Suspected rupture of membranes

Suspected rupture of membranes is a woman's report of a gush or continuous trickle of fluid from the vagina during pregnancy, before or in the absence of labour. Vaginal fluid leakage also includes urine, increased discharge and cervical mucus.

The main clinical points are:

• to confirm or exclude rupture with a sterile speculum examination and a biomarker rather than digital examination
• to detect intra amniotic infection and cord prolapse
• to give antibiotics and corticosteroids for preterm prelabour rupture of membranes
• to time delivery by gestation and infection risk

Clinical relevance. Rupture of membranes before 37 weeks (preterm prelabour rupture of membranes) complicates a small share of pregnancies but accounts for a large share of preterm births, with risks of infection, abruption, cord prolapse, pulmonary hypoplasia (earlier gestations) and neonatal death. At term, rupture before labour (term prelabour rupture) carries a small risk of infection that rises with time.

Physiology. Amniotic fluid is produced by the foetal kidneys and lungs after 16 weeks, with a volume of about 800 mL at 36 weeks. Its pH is 7.0 to 7.5, whereas the normal vagina has a pH of 3.8 to 4.5. Membranes weaken near term through collagen breakdown and apoptosis.

Mechanisms. Preterm rupture follows infection or inflammation, decidual bleeding (abruption), overdistension (polyhydramnios, multiple pregnancy), cervical insufficiency, smoking, procedures (amniocentesis, cerclage), trauma or collagen disorders. Many cases have no clear cause.

Classification. Term prelabour rupture (37 weeks or more, before onset of labour); preterm prelabour rupture (under 37 weeks); previable rupture (under 24 weeks); prolonged rupture (over 18 to 24 hours); high leak and low leak; amnion rupture with intact chorion (rare). By finding: confirmed rupture, equivocal, or not ruptured (other fluid).

Key distinctions. Pooling of clear fluid in the posterior fornix on speculum examination, that increases with cough or fundal pressure, confirms rupture. Urine, discharge, mucus, semen and bleeding can mimic leakage. Fever, uterine tenderness, foul fluid or tachycardia indicate infection. A palpable cord or visible loop is cord prolapse.

History

• Gestation and dates; plurality.
• Leak: onset time (date and hour), gush or continuous trickle, volume (pad soaked or wet underwear), colour (clear, green meconium, blood stained), smell (sweet versus urine or foul), whether it continues, wetting after coughing or movement.
• Contractions, abdominal pain, backache, bleeding, foetal movements, fever, rigors, urinary symptoms, itching, vaginal discharge, recent intercourse.
• Risk factors: previous preterm rupture, previous preterm birth, bleeding in pregnancy, smoking, infection, low body mass index, cervical surgery or cerclage, amniocentesis, multiple pregnancy, polyhydramnios, trauma, uterine anomaly, drug use, intimate partner violence.
• Obstetric: previous caesarean section, group B streptococcus status, antenatal screening, previous term prelabour rupture.
• Medical: diabetes, HIV, hypertension, thyroid disease, connective tissue disease.
• Drugs: antibiotics already given, tocolytics, corticosteroids, immunosuppression.
• Social: distance to hospital, transport.

Examination

• Vital signs: temperature, pulse, blood pressure, respiratory rate; hydration.
• Abdomen: uterine tenderness and tone, fundal height, lie, presentation, engagement, foetal heart.
• Sterile speculum examination (do this before any digital examination): pooling of fluid in the posterior fornix, fluid leaking from the cervical canal on cough or fundal pressure, cervical dilatation, visible cord or membranes, odour and colour of fluid, bleeding, signs of infection (discharge, cervicitis).
• Do not perform digital vaginal examination unless the woman is in established labour or birth is planned, because it shortens latency and raises infection risk.
• Cardiotocography and tocography.
• Bedside tests: urine dipstick, capillary glucose, nitrazine paper test (pH over 6.5 suggests amniotic fluid).

Red flags

• Fever of 38.0°C or more, maternal tachycardia (over 100 beats/min), foetal tachycardia (over 160 beats/min), uterine tenderness or foul fluid (intra amniotic infection).
• Palpable or visible cord in the vagina (cord prolapse), or abnormal presentation (breech, transverse lie).
• Meconium stained fluid, thick or bloody fluid, vaginal bleeding or constant pain (abruption).
• Abnormal cardiotocography or reduced movements.
• Gestation under 34 weeks, or under 24 weeks (periviable).
• Group B streptococcus positive, previous infant with group B streptococcus disease.
• Contractions or advanced cervical dilatation.
• Maternal sepsis (hypotension, hypoxia, altered consciousness).
• Previous caesarean section (scar), HIV with unsuppressed viral load, active genital herpes.

Special groups. Women with HIV: continue antiretroviral therapy, check viral load, and plan mode of birth. Women with active herpes: caesarean section. Women with previous preterm prelabour rupture: higher recurrence. Region specific: delay to presentation, absent sterile speculum equipment and poor access to antibiotics worsen outcomes; use clean technique and a sterile pad test.

Organised by the nature of the fluid. Each cause is common unless marked serious or uncommon.

Amniotic fluid

• Serious: preterm prelabour rupture of membranes.
• Term prelabour rupture of membranes.
• Rupture of the forewaters or high leak (intermittent leakage with a small defect).
• Rupture with oligohydramnios or polyhydramnios.
• Serious: intra amniotic infection (chorioamnionitis) as a complication.
• Serious: cord prolapse as a complication.
• Serious: placental abruption as a complication.

Urinary

• Stress urinary incontinence (leaks with cough, laughter, exertion).
• Urge incontinence and overactive bladder.
• Urinary tract infection, bladder compression by the uterus, nocturia.
• Vesicovaginal fistula (rare).

Vaginal and cervical discharge

• Physiological leucorrhoea (increased in pregnancy).
• Cervical mucus and show, mucous plug loss (thick, may be bloody).
• Bacterial vaginosis, vulvovaginal candidiasis, trichomoniasis.
• Chlamydial or gonococcal cervicitis.
• Genital herpes, other vulval conditions.
• Cervical ectropion with watery discharge.

Other fluids

• Semen after intercourse.
• Blood stained loss, lochia (postpartum).
• Sweat, lubricants, creams, douche solutions.
• Faecal soiling, rare fistula.
• Rare: hydrorrhoea gravidarum (watery fluid from the uterus, a decidual or retrochorionic leak without membrane rupture), leaking chorion or cervical polyp discharge.

Stepwise reasoning

1. Confirm gestation and the time of onset, and assess for infection, labour and foetal condition.
2. Perform a sterile speculum examination: observe pooling or leaking fluid.
3. If no pooling and the history is suggestive, use a biochemical test (placental alpha microglobulin 1 or insulin like growth factor binding protein 1) and ultrasound for liquor volume.
4. If still equivocal, repeat the examination after lying flat for 30 to 60 minutes, or use an amniotic dye test.
5. Decide on management by gestation, infection and labour status.

First line tests

• Speculum examination with direct visualisation of fluid.
• Nitrazine (pH) test: a pH over 6.5 (blue paper) suggests rupture, but false positives occur with blood, semen, bacterial vaginosis, trichomoniasis, alkaline antiseptics and cervical mucus; false negatives occur with minimal fluid. It is not used alone.
• Ferning (arborisation) test of dried fluid on a slide: sensitivity and specificity are limited and are reduced by blood, cervical mucus and contamination.
• Biochemical immunoassays: placental alpha microglobulin 1 (high sensitivity and specificity, not affected by blood or semen in most cases) and insulin like growth factor binding protein 1 (similar performance, false positives with blood contamination, rare). A positive test confirms rupture; a negative test in a clinically doubtful case makes rupture unlikely.
• Ultrasound: amniotic fluid index or deepest vertical pool (oligohydramnios: index under 5 cm, pool under 2 cm). Normal liquor does not exclude rupture because production continues.
• Cardiotocography and temperature measurement.
• Full blood count, C reactive protein (baseline and repeat; a rise supports infection), high vaginal swab, low vaginal and rectal swab for group B streptococcus, nucleic acid amplification tests for chlamydia and gonorrhoea, urine culture.
• Group and screen.

Amniotic dye test (equivocal cases). Indigo carmine 1 mL diluted in 9 mL sodium chloride 0.9% injected into the amniotic sac by amniocentesis; a blue stained tampon after 30 minutes confirms rupture. Rarely used because it is invasive; methylene blue is avoided (haemolysis and foetal toxicity).

Targeted tests

• Amniotic fluid assessment for infection (glucose, culture, Gram stain, interleukin 6) is rarely required.
• Maternal blood cultures if febrile.
• Foetal growth and Doppler ultrasound.
• Foetal fibronectin is not valid after rupture.
• Kleihauer test in rhesus negative women with bleeding.

Limitations. Digital examination and lubricant contaminate tests. Intermittent leaks can be missed. C reactive protein rises after corticosteroids; white cell count also rises after steroids, which limits their use for infection screening. Ultrasound liquor volume can be normal soon after rupture. A negative test does not remove the need for safety netting and review.

Immediate steps. Assess maternal and foetal condition.

If the cord is palpable or visible, this is an emergency: call for help, relieve pressure on the cord by elevating the presenting part manually, and place the woman in the knee chest or exaggerated left lateral head down position.

Fill the bladder with 500 to 750 mL sodium chloride 0.9% via a catheter, avoid handling the cord, and give terbutaline 0.25 mg subcutaneously to reduce contractions if available.

Proceed to immediate caesarean section (category 1, decision to delivery under 30 minutes) unless vaginal birth is imminent.

Admit women with preterm rupture, signs of infection, or abnormal foetal findings.

Term prelabour rupture of membranes (37 weeks or more)

• Discuss induction of labour or expectant management. Offer induction within 24 hours (or earlier if group B streptococcus positive, maternal infection, meconium or high risk).
• Induce with oxytocin or prostaglandin, depending on the cervix: dinoprostone 1 mg (or 3 mg) vaginal tablet or gel, or misoprostol 25 microgram vaginally every 4 hours (maximum 6 doses; avoid with previous caesarean section), then oxytocin.
• Expectant management is acceptable for up to 24 hours in well women. Give hygiene advice (no tampons, no intercourse, showers rather than baths), check temperature every 4 hours, and give a diary of foetal movements.
• Antibiotics for fever or group B streptococcus (benzylpenicillin 3 g intravenously, then 1.5 g every 4 hours until birth).
• Avoid repeated digital examination.

Preterm prelabour rupture of membranes (24 to 36 weeks and 6 days)

• Admit to a unit with neonatal capability, avoiding digital examination.
• Antibiotics (to prolong latency and reduce infection): erythromycin 250 mg orally four times daily for 10 days or until labour begins (the usual first line).
• Azithromycin 1 g orally as a single dose is an acceptable substitute where erythromycin is not tolerated.
• An alternative regimen is ampicillin 2 g intravenously every 6 hours with erythromycin 250 mg intravenously every 6 hours for 48 hours. Then give amoxicillin 500 mg orally every 8 hours with erythromycin 333 mg orally every 8 hours to complete 7 days.
• Avoid co-amoxiclav because of the risk of necrotising enterocolitis in the newborn. For penicillin allergy use erythromycin alone.
• Antenatal corticosteroids: betamethasone 12 mg intramuscularly twice, 24 hours apart (or dexamethasone 6 mg intramuscularly every 12 hours for four doses), from 24 weeks to 34 weeks and 6 days, and consider later on specialist advice.
• Magnesium sulphate for neuroprotection if birth is expected before 30 weeks (34 weeks in some services): 4 g intravenously over 15 to 30 minutes, then 1 g/h for up to 24 hours.
• Tocolysis is not given routinely. If contractions start, a short course (nifedipine 20 mg orally then 10 to 20 mg every 6 to 8 hours for up to 48 hours) may be used to complete steroids in the absence of infection.
• Group B streptococcus prophylaxis when labour starts: benzylpenicillin 3 g (5 million units) intravenously, then 1.5 g every 4 hours until birth.
• For penicillin allergy with low risk: cefazolin 2 g, then 1 g every 8 hours. For high risk allergy: clindamycin 900 mg every 8 hours or vancomycin 20 mg/kg every 8 hours (maximum 2 g a dose).
• Timing of birth: induce or deliver at 34 weeks (many services offer between 34 and 37 weeks, with induction at 37 weeks at the latest), earlier if infection, abruption, non reassuring foetal status or labour.
• Expectant management between 34 and 36 weeks and 6 days is individualised, because the infection risk increases with latency.
• Rhesus negative women: anti D immunoglobulin 250 IU intramuscularly within 72 hours (500 IU from 20 weeks) if bleeding.

Previable rupture (under 24 weeks)

• Counsel on survival, pulmonary hypoplasia, limb contractures and infection by gestation and residual liquor. Offer expectant management or termination (where legal).
• Expectant care: admit for 48 to 72 hours and give erythromycin 250 mg orally four times daily for 10 days.
• Consider outpatient care once stable and infection excluded (temperature twice daily, no digital examination, no intercourse). Give steroids and magnesium sulphate from the gestation at which resuscitation would be offered.
• Review the decision if infection, abruption or labour occurs.

Intra amniotic infection

• Diagnosis: maternal temperature 38.0°C or more with one or more of maternal tachycardia (over 100 beats/min), foetal tachycardia (over 160 beats/min), uterine tenderness, foul fluid or raised inflammatory markers.
• Treatment: deliver irrespective of gestation.
• Antibiotics: ampicillin 2 g intravenously every 6 hours with gentamicin 5 mg/kg intravenously once daily (adjusted to renal function), and metronidazole 500 mg intravenously every 8 hours after caesarean birth (or clindamycin 900 mg every 8 hours).
• Give paracetamol 1 g every 4 to 6 hours (maximum 4 g daily) and cooling. Continue antibiotics until afebrile for 24 hours.
• Alternative: ceftriaxone 2 g intravenously once daily with metronidazole 500 mg every 8 hours. Mode of birth is decided by obstetric indications.
• Notify the neonatal team (sepsis evaluation of the newborn) and obtain placental histology.

Special groups

• Women with HIV: continue antiretroviral therapy; if viral load is over 1000 copies/mL, discuss caesarean section and intravenous zidovudine in labour.
• Active genital herpes: caesarean section; aciclovir 400 mg orally three times daily from 36 weeks in women with a history.
• Rhesus negative: anti D immunoglobulin if bleeding.
• Previous caesarean section: avoid misoprostol; use mechanical methods or oxytocin.
• Women who do not have access to a speculum or biomarker: a sterile pad test (wear a clean pad for 1 hour and compare), the patient's history, and ultrasound for liquor.
• Region specific: give antibiotics early when delivery in a facility is far, and refer to a hospital where care for preterm infants is available.

Vaginal fluid leakage not due to rupture. If the speculum examination and biomarker are negative, reassure and treat the cause:

• pelvic floor exercises for stress incontinence
• urine culture and treatment (cefalexin 500 mg orally every 12 hours for 5 to 7 days)
• bacterial vaginosis (metronidazole 400 mg orally twice daily for 5 to 7 days)
• candidiasis (clotrimazole 500 mg pessary once, or clotrimazole 1% cream, avoiding oral fluconazole in pregnancy)
• trichomoniasis (metronidazole 400 mg orally twice daily for 5 to 7 days, or 2 g once)

Advise to return if leakage continues, increases or the fluid is green or bloody.

Monitoring. Temperature every 4 hours (every 2 hours if febrile), pulse, blood pressure, uterine tenderness, fluid colour and smell, foetal heart rate daily or more often, and cardiotocography as indicated. Check C reactive protein and white cell count at least twice weekly (interpretation is limited after corticosteroids), liquor volume and growth ultrasound every 1 to 2 weeks, and weekly high vaginal swabs.

Referral and escalation. Refer the same day to the obstetric team for any suspected rupture of membranes. Refer to a unit with neonatal intensive care for preterm rupture under 34 weeks. Refer to foetal medicine for previable rupture. Call the anaesthetic and neonatal teams for suspected infection or cord prolapse.

Admission criteria. Confirmed or probable rupture before 37 weeks, rupture with fever or infection, cord prolapse, abnormal foetal heart, meconium, bleeding, contractions, group B streptococcus positive, malpresentation, previous caesarean section, or difficulty returning to hospital. At term, women with rupture in good health may begin expectant management at home for 24 hours only with close instructions.

Discharge and follow up. After preterm prelabour rupture, women are managed as inpatients until 34 weeks (and sometimes beyond). Selected stable women with no infection may be followed as outpatients after a week with twice daily temperature, no digital examination, and ready access. Plan follow up and birth planning at each visit.

Safety netting. Return at once for fever, chills, offensive or green discharge, abdominal pain or tenderness, contractions, bleeding, reduced foetal movements, feeling unwell, or the cord felt at the vagina.