Table 8-3. Hazards Associated with PROM
| If Fetus Remains In Utero | If Preterm Delivery Occurs | |||
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| Neonatal conditions | Neonatal conditions | |||
| • | Infection and sepsis | • | Respiratory distress syndrome (most common) | |
| • | Deformations | • | Patent ductus arteriosus | |
| • | Umbilical cord compression | • | Intraventricular hemorrhage | |
| • | Pulmonary hypoplasia | • | Necrotizing enterocolitis | |
| • | Retinopathy of prematurity | |||
| Maternal conditions | ||||
| • | Bronchopulmonary dysplasia | |||
| • | Chorioamnionitis, sepsis | |||
| • | Cerebral palsy | |||
• Deep venous thrombosis (DVT)
• Psychosocial separation
POSTTERM PREGNANCY
A 21-year-old primigravida at 42 weeks’ gestation by dates comes to the outpatient prenatal clinic. She has been seen for prenatal care since 12 weeks’ gestation, confirmed by an early sonogram. She states that fetal movements have been decreasing. Fundal height measurement is 42 cm. Her cervix is long, closed, posterior, and firm. Nonstress test is reactive, but amniotic fluid index is 4 cm.
Definition
• Academic. The most precise definition is a pregnancy that continues for≥40 weeks or
≥280 days postconception. This includes 6% of all pregnancies.
• Practical. Because most of the time the date of conception is not known, a practicaldefinition is a pregnancy that continues >42 weeks or ≥294 days after the first day of the last menstrual period.
• Statistics. Generally, 50% of patients deliver by 40 weeks, 75% by 41 weeks, and 90%by 42 weeks. These statistics assume ovulation occurred on day 14 of a 28-day men-strual cycle. These figures probably overstate the actual number because up to half of these patients had cycles longer than 28 days.
Etiology. The most common cause of true postdates cases are idiopathic (no known cause). Itdoes occur more commonly in young primigravidas and rarely with placental sulfatase defi-ciency. Pregnancies with anencephalic fetuses are the longest pregnancies reported.
Significance. Perinatal mortality is increased two- to threefold. This is a direct result of changeson placental function over time.
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• Macrosomia syndrome. In most patients, placental function continues providingnutritional substrates and gas exchange to the fetus, resulting in a healthy but large fetus. Cesarean rate is increased owing to prolonged or arrested labor. Shoulder dys-tocia is more common with risks of fetal hypoxemia and brachial plexus injury.
• Dysmaturity syndrome. In a minority of patients, placental function declines asinfarction and aging lead to placental scarring and loss of subcutaneous tissue. This reduction of metabolic and respiratory support to the fetus can lead to the asphyxia
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USMLE Step 2 l Obstetrics
that is responsible for the increased perinatal morbidity and mortality. Cesarean rate is increased owing to nonreassuring fetal heart rate patterns. Oligohydramnios results inumbilical cord compression. Hypoxia results in acidosis and in utero meconium passage.
Management. Management is based on 2 factors.
• Confidence in dates. Identify how much confidence can be placed on the gestationalage being truly >42 weeks.
• Favorableness of the cervix. Assess the likelihood of successful induction of labor byassessing cervical dilation, effacement, position, consistency, and station. The Bishop score is a numerical expression of how favorable the cervix is and the likelihood of successful labia induction.
– Favorable cervix is dilated, effaced, soft, and anterior to mid position. Bishop score is >8.
– Unfavorable cervix is closed, not effaced, long, firm, and posterior. Bishop score is <5.
Bishop Scoring Method
| Parameter\Score | 0 | 1 | 2 | 3 |
| Position | Posterior | Intermediate | Anterior | - |
| Consistency | Firm | Intermediate | Soft | - |
| Effacement | 0–30% | 31–50% | 51–80% | >80% |
| Dilation | 0 cm | 1–2 cm | 3-4 cm | >5 cm |
| Fetal station | -3 | -2 | -1, 0 | +1,+2 |
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Patients can be classified into 3 groups.
• Dates sure, favorable cervix. Management isaggressive. There is no benefit to thefetus or mother in continuing the pregnancy. Induce labor with IV oxytocin and artifi-cial rupture of membranes.
• Dates sure, unfavorable cervix. Management iscontroversial. Management could beaggressive, with cervical ripening initiated with vaginal or cervical prostaglandin E2 followed by IV oxytocin. Or management could be conservative with twice weekly
NSTs and AFIs awaiting spontaneous labor.
• Dates unsure. Management isconservative.Perform twice weekly NSTs and AFIs toensure fetal well-being and await spontaneous labor. If fetal jeopardy is identified, delivery should be expedited.
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