Threatened miscarriage

Alternative names

Abortion - threatened; Threatened spontaneous abortion

Definition

A threatened abortion is a condition of pregnancy, occurring before the 20th week of gestation, that suggests potential miscarriage may take place.

Causes, incidence, and risk factors

Approximately 20% of pregnant women experience some vaginal bleeding, with or without abdominal cramping, during the first trimester. This is known as a threatened abortion. However, most of these pregnancies go on to term with or without treatment. Spontaneous abortion occurs in less than 30% of the women who experience vaginal bleeding during pregnancy.

In the cases that result in spontaneous abortion, the usual cause is fetal death. Such death is typically the result of a chromosomal or developmental abnormality. Other potential causes include infection, maternal anatomic defects, endocrine factors, immunologic factors, and maternal systemic disease.

Estimates report that up to 50% of all fertilized eggs abort spontaneously, usually before the woman knows she is pregnant. Among known pregnancies, the rate is approximately 10%. These usually occur between 7 and 12 weeks of gestation. Increased risk is associated with women over age 35, women with systemic disease (such as diabetes or thyroid dysfunction), and those with a history of 3 or more prior spontaneous abortions.

Symptoms

• Vaginal bleeding during the first 20 weeks of pregnancy (last menstrual period was less than 20 weeks ago)
  
• Abdominal cramps may or may not accompany vaginal bleeding
  

Note: With true miscarriage, low back pain or abdominal pain (dull to sharp, constant to intermittent) typically occurs and tissue or clot-like material may pass from the vagina.

Signs and tests

Pelvic examination reveals a cervix that is neither thinned (effaced) nor open (dilated). The presence of effacement or dilation is consistent with impending miscarriage.

• A serum HCG may be performed to confirm that a pregnancy exists.
  
• Beta HCG (quantitative) test may be repeated over a period of days or weeks to confirm either continued pregnancy or fetal death.
  
• A CBC may be obtained to determine the degree of blood loss.
  
• A WBC with differential may be obtained to rule out infection.
  
• A pregnancy ultrasound is used to detect fetal heartbeat.
  

This disease may also alter the results of the following tests: