Pocket ObGyn – Preterm Mature Rupture of Membrances
See Abbreviations

Definition and Epidemiology (Obstet Gynecol 2013;122:918)

• PROM: Rupture of membranes before the onset of active labor (“premature” to labor)
• PPROM: Premature rupture of membranes <37 w (preterm GA and prior to labor)
• Occurs prior to 1/3 of preterm births

Etiology

• No consensus on the cause of PPROM – thought to be on spectrum of preterm labor
• Risk factors include intra-amniotic infxn, uterine over distension, smoking, connective tissue disorders, 2nd & 3rd trimester bleeding, nutritional deficiency, prior preterm deliv, symptomatic contractions, amniocentesis (leakage after amniocentesis more likely to stop & not lead to deliv)

Clinical Manifestation

• Leakage of amniotic fluid prior to labor
• If accompanied by mat fever or tachy, uterine fundal tenderness, fetal tachy, purulent or malodorous fluid there should be concern for intra-amniotic infxn

Physical Exam

• Sterile speculum exam (Obstet Gynecol. 1992;80:630; Am J Obstet Gynecol. 2000;183:1003)
• Avoid digital exam, esp if Single digital exam decreases latency to deliv.

Diagnostic Workup/Studies

• Clinical dx:

Leakage of fluid per vagina that is consistent w/ amniotic fluid (see below)

Signs of infxn should prompt deliv, regardless of prematurity, to ¯ risk of mat & neonat sepsis

Sterile speculum exam: Pooling of fluid in the vaginal vault sugg ROM US: Oligohydramnios is often present, though not diagnostic

NST: Fetal tachy is often present w/ intra-amniotic infxn Oligohydramnios ® variable decelerations

•   Lab tests:

Ferning: Place fluid from vaginal vault on a dry slide; salts in the amniotic fluid produce a delicate ferning pattern under microscope.

pH: Amniotic fluid has a basic pH ® turns pH paper blue (nitrazine test) Also nitrazine positive: Bld, bact vaginosis, semen.

• Diagnostic procedures

Indigo carmine amniotic infusion “tampon test”

Indigo carmine injected into the amniotic sac via amniocentesis

Tampon inserted vaginally to detect blue color indicating leakage of amniotic fluid

If amniocentesis performed to assess chorioamnionitis, get cell count, gram stain, gluc, & cx (aerobic/anaerobic/mycoand ureaplasma)

Management

• Previable (<24 w): May be managed outpt, w/o Abx, until viability Major complications: Limb contractures, pulm hypoplasia Should be offered termination via D&E or induction
• Early preterm (24–34 w):

Antenatal corticosteroids (up to 32–34 w depending on institutional protocol) Admit to inpt observation in nearly all cases

No indication for tocolytics Collect GBS culture Latency Antibiotics

­ duration of Preg (“latency period”) on avg 1 w

¯ neonat morbidity (respiratory distress, NEC) Does not ¯ incid of chorio

Induction at 34 w gest or w/ signs of preterm labor, chorio, abruption, fetal distress

 

Latency antibiotics regimen*

Ampicillin 2 g IV q6h ´ 48 h ® Amoxicillin 250 mg PO q8h ´ 5 d AND Erythromycin 250 mg IV q6h ´ 48 hr ® Erythromycin 330 mg PO q8h (or 250 mg q6h) ´ 5 d

*, other regimens can be employed (eg, azithromycin instead of erytho). For severe PCN allergy, use erythro alone. Augmentin should NOT be used in place of amp (inc risk of NEC). From Mercer BM, Miodovnik M, Thurnau GR, et al. Antibiotic therapy for reduction of infant morbidity after preterm premature rupture of the membranes. A randomized controlled trial. National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. JAMA. 1997;278(12):989–995.

• ≥34 w (PLoS Med 2012;9:e1001208):

Unless contraindications exist to vaginal deliv, induction may be attempted

After 34 w, no difference in neonat sepsis btw induction & conservative mgmt, but trend toward ¯ neonat morbidity w/ induction

More likely to see variable decelerations during labor ® ­ CD for fetal intolerance

GBS status should be assessed during latency & appropriate therapy in labor

Preterm Labor

Definition and Epidemiology

• Labor (ctx + cervical dilation) occurring before 37 w gest
• Preterm labor occurs in ~40–50% of all pregnancies
• Preterm deliv occurs in roughly 12% of pregnancies ® ~35% of all health care spending for infants in US

Etiology

• Poorly understood, but risk factors include multi gest/uterine over distension, bact infxn, placental abruption, cervical insufficiency, prior preterm labor

Clinical Manifestation

• Physical exam findings of labor including persistent uterine contractions (>4/20 min or 8/h) leading to changes in cervical effacement &
• Occ includes rupture of membranes

Physical Exam

• Painful uterine contractions leading to cervical change, and eval for PPROM, abruption, etc

 

Diagnostic Workup/Studies (Obstet Gynecol 2012;120:964)

•   Pelvic exam:

Sterile speculum and digital exam to evaluate cervical dilation Collect fFN swab

GBS swab if deliv is not imminent & has not been collected previously Sterile vaginal exam to directly assess cervix (must be after fFN collected!)

•   Labs:

fFN: Basement membrane peptide present in amniotic membranes. Can be tested via cervical swab – not reliable w/ vaginal bleeding, recent (<24 h) intercourse or vaginal exam. If negative, 95% do not deliver in 14 d (Br J Obstet Gyneacol 1996;103:648)

•   US:

Transvaginal US measurement of cervical length <25 mm is a/w preterm deliv

Treatment and Medications (Obstet Gynecol 2012;119:1308)

 

Tocolytic medications
Category	Example	Contraindication	Mat effects	Fetal effects
Beta-mimetics	Terbutaline	Arrhythmias	Pulm edema, MI, HTN	Tachy, hyperglycemia
Magnesium sulfate	Magnesium sulfate	Myasthenia gravis	Flushing, muscle weakness, pulm edema, MI	Hypotonia, respiratory depression
CCBs	Nifedipine	Cardiac dz, renal dz (relative)	Flushing, HoTN, nausea	None
Prostaglandin synthetase inhib	Indomethacin	Renal or hepatic dysfxn; peptic ulcer dz, coagulopathy	Nausea, heartburn	Closure of ductus arteriosus, oligohydramnios

•   Prior to 34 w gest:

Administer corticosteroids for fetal lung maturation

Tocolytics only to allow for Cort administration or mat xfer – no pharmacotherapy proven to stop preterm labor

•   Prior to 32 w gest:

Magnesium sulfate administration for fetal neuroprotection (N Engl J Med 2008;359:895)

•   Prevention of recurrent preterm birth:

17-OH progesterone caproate (250 mg IM weekly) starting at 16 w until 36 w (30% reduction in recurrent preterm deliv) (N Engl J Med 2003;348:2379)

Serial cervical length measurements starting at 16–24 w/ poss cerclage placement if cervical length <25 mm. See short cervix, above. (Am J Obstet Gynecol 2009;201:375)

 

See Abbreviations