9/8/24, 22:32 Prelabor Rupture of Membranes - Lecturio
Prelabor Rupture of Membranes
Prelabor rupture of membranes (PROM), previously known as premature rupture of
membranes, refers to the rupture of the amniotic sac before the onset of labor.
Prelabor rupture of membranes may occur in term or preterm pregnancies. The
presentation includes a painless discharge of clear or pale-yellow fluid from the vagina
in the form of a large gush or as small, intermittent trickles. Management depends on
gestational age. Beyond 34 weeks, the recommendation is to induce labor and, if
indicated, use antibiotics for group B streptococcus (GBS) prophylaxis. Prior to 34
weeks, management involves prolonging the pregnancy as long as possible while
avoiding intra-amniotic infection (IAI), also known as chorioamnionitis, and minimizing
risk to the fetus. The primary complications associated with PROM are related to
infections and preterm birth.
Last updated: September 29, 2022
CONTENTS
Overview
Pathophysiology and Clinical Presentation
Diagnosis
Management
Complications
Differential Diagnosis
References
Overview
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Definition
Prelabor rupture of membranes (PROM) is defined as the rupture of fetal
membranes (the fused chorion and amnion) before the onset of labor (regular
uterine contractions causing cervical change).
Epidemiology
Prelabor rupture of membranes complicates approximately 2%–3% of pregnancies.
Risk factors:
Genital tract infections (e.g., bacterial vaginosis)
PROM or preterm delivery in previous pregnancies
Uterine distension:
Polyhydramnios
Multiple gestation
Cervical incompetence
Trauma
Cigarette smoking
Table: Epidemiology of PROM
Pre-viable Preterm PROM Term PROM
PROM (PPROM)
Gestational < 24 weeks 24–36 weeks > 37 weeks
age
Frequency < 1% of ~ 3% of pregnancies ~ 8% of
pregnancies overall pregnancies
~ 30% of preterm
pregnancies
PROM: prelabor rupture of membranes
Pathophysiology and Clinical Presentation
Anatomy
The fetal membranes create the amniotic sac to surround the fetus and protect it
from infection.
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Composed of 2 layers:
Amnion:
Innermost layer
Contains amniotic fluid and fetus
Chorion:
Separates amnion from maternal decidua (innermost uterine layer)
Acts as a protective barrier
Early in pregnancy: 2 distinct layers with the chorionic cavity between
Later in pregnancy: Layers fuse to become a single amniochorion.
Amniotic fluid:
Produced primarily from fetal urine
Allows for:
Fetal movement → skeletal development
Fetal breathing → lung development
Fetal membranes at 7 weeks and 4 months of development:
The membranes arise from trophoblastic and mesodermal tissue. Early in pregnancy, the chorion
and amnion are 2 distinct layers with a cavity between. As the pregnancy progresses, the 2 layers
fuse to form a single amniochorion in direct contact with the maternal decidua.
Image by Lecturio.
Pathophysiology
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Poorly understood
Membrane strength comes from:
Collagen
Fibronectin
Laminin
Possible mechanism for PROM is the imbalance between matrix metalloprotease
(MMP) and MMP inhibitors:
MMP degrades collagen.
MMP inhibitors maintain membrane integrity.
Potential pathologic events may disrupt membranes:
Infection
Inflammation
Mechanical stress
Bleeding
Clinical presentation
Sudden gush of fluid without labor contractions
Often copious, but also small amounts
Continuous or intermittent leakage
Color of fluid may be:
Clear
Straw colored
Greenish (meconium stained)
Blood tinged (concern for associated placental abruption)
Purulent (infected)
Diagnosis
Once labor is excluded, a sterile speculum exam and ultrasound should be
performed to diagnose PROM.
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Pooling:
Visualize the cervix on sterile speculum exam and ask the mother to bear
down (Valsalva maneuver).
Positive test: visualization of fluid coming from the cervix (often significant)
Most accurate diagnostic test
Nitrazine test:
Collect sample of vaginal fluid on sterile speculum exam.
Positive test: pH paper turns blue in presence of basic amniotic fluid.
Low positive predictive value → also turns blue in presence of:
Semen
Bacterial vaginosis
Blood
Ferning:
Obtain swab of vaginal fluid → allow to dry on a glass slide
Positive result: Ferning pattern appears on a slide and is visible on
microscopy.
Cervical mucus can leave a similar ferning pattern (false positive).
Ultrasound:
Suggestive of PROM: oligohydramnios (maximal vertical pocket of fluid < 2
cm)
Relatively low sensitivity and specificity:
PROM often exists without oligohydramnios.
Oligohydramnios often exists without PROM.
Exclude labor:
Assess contractions on tocometry.
Assess cervical dilation visually on sterile speculum exam (try to avoid digital
exam which ↑ risk of intra-amniotic infection (IAI)).
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Intrapartum fetal monitoring with tocometry:
The bottom panel shows tocometry (records uterine contractions). The upper panel shows the
fetal heart rate (baseline of around 140/min) with moderate variability and late heart rate
decelerations (descent time > 60 sec with nadir after the peak of the contraction, and slow return
up to baseline of 140). The tracing is from a case of fetal cord prolapse through the cervix (a
potential complication of PROM), which compromises fetal blood flow. The fetal heart rate pattern
is nonreassuring.
Image (https://openi.nlm.nih.gov/detailedresult?img=PMC4522983_jocmr-07-672-
g002&query=fetal%20monitoring&it=xg&lic=by&req=4&npos=9): “CTG in a case of prelabor rupture of
membranes” by Department of Obstetrics and Gynaecology, Royal United Hospital Bath NHS Trust, Bath, UK.
License: CC BY 2.0 (http://creativecommons.org/licenses/by/2.0/)
Management
Management is based on gestational age, group B streptococcus (GBS) status,
signs of labor or contractions, and signs of IAI.
General management
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Confirm fetal well-being:
Non-stress test (fetal monitoring with tocometry)
Assess amniotic fluid levels with ultrasound.
Deliver if:
> 34 weeks gestational age
IAI is present (regardless of gestational age).
Monitor for development of IAI; ↑ risk in PROM, ↑↑↑ risk in preterm prelabor
rupture of membranes (PPROM):
Fever
Maternal leukocytosis > 15,000/L
Maternal tachycardia
Fetal tachycardia > 160/min for ≥ 10 minutes
Purulent amniotic fluid on exam
Fundal tenderness
Contractions/labor
Antibiotics for group B streptococcus (GBS):
IV penicillin or ampicillin in labor
If preterm and/or GBS status is unknown → collect a swab at presentation
Treat in labor if:
GBS positive
GBS unknown with risk factors
Risk factors for fetal GBS disease:
Preterm (< 37 weeks gestation)
Rupture of membranes (ROM) ≥ 18 hours
Fever ≥ 100.4°F (≥ 38°C)
Prior documented GBS colonization in urine
Prior infant with early-onset GBS disease
Management of PROM by gestational age
Fetal age > 34 weeks:
Induction of labor
Antibiotics:
For GBS prophylaxis only
Given if patient is:
GBS positive
Unknown with risk factors
Gestational age of 34–37 weeks (risk factor)
Fetal age 24–33 weeks:
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Antibiotics:
Latency antibiotics:
Attempt to ↑ time to delivery by preventing IAI
Regimen: azithromycin + ampicillin/amoxicillin
GBS prophylaxis: Treat when delivery is imminent and GBS is positive or
unknown.
Corticosteroids:
Betamethasone
Benefits:
↑ Fetal lung maturity
↓ Intraventricular hemorrhage (IVH)
↓ Necrotizing enterocolitis
Magnesium sulfate: for fetal neuroprotection against cerebral palsy
Tocolytics:
Given only for initial 48 hours (allows time for maximum benefit of steroids)
Prevents contractions if not yet started
Do not give if contractions are already present → likely due to infection → ↑
risk of morbidity
Delivery indications:
Achieve 34 weeks of gestation
IAI
Spontaneous labor
Fetal distress
Fetal age < 24 weeks:
Expectant management or induction of labor
No antibiotics, corticosteroids, tocolysis, or magnesium sulfate
↑↑ Risk of infection if pregnancy continues
Complications
Neonatal complications
Complications can be related to:
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Infection:
Fetal infection
Sepsis
Neurodevelopmental impairment
Compromised blood flow:
Umbilical cord compression and/or prolapse
Placental abruption:
Occurs with rapid decompression of uterus
Obstetric emergency
Oligohydramnios (with early PPROM):
Pulmonary hypoplasia
Orthopedic and facial abnormalities
Preterm delivery:
Respiratory distress syndrome (most common)
IVH
Necrotizing enterocolitis
Retinopathy of prematurity
Cerebral palsy
Patent ductus arteriosus
Maternal complications
Infections:
IAI/chorioamnionitis
Postpartum endometritis
Sepsis
Postpartum hemorrhage (common after IAI)
Deep vein thrombosis (due to prolonged bed rest in PPROM)
Differential Diagnosis
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Urinary incontinence: an involuntary loss of urine. Urinary incontinence is
common towards the end of pregnancy due to increased pressure on the bladder
from the fetus. Prelabor rupture of membranes (PROM) should always be ruled out
1st (pooling, nitrazine test, ferning, and ultrasound). Urinalysis should also be
obtained to rule out urinary tract infection (UTI), which can increase the risk of
urinary incontinence. Management in pregnancy is usually reassurance and
observation since incontinence is typically minor.
Urinary tract infection: an infection of the urinary system most commonly caused
by Enterobacteriaceae, especially Escherichia coli. Presentation typically includes
suprapubic pain, dysuria, and urinary urgency. Diagnosis is made with urinalysis
and culture. Pyelonephritis is more common in pregnancy and is diagnosed when
flank pain and fever accompany the UTI. Management is with antibiotics.
Vaginal infection/vaginitis: inflammation of the vagina can resulting in discharge,
itching, and discomfort. The most common causes include bacterial vaginosis (BV
), candidiasis, and trichomoniasis. Sexually transmitted infections can also cause
cervicitis with purulent discharge. Discharge from vaginitis (especially BV) can be
confused with amniotic fluid. Diagnosis is made on microscopy with KOH and wet
prep of vaginal discharge. Management is with antimicrobials.
Semen: If the patient presents to labor and delivery complaining of PROM, ask
directly about recent sexual activity. Semen will cause nitrazine paper to turn blue
(false positive), and sperm can be seen on microscopy. If PROM is confidently
ruled out and history or exam suggest recent unprotected intercourse, the gush of
fluid is commonly semen.
References
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A. (Ed.), UpToDate. Retrieved February 22, 2021, from
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2. Duff, P. (2020). Preterm prelabor rupture of membranes: Clinical manifestations and diagnosis. In
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3. Duff, P. (2020). Preterm prelabor rupture of membranes: Management and outcomes. In Barss, V. A.
(Ed.), UpToDate. Retrieved February 24, 2021, from https://www.uptodate.com/contents/preterm-
prelabor-rupture-of-membranes-management-and-outcome
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4. Baker, C. J. (2020). Neonatal group B streptococcal disease: Prevention. In Barss, V. A. (Ed.),
UpToDate. Retrieved February 24, 2021, from https://www.uptodate.com/contents/neonatal-group-
b-streptococcal-disease-prevention (https://www.uptodate.com/contents/neonatal-group-b-
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5. American College of Obstetrics and Gynecology (2020). Practice Bulletin No. 217: Prelabor rupture
of membranes. Retrieved February 22, 2021, from https://www.acog.org/clinical/clinical-
guidance/practice-bulletin/articles/2020/03/prelabor-rupture-of-membranes
(https://www.acog.org/clinical/clinical-guidance/practice-bulletin/articles/2020/03/prelabor-rupture-
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6. Cunningham, F. G., Leveno, K. J., et al. (2010). Williams Obstetrics (23rd ed. pp. 50‒54).
7. Dayal, S. (2020). Premature rupture of membranes. In Hong, P. (Ed.) StatPearls. Retrieved February
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(https://www.statpearls.com/articlelibrary/viewarticle/27659/)
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