A 29-year-old woman, gravida 2 para 1, comes to the office at 20 weeks gestation for a routine obstetric examination. The patient has felt normal fetal movement and has had no contractions, vaginal bleeding, or pelvic pain. She had diet-controlled gestational diabetes mellitus during her first pregnancy and underwent a cesarean delivery at 36 weeks gestation for preterm labor complicated by breech presentation. The patient has chronic hypertension, currently requiring 2 antihypertensive medications. She had a copper-releasing intrauterine device, placed after her first delivery, that was removed last year to try for pregnancy. The patient does not use tobacco, alcohol, or illicit drugs. Blood pressure is 144/96 mm Hg. BMI is 38 kg/m². Ultrasound shows a single cephalic fetus at the 40th percentile for growth. Cervical length is 4.4 cm and a posterior placenta extends over the cervix. Amniotic fluid index measures 18 cm. Which of the following is the greatest risk factor for this patient's ultrasound findings?

Question

A 29-year-old woman, gravida 2 para 1, comes to the office at 20 weeks gestation for a routine obstetric examination.  The patient has felt normal fetal movement and has had no contractions, vaginal bleeding, or pelvic pain.  She had diet-controlled gestational diabetes mellitus during her first pregnancy and underwent a cesarean delivery at 36 weeks gestation for preterm labor complicated by breech presentation.  The patient has chronic hypertension, currently requiring 2 antihypertensive medications.  She had a copper-releasing intrauterine device, placed after her first delivery, that was removed last year to try for pregnancy.  The patient does not use tobacco, alcohol, or illicit drugs.  Blood pressure is 144/96 mm Hg.  BMI is 38 kg/m².  Ultrasound shows a single cephalic fetus at the 40th percentile for growth.  Cervical length is 4.4 cm and a posterior placenta extends over the cervix.  Amniotic fluid index measures 18 cm.  Which of the following is the greatest risk factor for this patient's ultrasound findings?

Quizplus · Accepted Answer

11ec25c8_da17_278b_bc81_f978f6f667a8_MD0003_00 This patient has placenta previa, in which the placenta extends over and covers the cervix. Most patients are asymptomatic and are incidentally diagnosed on second-trimester ultrasound (as in this patient). Patients with placenta previa require pelvic rest (no intercourse or digital cervical examination) because minimal cervical manipulation can cause cervical changes (eg, shortening, dilation) that can result in partial placental detachment and massive maternal hemorrhage. Placenta previa can occur in any pregnancy; however, this patient's major risk factor is her prior cesarean delivery. Increasing cesarean delivery rates have caused an increased incidence of placenta previa because the uterine scar and change in vascularity likely alter early pregnancy implantation. Additional risk factors include prior placenta previa, multiple gestation (ie, increased placental surface area), and advanced maternal age (age ≥35) (Choice C). Most cases resolve spontaneously by the third trimester due to physiologic lower uterine segment lengthening and/or placental growth toward the fundus. Patients with persistent previa undergo cesarean delivery at 36-37 weeks gestation (ie, prior to the onset of labor). (Choice A) Obesity in pregnancy (ie, prepregnancy BMI ≥30 kg/m²) increases risks of fetal demise and fetal macrosomia (>90th percentile), which are not seen in this patient. (Choice B) Pregnancy complicated by chronic hypertension confers an elevated risk of fetal growth restriction (<10th percentile) and oligohydramnios (amniotic fluid index [AFI] ≤5 cm) due to uteroplacental insufficiency. This patient has a normal estimated fetal weight and AFI. (Choice E) Prior gestational diabetes mellitus increases the risk for recurrent gestational and future type 2 diabetes mellitus. Diabetes mellitus in pregnancy increases the risk for fetal macrosomia (>90th percentile) and polyhydramnios (AFI ≥24 cm), which are not seen in this patient. (Choice F) Prior preterm birth increases the risk for recurrent preterm birth, typically at similar gestational ages. Patients at risk for preterm birth often have shortened cervical lengths (eg, ≤2.5 cm). This patient's cervical length is normal. (Choice G) Although pregnancy complicated by current intrauterine device use has an elevated risk of ectopic pregnancy, spontaneous abortion, and intra-amniotic infection, prior intrauterine device use is not associated with obstetric complications. Educational objective: Placenta previa occurs when the placenta extends over and covers the cervix and is typically diagnosed incidentally on ultrasound. Prior cesarean delivery is a major risk factor for placenta previa, and persistent cases are managed with cesarean delivery at 36-37 weeks gestation. References: Abnormal placentation: current evidence and review of the literature. (http://www.ncbi.nlm.nih.gov/pubmed/29913334) Using ultrasound in the clinical management of placental implantation abnormalities. (http://www.ncbi.nlm.nih.gov/pubmed/26428505) Society for Maternal-Fetal Medicine (SMFM) consult series #44: management of bleeding in the late preterm period. (http://www.ncbi.nlm.nih.gov/pubmed/29079144)

A 29-Year-Old Woman, Gravida 2 Para 1, Comes to the Office