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. For most women, miscarriage is a one-off event and they go on to have successful pregnancies in the future but around 1% of couples will experience recurrent miscarriage. 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. A previous livebirth does not preclude a woman developing recurrent 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 anesthetic. 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 transvaginal scan, this is called “pregnancy of unknown location”. Blood tests to measure HCG and progesterone levels is recommended. Furthermore, a repeat scan after 7-10 days is necessary to make the diagnosis (RCOG Guidelines). The majority of women with pregnancy of unknown location attend for ultrasound examination following complete miscarriage, when the pregnancy test is still positive. Only 6-9% of these women will eventually be diagnosed with an ectopic pregnancy (Bottomly et al,Human Reproduction, 2009).
If the scan shows a gestational sac that is less than 25 mm in diameter and with no obvious yolk sac or a fetus or the scan shows a fetus less than 7 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). If the sac does not grow, it is assumed that a miscarriage has occurred. However, a recent study led by Professor Tom Bourne from Imperial College London UK found that perfectly healthy pregnancies may show no measurable growth over this period of time.
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. Expectant management 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).
A recent trial assessing the long-term follow up after expectant, medical and surgical management of spontaneous first trimester miscarriage shows that the method of miscarriage does not affect subsequent pregnancy rates with around four in five women giving birth within five years of the miscarriage (Smith et al BMJ 2009).
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 that could affect a future Rh-positive baby. In the vast majority of women, fertility
is not impaired after miscarriage.
How soon will the periods return after a miscarriage?
The periods usually return within 4 to 6 weeks, but this may vary depending on the usual menstrual cycle.
How soon can a woman try again after an initial miscarriage?
The most important thing is to try to give yourself the chance to recover emotionally and to try again when you and your partner feel ready. Depression and feeling tearful are common feelings experienced by women following a miscarriage. Many women experience feeling of guilt. These feelings may go on for weeks or months.Love and colleagues (BMJ 2010) retrospectively analysed data from Scottish hospitals for over 30,000 women who had a miscarriage between 1991 and 2000 and reported that women had the best outcome in subsequent pregnancy if they conceive within 6 month.