12-phase flow (12)

1. 1FRAME
   Preterm labor (PTL) at 20+0 to 36+6 wk gestation defined by regular contractions + cervical change. PPROM is the variant in which membrane rupture precedes / accompanies contractions. Partition by GA tier (periviable 20-23+6 / extreme preterm 24-27+6 / very preterm 28-31+6 / moderate preterm 32-33+6 / late preterm 34-36+6) and membrane status (intact PTL vs PPROM). Distinguishes from term labor (≥ 37 wk; routine), term PROM (≥ 37 wk; ob.prom.v1 if authored, otherwise term PROM management inline), placental abruption (painful bleed + tachysystole; different mechanism), pre-eclampsia indicated preterm birth (BP-driven decision, routes to ob.pre-eclampsia.core.v1 / ob.preeclampsia-early-onset.v1), and Braxton-Hicks (irregular non-progressive contractions without cervical change).
   inputs: gestational_age_weeks, membrane_status_intact_vs_ruptured
   advance: GA tier + membrane status tagged; PTL vs PPROM classification assigned
2. 2ENTRY
   Recognise PTL via regular contractions ≥ 4 in 20 min OR ≥ 8 in 60 min with cervical change OR cervix ≥ 2 cm dilated at < 37 wk. Recognise PPROM via patient-reported gush + speculum pooling + nitrazine + ferning OR AmniSure / ROM Plus assay positive at < 37 wk. Avoid digital cervical exam in PPROM until delivery anticipated (increases ascending-infection risk).
   inputs: gestational_age_weeks
   advance: PTL or PPROM diagnosed; speculum / TVUS confirmation documented
3. 3CONTEXT
   GA exact + ROM duration + prior preterm birth history + cervical length screening result + multifetal status + GBS status + IAP adequacy + maternal pen-allergy severity + comorbidities (DM, HTN, smoking, substance use) + prior cerclage. Critical decision context for tocolysis selection, corticosteroid timing, magnesium indication, and delivery-vs-expectant decision (PPROM ≥ 34 wk).
   inputs: gestational_age_weeks, membrane_status_intact_vs_ruptured, rom_duration_hours, prior_spontaneous_preterm_birth_count_and_GA, maternal_gbs_status_and_iap_adequacy, maternal_pen_allergy_severity, multifetal_gestation_status, maternal_hr, maternal_rr, maternal_spo2, fetal_heart_rate_baseline
   advance: Risk-factor profile + GA-tier-specific decision context captured
4. 4RED_FLAGS
   Maternal fever ≥ 39.0 °C OR 38.0-38.9 °C × 2 + secondary criteria → ob.chorioamnionitis.v1 with PTL/PPROM carryover. Maternal sepsis features (qSOFA ≥ 2 / SIRS ≥ 2 / lactate ≥ 2 / hypotension) → emergent delivery + id.sepsis.core.v1 with OB carryover. Painful vaginal bleeding + tachysystole → ob.placental-abruption.v1. Severe HTN ≥ 160/110 → ob.preeclampsia-early-onset.v1. Non-reassuring FHR Category III → emergent delivery. PROM with prolapsed cord → emergent cesarean.
   inputs: maternal_temperature, maternal_bp, maternal_hr, fetal_heart_rate_baseline
   actions: protocol.septic_shock
   advance: Red-flag routing decisions documented (chorio / sepsis / abruption / severe-PE / fetal Cat III / cord-prolapse)
5. 5INITIAL_WORKUP
   Maternal CBC + CMP (renal for magnesium dosing), urine culture + UA (asymptomatic bacteriuria / pyelonephritis), cervicovaginal GBS + chlamydia / gonorrhea swabs, fFN (intact membranes 22-34 wk if symptomatic), TVUS cervical length, obstetric US for growth + fluid + placenta location. Continuous EFM once admitted. Speculum confirmation if PPROM suspected. Document GA tier exactly (24+0 / 28+0 / 32+0 / 34+0 / 36+6 are decision-tier boundaries).
   inputs: maternal_cbc_with_diff, maternal_metabolic_panel, maternal_urine_culture_and_ua, cervicovaginal_swab_GBS_and_chlamydia_gonorrhea, transvaginal_cervical_length_ultrasound, obstetric_ultrasound_growth_and_fluid
   actions: workup.preeclampsia, panel.cbc, panel.renal, panel.ua
   advance: Diagnostic labs + imaging drawn; GA tier confirmed; risk-stratification ready
6. 6BRANCHING_WORKUP
   Branching by GA tier + membrane status + risk-stratification result. Periviable 20-23+6 wk: counseling on neonatal viability + maternal risks + termination consideration. 24-31+6 wk PTL or PPROM: full tocolysis + corticosteroid + magnesium + IAP. 32-33+6 wk: tocolysis + corticosteroid + IAP (NO magnesium ≥ 32 wk). 34-36+6 wk PPROM: deliver (induction or expectant per local protocol — ACOG PB 188 favors delivery). 34-36+6 wk PTL intact: late-preterm steroids per ALPS 2016 if no prior course + delivery anticipated within 7 d; tocolysis controversial here (limited efficacy). Amniocentesis selectively for suspected subclinical IAI (chorio without clinical fever).
   inputs: amniotic_fluid_studies_if_amniocentesis, maternal_blood_culture
   actions: workup.fuo
   advance: GA-tier-specific treatment plan documented; branching decisions complete
7. 7DIFFERENTIAL
   Braxton-Hicks (irregular, non-progressive, no cervical change), placental abruption (painful bleed + tachysystole + tender uterus → ob.placental-abruption.v1; tocolysis CONTRAINDICATED), chorioamnionitis (fever + Higgins 2016 → ob.chorioamnionitis.v1; tocolysis contraindicated in confirmed chorio), pre-eclampsia with indicated preterm birth (BP ≥ 140/90 + proteinuria → ob.preeclampsia-early-onset.v1 if < 34 wk), urinary tract infection (asymptomatic bacteriuria / pyelonephritis can present with contractions — treat per UA / culture), gastroenteritis with cramping (vital signs + GI features), round ligament pain (unilateral, sharp, related to movement; benign), term PROM (≥ 37 wk; routine).
   advance: Mimics excluded or co-managed; tocolysis contraindications ruled out
8. 8RISK_STRATIFICATION
   GA tier + cervical length + fFN + symptom severity + prior preterm birth history drive imminence: very-high-risk (CL < 15 mm + fFN-positive + symptomatic) → expedited admission + full intervention; moderate-risk (CL 15-25 mm + fFN-positive OR negative + symptomatic) → admit + intervene; low-risk (CL ≥ 25 mm + fFN-negative + symptomatic) → discharge with return precautions (LR- ~ 0.1 for delivery within 7-14 d). PPROM at any GA always full admission + intervention.
   inputs: gestational_age_weeks, fetal_fibronectin_fFN, transvaginal_cervical_length_ultrasound
   actions: calc.qsofa, calc.sirs
   advance: Imminence tier set; admit-vs-discharge decision documented
9. 9TREATMENT
   TOCOLYSIS (24+0 - 33+6 wk PTL with intact membranes; NOT for chorio / abruption / non-reassuring fetal status): nifedipine 20-30 mg PO load → 10-20 mg q4-6h (max 180 mg/day) is first-line (calcium-channel blocker; reduces preterm birth + improves neonatal outcome; preferred over indomethacin and terbutaline). Indomethacin 50-100 mg PO load → 25-50 mg q6h × 48 h is alternative ONLY at < 32 wk (oligohydramnios + ductal closure risk after 32 wk). Atosiban (EU only; oxytocin receptor antagonist). Terbutaline 0.25 mg SC q20 min × 3 doses for ACUTE short-term tocolysis only (FDA black box restricts chronic use; cardiac death risk). MAGNESIUM NEUROPROTECTION (< 32 wk PTL or PPROM): 4-6 g IV load over 20-30 min + 1 g/h × 12-24 h (BEAM NEJM 2008 PMID 18753646; Doyle Cochrane 2009 PMID 19160238). CORTICOSTEROIDS (24+0 - 33+6 wk: betamethasone 12 mg IM q24h × 2 doses OR dexamethasone 6 mg IM q12h × 4 doses; 34+0 - 36+6 wk late preterm if delivery anticipated < 7 d + no prior course: betamethasone same regimen per ALPS NEJM 2016 PMID 26842679). PPROM LATENCY ANTIBIOTICS (< 34 wk): ampicillin 2 g IV q6h × 48 h then amoxicillin 250 mg PO q8h × 5 d + erythromycin 250 mg IV q6h × 48 h then 333 mg PO q8h × 5 d (NICHD-MFMU PPROM trial Mercer JAMA 1997 PMID 9307346); AVOID amoxicillin-clavulanate (NEC risk per ORACLE-II Kenyon 2008). GBS IAP intrapartum: penicillin G 5 mU IV load → 2.5-3 mU q4h until delivery (or ampicillin 2 g + 1 g q4h; cefazolin 2 g + 1 g q8h mild pen-allergy; vancomycin / clindamycin per GBS susceptibility for severe pen-allergy — CDC Verani 2010 PMID 21088663 + ACOG CO 797 2020). VAGINAL PROGESTERONE for asymptomatic short cervix < 20 mm at 16-24 wk: 200 mg PV nightly through 36+6 wk. CERCLAGE for history-indicated (≥ 3 prior 2nd-tri losses or preterm births) or US-indicated (prior preterm birth + current CL < 25 mm) or exam-indicated (dilation in 2nd tri without contractions; cerclage may help) per Berghella Cochrane 2017.
   inputs: gestational_age_weeks, membrane_status_intact_vs_ruptured, maternal_gbs_status_and_iap_adequacy, maternal_pen_allergy_severity
   advance: Tocolysis (if indicated), corticosteroids, magnesium (if < 32 wk), latency antibiotics (if PPROM), and IAP plan documented and started
10. 10DISPOSITION
    L&D / antepartum unit for active PTL or PPROM (most admissions). Periviable counseling consultation if 20-23+6 wk. ICU only if maternal sepsis / pulmonary edema / multi-organ dysfunction. Transfer to tertiary center if < 32 wk and current facility lacks NICU. Outpatient cervical-length surveillance + vaginal progesterone for asymptomatic short cervix at < 24 wk. Discharge symptomatic intact-membrane PTL with negative fFN + CL ≥ 25 mm + arrested progression after 4-6 h observation with return precautions and close follow-up.
    inputs: gestational_age_weeks, maternal_bp, maternal_spo2
    advance: Maternal level of care set; NICU coordination if delivery imminent; tertiary-transfer decision if indicated
11. 11MONITORING
    Continuous EFM intrapartum (Category I/II/III); maternal vitals q15 min during active labor or magnesium loading; q1 h post-load; q4 h stable. Magnesium toxicity surveillance: hourly DTRs + RR + UO (toxicity if RR < 12 / DTR loss / UO < 0.5 mL/kg/h; calcium gluconate 1 g IV antidote). Daily CBC + CMP if expectantly managing PPROM. Maternal temperature q4 h (chorio surveillance). PPROM amniotic fluid volume serial US weekly. Cervical length serial if expectant PTL. Continuous EFM during corticosteroid administration + magnesium load (transient fetal-heart-rate variability reduction expected).
    inputs: maternal_temperature, maternal_hr, maternal_rr, fetal_heart_rate_baseline, fetal_doppler_and_efm_continuous_intrapartum
    actions: panel.cbc, panel.renal
    advance: Maternal-fetal status stable + no chorio emergence + tocolysis effective (48 h achieved) OR delivered with appropriate neonatal coordination
12. 12FOLLOWUP
    6-week postpartum visit + preterm-birth-specific anticipatory guidance: recurrence ~ 15-30% in subsequent pregnancy; preconception MFM consult for next pregnancy planning (early CL surveillance, vaginal progesterone planning, cerclage indication review per Berghella Cochrane 2017). Mental health screen (EPDS for postpartum depression; PCL-5 for peripartum PTSD especially after extreme preterm or NICU outcomes). Contraception counseling + interpregnancy interval ≥ 18 mo. Immunization audit (Tdap, flu, COVID per ACIP). Newborn outpatient peds visit 24-48 h post-discharge if late preterm; first-year developmental tracking if very preterm or extreme preterm (cerebral palsy + BPD + IVH risk monitoring per AAP NRN framework).
    advance: Postpartum visit complete; preconception MFM counseling delivered; mental health + immunization + newborn developmental tracking arranged