Recurrent miscarriage: understanding the testing process

Miscarriage can be a sad, distressing and scary experience. This is even truer if it is not the first one a person has had. Unfortunately, as many as 1% of couples trying to have a baby are experiencing recurrent miscarriage. As upsetting as this can be, it is important to identify the cause to see if there is a possible solution. Here,  distinguished consultant obstetrician and gynaecologist, Miss Elaine Scott, explains more about recurrent miscarriage. 

When should I have tests to find out the cause of recurrent miscarriage?

Most of the tests are done when the patient is not pregnant. This is because pregnancy can affect the results of some tests or make them difficult to interpret. However, if a miscarriage occurs in hospital or the patient requires a surgical procedure due to the miscarriage, genetic testing of the pregnancy tissue can be performed at the time. Your doctor will be able to advise you on this further.

What kind of tests are recommended?

The most useful tests include:

• Genetic testing of the failed pregnancy tissue to exclude chromosomal abnormalities (e.g. Down’s syndrome)
• Parental karyotype to exclude balanced reciprocal or Robertsonian translocation
• Antiphospholipid screening: anticardiolipin and lupus anticoagulant screening (these can cause blood clots and associated problems)
• Anti-thyroid antibodies, e.g. thyroid peroxidase antibodies (these are markers for autoimmune thyroid disease)
• Assessment of the uterus with 3-D vaginal ultrasound, hysteroscopy or saline transvaginal ultrasound to exclude scar tissue (adhesions within the uterus) or an abnormally shaped uterus (uterus with a dividing septum) or to exclude intracavity fibroids (fibroids within the lining of the uterus)

There are also a number of other tests that the doctor may run.

A full thrombophilia screen can exclude inherited blood clotting disorders, such as:

• MTHFR gene deficiency
• PT and aPTT test
• Protein C
• Protein S deficiency
• Factor V Leiden
• Prothrombin gene mutation
• Antithrombin III deficiency

There are also a series of investigations known as natural killer cells testing. These involve screening for a specific group of lymphocytes (white blood cells, which form part of the immune system) called natural killer cells (NK cells). Elevations in the total number of NK cells have not been shown to cause recurrent miscarriages, but elevated levels of CD-69 (a subgroup of activated NK cells) have been shown to be attributable to poor pregnancy outcome or poor outcomes in IVF.

The doctor may also order an ovarian reserve test, checking the levels of the anti-mullerian hormone. Finally, the cervix may be assessed for weakness. This is only useful in women who had late miscarriages (miscarriages between 13-23 weeks). Assessing the cervix for weakness or shortening is done by performing an ultrasound on the cervix in the second trimester of pregnancy on a fortnightly basis. Women with suspected cervical weakness may be offered a cervical stitch in a subsequent pregnancy by their doctor or ultrasound scans to exclude cervical weakness in the second trimester.

What kind of tests should I avoid?

Depending on when your miscarriage happens (early miscarriage or late miscarriage) some tests may not be useful in diagnosing the cause. Your doctor will be able to advise you on tests to avoid.

What are the chances of finding out the cause?

In approximately 50 per cent of cases, a cause or contributory factor can be found. Unfortunately, in the rest, it may continue to be unclear as to why the patient has had multiple miscarriages.

To book an appointment with Miss Elaine Scott, simply head on over to her Top Doctors profile today.