A 34-year-old woman, gravida 3 para 0 aborta 2, at 18 weeks gestation comes to the office for a routine prenatal visit. The patient feels well and has no concerns. She has no chronic medical conditions, and her only medication is a daily prenatal vitamin. The patient's prior pregnancies ended in 2 dilation and curettage procedures for spontaneous abortions due to fetal aneuploidy. She does not use tobacco, alcohol, or illicit drugs. Blood pressure is 126/84 mm Hg and pulse is 88/min. Prepregnancy BMI was 22 kg/m², and she has gained 4.5 kg (10 lb) so far during this pregnancy. Fetal heart tones are 148/min. Transabdominal ultrasound shows a singleton fetus in breech presentation measuring 18 weeks gestation. Amniotic fluid index and fetal anatomy are within normal limits. The placenta is anterior and low-lying, with numerous lacunae and myometrial thinning. Cervical length is 3.8 cm (normal: 2.5 cm). This patient is at greatest risk for which of the following pregnancy-related complications?

Question

A 34-year-old woman, gravida 3 para 0 aborta 2, at 18 weeks gestation comes to the office for a routine prenatal visit. The patient feels well and has no concerns. She has no chronic medical conditions, and her only medication is a daily prenatal vitamin. The patient's prior pregnancies ended in 2 dilation and curettage procedures for spontaneous abortions due to fetal aneuploidy. She does not use tobacco, alcohol, or illicit drugs. Blood pressure is 126/84 mm Hg and pulse is 88/min. Prepregnancy BMI was 22 kg/m², and she has gained 4.5 kg (10 lb) so far during this pregnancy. Fetal heart tones are 148/min. Transabdominal ultrasound shows a singleton fetus in breech presentation measuring 18 weeks gestation. Amniotic fluid index and fetal anatomy are within normal limits. The placenta is anterior and low-lying, with numerous lacunae and myometrial thinning. Cervical length is 3.8 cm (normal: >2.5 cm). This patient is at greatest risk for which of the following pregnancy-related complications?

Quizplus · Accepted Answer

11ec25c8_da68_c98c_bc81_452ee490f8fb_MD0003_00 This patient has ultrasound findings consistent with placenta accreta, the abnormal attachment of placental villi directly onto the uterine myometrium (rather than the decidua basalis) through defects in the decidua. Risk factors include prior uterine surgery (eg, dilation and curettage [D&C], cesarean delivery) because areas of uterine scarring cannot undergo normal decidualization. Patients also typically have concomitant placenta previa because prior uterine surgery can decrease fundal perfusion and promote abnormal placentation in the lower uterus (eg, low-lying placenta). placenta previa Patients with placenta accreta are typically asymptomatic and often diagnosed incidentally on second-trimester ultrasound. Common findings include a low-lying placenta and signs of abnormal placental attachment or invasion into the uterine wall, such as myometrial thinning and numerous placental lacunae (ie, vascular spaces filled with maternal blood). The result of this abnormal placental attachment is a morbidly adherent placenta that does not spontaneously detach after fetal delivery. Attempts to manually remove the placenta can disrupt the placental lacunae and cause profuse maternal bleeding (ie, postpartum hemorrhage). This bleeding can lead to hemorrhagic shock, disseminated intravascular coagulation, and maternal death. Patients diagnosed prenatally typically undergo planned cesarean hysterectomy to decrease these risks, but patients diagnosed at the time of delivery usually require emergency hysterectomy to achieve hemostasis. (Choice A) Abruptio placentae is the premature placental separation from the uterus. Risk factors include preeclampsia and tobacco use. In contrast, placenta accreta causes an adherent placenta, making premature placental separation unlikely. Abruptio placentae (Choice B) Risk factors for intraamniotic infection include prolonged rupture of membranes and genitourinary infection (eg, group B Streptococcus), not placenta accreta. (Choice D) Preeclampsia likely occurs due to insufficient trophoblast invasion and resultant low uteroplacental perfusion. In contrast, patients with placenta accreta have excessive trophoblast invasion and placental hyperperfusion (eg, numerous lacunae). insufficient trophoblast invasion (Choice E) Risk factors for preterm labor include prior spontaneous preterm delivery, multiple gestation, and short cervical length, which are not present in this patient. Educational objective: Placenta accreta is the abnormal attachment of placental villi directly onto the myometrium rather than the decidua basalis. It is often diagnosed incidentally on second-trimester ultrasound revealing a low-lying placenta, myometrial thinning, and numerous placental lacunae. Patients are at increased risk of postpartum hemorrhage because the placenta is morbidly adherent and attempted removal can disrupt the placental lacunae, causing profuse maternal bleeding. References: Epidemiology, etiology, diagnosis, and management of placenta accreta. (http://www.ncbi.nlm.nih.gov/pubmed/22645616) Placenta accreta: diagnosis, management and the molecular biology of the morbidly adherent placenta. (http://www.ncbi.nlm.nih.gov/pubmed/26135782)

A 34-Year-Old Woman, Gravida 3 Para 0 Aborta 2, at 18