Miscarriage (Spontaneous Abortion)

Defined as the termination of pregnancy before 24 weeks' gestation and/or fetus/embryo weighing 500 grams or less. Ectopic pregnancy and gestational trophoblastic disease are not included. The medical term 'spontaneous abortion' should be replaced with the term 'miscarriage'.¹

Bleeding after 24 weeks is termed antepartum haemorrhage.

• Threatened miscarriage: mild symptoms of bleeding. Usually little or no pain. The cervical os is closed.
• Inevitable miscarriage: heavy bleeding with clots and pain. The cervical os is open. Excessive bleeding may cause collapse.
• Incomplete miscarriage: if either conception sac or placenta remain (or suspected).
• Missed miscarriage: fetus dead but retained. Uterus small for dates. Pregnancy test positive for several days after fetus dies. Presents with history of threatened miscarriage and persistent, dirty, brown discharge. Early pregnancy symptoms may have decreased or gone.
• Habitual or recurrent miscarriage: three or more consecutive abortions.

Often no cause is found but common recognised causes include:

• Abnormal fetal development.
• Genetic balanced parental translocation.
• Uterine abnormality.
• Incompetent cervix (second trimester).
• Placental failure.
• Multiple pregnancy.
• Immunological.
• Infections.
• Endocrine, e.g. luteal phase deficiency, polycystic ovary syndrome.

• Miscarriage occurs in 10-20% of clinical pregnancies.¹
• One study of 198 pregnancies found that 22% were lost before the expected onset of menses and another 10% were later, clinically-recognised losses.²
• 85% of spontaneous miscarriages occur in the first trimester.

Risk Factors

• Age: more frequent in women aged >30 years and even more common in those aged >35 years.
• Incidence increases with number of births: 6% in first and second pregnancies and 16% in further pregnancies.
• Cigarette smoking >14 per day doubles risk over non-smokers.
• Alcohol abuse: risk doubled with twice-weekly alcohol and trebled with daily alcohol use.
• Illicit drug use.
• Uterine surgery or abnormalities, e.g. incompetent cervix.
• Connective tissue disorders (systemic lupus erythematosus, anti-phospholipid antibodies - lupus anticoagulant/anticardiolipin antibody).
• Uncontrolled diabetes mellitus.

• Most cases present with vaginal bleeding and pain that should be worse for the patient than a period.
• Patient may also have seen products of conception but may confuse these with clots.
• Signs In cases of first trimester bleeding:
  • Is patient shocked through blood loss?
  • Are there products of conceptions in the cervical canal? (Remove with sponge forceps).
  • Is cervical os open? (External os of multigravida usually admits the tip of the finger).
  • Is bleeding from cervical lesions and not uterus?
  • Is uterine size appropriate for dates?

• Ectopic pregnancy:
  • The single most important diagnosis to exclude.
  • In ectopic pregnancy, the pain is usually greater, may be unilateral and usually precedes the bleeding.
  • Compared to a miscarriage, the loss is usually lighter and darker - almost black in some cases - and there is acute pain on manipulating the cervix ('cervical excitation').
• Neoplasia.
• Hydatiform mole.
• Chorionic cyst.
• Subchorionic haemorrhage.

Provided GPs have access to an effective Early Pregnancy Assessment Unit (EPAU) hospital admission can be avoided in up to 40% of patients.¹ The ideal EPAU should have an efficient appointments' system, ultrasound equipment (including transvaginal probes) and easy access to laboratory facilities for rhesus antibody testing and selective serum human chorionic gonadotrophin (hCG) and progesterone estimation. A regular service should run throughout the working week, ideally with additional access at weekends. Printed literature should be available for patients and standardised discharged letters sent. Women who may be at risk in the future (e.g. with a history of previous ectopic pregnancy or recurrent miscarriage) should be told how they can access the service in the event of a future pregnancy.

Investigations¹

• Ultrasound:
  • The majority of women will require a transvaginal ultrasound (TVS) and 98% of complete miscarriages can be diagnosed in this way.
  • In a number of women with a positive pregnancy test (8-31%) there are no signs of intra- or extra-uterine pregnancy or retained products of conception. The number can be reduced by increased training of ultrasonographers. Such cases are sometimes termed 'pregnancy of unknown location'.
  • Approximately a further 10% of women will have an intra-uterine sac <20 mm mean diameter with no obvious yolk sac or fetus or a fetal echo <6 mm crown–rump length with no obvious fetal heart activity. These are termed 'pregnancy of uncertain viability'. Certain recognised criteria (e.g whether on not the yolk sac is eccentric or midline) can help to determine whether the pregnancy is intra- or extra-uterine. A repeat scan at a minimal interval of one week will be required to confirm or refute viability.
  • Abdominal ultrasound is occasionally required as an adjunct to TVS.
• Serum human chorionic gonadotrophin:
  • Urine-based hCG tests can be used in the majority of women attending an EPAU. The main use of this test is to exclude an ectopic pregnancy in women with a complete miscarriage or pregnancy of unknown location determined by ultrasound.
  • Serial tests will often be required. At levels above 1500 iu/l an ectopic pregnancy will usually be seen with TVS. Levels below 1000 iu/l are seen in pregnancy of unknown location or complete miscarriage but a rapid increase (often double the initial level) is highly suspicious of ectopic pregnancy.
  • Rare causes of a raised hCG should also be borne in mind, including gestational trophoblastic disease or cranial germ cell tumour, which must be considered.
• Serum progesterone:
  • This can be a helpful adjunct when ultrasound suggests a pregnancy of unknown location.
  • A level below 25 nmol/l suggests a non-viable pregnancy.
  • A level above 25 nmol/l is likely to indicate a viable pregnancy.
  • If the level is above 60 nmol/l a normal pregnancy is highly likely.
  • A level below 20 nmol/l suggests that a pregnancy of unknown location is resorbing spontaneously and this may help to confirm whether expectant management is sufficient or whether uterine evacuation should be considered.
  • It should be emphasised that serum progesterone levels are in themselves not diagnostic and need to be supported by other tests such as serial hCGs and ultrasound.
• Histological examination of fetal tissue: If the woman miscarries at home, any tissue passed should be sent to confirm that it is fetal in origin, to exclude ectopic pregnancy and gestational trophoblastic disease.

• Admission to hospital can be avoided in 40% of women with threatened or actual early pregnancy loss.
• Following a miscarriage, all women should have access to support, follow-up and formal counselling when necessary.
• Consider rhesus prophylaxis if patient is rhesus negative - see our dedicated article on Anti-D Immunoglobulin and Rhesus Haemolytic Disease.

Conservative Management

• If a scan at the EPAU confirms a first trimester miscarriage, expectant management at home can be offered. Medical or surgical management may be needed if bleeding becomes heavy and access to 24-hour telephone advice and admission to hospital is vital.
• Women should be counselled so they are fully aware of what to expect. In most cases resorption of fetal tissue occurs without much bleeding. However loss of fetal tissue vaginally can be associated with heavy bleeding and pain and the patient may prefer to opt for medical or surgical management rather than put up with this.
• When disposing of fetal tissue which is not being sent for histology, the guidelines of the Human Tissue Authority should be followed.³
• A low serum progesterone level can be helpful in predicting those pregnancies which are most likely to resolve spontaneously.

Medical Management

• Women may opt for medical management at the initial stage or following expectant treatment. Medical management can cause more pain and bleeding than surgical management but patients who opt for this approach cite 'being in control' and avoiding general anaesthesia as the main reasons for their choice.
• The prostaglandin analogue misoprostol is the commonest medical method used. It appears to be equally effective whether given orally, sublingually or vaginally. Mifepristone - an antiprogesterone - is sometimes given to increase the efficiency of the technique.
• Women should be advised that bleeding can continue for up to three weeks.
• One randomised trial showed no statistical difference in efficacy between surgical and medical evacuation for incomplete miscarriage and for early fetal demise at gestations less than 71 days or sac diameter less than 24 mm. Patient acceptability for both methods was equal. There was a reduction in clinical pelvic infection after medical evacuation. With increasing gestation and sac size, the acceptability of medical methods fell to 85%.¹
• If bleeding is profuse consider ergometrine.

Surgical Management

• Clinical indications for offering surgical evacuation include: persistent excessive bleeding, haemodynamic instability, evidence of infected retained tissue and suspected gestational trophoblastic disease.¹
• Suction curettage is safer and easier than sharp/blunt curettage. Serious complications of surgery include perforation, cervical tears, intra-abdominal trauma, intra-uterine adhesions and haemorrhage.
• Screening for infection, including Chlamydia trachomatis, should be considered in women undergoing surgical uterine evacuation.¹
• Tissue obtained at the time of miscarriage should be examined histologically to confirm pregnancy and to exclude ectopic pregnancy or gestational trophoblastic disease.¹
• With missed abortion, confirm with ultrasound and perform suction evacuation or medical treatment with mifepristone followed by vaginal or oral prostaglandins. A minority of women may wish for conservative managements and to await events.
• Following a miscarriage, all women should have access to support, follow-up and formal counselling when necessary.

• Septic abortion:
  • Usually presents with malodorous pink vaginal discharge and fever (80% of cases where infection confined to decidua).
  • In more severe form that spreads to the uterine wall, tender lower abdomen and boggy, tender uterus. Tachycardia and occasionally leads to shock and disseminated intravascular coagulation.
  • Take high vaginal/cervical swab for culture. If temperature above 38.4 degrees C, send bloods for culture.
  • Most cases are due to E. coli, streptococci spp. and/or anaerobes. Start metronidazole with a broad spectrum antibiotic, e.g. co-amoxiclav. If necessary, modify treatments according to sensitivities.
  • Evacuate contents of uterus 12 hours later (once patient has stabilised), or earlier if bleeding severe.
  • Hysterectomy may be needed if infection uncontrolled.
• Bleeding normally ceases after complete abortion within 10 days. If part of placenta remains, bleeding may continue with cramps. Confirm with ultrasound, curette again and send tissue for histopathology to exclude choriocarcinoma.

• Threatened abortion is associated with risk of preterm delivery.
• Increased risk of further miscarriages. After three of these consider as recurrent spontaneous miscarriage.

• Encourage reduction of alcohol consumption.
• Smoking cessation and stop illicit drug use.