Obstetrics and Gynaecology

at a Glance

Fourth EditionErrol R. Norwitz, John O. Schorge

Case Studies

Case 7: Preterm PROM

A 30-year-old G2P1001 at 29 weeks’ gestation presents to the obstetric triage unit with suspected leakage of clear fluid, described as a constant trickle since 2 a. m. She has a history of systemic lupus erythematosus (SLE) and is maintained on prednisone 20 mg daily. In addition, she reports having experienced scant vaginal bleeding throughout the first trimester only. Currently, fetal wellbeing is reassuring and the patient has no contractions noted on tocometry. Her abdomen is soft, and she is afebrile.

  • 1. Does the patient have any specific risk factors for preterm PROM?

    Correct answer: Premature rupture of membranes (PROM) is defined as rupture of membranes before the onset of labor (uterine contractions) and can occur at any gestational age. Preterm PROM (PPROM) refers to PROM <37 weeks’ gestation. Specific risk factors in this case include a history of a connective tissue disease (SLE), use of chronic steroids, and first- and second-trimester bleeding. Other risk factors that should be asked about include prior PPROM (recurrence risk is 20–30% compared with 4% in women with a prior uncomplicated delivery), placental abruption (may account for 10–15% of PPROM), a history of cervical insufficiency, cervicovaginal infection or chorioamnionitis, amniocentesis or chorionic villous sampling, cigarette smoking, multiple gestation, polyhydramnios, in utero diethylstilbestrol (DES) exposure, anemia, and demographic factors (such as low socioeconomic class and unmarried status). Factors that are known not to be associated with PPROM include coitus, cervical examinations, maternal exercise, and parity.

  • 2. How do you confirm the diagnosis of preterm PROM?

    Correct answer: PROM is a clinical diagnosis. It is usually suggested by a history of watery vaginal discharge, and confirmed on sterile speculum examination by finding a pool of vaginal fluid that has an alkaline pH (it turns yellow nitrazine paper blue) and demonstrates microscopic ferning on drying. Findings of diminished amniotic fluid volume on ultrasound may further suggest the diagnosis. However, normal amniotic fluid volume on ultrasound does not exclude the diagnosis. If equivocal, transabdominal instillation of dye into the amniotic cavity (indigo carmine rather than methylene blue because of the association of methylene blue dye with methemoglobinemia) and documentation of leakage of dye into the vagina by staining of a tampon within 20–30 min will confirm the diagnosis. However, this amnio/dye test (“tampon test”) is rarely performed because of the risks of amniocentesis, which includes PPROM.

  • 3. What other diagnoses should be considered?

    Correct answer: Your differential diagnosis should include urinary incontinence, vaginal discharge or infection, cervical mucus, and a “show” (early labor).

  • 4. What are the complications of preterm PROM?

    Correct answer: Neonatal complications are related primarily to prematurity. PPROM is associated with a fourfold increase in perinatal mortality and a threefold increase in neonatal morbidity, including respiratory distress syndrome (RDS), intra-amniotic infection (occurs in 15–30% of women with PPROM and accounts for 3–20% of neonatal deaths), and intraventricular hemorrhage (IVH). Other neonatal complications include fetal pulmonary hypoplasia (develops in 25% of PPROM <22 weeks), skeletal deformities (complicates 12% of PPROM and is related to the severity and duration of PPROM), cord prolapse (especially if non-vertex presentation), and increased cesarean section delivery (for malpresentation). Placental abruption is associated with PPROM in 10–15% of cases; whether it is a cause or a result of PPROM is unclear.

    Maternal complications include chorioamnionitis (occurs in 15–30% of women with PPROM compared with 1% at term) and postpartum endometritis.

  • 5. Is this patient a candidate for expectant management?

    Correct answer: Yes. She has no evidence of non-reassuring fetal testing (“fetal distress”), unstoppable preterm labor, unexplained bleeding, intra-amniotic infection (chorioamnionitis), and she is not at a favorable gestational age (>34 weeks). However, the likelihood of this woman going into labor within 24–48 hours and 7 days is 50% and 70–90%, respectively. As intra-amniotic infection/inflammation is a major cause of PPROM, amniocentesis should be considered to exclude subclinical infection. Laboratory values consistent with infection include evidence of bacteria on Gram stain or culture, glucose <20 mg/dL, white blood cell count (WBC) >100 cells/mm3, and lactate dehydrogenase (LDH) ≥400 U/L.

  • 6. Is this patient a candidate for antenatal corticosteroids?

    Correct answer: Yes. Both the American Congress of Obstetricians and Gynecologists (ACOG) and the National Institutes of Health (NIH) recommend administration of a single course of antenatal steroids in a patient with PPROM <32 weeks’ gestation to decrease RDS, necrotizing enterocolitis (NEC), and IVH by approximately 50%.

  • 7. How should this patient be managed?

    Correct answer: When managing patients with PPROM, obstetric care providers have to weigh the risk of prematurity against the risk of expectant management, primarily ascending infection. As such, the management of PPROM should be individualized. In general, PPROM is a relative contraindication to the use of tocolytic agents. Tocolysis may be able to delay delivery by 1–2 days, but does not appear to improve perinatal morbidity or mortality, and may be associated with increased incidence of maternal and neonatal infectious morbidity. Prophylactic broad-spectrum antibiotics have been shown to prolong latency in the setting of PPROM, but it is unclear whether this translates into an improvement in perinatal outcome or whether antibiotics can prevent intra-amniotic infection. Several broad-spectrum antibiotic regimens have been studied and there is currently no evidence to recommend one regimen over another. Delivery is recommended immediately if there is evidence of intra-amniotic infection (chorioamnionitis), excessive unexplained vaginal bleeding, non-reassuring fetal testing (“fetal distress”), preterm labor, or once a favorable gestational age has been reached (>34 weeks).

See Chapter 59.

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