Miscarriage is defined as fetal demised and/or expulsion before the fetus reaches viability (ability to survive if delivered). The gestation in which a fetus is considered viable varies between 20 to 24 weeks in different countries. In the United Kingdom it is less than 24 weeks gestation, while the WHO uses less than 22 weeks or if fetus weigh less than 500 gm. In Malaysia, a fetus weighing less than 500gm is considered as a miscarriage or if it is less than 22 weeks gestation. It is the commonest complication of early pregnancy, with an incidence of 8-20% among known pregnant women. The majority (80%) occurs in early pregnancy, usually between the 9th to the 13th week.
Causes
There are many factors which can lead to a miscarriage but in the overwhelmingly large majority of cases, no cause cannot be identified. Some of the known causes of miscarriage include;
- Chromosomal abnormality: this is the commonest cause of miscarriage that occurs in early pregnancy or in the first 13 weeks.
- Mothers with specific medical conditions: e.g. uncontrolled diabetes mellitus, uterine abnormalities, positive for anti-phospholipid syndrome or those with infection
Factors which may increase the risk of miscarriage
The factors below are not direct cause of miscarriage but patients with these conditions have a higher risk of miscarriage:
- Mother’s age: older mothers have a higher risk of heaving foetuses with chromosomal abnormalities compared to younger mothers.
- Previous history of miscarriage: e.g. with history of 1 previous miscarriage, the risk miscarriage in the next pregnancy is 20%. With 2 previous consecutive miscarriage the risk is 30%. The risk increases to 43% if she has had 3 or more previous miscarriages.
- Smoking: smoking (or passive smoking – inhaling smoke) more than 10 sticks a day increases the risk of miscarriage.
- Alcohol: consumption of alcohol is associated with a slight increase in miscarriage rate.
- High grade fever
- Trauma: to the uterus during pregnancy (e.g. road traffic accidents, fall, abdominal massage). This also include invasive procedures like amniocentesis or chronic villous sampling.
- Caffeine: excessive intake of coffee or caffeinated drinks (Cola) is not advisable. Mothers are recommended not to take more than 300mg a day.
- Other causes: the risk increase if the mother is exposed to infections, certain medications or drugs, severe physical stress, radiation, or chemicals.
Types of miscarriages
- Threatened miscarriage – the mother will usually experience only minimal vaginal bleeding or ‘spotting’ and either slight or no pain at the lower abdomen. The cervix is closed and the uterine (rahim) size is equal to the gestation age. An ultrasound scan would show a viable or living fetus. In large majority of cases, bleeding will stop and the pregnancy continue to progress.
- Missed miscarriage – These are fetuses that are no longer viable but usually did not present with the signs and symptoms of miscarriage. The mothers usually stop having morning sickness and the uterus is usually smaller than the gestation age. The ultrasound would show a pregnancy which is smaller than the gestation and the fetus does not show any signs of life. Occasionally, these mothers may present with per vaginal spotting.
- Inevitable miscarriage- The fetus will usually end up being expulsed. In such cases, the mother will experience significant lower abdominal pain. The cervix is usually open and vaginal bleeding may be profuse. The uterine size is equal to the gestation age and the fetus may or may not be alive.
- Incomplete miscarriage- Part of the fetus or placenta may have been expulsed but some still remains in the uterus. The uterine size is usually smaller than her gestation. The cervix is open and is associated with profuse vaginal bleeding and significant lower abdominal pain. There is a risk the patient might go into hypovolemic shock and collapse due to the excessive bleeding and pain, if the remaining tissue in the uterus is not evacuated or removed.
- Complete miscarriage- The mother will give a history of expelling out some tissue from the vagina and after that the vaginal bleeding and pain decreases. The uterus will be smaller than the gestation. The ultrasound may show an empty uterus. The cervix may still be partially open initially but will close after a couple of days. The mother will stop having early morning sickness.
- Septic miscarriage- Any of the above types of miscarriage which is complicated with infection of the uterus. Symptoms include fever, vaginal bleeding and discharge (yellowish, thick and foul smelling).
Clinical presentation
Symptoms include vaginal bleeding and lower abdominal pain. This bleeding and pain can become more severe and it’s advisable to seek medical attention if it occurs.
Diagnosis
In most cases, ultrasound is use to determine if the foetus is viable or not. Ultrasound is also important to determine the location of the foetus (see ectopic pregnancy)
Treatment
- Observation- most mother do not need medical or surgical treatment. If miscarriage occurs below 13 weeks and the mother is stable (no excessive vaginal bleeding and no signs of infection), she can be treated conservatively. The foetus usually expels spontaneously in a week or two, however, uncommonly it can happen 3 to 4 weeks later. Once the foetus has been expelled, the doctor will do an ultrasound to rule our retained product of conception.
- Medical treatment– in some conditions, the doctor may insert tablets into the vagina and/or pills to be taken orally by the mother to expel the dead foetus.
- Surgical treatment– this procedure is called dilatation & curettage (D&C). The doctor, under anaesthesia, will dilate the cervix and curette out the product of conception. D&C is perform if the mother do not wish to wait for spontaneous expulsion of the foetus or vaginal bleeding is severe.
What happens after a miscarriage?
After miscarriage, the mother is advice not to insert any foreign objects (tampon) or douching for 2 weeks. Usually it is advisable to wait 2 to 3 months before trying to get pregnant again. There are no contraindications for family planning (even IUCD) after a miscarriage. In severe anaemic patient, hematinic may be given and antibiotic are given if infection occurs or suspected.
| Last Reviewed | : | 23 August 2019 |
| Writer / Translator | : | Dr. Hj. Mohamed Hatta b. Mohamed Tarmizi |
| Accreditor | : | Dr. Haris Njoo Suharjono |
| Reviewer | : | Dr. Rafaie bin Amin |
