Abortion, Spontaneous



  • Spontaneous termination of a <20 wk intrauterine pregnancy
  • Synonyms: Early pregnancy loss, miscarriage
  • Occurs in up to 15–20% of recognized pregnancies (most common complication of early pregnancy)
  • Vaginal bleeding in the 1st trimester seen in about 25% of pregnant patients:
    • 50% of these women will eventually mis-carry
  • Definitions:
    • Threatened abortion: Vaginal bleeding, cervical os is closed, viable intrauterine pregnancy confirmed:
      • 50% of women seen in the ED for threatened abortion will eventually miscarry
    • Inevitable abortion: Vaginal bleeding, cervical os is open; products of conception (POC) have not been expelled
    • Incomplete abortion: Vaginal bleeding, cervical os is open with partial passage of some POC and some retained POC
    • Complete abortion: Vaginal bleeding, cervical os closed, complete passage of POC; no surgical or medical intervention
    • Missed abortion: Fetal demise with no uterine activity to expel
    • Septic abortion: Spontaneous abortion complicated by intrauterine infection
    • Recurrent spontaneous abortion: 3 or more consecutive pregnancy losses


  • Chromosomal abnormalities of the fetus
  • Uterine abnormalities
  • Risk factors include:
    • Increased age of both the mother and father
    • Increased parity
    • Alcohol use
    • Cigarette smoking
    • Cocaine use
    • Conception within 3–6 mo after delivery
    • Chronic maternal disease:
      • Poorly controlled diabetes
      • Autoimmune disease
      • Celiac disease
    • Intrauterine device
    • Maternal BMI < 18 or >25 kg/m2
    • Maternal infections:
      • Bacterial vaginosis
      • Mycoplasmosis
      • Herpes simplex
      • Toxoplasmosis
      • Listeriosis
      • Chlamydia/gonorrhea
      • HIV
      • Syphilis
      • Parvovirus B19
      • Malaria
      • CMV
      • Rubella
    • Medications:
      • Misoprostol
      • Methotrexate
      • NSAIDs
    • Multiple previous elective abortions
    • Previous early pregnancy loss
    • Toxins
    • Uterine abnormalities (e.g., leiomyoma, uterine adhesions, congenital anomalies)


Signs and Symptoms

  • Last menstrual period (LMP)
  • Obstetric history:
    • Parity
    • Risk factors for pregnancy loss
    • Prenatal care
  • Abdominal pain, cramping
  • Vaginal bleeding:
    • Duration
    • Amount of bleeding (quantify by number of pads used, compare with normal menstrual period for patient)
    • Passage of clots
  • Dizzy, syncope

Physical Exam
  • Determine hemodynamic status of patient:
    • Pregnant patients in late 1st trimester have an increased blood volume
    • Can lose substantial amount of blood before having abnormal vital signs
  • Pelvic exam:
    • Determine whether the internal cervical os is opened or closed
    • Amount of bleeding
    • Presence of POC
    • Presence of adnexal tenderness or peritoneal irritation can be consistent with an ectopic pregnancy
  • Bimanual exam to determine the size of the uterus:
    • Size of an orange: 6–8 wk
    • Fundus at the symphysis pubis: 12 wk
    • Fundus at the umbilicus: 16–20 wk

Essential Workup

  • Pregnancy test as below
  • Imaging as below

Diagnostic Tests and Interpretation

  • Confirm pregnancy with a urine or serum test:
    • Urine pregnancy test: Most are positive at β-hCG levels of 25–50 mIU/mL ∼1 wk gestational age and remain positive 2–3 wk after induced or spontaneous abortions
  • CBC
  • Rapid hemoglobin determination: Type and Rh
  • Type and cross-match for woman with low Hct or signs of active blood loss
  • Quantitative β-hCG
  • Any POC passed should be sent to pathology for confirmation

  • Transvaginal ultrasound (TVS):
    • Gestational sac seen at 5 wk
    • Cardiac activity seen at 6.5 wk
  • Transabdominal ultrasound (TAS):
    • Gestational sac at 6 wk
    • Cardiac activity seen at 8 wk
  • Discriminatory zone: Level of β-hCG where a normal IUP should be detected:
    • 1,500–2,000 for TVS
    • 6,500 for TAS

Differential Diagnosis

  • Positive pregnancy test with vaginal bleeding:
    • Cervicitis
    • Ectopic pregnancy
    • Molar pregnancy
    • Pregnancy of unknown location (PUL)
    • Septic abortions
    • Subchorionic hemorrhage
    • Trauma
  • 2nd- and 3rd-trimester vaginal bleeding:
    • Placenta previa
    • Placental abruption


Pre Hospital

  • IV fluids, oxygen, and cardiac monitor
  • Monitor vital signs and transport
  • Cautions:
    • Patients with spontaneous abortion/vaginal bleeding can have severe hemorrhage and present in shock, especially at >12 wk
    • BP drops during the 2nd trimester of pregnancy with an average of 110/70

Initial Stabilization/Therapy

  • Stable patients:
    • IV
    • Pelvic exam
  • Unstable patients:
    • Oxygen, IV fluids via 2 large-bore IVs, cardiac monitor
    • Transfuse PRBC if patient does not stabilize after 2–3 L of crystalloid
    • Gynecologic consultation immediately
    • Oxytocin or methylergonovine may be necessary to control hemorrhage
    • These patients are at high risk for having ruptured ectopic pregnancies and may need emergent operative intervention

Ed Treatment/Procedures

  • Threatened abortion:
    • Pelvic rest, close follow-up with obstetrics
    • Patients <6.5 wk pregnant with no documented cardiac activity by vaginal US need to be followed with serial β-hCG to assess the viability of the fetus and to rule out ectopic pregnancy
  • Inevitable and incomplete abortions:
    • Expectant management:
      • Successful in up to 85%
      • Increased risk of unplanned surgical intervention and blood loss as compared to surgical management
    • Medical management:
      • Misoprostol
      • Successful in up to 85%
    • Surgical management:
      • Dilation and curettage (D&C) or evacuation, removal of POC at the cervical os to help decrease bleeding and cramping
      • Less unplanned hospital admissions, curettages, and blood transfusions
      • The confirmation of POC by pathology rules out ectopic pregnancy
  • Complete abortion:
    • May treat with methylergonovine or oxytocin if bleeding is heavy
    • If quantitative β-hCG is <1,000 and the US is negative, may follow-up with obstetrics for serial β-hCG to confirm the levels are decreasing
  • Missed abortion:
    • These patients are at risk for disseminated intravascular coagulation (DIC), especially if fetus is retained >4–6 wk
    • Obtain CBC, PT/PTT, fibrin-split products (FSP), and fibrinogen levels
    • These patients may be followed closely as outpatients if stable with an early, confirmed IUP and no evidence of DIC
    • Patients may choose to have a D&C at a later date or miscarry at home with medication or no intervention; this decision should be made in consultation with OB/GYN


First Line
  • RHO immunoglobulin in Rh-negative women:
    • 50 μg for women with threatened or complete abortion at <12 wk
    • 300 μg for women with threatened or complete abortion at ≥12 wk
  • Patients need RhoGAM administration within 72 hr to prevent future isoimmunization
  • Misoprostol 800 μg vaginally if medical management is chosen in consultation with OB/GYN
  • Repeat dose required in 48 hr

Second Line
Usually given in consultation with OB/GYN:
  • Oxytocin: 20 IU in 1,000 mL of NS at a rate of 20 mIU/min titrated to decrease bleeding; may repeat for a max. dose of 40 mIU/min
  • Methylergonovine: 0.2 mg IM/PO QID for bleeding

Ongoing Care


Admission Criteria
  • Suspected unstable ectopic pregnancy (see “Ectopic Pregnancy”)
  • Hemodynamically unstable patients with hypovolemia or anemia
  • DIC
  • Septic abortions
  • Suspected gestational trophoblastic disease

Discharge Criteria
  • D&Cs can be done in the ED for incomplete and inevitable abortions, and patients may be discharged home if stable after 2–3 hr
  • Some early inevitable miscarriages can be discharged to complete their miscarriages at home without a D&C
  • Discharge with pain medications and close OB/GYN follow-up
  • Patients with threatened abortions should be told to avoid strenuous activity
  • Pelvic rest (i.e., “nothing in the vagina” during active bleeding; may increase risk of infection)
  • Patients should be instructed to return to the ED for any increase in bleeding, dizziness, or temperature >100.4°F
  • Patients and their partners should be counseled that early pregnancy loss is common and that it is not anyone's fault

Follow-Up Recommendations

Patients with positive pregnancy tests and vaginal bleeding with or without abdominal pain should be followed by OB/GYN.

Pearls and Pitfalls

  • Recognize the possibility of ectopic pregnancy
  • Patients with spontaneous abortion may have clinically significant blood loss

Additional Reading

  • Huancahuari N. Emergencies in early pregnancy. Emerg Med Clin North Am. 2012;30:837–847.  [PMID:23137398]
  • Martonffy AI, Rindfleisch K, Lozeau AM, et al. First trimester complications. Prim Care. 2012;39:71–82.  [PMID:22309582]
  • Marx JA, Hockberger RS, Walls RM, et al. Rosen's Emergency Medicine: Concepts and Clinical Practice. 7th ed. St. Louis, MO: Mosby; 2009.
  • Prine LW, MacNaughton H. Office management of early pregnancy loss. Am Fam Physician. 2011;84:75–82.  [PMID:21766758]

See Also

  • Ectopic Pregnancy
  • Vaginal Bleeding



  • 634.90 Spontaneous abortion, without mention of complication, unspecified
  • 634.91 Spontaneous abortion, without mention of complication, incomplete
  • 634.92 Spontaneous abortion, without mention of complication, complete
  • 632 Missed abortion
  • 634.9 Spontaneous abortion without mention of complication


  • Missed abortion
  • Incomplete spontaneous abortion without complication
  • Complete or unspecified spontaneous abortion without complication


  • 17369002 Spontaneous abortion (disorder)
  • 156072005 Incomplete miscarriage (disorder)
  • 156073000 Complete miscarriage (disorder)
  • 59363009 Inevitable abortion
  • 16607004 Missed abortion (disorder)
  • 19169002 Spontaneous abortion in first trimester (disorder)
  • 85116003 Spontaneous abortion in second trimester (disorder)


Ivette Motola
Aviva Jacoby Zigman

© Wolters Kluwer Health Lippincott Williams & Wilkins

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