February 3, 2023

A Short Review of Spontaneous Abortion or Miscarriage

  • October 25, 2012
  • 3 min read
A Short Review of Spontaneous Abortion or Miscarriage

Abortion is defined as the termination of pregnancy, either spontaneously or intentionally:

1. Prior to age of viability (28 weeks) OR
2. < 500 gm birth weight

Common Causes of Spontaneous Abortion (Miscarriage):

A) 1st trimester (GEI)

  • Genetic factors: Autosomal trisomy, Polyploidy, Monosomy X, Mosaic, Double trisomy
  • Endocrine disorders: Luteal phase defect (LPD), Thyroid abnormalities, DM
  • Immunological: Autoimmune (ANAs, Anti-DNA antibodies, Anti-phospholipid antibodies), Alloimmune, Antifetal antibodies (Rh isoimmunization)
  • Infection (ToRCH, Ureaplasma, Chlamydia, Brucella, Malaria)
  • Unexplained

B) 2nd trimester (AM)

  • Anatomic abnormalities: Cervical incompetence, Mullerian fusion defects, Uterine synechiae, Uterine fibroid
  • Maternal medical illness: Cyanotic heart disease, Hemoglobinopathies
  • Unexplained

C) Other: Premature ROM (Thrombophilias), Environmental (Smoking, Alcohol, Contraceptives, Drugs, Radiation)

Mechanisms of Spontaneous abortion:

  1. Before 8 weeks: Ovum surrounded by villi with decidual covering is expelled out
  2. 8-14 weeks: Expulsion of fetus leaving behind placenta and membranes
  3. Beyond 14 weeks: Expulsion of fetus followed by expulsion of placenta after varying interval


  1. Hemorrhage into deciduas, followed by necrosis of tissue adjacent to bleeding
  2. If early: ovum detaches, simulating uterine contractions that result in its ovulation
  3. Blighted ovum: Absence of fetal pole in gestational sac with diameter 3 or more (USG)
  4. Later abortion: fetus may undergo maceration
  5. Fetus compressus: Amniotic fluid is absorbedà fetus may become compressed and dessicated
  6. Fetus papyraceous: Fetus become so dry and compressed that it resembles parchment


ThreatenedMiscarriage has started but recovery is possible

  • No POC expelled
  • Membranes intact
  • Uterine bleeding +nt
  • Abdominal pain may be +nt (following bleeding)
  • Fetus is still viable
Os is closedUSG is normalPelvic rest for 1-2 days with gradual resumption of activities but abstinence from coitus and douchingDiazepam analgesic
InevitableProgressed to irrecoverable state

  • No POC expelled
  • Uterine bleeding and cramps
Os is open +/- ROMPOC felt through open osBleeding control with methergin 0.2mg<12 wks: D+C or Suction evacuation

>12 wks: Oxytocin

CompleteAll POC expelledPain ceases

Spotting may be +nt

Os is closedUSG shows empty uterus

Uterus small for duration of amenorrhea

D+C if increased likelihood that abortion was incomplete
IncompleteSome POC expelledMild cramping and bleeding

Visible tissue in vagina or endocervical canal

Os is openUSG reveals retained fetal tissuesHemodynamic stabilityEvacuation of Retained Products of Conception (ERCP i.e. D+C)

OR Tab. Misoprostol 200ug vaginally ever 4hrs

MissedPregnancy has ceased to develop

  • No POC is expelled
  • Fetal tissue is retained
  • No uterine bleeding
  • Symptoms of pregnancy disappear
  • Brownish vaginal discharge
Os is closedUSG reveals no fetal cardiac activity

Fetal tissue is retained

<12 wks: Expectant or Misoprostol 800mg vaginally repeated after 24 hrs if needed or Suction evacuation or D+C>12 wks: Misoprostol, Oxytocin, D+C
SepticInfection of uterus and uterine contents with abortionEndometritis → Septicemia

Maternal mortality 10-15%

  • Fever: >100.4F or 38c for 24 hrs or more
  • Offensive/purulent vaginal discharge
  • Evidences of pelvic infection (pain/tender)
Cervical/High vaginal swab

  • Culture
  • Sensitivity
  • Gram stain

Blood: Hb, TLC, DLC, ABO, Rh, culture, electrolytes, coagulation profile




HospitalizationIV antibiotics

Complete uterine evacuation


Recurrent= or > 3 cosecutive miscarriageIf early, often due to chromosomal abnormalities à karyotyping of both parents

Incompetent cervix should be suspected with a history of repeated midtrimester painless cervical dilation and escape of liquor followed by painless expulsion of POC

Cervical cultures for gonococcus, Chlamydia,  group B streptococcus

Evaluate for uterine abnormalities

Management of Cervical incompetence:Circlage operation

  • Shirodkar’s or McDonald’s
  • Suture cervix close by non-absorbable tape around internal os level

Restriction of activities

About Author

Sulabh Shrestha

Intern doctor and Medical Blogger Sulabh Shrestha

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.