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ob.placenta-previa.v1

Placenta Previa & Placenta Accreta Spectrum

obstetricsacuteadultpregnancyacuteinpatientoutpatient
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NEW Phase C dossier — authored 2026-05-15 for shard-5-obped-id. Covers placenta previa & placenta accreta spectrum (PAS) — antepartum hemorrhage syndromes of abnormal placentation. Placenta previa at term ~ 0.4-0.5% (~ 1 in 200); low-lying placenta at 18-20 wk ~ 1-6% with ~ 90% migration by term; PAS ~ 1 in 272-500 deliveries (rising with the cesarean rate; ~ 75-80% accreta / ~ 15% increta / ~ 5% percreta). PAS pretest probability given previa rises steeply with prior CS count (Silver 2006 PMID 16738145): 0/1 CS ~ 3%, 2 ~ 11%, 3 ~ 40%, 4 ~ 61%, ≥ 5 ~ 67%. Maternal mortality with PAS ~ 1-7% (near-zero at expert accreta centers with planned delivery). PROMOTED PLANNED -> INTEGRATED (2026-05-25 verify-wave-2). A dedicated seed manifest was authored at prisma/seed/manifests/ob.placenta-previa.v1.ts via defineBatch23ScaffoldManifest (engineId "ob.placenta-previa.v1", specialtyPack "obstetrics_gynecology", sourceWorkupIds ["placenta_previa"], evidenceIds ["ev_placenta_previa_guideline_review_required"], terminology projected 1:1 from the dossier block — no new codes), mirroring the verified ob.amniotic-fluid-embolism.v1 exemplar. INTEGRATED criteria met: non-blank manifest pointing to an on-disk file + registry-resolvable workups (workup.pph adapter_id "pph" w/ "accreta" search_keyword + workup.preeclampsia adapter_id "preeclampsia", both in src/lib/systems/clinical-tools-registry.ts). Prior blank-manifest + PLANNED rationale (deferral to a future shard; rejected reuse of the non-existent ob.postpartum-hemorrhage.core.v1 manifest or the semantically-mismatched ob.pre-eclampsia.core.v1 manifest) is superseded. _registry.ts NOT modified per refined shard-5 pattern (3-file set only: dossier TS + brief + research bundle). Registry edit deferred to a future shard. Distinct from ob.placental-abruption.v1 (sibling — PAINFUL bleed + uterine tenderness/hypertonus; previa is the classically PAINLESS mirror-image; named painless-vs-painful pivot), ob.postpartum-hemorrhage.core.v1 (sibling — previa/PAS is a top antepartum PPH risk factor; cesarean-hysterectomy + MTP + TXA framework shared), ob.pprom.v1 (sibling — PPROM can complicate a previa pregnancy; vasa previa overlaps the abnormal-placentation differential), ob.pre-eclampsia.core.v1 (sibling — independent delivery-timing co-driver; methylergonovine CI in HTN). Sibling differentiation explicitly encoded for all four. id.sepsis.core.v1 routing for conservative-PAS endometritis/sepsis. Phenotype matrix (previa-type × PAS-depth × clinical-state × prior-CS-count × GA × maternal-stable × fetal-status cross-product — collapsed to 10 anchor combinations) encoded indirectly via regimen_axes.placenta_previa_pas_management.steps (hemorrhage_resuscitation / expectant_vs_delivery / pas_surgical_planning / tocolysis_consideration / rh_negative_rhogam) + severity_triggers (10 phenotype-specific triggers) + setting playbooks (ed / inpatient / icu / outpatient). First-class TS phenotype field is schema-blocked. Severity triggers (10): previa_pas_with_massive_hemorrhage_maternal_instability (life_threatening — emergent cesarean ± hysterectomy + MTP + TXA + ICU; no digital exam; do NOT delay for imaging), previa_pas_with_fetal_distress (life_threatening — emergent cesarean if viable GA + alive fetus), placenta_percreta_with_bladder_or_parametrial_invasion (life_threatening — accreta center; multidisciplinary; placenta in situ + hysterectomy; consider staged surgery), suspected_PAS_high_risk_prior_cs_anterior_previa (severe — accreta-center referral; targeted US ± MRI; planned CS-hysterectomy 34-35+6 wk; ureteral stents; IR balloon; Silver 2006 prior-CS gradient), complete_previa_recurrent_or_heavy_antepartum_bleed (severe — inpatient; type & crossmatch; betamethasone; deliver if recurrent/heavy), sentinel_bleed_stable_preterm_previa (severe — inpatient observation; betamethasone; limited tocolysis only for steroid window), low_lying_placenta_second_trimester_surveillance (mild — repeat TVUS 32 wk; ~ 90% migrate), scheduled_late_preterm_delivery_previa_vs_pas (severe — previa 36-37+6 wk vs PAS 34-35+6 wk at accreta center), rh_negative_with_previa_pas_bleed (severe — Kleihauer-Betke + RhoGAM 300 mcg dose-adjusted), conservative_placenta_in_situ_PAS_surveillance (severe — delayed-hemorrhage/infection/interval-hysterectomy surveillance; non-routine). Bayesian linkage (per §5.5.2): pre-test priors documented in _research-bundles/ob.placenta-previa.v1.md — previa at term ~ 0.4-0.5%; low-lying at 18-20 wk ~ 1-6% with ~ 90% migration; PAS ~ 1 in 272-500; PAS pretest given previa by prior-CS count (Silver 2006 PMID 16738145): 0/1 ~ 3%, 2 ~ 11%, 3 ~ 40%, 4 ~ 61%, ≥ 5 ~ 67%; PAS without previa ≤ 1%. Key LRs: multiple placental lacunae LR+ ~ 7-12; bridging vessels / uterovesical hypervascularity LR+ ~ 8-10; loss of clear retroplacental zone LR+ ~ 4-7; myometrial thinning < 1 mm LR+ ~ 3-5; bladder-wall interruption LR+ very high for percreta; painless bright-red bleed = named previa-vs-abruption pivot. Conditional dependencies modeled: prior-CS-count × previa × PAS-risk (dominant; Silver 2006 gradient), anterior-placenta-over-scar × PAS, GA × scheduled-delivery-timing, bleeding-severity × tocolysis-eligibility. Decision thresholds: T_deliver-emergent (maternal-fetal compromise / uncontrollable hemorrhage → emergent cesarean ± hysterectomy regardless of GA), T_deliver-scheduled-previa (36+0-37+6 wk complete previa), T_deliver-scheduled-PAS (34+0-35+6 wk accreta center), T_massive-transfusion (EBL > 1500 mL OR DIC), T_PAS-workup (prior CS + previa → targeted US ± MRI), T_tocolysis (self-limited stable bleed + steroid window only), T_no-digital-exam, T_kleihauer-betke/RhoGAM. Cross-dossier routing: ob.postpartum-hemorrhage.core.v1 (catastrophic intrapartum/postpartum hemorrhage), ob.placental-abruption.v1 (painless-vs-painful pivot, bidirectional), ob.pre-eclampsia.core.v1 (delivery-timing carryover), ob.pprom.v1 (PPROM in a previa pregnancy), id.sepsis.core.v1 (conservative-PAS endometritis/sepsis with OB carryover). ROS/DDx LR seed data NOT touched (cross-cutting; not in shard scope). Settings (4): ED (painless antepartum bleed ≥ 20 wk → IV access + STAT type/screen/crossmatch + STAT CBC + STAT coag + TVUS for placental localisation + NO digital exam + immediate L&D transfer with continuous fetal monitoring; expedited accreta-center transfer if PAS markers + prior CS + anterior previa; do NOT delay for imaging if unstable), Inpatient L&D/accreta center (primary venue; expectant + serial TVUS + pelvic rest + betamethasone for stable preterm previa; scheduled cesarean 36-37+6 wk for complete previa; accreta-center cesarean hysterectomy 34-35+6 wk with placenta in situ + ureteral stents + IR balloon for PAS; postpartum-hemorrhage continued surveillance), ICU (massive hemorrhage / DIC / massive transfusion / refractory shock; emergent delivery as source control + MTP 1:1:1 + TXA + vasoactive; routes to id.sepsis.core.v1 if conservative-PAS sepsis overlap), Outpatient (asymptomatic-previa antepartum surveillance for never-bled patients + 6-wk postpartum visit + previa/PAS anticipatory guidance — recurrence ~ 4-8%; PAS history → accreta-center planning + interpregnancy-interval counseling + iron repletion + mental-health screen + immunization + newborn high-risk peds 24-48 h post-discharge). Drug guidance grounded in ACOG/SMFM OCC 7 2018/2024 + RCOG GTG 27a/27b 2018/2024 + FIGO 2024 + Pacheco LD AJOG 2016 + WOMAN 2017 + ACOG PB 181 2017 + ACOG CO 713 2017 / ALPS NEJM 2016 + ACOG PB 222 2020. RxCUIs (RxNav-verified live 2026-05-25; the originally-carried set was corrupted and corrected this pass): betamethasone (1514 ✓), magnesium sulfate (6585 — was wrong 6845=methocarbamol), oxytocin (7824 — was wrong 11149=vasopressin), tranexamic acid (10691 — was wrong 10689=tramadol), rho(d) immune globulin (35465 — was invalid 38879), norepinephrine (7512 — was wrong 7980=penicillin G), hydrocortisone (5492 ✓), nifedipine (7417 ✓ — limited tocolysis), acetaminophen (161 ✓), ferrous sulfate (24947 — was wrong 4053=erythromycin), influenza/COVID/Tdap vaccines (no single generic RxCUI; invalid 1656584 removed — NEEDS_SOURCE_REVIEW). Open gaps: (1) Phenotype matrix not first-class TS field — schema-blocked. (2) Bayesian LR seed data (prior-CS PAS gradient, lacunae/clear-zone/bridging-vessel LRs) not encoded in dossier (narrative + research bundle only); ROS/DDx seed edit cross-cutting. (3) RESOLVED — dedicated seed manifest authored at prisma/seed/manifests/ob.placenta-previa.v1.ts (2026-05-25); cross-engine reuse no longer needed. (4) RESOLVED — manifest file authored this pass (defineBatch23ScaffoldManifest scaffold; full disease-specific atom authoring still a future depth-pass item). (5) Co-located test file (ob.placenta-previa.test.ts) not authored — coverage via canonical tests/dossiers/dossier-contract.test.ts only. (6) _registry.ts NOT modified per refined shard-5 pattern. (7) ACOG/SMFM/RCOG/FIGO guidelines do not carry stable PubMed PMIDs — cited by year + document number; closest indexed PMIDs are the underlying landmark studies (Silver 2006 PMID 16738145; Oyelese Ananth 2006 PMID 17012465; Pacheco LD AJOG 2016 PMID 26348379; WOMAN 2017 PMID 28456509). (8) Vasa previa noted in the differential (RCOG GTG 27b) but not authored as a dedicated engine. Status INTEGRATED with manifest: "prisma/seed/manifests/ob.placenta-previa.v1.ts" (on disk) — the manifest pointer resolves (broken_pointers clean) and the dossier carries registry-resolvable workups, so declared == actual INTEGRATED. (Was PLANNED + manifest:"" until the 2026-05-25 verify-wave-2 manifest authoring + safety remediation.)

Entry points (8)

  • symptom
    Painless bright-red vaginal bleeding in pregnancy ≥ 20 wk — gateway feature of placenta previa; distinguishes from the painful, tender, hypertonic uterus of placental abruption (Oyelese Smulian 2006; cross-anchor Oyelese Ananth 2006 PMID 17012465)
    painless_bright_red_vaginal_bleeding_antepartum
  • symptom
    Self-limited painless herald (sentinel) bleed in a pregnancy ≥ 20 wk — frequently precedes a larger hemorrhage (RCOG GTG 27a 2018/2024)
    sentinel_herald_bleed_antepartum
  • imaging
    Placenta overlying or within 2 cm of the internal cervical os on TVUS at ≥ 20 wk (complete previa) OR placental edge < 2 cm from os not covering (low-lying placenta) (RCOG GTG 27a 2018/2024)
    sonographic_previa_low_lying_placenta
  • imaging
    Sonographic PAS markers — multiple placental lacunae, loss of the clear retroplacental hypoechoic zone, myometrial thinning < 1 mm, bridging vessels, bladder-wall interruption, uterovesical hypervascularity on color Doppler (FIGO 2024; ACOG/SMFM OCC 7 2018/2024)
    sonographic_pas_markers_lacunae_loss_of_clear_zone
  • history
    Prior cesarean delivery (especially multiple) with current anterior placenta previa overlying the hysterotomy scar — the dominant PAS risk combination (Silver 2006 PMID 16738145)
    prior_cesarean_with_anterior_previa
  • imaging
    Persistent fetal malpresentation (transverse/breech) with a low or previa placenta on US — previa obstructs engagement (RCOG GTG 27a 2018/2024)
    fetal_malpresentation_with_low_placenta
  • vital_abnormality
    Maternal tachycardia / hypotension / orthostatic features OR rapidly falling hemoglobin with an antepartum bleed ≥ 20 wk — hemorrhagic-shock flag (Pacheco LD AJOG 2016 PMID 26348379)
    hemodynamic_instability_with_pregnancy_bleed
  • imaging
    MRI showing placental invasion (dark intraplacental T2 bands, focal myometrial interruption, placental bulge, bladder tenting) — adjunct when US equivocal or to map parametrial/posterior extension (FIGO 2024)
    mri_placental_invasion

Required inputs (21)

  • maternal_bprequired
    vital • used at RED_FLAGS
    Hypotension is a hemorrhagic-shock flag; MAP < 65 demands rapid resuscitation + potential emergent delivery; previa/PAS hemorrhage can be catastrophic and abrupt
  • maternal_hrrequired
    vital • used at RED_FLAGS
    Maternal tachycardia > 110 disproportionate to visible bleed is an early shock clue; obstetric hypovolemia presents with tachycardia before hypotension
  • maternal_rrrequired
    vital • used at CONTEXT
    Tachypnea > 24 is a shock-index / qSOFA component; pregnant baseline ~ 16-22
  • maternal_spo2required
    vital • used at CONTEXT
    Hypoxemia raises suspicion for amniotic fluid embolism (mimics sudden collapse + DIC at delivery) or pulmonary edema with overlap
  • fetal_heart_rate_baselinerequired
    vital • used at CONTEXT
    Category I/II/III FHR interpretation drives delivery urgency — Category III with viable GA demands emergent cesarean
  • gestational_age_weeksrequired
    demographic • used at FRAME
    Extreme preterm < 28 / preterm 28-33 / late preterm 34-36 / term ≥ 37 wk drives scheduled-delivery timing (previa 36-37+6 wk vs PAS 34-35+6 wk) + steroid + NICU planning
  • prior_cesarean_countrequired
    history • used at CONTEXT
    Prior cesarean count with co-existing previa is the dominant PAS pretest-probability axis (Silver 2006 PMID 16738145): with previa 1 CS ~ 3%, 2 ~ 11%, 3 ~ 40%, 4 ~ 61%, ≥ 5 ~ 67% accreta
  • pregnancy_bleeding_volume_and_characterrequired
    history • used at CONTEXT
    Quantify visible vaginal blood loss + character (painless bright-red is classic previa); sentinel bleeds frequently precede a larger hemorrhage
  • placenta_location_and_pas_marker_historyrequired
    history • used at CONTEXT
    Known previa / low-lying placenta + any prior US/MRI PAS markers (lacunae, loss of clear zone, bridging vessels) anchor the workup and accreta-center referral decision
  • prior_uterine_surgery_or_pas_history
    history • used at CONTEXT
    Prior myomectomy, D&C, endometrial ablation, prior PAS — additional PAS risk factors beyond cesarean count; informs pretest probability
  • maternal_rh_statusrequired
    history • used at TREATMENT
    Rh-negative mother with antepartum bleed requires RhoGAM ± dose-adjustment per Kleihauer-Betke quantification (ACOG PB 181 2017)
  • hypertension_or_preeclampsia_status
    history • used at CONTEXT
    Pre-eclampsia is an independent delivery-timing co-driver; methylergonovine is contraindicated in HTN if uterotonics are needed at cesarean (ACOG PB 222 2020)
  • in_vitro_fertilization_or_multiparity
    history • used at CONTEXT
    IVF/ART, advanced maternal age, multiparity, smoking are previa risk factors; inform pretest probability + counseling
  • maternal_cbc_with_diffrequired
    lab • used at INITIAL_WORKUP
    Baseline hemoglobin + serial trend (falling Hgb with active bleed); platelet count for DIC surveillance during massive hemorrhage
  • maternal_type_and_crossmatchrequired
    lab • used at INITIAL_WORKUP
    Type & screen on arrival; crossmatch ≥ 2-4 units PRBC if active bleeding, known PAS, or unstable; massive transfusion protocol activation if EBL > 1500 mL (Pacheco LD AJOG 2016 PMID 26348379)
  • maternal_coagulation_panel_pt_inr_aptt_fibrinogenrequired
    lab • used at INITIAL_WORKUP
    DIC surveillance — fibrinogen < 200 mg/dL in pregnancy is critical (pregnancy baseline 350-650); PT/INR + aPTT prolonged → cryoprecipitate + FFP
  • maternal_metabolic_panelrequired
    lab • used at INITIAL_WORKUP
    Renal function (baseline for surgical planning + sepsis-AKI cross-reference) + liver function (HELLP overlap if pre-eclampsia)
  • maternal_kleihauer_betke_test
    lab • used at INITIAL_WORKUP
    Quantifies fetomaternal hemorrhage; required for Rh-negative mother RhoGAM dose-adjustment (300 mcg per 30 mL fetal whole blood; ACOG PB 181 2017)
  • maternal_lactate
    lab • used at INITIAL_WORKUP
    Lactate > 2 with shock features is a hemorrhagic-shock marker; drives massive transfusion + emergent delivery decision
  • transvaginal_ultrasound_placental_localisationrequired
    imaging • used at INITIAL_WORKUP
    TVUS is the safe gold standard for localising the placental edge relative to the internal os; serial at 32 wk (persistence) + 36 wk (delivery planning); ~ 90% of low-lying placentas migrate by term (RCOG GTG 27a 2018/2024)
  • targeted_pas_ultrasound_and_mri
    imaging • used at BRANCHING_WORKUP
    Targeted obstetric US for PAS markers (lacunae, loss of clear zone, myometrial thinning, bridging vessels, bladder-wall interruption); MRI adjunct if equivocal or to assess parametrial/posterior extension (FIGO 2024; ACOG/SMFM OCC 7 2018/2024)

12-phase flow (12)

  1. 1FRAME
    Acute obstetric emergency — abnormal placentation antepartum hemorrhage syndromes. Partition by previa type (low-lying < 2 cm not covering vs complete previa covering the internal os) × PAS depth (none / accreta / increta / percreta ± bladder/parametrial invasion) × clinical state (asymptomatic / sentinel bleed / massive hemorrhage) × prior-CS count (the dominant PAS pretest gradient) × gestational age. Distinguishes from placental abruption (PAINFUL bleed + uterine tenderness/hypertonus), vasa previa (fetal-vessel bleed at ROM), uterine rupture, and lower-genital-tract bleeding.
    inputs: gestational_age_weeks
    advance: Previa type + PAS-depth suspicion + clinical state + prior-CS count + GA cohort tagged
  2. 2ENTRY
    Recognise via painless bright-red antepartum vaginal bleeding ≥ 20 wk (distinguishes from painful abruption), sentinel/herald bleed, sonographic previa/low-lying placenta, sonographic PAS markers in a prior-CS + anterior-previa patient, fetal malpresentation, or hemodynamic instability. Differential includes placental abruption, vasa previa, uterine rupture, bloody show with labor, lower-genital-tract bleeding.
    inputs: pregnancy_bleeding_volume_and_character, placenta_location_and_pas_marker_history
    advance: Pre-test clinical probability for previa ± PAS documented (incl. prior-CS gradient)
  3. 3CONTEXT
    Gestational age, prior cesarean count + prior uterine surgery (PAS gradient), placenta location + prior PAS-marker history, Rh status, hypertension/pre-eclampsia status (delivery-timing co-driver), IVF/ART + multiparity + advanced maternal age + smoking (previa risk factors), maternal vitals + fetal heart rate baseline.
    inputs: gestational_age_weeks, prior_cesarean_count, placenta_location_and_pas_marker_history, maternal_rh_status, maternal_hr, maternal_rr, maternal_spo2, fetal_heart_rate_baseline
    advance: Risk-factor profile + PAS pretest probability + GA cohort + maternal-fetal stability tier captured
  4. 4RED_FLAGS
    Massive antepartum/intrapartum hemorrhage with maternal hemorrhagic shock (SBP < 90, MAP < 65, HR > 120, lactate > 2, rapid Hgb decline) + fetal distress (Category III FHR) + DIC features (oozing IV sites, fibrinogen < 200, platelets < 100, prolonged PT/aPTT) trigger emergent delivery (± hysterectomy) + massive transfusion + ICU. NO digital cervical exam if previa suspected (risk of provoking catastrophic hemorrhage). PAS surgery should not be attempted outside an accreta center if avoidable, but maternal-fetal instability mandates emergent delivery regardless of GA.
    inputs: maternal_bp, maternal_hr, fetal_heart_rate_baseline
    actions: protocol.septic_shock
    advance: Maternal-fetal stability tier set; emergent-vs-scheduled decision pending workup
  5. 5INITIAL_WORKUP
    Maternal CBC (Hgb + platelets), type & screen / crossmatch ≥ 2-4 units PRBC (more if known PAS), coag panel (PT/INR, aPTT, fibrinogen), CMP, lactate, Kleihauer-Betke if Rh-negative or to quantify FMH. Continuous fetal monitoring (Category I/II/III). TVUS for placental localisation relative to the internal os (rule in/out previa) + fetal viability + GA. NO digital cervical exam until previa excluded.
    inputs: maternal_cbc_with_diff, maternal_type_and_crossmatch, maternal_coagulation_panel_pt_inr_aptt_fibrinogen, maternal_metabolic_panel, transvaginal_ultrasound_placental_localisation
    actions: workup.pph, panel.cbc, panel.coag, panel.renal
    advance: Labs drawn; type & screen up; TVUS performed; fetal monitoring established
  6. 6BRANCHING_WORKUP
    Targeted PAS ultrasound (lacunae, loss of clear zone, myometrial thinning, bridging vessels, bladder-wall interruption, uterovesical hypervascularity) in any prior-CS + previa patient; MRI placenta if US equivocal or to assess parametrial/posterior/bladder extension; repeat coag at 1-2 h if active bleeding (DIC trajectory); blood culture if conservative-PAS endometritis/sepsis features; maternal echocardiogram if AFE-mimic features at delivery.
    inputs: targeted_pas_ultrasound_and_mri, maternal_lactate, maternal_kleihauer_betke_test
    actions: workup.preeclampsia
    advance: PAS-depth assessment + accreta-center referral decision + DIC trajectory completed
  7. 7DIFFERENTIAL
    Placental abruption (PAINFUL bleed + uterine tenderness/hypertonus; named painless-vs-painful pivot — routes to ob.placental-abruption.v1), vasa previa (fetal-vessel bleed at ROM; APT/Kleihauer for fetal Hgb; RCOG GTG 27b), uterine rupture (prior cesarean; loss of station; severe pain), bloody show with labor (small amount + mucus + cervical change), lower-genital-tract bleed (cervicitis, polyp, cervical CA), PAS subtype (accreta vs increta vs percreta ± bladder invasion).
    advance: Mimics excluded or co-managed; PAS subtype suspicion staged
  8. 8RISK_STRATIFICATION
    Previa type (low-lying vs complete) + PAS pretest probability (prior-CS gradient per Silver 2006 PMID 16738145 × sonographic markers) + maternal hemodynamic stability + fetal status (Category I/II/III) + GA + clinical state (asymptomatic / sentinel / massive). Drives: stable complete previa → scheduled CS 36-37+6 wk; suspected/confirmed PAS → accreta center + planned CS-hysterectomy 34-35+6 wk; instability or non-reassuring fetus + viable GA → emergent cesarean (± hysterectomy) regardless of GA; EBL > 1500 mL or DIC → massive transfusion.
    inputs: maternal_bp, maternal_hr, fetal_heart_rate_baseline, gestational_age_weeks, prior_cesarean_count
    actions: calc.qsofa, calc.sirs, calc.map
    advance: Previa type + PAS suspicion grade + delivery-urgency tier + scheduled-vs-emergent decision documented
  9. 9TREATMENT
    EXPECTANT (stable previa, no PAS): pelvic rest + serial TVUS (32/36 wk) + betamethasone 12 mg IM × 2 doses 24 h apart if delivery anticipated 24-34 wk + inpatient if has bled + scheduled cesarean 36+0-37+6 wk for complete previa. PAS PLANNING (suspected/confirmed): refer accreta center of excellence + multidisciplinary team (MFM, pelvic surgeon/gyn-onc, urology, IR, anesthesia, blood bank, NICU) + scheduled cesarean hysterectomy 34+0-35+6 wk + placenta left in situ (do NOT attempt removal) + preoperative ureteral stents + IR balloon occlusion where available + cell salvage. MASSIVE HEMORRHAGE (EBL > 1500 mL or DIC): emergent cesarean (± hysterectomy) regardless of GA + MTP 1:1:1 PRBC:FFP:platelets + cryoprecipitate if fibrinogen < 200 + tranexamic acid 1 g IV within 3 h of birth (WOMAN PMID 28456509) + norepinephrine for refractory hypotension + ICU. LIMITED TOCOLYSIS only for a 48 h steroid window in a stable self-limited bleed without fetal compromise; contraindicated with significant/ongoing hemorrhage. RhoGAM if Rh-negative (ACOG PB 181 2017).
    inputs: gestational_age_weeks, prior_cesarean_count, maternal_rh_status
    advance: Expectant-vs-PAS-planning-vs-emergent decision executed; betamethasone if preterm window; accreta-center referral if PAS; RhoGAM dosed if Rh-negative
  10. 10DISPOSITION
    Outpatient with pelvic rest + serial TVUS for stable asymptomatic previa with no/low PAS risk; inpatient L&D/OB for sentinel/recurrent bleed expectant management; ACCRETA CENTER OF EXCELLENCE transfer for suspected/confirmed PAS (scheduled CS-hysterectomy); OR for emergent cesarean; ICU for massive transfusion / DIC / shock. Postpartum-hemorrhage continued surveillance (previa/PAS is a top antepartum PPH risk factor → routes to ob.postpartum-hemorrhage.core.v1); neonatology/NICU coordination for preterm or compromised neonate.
    inputs: maternal_bp, maternal_spo2
    advance: Maternal level of care set; accreta-center referral placed if PAS; newborn pathway initiated; postpartum-hemorrhage surveillance activated
  11. 11MONITORING
    Antepartum expectant: serial TVUS (32/36 wk), pelvic rest adherence, bleeding-episode log, Hgb trend, fetal growth/wellbeing; inpatient maternal vitals + intermittent EFM if has bled. Perioperative/intrapartum: continuous EFM, maternal vitals q15 min, serial Hgb + coag q1-2 h while active, fluid balance, urine output ≥ 0.5 mL/kg/h, ureteral-stent patency post-PAS surgery. Postpartum: vitals q15 min × 2 h then q1 h × 4 h then q4 h × 24 h, fundal tone + lochia (atony surveillance — previa/PAS is a top PPH risk), repeat CBC + coag q4-6 h until stable; ICU continuous arterial line + central venous catheter + lactate q2-4 h until normalised + daily SOFA if critical.
    inputs: maternal_bp, maternal_hr, maternal_cbc_with_diff, maternal_coagulation_panel_pt_inr_aptt_fibrinogen
    actions: panel.cbc, panel.coag
    advance: Maternal stable + Hgb stable × 6 h + appropriate lochia + responsive newborn evaluation
  12. 12FOLLOWUP
    6-wk postpartum visit + previa/PAS-specific anticipatory guidance: previa recurrence ~ 4-8% in a subsequent pregnancy; PAS history → high recurrence risk + accreta-center planning for any future pregnancy; iron repletion for postpartum/hemorrhage anemia; contraception counseling + ≥ 18 mo interpregnancy interval discussion (cesarean-scar PAS risk rises with each repeat CS); mental-health screen (EPDS for PPD; PCL-5 for peripartum PTSD given peripartum hysterectomy / massive hemorrhage); pelvic-floor and surgical-recovery follow-up; immunization audit (Tdap, influenza, COVID per ACIP); newborn outpatient 24-48 h post-discharge peds visit + developmental tracking for the first year if preterm. Counsel that hysterectomy ends fertility where performed; fertility-sparing conservative PAS management carries delayed-hemorrhage/infection surveillance.
    advance: Postpartum visit complete; future-pregnancy / accreta-center counseling delivered; iron + mental-health + contraception addressed; newborn followup arranged