is a risk factor for placenta previa?
Placenta previa has been associated with multiparity, especially in women who are para 5 or greater. Prior cesarean delivery provides a two to fivefold increased risk of placenta previa, and this condition is increased twofold in women who smoke. Advancing age is also a risk factor, and some estimates indicate that the incidence is 1/100 for women over age 35. Nulliparity, history of D&C, uterine fibroids, and young age do not increase the incidence of placenta previa.
Which of the following is the best next step in the management of this patient?
In this patient who is starting to hemorrhage from a placenta previa, steps should be taken to stabilize the patient and prepare for possible emergent cesarean delivery. Patients with placenta previa are typically not candidates for vaginal delivery. The patient is not contracting, therefore there is no role for tocolysis. Terbutaline should never be used in a patient who is actively bleeding, because it is associated with maternal tachycardia and vasodilation. The actively bleeding patient should be resuscitated with intravenous fluids while blood is being cross-matched for possible transfusion. A Foley catheter should be placed because urinary output is a reflection of the patient’s volume status. Finally, anesthesia should be notified because the patient may require imminent delivery.
The patient continues to bleed heavily and you observe persistent late decelerations on the fetal heart tracing. Her blood pressure and pulse are normal. You explain to the patient that she needs to be delivered, and she is delivered by cesarean under general anesthesia. The baby and placenta are easily delivered, but the uterus is noted to be boggy and atonic despite intravenous infusion of Pitocin.
Which of the following is contraindicated in this patient for the treatment of uterine atony?
Methylergonovine (methergine), prostaglandin F2α (hemabate), prostaglandin E1 (misoprostol), and prostaglandin E2 (dinoprostone) are all uterotonic agents that can be used in situations where there is a postpartum hemorrhage caused by uterine atony. Terbutaline would be contraindicated in this situation because it is a tocolytic that is used to promote uterine relaxation.
A 25yo P0 at 25 weeks’ gestation presents to the emergency department, where she was a restrained passenger in a motor vehicle accident. She reports she was rear-ended while idling at a stop light. She was wearing her seatbelt, and the impact was significant enough that her airbags were deployed. On examination, her vitals are normal. Her fundus is nontender, but she has bruising on her abdomen from the seatbelt. The fetal heart tracing is reactive and she has no contractions on the tocometer. She reports light vaginal bleeding, which is confirmed on sterile speculum examination. Her blood type is A negative.
What is best test to determine whether there has been fetal-to-maternal hemorrhage?
The K-B test is based on the fact that fetal erythrocytes contain hemoglobin F, which is more resistant to acid elution than hemoglobin A. After exposure to acid, only fetal hemoglobin remains. Fetal red cells can then be identified by uptake of a special stain, and quantified on a peripheral smear. An apt test is usually used to detect the presence or absence (qualitative test, not quantitative) of fetal blood in a vaginal discharge, often to rule out vasa previa in late pregnancy. A type and screen, hemoglobin electrophoresis, or CBC will not provide information about fetomaternal hemorrhage.
A 39-year-old G2P1001 presents for a routine OB visit at 30 weeks’ gestation. Her obstetric history is significant for a vaginal delivery 10 years ago. That pregnancy was uncomplicated, and she delivered a 6 lb baby at 40 weeks. Her current pregnancy has also been uncomplicated. She has no significant medical history, and she does not use tobacco, alcohol, or other drugs. She weighed 95 lb prior to pregnancy, and she has gained 20 lb to date. Her 20-week anatomy ultrasound was normal, and her first trimester screen did not show an increased risk of chromosomal aneuploidies. Her blood pressure range has been 100 to 120/60 mm Hg to 70 mm Hg. During her examination, you note that her fundal height measures only 26 cm.
Which of the following is a most likely explanation for this patient’s decreased fundal height?
This fetus is measuring “size less than dates.” In a normal singleton pregnancy from about 18 to 36 weeks, the number of weeks of gestation should approximate the fundal height measurement, within 2 cm to 3 cm. The differential for a fundal height measurement that is less than expected includes incorrect dating, oligohydramnios, intrauterine growth restriction, or fetal demise. In this patient, heart tones are present, so the pregnancy is still viable. She had a first trimester ultrasound, so the dates are correct. Fetuses with chromosomal aneuploidies such as trisomy 13, 16, 18, or 21 are associated with growth restriction, but this patient has had a normal first trimester screen and anatomy scan. She has not given a history of leakage of fluid, nor does she have any risk factors for oligohydramnios. She is constitutionally small, and mothers who weigh less than 100 lb prior to pregnancy have a twofold increased risk of having a small-for-gestational age (SGA) infant. While poor maternal weight gain, especially in the second trimester, is associated with fetal growth restriction, the patient has gained 20 lb to date, which is adequate. Habits such as smoking, alcohol, or drug use are also associated with growth restriction, but this patient does not report a history of this. Chronic placenta hypoxia or uteroplacental insufficiency is typically associated with maternal conditions such as vascular disease, chronic renal insufficiency, pregestational diabetes, chronic hypertension, smoking, or pre-eclampsia.
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