II. Epidemiology

  1. Incidence of First Trimester Bleeding: 25-30%
    1. Miscarriage occurs in 50% of bleeding cases
    2. Even if viable, higher complication risk post-bleed
  2. Half of conceptions miscarry in first 12 weeks

III. Definitions

  1. Spontaneous Abortion (Miscarriage)
    1. Gestational age <20 weeks, fetal weight <500 grams
    2. Considered early spontaneous pregnancy loss if <13 weeks
  2. Inevitable Abortion
    1. Bleeding and rupture of Gestational Sac <20 weeks
    2. Cervix dilated
    3. Menstrual-type cramping
    4. No products of conception expelled yet
  3. Missed Abortion (Fetal Demise, Embryonic Demise)
    1. Embryo >7 mm without fetal heart activity
    2. Retained non-viable conception products up to 4 weeks
  4. Septic Abortion
    1. Incomplete Abortion with secondary ascending infection
    2. Results in Endometritis, parametritis or peritonitis
  5. Incomplete Abortion
    1. Incomplete evacuation of products of conception
  6. Complete Abortion
    1. Complete evacuation of products of conception
    2. Difficult to differentiate from Incomplete Abortion
      1. May require dilatation and curettage for diagnosis
  7. Blighted Ovum (Embryonic Resorption, Anembryonic Pregnancy)
    1. Gestational Sac (>25 mm) and placenta present
    2. Failure of Embryo to develop (no Yolk Sac or Embryo)
  8. Subchorionic Hemorrhage
    1. Blood collected between chorion and uterine wall
  9. Threatened Abortion
    1. Uterine bleeding before 20 weeks (often accompanied by abdominal cramping)
    2. Cervix closed
    3. Ultrasound with intrauterine pregnancy (typically, Embryo with fetal heart activity)
    4. Risk of Complete Abortion: 50%
  10. Decidua
    1. Pregnancy endometrium passed with Miscarriage
    2. Consider Ectopic Pregnancy if passed intact
      1. Known as Decidual Cyst
  11. Induced Abortion
    1. Elective Abortion or
    2. Therapeutic Abortion

IV. Causes: Spontaneous Abortion

  1. Autosomal Trisomy (most common Miscarriage etiology)
  2. Chromosomal Triploidy or Monosomy
  3. Uterine anomaly (e.g. Leiomyoma, DES Exposure)
  4. Incompetent Cervix
  5. Progesterone deficiency (late Luteal Phase defect)
  6. Environmental factors
    1. See risk factors below

V. Risk Factors: Associated with Spontaneous Abortion

  1. See Ectopic Pregnancy for associated risk factors
  2. Advanced maternal age
  3. Cigarette smoking increases risk of euploidic abortion
    1. Over 14 Cigarettes/day doubles risk over non-smokers
    2. Relative Risk increases 1.2x for each 10 cigs/day
  4. Alcohol Abuse increases risk of euplodic abortion
    1. Abortion risk doubled for twice weekly Alcohol
    2. Abortion risk tripled for daily Alcohol use
  5. Illicit Drug Use
  6. Occupational chemical exposure
  7. Caffeine may be associated with Miscarriage (variable evidence)
    1. Small amounts of Caffeine are safe in pregnancy
    2. Limit Caffeine intake to 200 mg/day (e.g. 12 ounces coffee)
    3. Be aware of all potential Caffeine sources
    4. Cnattingius (2000) N Engl J Med 343(25):1839-45 [PubMed]
    5. Savitz (2008) Epidemiology 19(1):55-62 [PubMed]
  8. Uterine surgeries or anomalies
  9. Incompetent Cervix
  10. Diabetes Mellitus (Uncontrolled)
  11. Progesterone deficiency
  12. Thyroid disease
  13. Connective Tissue Disorder
    1. Systemic Lupus Erythematosus
    2. Antiphospholipid Antibodies
      1. Lupus Anticoagulant
      2. Anticardiolipin Antibodies

VI. Myths: Factors not associated with pregnancy loss

  1. Stress
  2. Sexual activity
  3. Air Travel
  4. Exercise
  5. Contrceptive use
  6. HPV Infection

VII. Evaluation

VIII. Management: Threatened Abortion

  1. Maximize Hydration
    1. Intravenous isotonic crystalloid
    2. Oral hydration if tolerated
  2. Give RhoGAM if mother is Rh Negative (50 or 120 mcg at <12 weeks if available, otherwise 300 mcg)
    1. Evidence is weak for giving RhoGAM before 12 weeks for Threatened Abortion
    2. However Rh Sensitization 1-2% at this gestation, and safest to administer if any question
    3. RhoGAM is given within 72 hours of Early Pregnancy Loss, Abdominal Trauma, Ectopic Pregnancy, uterine aspiration
    4. In threatened Ab, most providers do not give RhoGAM for spotting, only for significant bleeding (or ectopic, Miscarriage)
    5. Karanth (2013) Cochrane Database Syst Rev (3):CD009617 [PubMed]
  3. Disposition: Expectant management
    1. Oral hydration
    2. Pelvic rest (including abstaining from intercourse)
    3. Precautions for return
    4. Close interval follow-up with obstetrics provider
    5. Repeat Transvaginal Ultrasound in 7-14 days

IX. Management: Inevitable, incomplete or Complete Abortion

  1. Precautions
    1. Incomplete Abortion requires prompt obstetric evaluation
      1. Risk of Septic Abortion or Hemorrhage with delay
  2. General
    1. Consider intravenous hydration
    2. Consider complications (e.g. Septic Abortion)
    3. Give RhoGAM if mother is Rh Negative (see above)
    4. Follow serial Quantitative hCGs until 0
  3. Observation Indications (effective in 85-90% of cases; only 66-76% in anembryonic gestation, Embryonic demise)
    1. Gestational age under 8 weeks
    2. Most first trimester losses may pass spontaneously
    3. Stable patient
  4. HCG monitoring indications (followed to <5 mIU/ml if indicated)
    1. Completed abortion not confirmed
    2. Resolving pregnancy of unknown location (risk of Ectopic Pregnancy)
    3. Possible Gestational Trophoblastic Disease (Abnormal Uterine Bleeding, malignancy suspected)
  5. Ultrasound Indications
    1. Confirm Early Pregnancy Loss
    2. Confirm intrauterine pregnancy (not Ectopic Pregnancy)
    3. Assess Gestational age
  6. Misoprostol and Mifepristone (preferred)
    1. See Mifepristone and Misoprostol Protocol for Early Pregnancy Loss
  7. Misoprostol Alone
    1. Other dosing in first trimester Miscarriage
      1. Vaginal: 800 mcg intravaginally for 1 dose (may be repeated after 3 days if not effective)
      2. Oral: 600 mcg orally for 1 dose (may be repeated after 3 days if not effective)
    2. Efficacy: Misoprostol alone (best efficacy is when combined with Mifepristone; see above)
      1. Highly effective in missed Spontaneous Abortion (esp. anembryonic gestation, Embryonic demise)
        1. Wood (2002) Obstet Gynecol 99:563-6 [PubMed]
      2. No benefit in incomplete Spontaneous Abortion
        1. Nielsen (1999) Br J Obstet Gynaecol 106:804-7 [PubMed]
      3. Completes first trimester Spontaneous Abortion within 2 weeks: 66%
        1. Blanchard (2004) Obstet Gynecol 103:860-5 [PubMed]
  8. Dilatation and Curettage (or Dilatation and Evacuation, or Uterine Aspiration) Indications
    1. Gestational age 8 to 14 weeks
    2. Excessive intrauterine bleeding (>1 pad/hour) or pain
    3. Prolonged symptoms or delayed passage of tissue
    4. Confirm intrauterine pregnancy (chorionic villi)
  9. Delivery options for 14-20 weeks gestation
    1. Pitocin
      1. Prepare 40 units/Liter in D5LR
      2. Start at 1 mu and double rate every 20-30 minutes
      3. Endpoint
        1. Contractions adequate
        2. Hyperstimulation
    2. Prostaglandin (PG) Cervical Ripening
      1. PGE2 intravaginal suppository
        1. Dose: 20 mg suppository intravaginally
        2. Insert q3 hours until contractions adequate
      2. PG F2 alpha intraamniotic preparation
        1. Test-Dose: 6 mg (6 mg/ml)
        2. Actual Dose: 40 mg vial slowly
  10. Manage intrauterine bleeding
    1. Typical bleeding
      1. Remove products at Cervix (helps to decrease bleeding by allowing cervical os to close)
      2. Intravenous Normal Saline with 30u Pitocin/Liter at 200 cc/hour
      3. Methergine 0.2 mg orally four times daily for 6 doses as needed for bleeding
    2. Hemorrhage
      1. Perform typical bleeding measures as above
      2. Emergency obstetrics Consultation
      3. ABC Evaluation
      4. Obtain 2 large bore IVs (14-16 gauge)
      5. Transfusion Packed Red Blood Cells (O negative)
      6. Emergent dilatation and curettage (D & C)
      7. Vaginal packing with moist sterile gauze may be attempted for vaginal packing
      8. Foley Catheter inflated within Uterus
      9. Consider Tranexamic Acid IV
      10. Consider Vasopressin if suspected or known Von Willebrand Disease
    3. References
      1. Herbert and Cardy in Cardy (2017) EM:Rap 17(6):4

X. Management: Post-Pregnancy Loss Care

  1. See Grief in Pregnancy Loss
  2. Contraception may start immediately (unless patient wishes to try to conceive)
  3. Conception desired
    1. Take Folic Acid supplementation
    2. No need to delay repeat attempt at pregnancy
      1. In fact, chance of pregnancy is higher within 3 months of Early Pregnancy Loss
      2. Sundermann (2017) Obstet Gynecol 130(6): 1312-18 [PubMed]

XI. Complications

  1. Septic Abortion (septic Miscarriage)
  2. Hemorrhage
  3. Rh Sensitization

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Related Studies

Ontology: Spontaneous abortion (C0000786)

Definition (MEDLINEPLUS)

A miscarriage is the loss of pregnancy from natural causes before the 20th week of pregnancy. Most miscarriages occur very early in the pregnancy, often before a woman even knows she is pregnant. There are many different causes for a miscarriage. In most cases, there is nothing you can do to prevent a miscarriage.

Factors that may contribute to miscarriage include

  • A genetic problem with the fetus. This is the most common cause in the first trimester.
  • Problems with the uterus or cervix. These contribute in the second trimester.
  • Polycystic ovary syndrome

Signs of a miscarriage can include vaginal spotting or bleeding, abdominal pain or cramping, and fluid or tissue passing from the vagina. Although vaginal bleeding is a common symptom of miscarriage, many women have spotting early in their pregnancy but do not miscarry. But if you are pregnant and have bleeding or spotting, contact your health care provider immediately.

Women who miscarry early in their pregnancy usually do not need any treatment. In some cases, you may need a procedure called a dilatation and curettage (D&C) to remove tissue remaining in the uterus.

Counseling may help you cope with your grief. Later, if you do decide to try again, work closely with your health care provider to lower the risks. Many women who have a miscarriage go on to have healthy babies.

NIH: National Institute of Child Health and Human Development

Definition (NCI_FDA) Loss of the products of conception from the uterus before the fetus is viable; spontaneous abortion.
Definition (NCI) Fetal loss at less than 20 weeks of gestation.(NICHD)
Definition (CSP) the natural premature expulsion from the uterus of the products of conception, the embryo, or non-viable fetus.
Definition (MSH) Expulsion of the product of FERTILIZATION before completing the term of GESTATION and without deliberate interference.
Concepts Pathologic Function (T046)
MSH D000022
ICD9 634
ICD10 O03 , O03.9
SnomedCT 17369002, 156074006, 198689000, 267294003, 198643007, 156071003, 198631006
LNC MTHU002836, LA14272-1
English Abortion, Spontaneous, Abortions, Spontaneous, Miscarriage, Miscarriages, Spontaneous Abortions, Spontaneous abortion, Spontaneous Abortion, Spontaneous abortion unsp.NOS, Spontaneous abortion unspecif., Spontaneous abortion unspecified, Unspecified spontaneous abortion NOS, Vagin expulsion product concep, spontaneous abortion, miscarriage, spontaneous abortion (diagnosis), Abortion spontaneous NOS, Miscarriage of pregnancy, Spontaneous abortion NOS, Miscarriage NOS, Abortion, Spontaneous [Disease/Finding], Abortion;spontaneous, pregnancy miscarriage, miscarriage pregnancy, miscarriages, abortion spontaneous, miscarriages pregnancy, spontaneous abortions, abortions spontaneous, miscarriage of pregnancy, Abortions spontaneous, Spontaneous abortion NOS (disorder), Abortion - spontaneous, Unspecified spontaneous abortion NOS (disorder), Spontaneous abortion (disorder), Miscarriage (disorder), Spontaneous abortion unspecified (disorder), Abortions.spontaneous, MISCARRIAGE, Abortion spontaneous, Vaginal expulsion of fetus, Vaginal expulsion of product of conception, abortion; spontaneous, fetus, abortion; spontaneous, spontaneous; abortion, fetus, spontaneous; abortion, Miscarriage, NOS, Spontaneous abortion, NOS, Abortion (Spontaneous), Spontaneous abortion, fetus
Spanish ABORTO ESPONTANEO, Pérdida del feto, Fracaso de embarazo, Aborto espontáneo NEOM, aborto espontáneo, SAI, aborto espontáneo no especificado, SAI (trastorno), aborto espontáneo, no especificado (trastorno), aborto espontáneo, no especificado, Spontaneous abortion NOS, aborto espontáneo no especificado, SAI, aborto espontáneo, SAI (trastorno), aborto espontáneo (trastorno), aborto espontáneo, expulsión vaginal del producto de la concepción, Aborto espontáneo, Abortos espontáneos, expulsión vaginal del feto, Aborto Espontáneo
Italian Aborti spontanei, Aborto spontaneo, NAS, Interruzione di gravidanza, Aborto spontaneo
Dutch miskraam, spontane miskraam NAO, spontane abortus, abortus; spontaan, foetus, abortus; spontaan, spontaan; abortus, foetus, spontaan; abortus, abortus spontaan, spontane miskraam, Spontane abortus, Abortus, spontane, Miskraam
French Avortement spontané SAI, Fausse couche de grossesse, Fausse couche, AVORTEMENT AU-DELA DE TROIS MOIS, Avortements spontanés, Avortement spontané, Fausse-couche
German Fehlgeburt, Abortus spontaneus NNB, FEHLGEBURT, Aborte spontan, Abort, spontaner, Spontanabort
Portuguese Aborto espontâneo NE, Interrupção espontânea da gravidez, ABORTO COM MAIS DE TRES MESES, Aborto espontâneo, Abortos espontâneos, Aborto Espontâneo
Japanese 自然流産NOS, シゼンリュウザン, シゼンリュウザンNOS, 自然流産, 流産, 流産-自然
Swedish Missfall
Czech potrat spontánní, Spontánní potraty, Spontánní potrat, Spontánní potrat NOS
Finnish Itsestään tapahtuva keskenmeno
Korean 자연 유산
Polish Przerwanie ciąży samoistne, Poronienie samoistne
Hungarian Abortusz, Koraszülés terhességben, Abortuszok spontán, Spontán abortus, Spontán vetélés, Spontán vetélés k.m.n.
Norwegian Spontanabort, Spontan abort, Abortus spontaneus

Ontology: Missed abortion (C0000814)

Definition (NCI) Retention in uterus of an abortus.(NICHD)
Definition (NCI_FDA) Retention in uterus of an abortus that has been dead at least 4 weeks.
Definition (MSH) The retention in the UTERUS of a dead FETUS two months or more after its DEATH.
Concepts Disease or Syndrome (T047)
MSH D000030
ICD9 632
ICD10 O02.1
SnomedCT 156087000, 198616002, 267187007, 16607004
English Abortion, Missed, Abortions, Missed, Missed Abortions, ABORTION MISSED, Missed Abortion, Missed abortion, missed abortion, missed abortion (diagnosis), missed abortion (history), Abortion missed, Abortion, Missed [Disease/Finding], Missed;abortion, missed abortions, abortion missed, miss abortion, abortion miss, missed miscarriage, Missed miscarriage, ABORTION, MISSED, MA - Missed abortion, Missed abortion (disorder), Silent miscarriage, abortion; missed abortion, abortion; missed, missed abortion; abortion, missed; abortion
Italian Aborto ritenuto, Aborto interno
Dutch missed abortion, abortus; gemist, abortus; missed abortion, gemist; abortus, missed abortion; abortus, 'Missed abortion', gemiste miskraam, Abortion, missed, Missed abortion
German verhaltener Abort, ABORT VERHALTENER, Missed abortion [Verhaltene Fehlgeburt], Abort und Totgeburt, Abort, verhaltener, Missed Abortion, Verhaltene Fehlgeburt
Portuguese Aborto retido, ABORTO FALHADO, Aborto oculto, Aborto Retido
Japanese 稽留流産, ケイリュウリュウザン
Swedish Missfall, utebliven
Spanish aborto fracasado, ABORTO DIFERIDO, Aborto Frustrado, Aborto diferido, aborto fracasado (trastorno), aborto inadvertido (trastorno), aborto inadvertido, Aborto Retenido
Czech potrat zamlklý, Zamlklý potrat
Finnish Keskeytynyt keskenmeno
French RETENTION D'UN OEUF MORT, Avortement manqué, Rétention d'oeuf mort, Rétention d'un oeuf mort, Rétention foetale
Korean 계류 유산
Polish Ciąża obumarła, Poronienie zatrzymane
Hungarian Missed abortion, Abbamaradt vetélés
Norwegian Abortus inhibitus, Abortus retentus, Missed abortion

Ontology: Threatened abortion (C0000821)

Definition (NCI) Vaginal bleeding preceding the 20th week of gestation.
Definition (MSH) UTERINE BLEEDING from a GESTATION of less than 20 weeks without any CERVICAL DILATATION. It is characterized by vaginal bleeding, lower back discomfort, or midline pelvic cramping and a risk factor for MISCARRIAGE.
Concepts Pathologic Function (T046)
MSH D000033
ICD9 640.03, 640.0
ICD10 O20.0
SnomedCT 198885008, 156098004, 54048003, 198882006, 22689002
English Abortion, Threatened, Abortions, Threatened, Threatened Abortions, Threatened abortion, antepartum, ABORTION THREATENED, Threatened abortion NOS, Threatened abortion unspecified, Threatened abortion-unspecif., pregnancy with threatened abortion (diagnosis), pregnancy with threatened abortion, Abortion threatened, Threaten abort-antepart, Abortion, Threatened [Disease/Finding], abortion threatened, Abortion;threatened, threatened abortion, miscarriage threatening, Miscarriage;threatened, threaten abortion, Threatened abortion, antepartum condition or complication, Threatened abortion NOS (disorder), Threatened miscarriage (disorder), Threatened abortion unspecified (disorder), Threatened miscarriage, Threatened abortion (antepartum) (disorder), Threatened Abortion, Threatened abortion (antepartum), Threatened abortion (disorder), abortion; threatened, miscarriage; threatened, pregnancy; abortion, threatened, pregnancy; threatened abortion, threatened; abortion, threatened; miscarriage, Threatened abortion, NOS, Threatened abortion, threatened miscarriage
Italian Minaccia di aborto, Minaccia d'aborto, condizione o complicazione antepartum, Minaccia d'aborto
Dutch dreigende abortus, dreigende abortus, antepartum, abortus; dreigend, dreigend; abortus, dreigend; miskraam, miskraam; dreigend, zwangerschap; abortus, dreigend, zwangerschap; dreigende abortus, behandelde abortus, Abortus, dreigende, Dreigende abortus
French Risque d'avortement spontané, Menace d'avortement, antepartum, MENACE D'AVORTEMENT, Avortement imminent, Menace d'avortement, Menaces d'avortement
German drohender Abort, drohender Abort, antepartal, ABORT DROHENDER, Drohender Abort, Abort drohend, Abort, drohender, Abortus imminens
Portuguese Ameaça de aborto, anteparto, AMEACA DE ABORTO, Ameaço de Aborto, Ameaça de aborto, Ameaça de Aborto
Spanish Amenaza de aborto, anteparto, ABORTO, AMENAZA DE, amenaza de aborto, SAI, amenaza de aborto (trastorno, preparto) (concepto no activo), amenaza de aborto, no especificada (trastorno), amenaza de aborto (anteparto), amenaza de aborto, SAI (trastorno), amenaza de aborto, no especificada, amenaza de aborto (trastorno), amenaza de aborto, Amenaza de aborto, Amenaza de Aborto
Japanese 切迫流産, 切迫流産、分娩前, セッパクリュウザン, セッパクリュウザンブンベンゼン, セッパクリュウザンブンベンマエ
Swedish Missfall, hotande
Finnish Uhkaava keskenmeno
Czech Hrozící potrat, Hrozící potrat, před potratem, potrat hrozící, hrozící potrat
Korean 절박 유산
Polish Poronienie zagrażające
Hungarian Fenyegető vetélés, Fenyegető vetélés, antepartum
Norwegian Abortus imminens, Truende abort

Ontology: Decidua (C0011106)

Definition (NCI) The epithelial tissue of the endometrium.
Definition (CSP) endometrium of the pregnant uterus; shed at parturition, except for the deepest layer.
Definition (MSH) The hormone-responsive glandular layer of ENDOMETRIUM that sloughs off at each menstrual flow (decidua menstrualis) or at the termination of pregnancy. During pregnancy, the thickest part of the decidua forms the maternal portion of the PLACENTA, thus named decidua placentalis. The thin portion of the decidua covering the rest of the embryo is the decidua capsularis.
Concepts Body Part, Organ, or Organ Component (T023)
MSH D003656
SnomedCT 34863009, 72649005
English Deciduas, Decidual, Decidua, Decidous membrane, decidua, Deciduum, Endometrial decidua, Decidua structure (body structure), Decidua structure, Endometrial decidua (body structure), Menstrual decidua, Decidua, NOS, Decidua Graviditas
French Decidua, Caduques, Caduque, Deciduum, Décidue
Swedish Decidua
Czech decidua
Portuguese Decídua
Finnish Katokalvo
Japanese 脱落膜
Italian Deciduum, Decidua
Croatian DECIDUA
Polish Doczesna, Błona śluzowa ciężarnej macicy
Norwegian Decidua, Indre slimhinne i livmoren
Spanish estructura de la membrana caduca (estructura corporal), estructura de la membrana caduca, membrana caduca, membrana decidua endometrial (estructura corporal), membrana decidua endometrial, Decidua
German Dezidua
Dutch Decidua