Miscarriage 

Miscarriage is the expulsion of the fetus from the uterus before it is capable of sustaining life independently. Interestingly, 50-75% of all conceptions end in a miscarriage but most go unnoticed because they occur before or during the subsequent period. 

Spontaneous miscarriage 

Loss of pregnancy before 20 weeks gestation or <500g mass. Advanced maternal age, prior miscarriages and smoking are the most significant risk factors. Most pregnant women experience vaginal bleeding followed by lower abdominal cramping. A physical exam should include vital sign assessment (for hemodynamic instability), a speculum exam (to assess the cervix) and a bimanual exam to estimate the gestational age.

Management should include Rh blood typing and all Rh-negative patients should receive anti-D immunoglobulin prophylaxis. 

Etiology

Most of the pregnancies ending with a miscarriage do so within the first trimester. The fetus is often already dead by the time of expulsion. At least half of these fetuses die due to chromosomal abnormalities. Second trimester miscarriages are more likely to result from anatomic factors and the fetus is usually not dead by the time of expulsion. 

• Fetal factors 
  • Chromosomal issues 
    • Autosomal trisomies are the most common cause (13, 16, 18, 21, 22)
    • Monosomy X is the second most common cause 
    • 
  • Developmental issues
    • Common in first trimester miscarriages 
• Maternal factors 
  • Uterine defects 
    • Fibroids are usually not the cause of miscarriages 
    • Asherman syndrome (from multiple curettages) can make the endometrium insufficient to host a pregnancy 
    • 
    • Incompetent cervix is a correctable cause of miscarriages
  • Infections 
  • Endocrine issues
  • Immune reasons 
  • Trauma 
    • Especially abdominal trauma 

Classification

Types of miscarriages

Miscarriage	Symptoms	Pelvic exam	Ultrasound findings
Threatened	Mild vaginal bleeding Mild abdominal pain  Membranes intact  Fetal cardiac activity important	Cervix closed	Intrauterine pregnancy viable
Inevitable	Vaginal bleeding and abdominal pain  Membranes may be broken or non-broken	Cervix open	Pregnancy mostly non-viable
Incomplete	Heavy vaginal bleeding  Partial passage of products	Cervix open	Retained uterine products
Complete	Vaginal bleeding and complete passage of products	Cervix open early Cervix closed later	Empty uterus
Missed	Not many symptoms  Brown vaginal discharge	Cervix closed	No fetal cardiac activity Non-viable pregnancy
Recurrent	More than 3 miscarriages  (Can be any type, incomplete, complete...)	Variable	Empty uterus and uterine abnormalities may be seen

• Threatened miscarriage 
  • Cervical is closed but there is vaginal bleeding before 20 weeks 
  • Half of these pregnancies will result in a miscarriage but the presence of fetal cardiac activity is a positive sign 
  • Management 
    • No effective treatment exists 
    • Monitoring is done unless the pregnancy is thought to be non-viable 
• Inevitable miscarriage 
  • Vaginal bleeding and an open cervical os before 20 weeks
  • Management
    • Suction curettage  
• Incomplete miscarriage 
  • Partial expulsion of the fetal products from the uterus before 20 weeks
  • Internal cervical os is usually open and allows the passage
  • Most common between 6 and 14 weeks 
  • Management
    • Suction curettage
  • 
• Complete miscarriage 
  • Complete expulsion of the fetal products from the uterus before 20 weeks 
  • Cervical os initially open but closed at the end of complete expulsion 
  • Most common <6 weeks and >14 weeks
  • Management 
    • Managed expectantly  
  • 
• Septic abortion 
  • Fever plus one of threatened, inevitable or incomplete miscarriage before 20 weeks 
  • Retained products, illegal abortions, and legal abortions can lead to this condition 
  • Fever can be accompanied by leukocytosis, foul-smelling vaginal discharge, and lower abdominal tenderness
  • Can be fatal if sepsis develops 
  • Management 
    • Broad-spectrum antibiotics 
    • Uterine evacuation 
    • Prostaglandins may be administered to evacuate the uterus to avoid uterine perforation due to infection 
• Missed abortion 
  • Fetal demise before 20 weeks with no detachment from the placenta 
  • Products are retained for days or even weeks behind a closed cervical os
  • Symptoms can be subtle 
    • Mild bleeding after fetal demise and brown vaginal discharge that follows 
    • Rarely coagulopathy can ensue in the mother after a prolonged retention 
  • Management 
    • Individualized based on the emotional state 
    • Expectant management can be done but often difficult for the mother
    • Medically induced uterine evacuation is commonly the safest option
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