Spontaneous miscarriage is the loss of fetus before 20 weeks of gestation or delivery of a fetus weighing <500 g, in the absence of elective medical or surgical measures to terminate pregnancy.
Early loss is considered if it occurred before menstrual week 12 while late loss refers to those that occurred from menstrual week 12-20.
It is also known as spontaneous abortion, spontaneous pregnancy loss or early pregnancy failure.

Miscarriage%20-%20spontaneous Diagnosis


  • Should include previous obstetric history (eg nature of previous pregnancy losses particularly the actual gestational age), last menstrual period (LMP), presence of pain or bleeding, and if products of conception were passed
    • Classification of miscarriage may primarily be determined by patient’s presentation
      • Incomplete miscarriage often presents with vaginal bleeding and midline cramping
      • Threatened miscarriage usually presents with vaginal bleeding, lower back discomfort, or midline pelvic cramping
  • Determine risk factors
    • Advanced maternal and paternal age
      • Maternal age is associated with decline in number and quality of remaining oocytes; the older the oocyte, the higher the aneuploidy rate
      • Risk of miscarriage is highest in couples where the woman is ≥35 years old and the man is ≥40 years old
    • Obesity
      • Recent studies have shown that obesity increases the risk of both sporadic and recurrent miscarriage
    • Use of medications such as Misoprostol, retinoids, Methotrexate, etc
    • History of spontaneous miscarriage or multiple elective abortions
    • Conception within 3-6 months after delivery
    • Presence of uterine abnormalities (eg adhesions, leiomyoma) or use of intrauterine device

Physical Examination

  • Perform pelvic examination with emphasis on possible findings associated with uterine or cervical abnormalities
  • Examine patient for findings suggestive of diabetes or thyroid disease

Laboratory Tests

Serum hCG
  • Useful when a complete miscarriage is suspected in the absence of previous ultrasonographic evidence of an intrauterine pregnancy
    • Usually returns to normal in 2-4 weeks
  • Also used to diagnose pregnancy of unknown location or asymptomatic ectopic pregnancy
Serum Progesterone
  • Progesterone level >25 nmol/L indicates an ongoing pregnancy while those <25 nmol/L is associated with pregnancies subsequently confirmed to be non-viable; however some viable pregnancies presented with low progesterone levels

Antiphospholipid Antibodies (eg lupus anticoagulant, anticardiolipin antibodies, anti-β2 glycoprotein I antibodies)

  • Should be requested before pregnancy in women with recurrent first trimester miscarriage and women with ≥1 second trimester miscarriage
  • Initial miscarriage management may include checking fluid balance and blood grouping and crossmatching 
  • If clinically indicated, screen patients for infection (eg Chlamydia trachomatis, Neisseria gonorrhea, bacterial vaginosis)
    • A blood culture may be requested if patient is febrile
  • Women with second trimester miscarriage should be screened for inherited thrombophilias (ie factor V Leiden, prothrombin gene mutation, protein S)
  • If suggested by history or physical examination, screen patient for thyroid disease or diabetes

Histological Examination of Tissues Obtained via Surgical Evacuation

  • Confirms the diagnosis and basic pathology of miscarriage and helps rule out ectopic pregnancy or gestational trophoblastic disease


  • Should be done on products of conception of the third and subsequent consecutive miscarriages
    • If results show unbalanced structural chromosomal abnormality, parental peripheral blood karyotyping should also be performed
    • Allows to know the prognosis of future pregnancy outcome
      • If the miscarried pregnancy has an abnormal karyotype, the next pregnancy has a better prognosis


  • Preferred imaging study in identifying the status of pregnancy and rule out other possible diagnosis like ectopic pregnancy
    • Transvaginal ultrasonography is 90-100% sensitive and 80-92% specific in determining the product of conception
    • Result showing empty uterus may signal a completed spontaneous miscarriage
    • To know the viability of the fetus, fetal heartbeat should be identified first; if heartbeat is not visible, crown-rump length should be measured. If crown-rump length cannot be measured, obtain the mean gestational sac diameter
      • Repeat transvaginal ultrasound after 1 week if crown-rump length is < or > 7.0 mm, or the mean gestational sac diameter is < or > 25 mm and there is no visible heartbeat; after 2 weeks if transabdominal ultrasound was initially used
  • Used to assess uterine anatomy of women with recurrent first trimester miscarriage and women with ≥1 second trimester miscarriage
  • Helps in determining treatment options for patients with incomplete, inevitable, or missed miscarriage
    • <40 mm endometrial thickness: Conservative management  
    • >40 mm endometrial thickness: Conservative management, medical or surgical evacuation 
  • Hysteroscopy, laparoscopy, 3-dimensional pelvic ultrasound, magnetic resonance imaging (MRI) may be used to confirm the presence of uterine anomaly
    • Sonohysterography and hysterosalpingography are noninvasive screening tests used to evaluate uterine cavity and shape


Threatened Miscarriage
  • Presence of uterine bleeding with no cervical dilatation nor passage of fetal tissue
Complete Miscarriage
  • Passage of all products of conception with no surgical or medical intervention
Incomplete Miscarriage
  • Partial passage of fetal tissue through partially dilated cervix
Inevitable Miscarriage
  • Presence of cervical dilatation but no passage of fetal tissue
Missed Miscarriage
  • Presence of intrauterine fetal demise but no passage of fetal tissue
Recurrent Spontaneous Miscarriage
  • Loss of ≥3 consecutive pregnancies which occurs in approximately 1% of couples trying to have a child
    • Other experts consider 2 consecutive losses to define recurrent miscarriage or habitual miscarriage because recurrence rate is similar to that after 3 pregnancy losses
  • Prognosis is often favorable even without treatment
Septic Miscarriage
  • Spontaneous miscarriage that is complicated by intrauterine infection that commonly occurs with incomplete miscarriage
  • Common in illegal induced abortion using nonsterile procedures
  • Causative pathogens include Enterobacter aerogenes, Escherichia coli, Proteus vulgaris, staphylococci, hemolytic streptococci, and some anaerobic organisms (eg Clostridium perfringens)
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