A 30-year-old woman, gravida 3 para 1 aborta 1, at 26 weeks gestation comes to the office for evaluation of increased vaginal discharge that started yesterday. She now changes her pad every hour and has noticed some spotting. Her initial prenatal visit was 2 weeks ago, and laboratory evaluation revealed a positive urine culture. The patient has not started her antibiotics because she has no symptoms. Her last delivery was 2 years ago via term cesarean delivery for recurrent late fetal decelerations. Vital signs are normal. The abdomen is soft, and the uterus is nontender. On speculum examination, there is pooling of clear, nitrazine-positive fluid in the vagina; the cervix is visibly closed. Fetal heart rate tracing shows a baseline of 150/min, accelerations, and no decelerations. There are irregular contractions on tocodynamometry. Transabdominal ultrasound shows an anterior placenta and an amniotic fluid index of 3 cm. Which of the following most likely contributed to this patient's presentation?
Preterm prelabor rupture of membranes (PPROM) | |
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ASB = asymptomatic bacteriuria; BV = bacterial vaginosis; PPROM = preterm prelabor rupture of membranes. | |
This patient at 26 weeks gestation has a pool of nitrazine-positive vaginal fluid and a closed cervix, consistent with preterm prelabor rupture of membranes (PPROM). Risk factors include prior PPROM; conditions that overdistend the membranes (eg, polyhydramnios); and conditions that inflame or weaken the membranes, such as antepartum bleeding, genital tract infection (eg, bacterial vaginosis, gonorrhea), or asymptomatic bacteriuria.
Due to the proximity of the bladder, perineum, and rectum, bacteria from one source can migrate readily to another; this is particularly common in pregnancy with bladder infections (even if asymptomatic), as the bacteria can spread to the vagina and uterus. As bacteria spreads to the uterus, the intrauterine bacterial enzymatic activity may cause contractions (by stimulating prostaglandin release) or increase membrane fragility (by degrading collagen or activating inflammatory cytokines), resulting in either preterm labor or PPROM.
Due to these risks, all patients require urine culture screening at their initial prenatal visit, and high-risk patients (eg, age <25) undergo sexually transmitted infection screening. Those who screen positive require timely treatment and repeat cultures after treatment (ie, test of cure) to reduce risks of persistent infection.
(Choice B) Extremes of maternal age (eg, age <17 or >35) are associated with preterm labor and PPROM; this patient is age 30.
(Choice C) Multiparity is associated with precipitous labor and increased risk for postpartum hemorrhage, not PPROM.
(Choice D) Patients with placenta previa can have antepartum bleeding with an increased risk of PPROM, likely due to blood causing inflammation and focal weakening of the fetal membranes. This patient has an anterior placenta, which is not a risk factor for PPROM. Her light spotting is likely the result of her rupture of membranes, but such spotting is unlikely to cause PPROM.
(Choice E) Previous cervical surgeries or uterine procedures (eg, multiple dilations and evacuations) are associated with preterm delivery. Previous spontaneous abortion is not associated with PPROM or preterm delivery.
(Choice F) Prior cesarean delivery increases the risk of abnormal placentation (eg, placenta accreta), not PPROM, in subsequent pregnancies.
Educational objective:
Genitourinary tract infection, particularly asymptomatic bacteriuria, is a risk factor for preterm prelabor rupture of membranes. Therefore, universal urine culture screening, timely treatment, and reculturing for test of cure are recommended in pregnancy.