Miscarriage is defined as pregnancy loss before 24 completed weeks of pregnancy. The occurrence of a miscarriage is a tragic loss for a couple trying to have a child and can be associated with significant psychological problems for the woman, their partner and family. Miscarriage is usually a single occurrence, and often followed by successful pregnancy. Recurrent miscarriage is defined as the loss of three or more consecutive pregnancies. Even after 3 consecutive losses, the chance of a successful pregnancy is over 60%. Most miscarriage occurs within the first 14 weeks of pregnancies. Maternal age and previous number of miscarriages are independent risk factors for a further miscarriage.
Vaginal bleeding is the most common symptom of a miscarriage; the bleeding may be slight spotting but sometimes very heavy with clots. The bleeding is usually followed by crampy lower abdominal pain.
Types of miscarriage (Abortion)
When vaginal bleeding is slight, there is no or mild pain, the cervix is closed and the uterus feels the correct size for date. The diagnosis of "threatened miscarriage" is made. The woman is usually advised bed rest, bleeding and pain may settle down and pregnancy may proceed normally. However, if the bleeding become very heavy, the cervix opens up and the woman complains of intense cramping, the fetus will subsequently pass out; this is called "inevitable abortion". If the fetus and placenta pass out of the womb completely, this is called "complete abortion". If any bits remain inside the cavity of the uterus it is called "incomplete abortion". The patient will then undergo evacuation of retained products of conception (ERPC) under a general anaesthetic. Should any tissue be left in the uterus there is a serious risk of infection. If infection intervenes the term "septic abortion" is used.
Sometimes, the fetus dies in the womb but not expelled, and the term "missed abortion" is used.The diagnosis of all these kinds of miscarriage is made by ultrasound scan, this may show an empty sac, viable pregnancy, retained pregnancy tissue or a dead baby. If the patient has a positive pregnancy test but there are no signs of a pregnancy on the scan, this is called "pregnancy of unknown location". A repeat scan after 7-10 days is necessary to make the diagnosis (RCOG Guidelines).
If the scan shows a gestational sac that is less than 20 mm in diameter and with no obvious yolk sac or a fetus or the scan shows a fetus less than 6 mm in length and no obvious fetal heart beating, this is called "pregnancy of uncertain viability". A repeat scan after 7-10 days is necessary to make the diagnosis (RCOG Guidelines).
Management of miscarriage
Surgical evacuation of miscarriage and routine examination of evacuated products of conception (called suction curettage) is the norm. It is the most effective method of ensuring complete evacuation of retained products of conception. Surgical evacuation is also the method of choice when bleeding is excessive or infected tissues are present in the womb cavity. Surgical evacuation provides a rapid resolution of the problem but is associated with a 2% risk of perforation of uterus.
Medical evacuation with drugs to aid expulsion of retained products is an effective alternative in selected cases. Medical management use a drug called prostaglandin analogue (misoprostol), with or without another drug called Mifepristone (also known as RU486) which blocks pregnancy hormones. The drugs are given orally or vaginally. Approximately 10% of patients treated medically will need surgical intervention to evacuate retained products of conception.
Expectant management (awaiting spontaneous passage of retained products of conception) has also been increasingly used as an alternative for certain cases provided that facilities for monitoring the patient are available. It is an effective treatment. However, it may take several weeks to resolve. About 40% of patients will need surgical intervention to remove retained products of conception.
The incidence of infection after surgical, medical or expectant management of first trimester miscarriage is low (2-3%) and the rate is independent of the method of management used (Trinder et al BMJ 2006).If the woman blood group is Rhesus negative and she miscarries after 12 weeks or experience heavy bleeding and abdominal pain, or has surgical evacuation of the pregnancy; it is important that she have Anti-D injection to prevent antibodies developing. In the vast majority of women, fertility is not impaired after miscarriage.