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OB/GYN · Clinical algorithm

Pregnant Vaginal Bleeding

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General Approach

Patients with early pregnancy plus vaginal bleeding and/or pelvic or abdominal pain enter this pathway. The first question is not the exact diagnosis—it is whether the patient is stable.

  • Unstable → resuscitate and identify the source of instability in parallel.
  • Think about where the blood may be going:
    • Internal hemorrhage → ruptured ectopic pregnancy.
    • External uterine hemorrhage → significant pregnancy loss.
    • Sepsis → septic abortion.
  • Once immediate instability has been addressed, determine where the pregnancy is located with transvaginal ultrasound:
    • Ectopic pregnancy.
    • Pregnancy of unknown location.
    • Intrauterine pregnancy.
  • IUP Status
    • Once an IUP is identified, determine pregnancy status.
    • IUP + cardiac activity + vaginal bleeding ± cramping → threatened miscarriage.
    • If cardiac activity is absent or US findings are abnormal → determine whether:
      • Too early / not diagnostic
      • Concerning for EPL
      • Diagnostic of EPL
      • EPL in progress → GS in lower uterine segment / cervix, being expelled
      • Incomplete EPL → residual intracavitary tissue ± persistent GS
      • Completed EPL → no residual GS / tissue after known EPL
    • Do not prematurely diagnose pregnancy loss from an early indeterminate US
  • Finally, consider RhD/RhIg, disposition, and other causes of bleeding.

01Unstable / Major Hemorrhage?

Resuscitate

  • Resuscitation and diagnosis occur together.
  • ABCs / cardiac monitor / IV access.
  • IV fluids while assessing the degree of blood loss.
  • Blood products early if significant hemorrhage or shock.
  • CBC and type and cross.
  • Bedside FAST/POCUS looking for intraperitoneal free fluid.
  • Urgent OB/GYN consultation whenever there is instability, major hemorrhage, suspected rupture, or septic abortion.

Critical Cause?

Ruptured Ectopic
  • Bleeding internally.
  • Abdominal / pelvic pain ± peritoneal signs.
  • Hypotension / shock / syncope.
  • FAST → free intraperitoneal fluid ± adnexal mass.
  • Type & cross → transfuse as needed.
  • Emergent GYN → OR.
  • Do not delay operative management for formal ultrasound if crashing.

ACOG: tubal ectopic pregnancy with hemodynamic instability is a medical emergency requiring prompt surgical intervention. ACOG

Uterine Hemorrhage
  • Bleeding externally.
  • Heavy vaginal bleeding / ongoing blood loss.
  • IV fluids / blood as needed.
  • Urgent GYN.
  • Ongoing hemorrhage / instability → uterine evacuation (D&C).
Septic Abortion
  • Fever / chills.
  • Uterine or pelvic tenderness.
  • Foul / purulent discharge.
  • Bleeding ± retained products.
  • Sepsis / shock.
  • Broad-spectrum IV antibiotics.
  • Urgent GYN → uterine evacuation / source control.

02Where Is The Pregnancy?

Diagnosis: Pelvic / Transvaginal Ultrasound

  • Pelvic US regardless of β-hCG level.
  • Do not wait for the discriminatory zone before imaging.
  • β-hCG helps interpret the pregnancy; does not determine whether US is obtained.
  • Ectopic pregnancy can occur at any β-hCG level.
  • Goal is finding the pregnancy location. Options:
    • 1. Ectopic.
    • 2. Pregnancy of unknown location.
    • 3. IUP.

ACEP Level B: “Perform or obtain a pelvic ultrasound for symptomatic pregnant patients with any β-hCG level.” ACEP

Ectopic Pregnancy

Diagnosis: TVUS
  • Definite ectopic
    • Pregnancy implanted in an abnormal location.
    • Yolk sac or embryo within the ectopic gestational sac.
  • Probable ectopic
    • Extraovarian / adnexal mass.
    • Tubal / adnexal ring.
    • No yolk sac or embryo seen.
  • Other concerning findings:
    • Complex adnexal mass.
    • Free pelvic / intraperitoneal fluid.
    • Hemoperitoneum.
    • Free fluid or adnexal mass alone → concerning, not definitive. SRU 2024
Treatment Options

Management → expectant vs methotrexate vs surgery, depending on clinical stability, symptoms, ectopic features, β-hCG trend, contraindications, and ability to follow up. ACOG: Tubal Ectopic Pregnancy ACOG: Ectopic Pregnancy

Expectant Management
  • Selected stable, minimally symptomatic patients.
  • No evidence of rupture / significant hemorrhage.
  • β-hCG low and spontaneously declining.
  • Reliable close follow-up required.
  • Serial β-hCG until resolution.
  • Worsening symptoms or failure to resolve → reassess treatment.
Methotrexate
  • Selected stable, unruptured ectopic pregnancy.
  • No significant symptoms suggesting rupture.
  • No contraindication to methotrexate.
  • Reliable follow-up required.
  • Serial β-hCG until resolution.
  • Inadequate response → additional treatment or surgery.
Surgery
  • Hemodynamic instability / rupture.
  • Significant or worsening pain.
  • Significant hemorrhage.
  • Contraindication to methotrexate.
  • Failed expectant or medical management.
  • Unable to reliably follow up.
  • Ectopic features making medical treatment less appropriate.
  • Patient preference / other GYN considerations.
Unstable / Ruptured Ectopic

Pregnancy Of Unknown Location — PUL

Definition
  • PUL = temporary diagnostic category, not a final diagnosis.
  • Positive hCG + TVUS shows:
    • no probable / definite IUP and
    • no probable / definite ectopic pregnancy
  • Possible outcomes:
    1. Early IUP not yet visualized.
    2. Ectopic pregnancy not yet visualized.
    3. Pregnancy loss
  • Ectopic remains possible until location established or pregnancy resolves. SRU 2024
Workup
1. β-hCG 48 Hours
  • Do not use a single β-hCG to determine pregnancy location.
  • Repeat quantitative β-hCG in approximately 48 hours.
  • hCG trend → helps determine pregnancy progression / next step, not location.
  • Symptoms > hCG trend → new / worsening pain, bleeding, syncope → reassess immediately.
  • Reliable close follow-up essential.

ACEP Level B: Do not use β-hCG to exclude ectopic pregnancy after an indeterminate TVUS.
ACEP Level C: Specialty consultation or close outpatient follow-up for all indeterminate studies. ACEP

Discriminatory Level — Pearl
  • Not a diagnostic cutoff.
  • Higher hCG + no IUP on TVUS → increases concern, but does not prove ectopic or pregnancy loss.
  • Never intervene solely because hCG is above the discriminatory level and no IUP is seen. SRU 2024
Pitfall — “Complete Miscarriage”
  • Empty uterus + history of bleeding / tissue passage does not prove completed pregnancy loss if an IUP was never previously documented.
  • No prior confirmed IUP → remain in the PUL pathway until location or resolution is established ACOG

Intrauterine Pregnancy

1. Definite IUP
  • Gestational sac in a normal intrauterine location + yolk sac or embryo.
  • Cardiac activity is not required to call it a definite IUP.
2. Probable IUP
  • Intrauterine empty gestational sac
  • No yolk sac or embryo yet. SRU 2024
3. Heterotopic Pregnancy
  • Remember heterotopic pregnancy if:
    • assisted reproduction,
    • significant risk factors,
    • adnexal findings / free fluid,
    • or the clinical picture remains concerning despite an IUP.
  • Heterotopic pregnancy is rare spontaneously; increased with assisted reproduction. SRU 2024

03IUP Status?

Threatened Miscarriage

  • IUP + cardiac activity + vaginal bleeding ± cramping. NICE
  • Not diagnostic of EPL.
  • Expectant management. NICE
  • OB follow-up / return precautions.

Concerning For Early Pregnancy Loss — EPL

  • US findings suggest pregnancy may not progress, but are not diagnostic. SRU 2024
  • Examples:
    • CRL <7 mm + no cardiac activity.
    • MSD 16–24 mm + no embryo.
    • No embryo with cardiac activity 7–13 days after prior GS without yolk sac.
    • No embryo with cardiac activity 7–10 days after prior GS with yolk sac.
    • Empty amnion.
    • Enlarged yolk sac >7 mm.
    • Small gestational sac relative to embryo.
  • Repeat TVUS → do not prematurely diagnose EPL. SRU 2024 NEJM 2013

Diagnostic Of Early Pregnancy Loss

  • US definitively establishes EPL. SRU 2024
  • CRL ≥7 mm + no cardiac activity.
  • MSD ≥25 mm + no embryo.
  • No embryo with cardiac activity:
    • ≥14 days after prior GS without yolk sac.
    • ≥11 days after prior GS with yolk sac. NEJM 2013
Specific Patterns
  • Embryonic / fetal demise
    • CRL ≥7 mm + no cardiac activity.
  • Anembryonic pregnancy
    • No embryo + diagnostic sac / interval criteria. SRU 2024

EPL In Progress

  • Gestational sac in lower uterine segment / cervix → in process of expulsion. SRU 2024
  • If cardiac activity present → consider cervical or cesarean-scar ectopic rather than assuming miscarriage.
  • Sliding sign / short-interval US may help if uncertain.

Incomplete EPL

  • Residual intracavitary tissue ± persistent gestational sac after EPL. SRU 2024
  • Thickened endometrium / internal vascularity may support diagnosis.
  • Persistent bleeding / cramping common.

Completed EPL

  • No persistent gestational sac or residual intracavitary tissue after known EPL. SRU 2024
  • Previously documented IUP / gestational sac no longer seen.
  • If pregnancy location was never confirmed → do not call completed EPL; return to PUL pathway. NICE

Confirmed EPL — Management

  • Stable / uncomplicated → expectant vs medical vs surgical management.
  • Hemorrhage / instability / infection → urgent GYN + uterine evacuation. ACOG

04Final Steps

RhD / RhIg

  • Determine Rh status when it may affect management.
  • Rh-negative + unsensitized? → consider RhIg based on gestational age, diagnosis, bleeding / procedure, and current OB protocol.
  • Very early pregnancy: recommendations vary and continue to evolve.
  • Already sensitized → RhIg not beneficial.

Other Cause?

  • If ectopic / EPL does not explain bleeding → consider subchorionic hemorrhage, vaginal / cervical source, molar pregnancy, other uterine pathology.

Disposition

  • Unstable / ruptured ectopic / major hemorrhage / septic abortion → GYN / OR / admit.
  • Stable tubal ectopic → expectant vs MTX vs surgery.
  • PUL → reliable 48-hour β-hCG follow-up + repeat TVUS as indicated.
  • Threatened miscarriage / uncomplicated EPL → outpatient OB follow-up when appropriate.
  • Return precautions → worsening pain, syncope, heavy bleeding, fever.

Knowledge Checks

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