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Details miscarriage and recurrent miscarriage. The causes, investigation and treatment of miscarriage are discussed.

What is miscarriage?

Ultrasound scan

Miscarriage is defined as pregnancy loss before 24 completed weeks of pregnancy. Miscarriage is the most common adverse outcome 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 such as depression, anxiety, feeling of emptiness, guilt and failure for the woman, their partner and family. For many, the miscarriage represents the loss of their baby. Woman sometimes ask herself "Did I caused the miscarriage?", "Could I have prevented it?".

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 two or more consecutive pregnancies. Ectopic and molar pregnancies should not be included in the definition. Primary recurrent miscarriage referred to women who suffered two or more consecutive early pregnancy losses without ever having successfully given birth to a child while secondary recurrent miscarriage is referred to women suffering from recurrent miscarriage following at least one previous successful birth. Most couples want an explanation for their losses and treatment that will prevent a recurrence. Even after 3 consecutive losses, the chance of a successful pregnancy is over 60%. Nearly 125000 early miscarriages occur annually in the UK, accounting for 50000 hospital admissions.

Miscarriages are classified as early (first trimester miscarriage) or late (mid trimester miscarriage). Most miscarriage occurs within the first 14 weeks of pregnancies (first trimester miscarriage). 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 and ultrasound scan confirm viable pregnancy. 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 miscarriage". If the fetus and placenta pass out of the womb completely, this is called "complete miscarriage". If any bits remain inside the cavity of the uterus it is called "incomplete miscarriage". Should any tissue be left in the uterus there is a serious risk of infection. If infection intervenes the term "septic miscarriage " is used.  Sometimes, the fetus dies in the womb but not expelled,without associated bleeding and pain, the term "missed miscarriage" is used.

Who is at risk of miscarriage?

The older the woman at the time of conception the higher the risk of miscarriage and also if the patient had a previous one or more miscarriages she is at a higher rate of miscarriage compared to control group. Furthermore, Nelson and colleagues from Denmark reported that underweight and obesity, alcohol consumption, lifting over 20 Kg daily, and night work increase risk of miscarriage (BJOG 2014). They estimated that this risk can be reduced by reduction of these factors.

How is miscarriage diagnosed?

Clinical diagnosis of miscarriage is unreliable. Measuring the blood levels of HCG and progesterone is not routinely used in the diagnosis of miscarriage. However, the test may be useful in the diagnosis of early pregnancy failure.

The diagnosis of all kinds of miscarriage is made by ultrasound scan, usually trans-vaginal, this may show an empty sac, viable pregnancy, retained pregnancy tissue or a dead baby. Early pregnancy Assessment Unit is where the ultrasound scanning is usually carried out and decisions about management made.

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 trans-vaginal ultrasound scan shows a gestational sac that is less than 25 mm in its mean 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 7-14 days is necessary to make the diagnosis (RCOG and NICE 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

    In the United Kingdom, NICE (2021) recommend offering hormone progesterone to women who experience bleeding in early pregnancy and have previously had a miscarriage but not to women with early pregnancy bleeding but no previous miscarriage nor to women who had previous miscarriage but no early bleeding.


    The management of miscarriage has radically changed over the past two decades. Treatment options include expectant management, surgical management and medical management. Each has its own advantages and disadvantages and is selected according to women's preference, and clinical indication.

  • Surgical evacuation of miscarriage and routine examination of evacuated products of conception (called suction curettage or ERPC) is the norm. It is the most effective method of ensuring complete evacuation of retained products of conception. This can be performed either by manual vacuum aspiration under local anaesthetic in an outpatient or clinic setting or surgical management in a theatre under general anaesthetic to ensure you are sleep during the procedure. The procedure takes 5-10 minutes. You may experience some abdominal cramps following evacuation. 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. Other complications include damage to the cervix (neck of the womb, Asherman syndrome (scar tissues inside the womb), haemorrhage and infection. The Association of Early pregnancy Units and the Miscarriage Association in the UK recommended that SMM (surgical management of miscarriage) should replace the terminology of ERPC (evacuation of retained products of conception).

    Manual vacum aspiration is effective and safe alternative for surgical management of miscarriages and can be carried out in the outpatient setting under local anaesthesia in an early pregnancy assessment unit. It can be used in selected group of patients

  • Medical evacuation with drugs to aid expulsion of retained products is an effective and safe alternative to surgery in selected cases. Medical management use a drug called prostaglandin analogue (misoprostol) 800 microgramme, with or without another drug called Mifepristone (also known as RU486) which blocks pregnancy hormones progesterone. The drugs are given either orally or vaginally and both are equally effective However, vaginal route is associated with less side effects than oral route and is the route usually recommended by the doctors. The miscarriage usually occur after about 24 to 36 hours.The success rate of medical management of miscarriage is higher in women with incomplete miscarriage than women with missed miscarriage. Women are advised to take a urine pregnancy test 3 weeks after medical management of miscarriage unless they experience worsening symptoms, in which case they should to return to the healthcare professional responsible for providing their medical management. Women with a positive urine pregnancy test after 3 weeks should return for a review by a healthcare professional to ensure that there is no molar or ectopic pregnancy. Approximately 10% of patients treated medically will need surgical intervention to evacuate retained products of conception. The main side effects of these medications include pain, nausea, vomiting, fever, and diarrhoea. Heavy bleeding requiring urgent surgical intervention occurs in about !-2%. The Association of Early pregnancy Units and the Miscarriage Association in the UK recommended that MMM (medical management of miscarriage) should replace the terminology of medical evacuation and expectant management of retained products of conception
  • Expectant management (awaiting spontaneous passage of retained products of conception without intervention) 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 and is becoming an increasingly popular option. In a recent study 70% of women opted to wait for the pregnancy to resolve naturally. 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 after the miscarriage, 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.

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