Miscarriage
Other names	spontaneous abortion, early pregnancy loss
An ultrasound showing a gestational sac containing a yolk sac but no embryo
Specialty	Obstetrics and Gynaecology, Neonatology, Pediatrics
Symptoms	Vaginal bleeding with or without pain[1]
Complications	Infection, bleeding,[2] sadness, anxiety, guilt[3]
Usual onset	Before 20 weeks of pregnancy[4]
Causes	Chromosomal abnormalities,[1][5] uterine abnormalities[6]
Risk factors	Being an older parent, previous miscarriage, exposure to tobacco smoke, obesity, diabetes, autoimmune diseases, drug or alcohol use[7][8][9]
Diagnostic method	Physical examination, human chorionic gonadotropin, ultrasound[10]
Differential diagnosis	Ectopic pregnancy, implantation bleeding.[1]
Prevention	Prenatal care[11]
Treatment	Expectant management, vacuum aspiration, emotional support[8][12]
Medication	misoprostol
Frequency	10–50% of pregnancies[1][7]

Miscarriage, also known in medical terms as a spontaneous abortion, is the death and expulsion of an embryo or fetus before it can survive independently.^[1][4] The term miscarriage is sometimes used to refer to all forms of pregnancy loss and pregnancy with abortive outcomes before 20 weeks of gestation.

Miscarriage before 6 weeks of gestation is defined by ESHRE as biochemical loss.^[13][14] Once ultrasound or histological evidence shows that a pregnancy has existed, the term used is clinical miscarriage, which can be "early" before 12 weeks and "late" between 12 and 21 weeks.^[13] Fetal death after 20 weeks of gestation is also known as a stillbirth.^[15] The most common symptom of a miscarriage is vaginal bleeding with or without pain.^[1] Sadness, anxiety, and guilt may occur afterwards.^[3][16] Tissue and clot-like material may leave the uterus and pass through and out of the vagina.^[17] Recurrent miscarriage (also referred to medically as Recurrent Spontaneous Abortion or RSA)^[18] may also be considered a form of infertility.^[19]

Risk factors for miscarriage include being an older parent, previous miscarriage, exposure to tobacco smoke, obesity, diabetes, thyroid problems, and drug or alcohol use.^[7][8] About 80% of miscarriages occur in the first 12 weeks of pregnancy (the first trimester).^[1] The underlying cause in about half of cases involves chromosomal abnormalities.^[5][1] Diagnosis of a miscarriage may involve checking to see if the cervix is open or sealed, testing blood levels of human chorionic gonadotropin (hCG), and an ultrasound.^[10] Other conditions that can produce similar symptoms include an ectopic pregnancy and implantation bleeding.^[1]

Prevention is occasionally possible with good prenatal care.^[11] Avoiding drugs, alcohol, infectious diseases, and radiation may decrease the risk of miscarriage.^[11] No specific treatment is usually needed during the first 7 to 14 days.^[8][12] Most miscarriages will be completed without additional interventions.^[8] Occasionally the medication misoprostol or a procedure such as vacuum aspiration is used to remove the remaining tissue.^[12][20] Women who have a blood type of rhesus negative (Rh negative) may require Rho(D) immune globulin.^[8] Pain medication may be beneficial.^[12] Emotional support may help with processing the loss.^[12]

Miscarriage is the most common complication of early pregnancy.^[21] Among women who know they are pregnant, the miscarriage rate is roughly 10% to 20%, while rates among all fertilisation is around 30% to 50%.^[1][7] In those under the age of 35, the risk is about 10% while in those over the age of 40, the risk is about 45%.^[1] Risk begins to increase around the age of 30.^[7] About 5% of women have two miscarriages in a row.^[22] Some recommend not using the term "abortion" in discussions with those experiencing a miscarriage to decrease distress.^[23] In Britain, the term "miscarriage" has replaced any use of the term "spontaneous abortion" for pregnancy loss and in response to complaints of insensitivity towards women who had suffered such loss.^[24] An additional benefit of this change is reducing confusion among medical laymen, who may not realize that the term "spontaneous abortion" refers to a naturally occurring medical phenomenon and not the intentional termination of pregnancy.

Signs and symptoms

Signs of a miscarriage include vaginal spotting, abdominal pain, cramping, fluid, blood clots, and tissue passing from the vagina.^[25][26][27] Bleeding can be a symptom of miscarriage, but many women also have bleeding in early pregnancy and do not miscarry.^[28] Bleeding during the first half of pregnancy may be referred to as a threatened miscarriage.^[29] Of those who seek treatment for bleeding during pregnancy, about half will miscarry.^[30] Miscarriage may be detected during an ultrasound exam or through serial human chorionic gonadotropin (HCG) testing.

Risk factors

Miscarriage may occur for many reasons, not all of which can be identified. Risk factors are those things that increase the likelihood of having a miscarriage but do not necessarily cause a miscarriage. Up to 70 conditions,^{[1][5][31][32][33][34]} infections,^[35][36][37] medical procedures,^[38][39][40] lifestyle factors,^{[7][8][41][35][42]} occupational exposures,^[11][43][44] chemical exposure,^[44] and shift work are associated with increased risk for miscarriage.^[45] Some of these risks include endocrine, genetic, uterine, or hormonal abnormalities, reproductive tract infections, and tissue rejection caused by an autoimmune disorder.^[46]

Trimesters

First trimester

Most clinically apparent miscarriages (two-thirds to three-quarters in various studies) occur during the first trimester.^{[1][35][49][50]} About 30% to 40% of all fertilised eggs miscarry, often before the pregnancy is known.^[1] The embryo typically dies before the pregnancy is expelled; bleeding into the decidua basalis and tissue necrosis cause uterine contractions to expel the pregnancy.^[50] Early miscarriages can be due to a developmental abnormality of the placenta or other embryonic tissues. In some instances, an embryo does not form but other tissues do. This has been called a "blighted ovum".^[51][52][47]

Successful implantation of the zygote into the uterus is most likely eight to ten days after fertilization. If the zygote has not been implanted by day ten, implantation becomes increasingly unlikely in subsequent days.^[53]

A chemical pregnancy is a pregnancy that was detected by testing but ends in miscarriage before or around the time of the next expected period.^[54]

Chromosomal abnormalities are found in more than half of embryos miscarried in the first 13 weeks. Half of embryonic miscarriages (25% of all miscarriages) have an aneuploidy (abnormal number of chromosomes).^[55] Common chromosome abnormalities found in miscarriages include an autosomal trisomy (22–32%), monosomy X (5–20%), triploidy (6–8%), tetraploidy (2–4%), or other structural chromosomal abnormalities (2%).^[50] Genetic problems are more likely to occur with older parents; this may account for the higher rates observed in older women.^[56]

Luteal phase progesterone deficiency may or may not be a contributing factor to miscarriage.^[57]

Second and third trimesters

Second-trimester losses may be due to maternal factors such as uterine malformation, growths in the uterus (fibroids), or cervical problems.^[35] These conditions also may contribute to premature birth.^[49] Unlike first-trimester miscarriages, second-trimester miscarriages are less likely to be caused by a genetic abnormality; chromosomal aberrations are found in a third of cases.^[50] Infection during the third trimester can cause a miscarriage.^[35]

Age

The age of the pregnant woman is a significant risk factor. Miscarriage rates increase steadily with age, with more substantial increases after age 35.^[58] In those under the age of 35, the risk is about 10% while it is about 45% in those over the age of 40.^[1] Risk begins to increase around the age of 30.^[7] Paternal age is associated with increased risk.^[59]

Obesity, eating disorders and caffeine

Not only is obesity associated with miscarriage; it can result in sub-fertility and other adverse pregnancy outcomes. Recurrent miscarriage is also related to obesity. Women with bulimia nervosa and anorexia nervosa may have a greater risk for miscarriage. Nutrient deficiencies have not been found to impact miscarriage rates but hyperemesis gravidarum sometimes precedes a miscarriage.^[43]

Caffeine consumption also has been correlated to miscarriage rates, at least at higher levels of intake.^[35] However, such higher rates are statistically significant only in certain circumstances.

Vitamin supplementation has generally not shown to be effective in preventing miscarriage.^[60] Chinese traditional medicine has not been found to prevent miscarriage.^[27]

Endocrine disorders

Disorders of the thyroid may affect pregnancy outcomes. Related to this, iodine deficiency is strongly associated with an increased risk of miscarriage.^[43] The risk of miscarriage is increased in those with poorly controlled insulin-dependent diabetes mellitus.^[43] Women with well-controlled diabetes have the same risk of miscarriage as those without diabetes.^[61][62]

Food poisoning

Ingesting food that has been contaminated with listeriosis, toxoplasmosis, and salmonella is associated with an increased risk of miscarriage.^[35][19]

Amniocentesis and chorionic villus sampling

Amniocentesis and chorionic villus sampling (CVS) are procedures conducted to assess the fetus. A sample of amniotic fluid is obtained by the insertion of a needle through the abdomen and into the uterus. Chorionic villus sampling is a similar procedure with a sample of tissue removed rather than fluid. These procedures are not associated with pregnancy loss during the second trimester but they are associated with miscarriages and birth defects in the first trimester.^[40] Miscarriage caused by invasive prenatal diagnosis (chorionic villus sampling (CVS) and amniocentesis) is rare (about 1%).^[39]

Surgery

The effects of surgery on pregnancy are not well-known including the effects of bariatric surgery. Abdominal and pelvic surgery are not risk factors for miscarriage. Ovarian tumours and cysts that are removed have not been found to increase the risk of miscarriage. The exception to this is the removal of the corpus luteum from the ovary. This can cause fluctuations in the hormones necessary to maintain the pregnancy.^[63]

Medications

There is no significant association between antidepressant medication exposure and miscarriage.^[64] The risk of miscarriage is not likely decreased by discontinuing SSRIs before pregnancy.^[65] Some available data suggest that there is a small increased risk of miscarriage for women taking any antidepressant,^[66][67] though this risk becomes less statistically significant when excluding studies of poor quality.^[64][68]

Medicines that increase the risk of miscarriage include:

• retinoids
• nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen
• misoprostol
• methotrexate^[35]
• statins^[69]

Immunisations

Immunisations have not been found to cause miscarriage.^[70] Live vaccinations, like the MMR vaccine, can theoretically cause damage to the fetus as the live virus can cross the placenta and potentially increase the risk for miscarriage.^[71][72] Therefore, the Center for Disease Control (CDC) recommends against pregnant women receiving live vaccinations.^[73] However, there is no clear evidence that has shown live vaccinations increase the risk of miscarriage or fetal abnormalities.^[72]

Some live vaccinations include: MMR, varicella, certain types of the influenza vaccine, and rotavirus.^[74][75]

Treatments for cancer

Ionising radiation levels given to a woman during cancer treatment cause miscarriage. Exposure can also impact fertility. The use of chemotherapeutic drugs to treat childhood cancer increases the risk of future miscarriage.^[43]

Pre-existing diseases

Several pre-existing diseases in pregnancy can potentially increase the risk of miscarriage, including diabetes, endometriosis, polycystic ovary syndrome (PCOS), hypothyroidism, certain infectious diseases, and autoimmune diseases. Women with endometriosis report a 76^[76] to 298%^[77] increase in miscarriages versus their non-afflicted peers, the range affected by the severity of their disease. PCOS may increase the risk of miscarriage.^[35] Two studies suggested treatment with the drug metformin significantly lowers the rate of miscarriage in women with PCOS,^[78][79] but the quality of these studies has been questioned.^[80] Metformin treatment in pregnancy is not safe.^[81] In 2007, the Royal College of Obstetricians and Gynaecologists also recommended against the use of the drug to prevent miscarriage.^[80] Thrombophilias or defects in coagulation and bleeding were once thought to be a risk of miscarriage but have been subsequently questioned.^[82] Severe cases of hypothyroidism increase the risk of miscarriage. The effect of milder cases of hypothyroidism on miscarriage rates has not been established. A condition called luteal phase defect (LPD) is a failure of the uterine lining to be fully prepared for pregnancy. This can keep a fertilised egg from implanting or result in miscarriage.^[83]

Mycoplasma genitalium infection is associated with an increased risk of preterm birth and miscarriage.^[37]

Infections can increase the risk of a miscarriage: rubella (German measles), cytomegalovirus, bacterial vaginosis, HIV, chlamydia, gonorrhoea, syphilis, and malaria.^[35]

Immune status

Autoimmunity is a possible cause of recurrent or late-term miscarriages. In the case of an autoimmune-induced miscarriage, the woman's body attacks the growing fetus or prevents normal pregnancy progression.^[9][84] Autoimmune disease may cause abnormalities in embryos, which in turn may lead to miscarriage. As an example, coeliac disease increases the risk of miscarriage by an odds ratio of approximately 1.4.^[33][34] A disruption in normal immune function can lead to the formation of antiphospholipid antibody syndrome. This will affect the ability to continue the pregnancy, and if a woman has repeated miscarriages, she can be tested for it.^[44] Approximately 15% of recurrent miscarriages are related to immunologic factors.^[85] The presence of anti-thyroid autoantibodies is associated with an increased risk with an odds ratio of 3.73 and 95% confidence interval 1.8–7.6.^[86] Having lupus also increases the risk of miscarriage.^[87] Immunohistochemical studies on decidual basalis and chorionic villi found that the imbalance of the immunological environment could be associated with recurrent pregnancy loss.^[88]

Anatomical defects and trauma

Fifteen per cent of women who have experienced three or more recurring miscarriages have some anatomical defect that prevents the pregnancy from being carried for the entire term.^[89] The structure of the uterus affects the ability to carry a child to term. Anatomical differences are common and can be congenital.^[90]

In some women, cervical incompetence or cervical insufficiency occurs with the inability of the cervix to stay closed during the entire pregnancy.^[36][35] It does not cause first-trimester miscarriages. In the second trimester, it is associated with an increased risk of miscarriage. It is identified after a premature birth has occurred at about 16–18 weeks into the pregnancy.^[89] During the second trimester, major trauma can result in a miscarriage.^[34]

Smoking

Tobacco (cigarette) smokers have an increased risk of miscarriage.^[41][35] There is an increased risk regardless of which parent smokes, though the risk is higher when the gestational mother smokes.^[42]

Morning sickness

Nausea and vomiting of pregnancy (NVP, or morning sickness) are associated with a decreased risk. Several possible causes have been suggested for morning sickness but there is still no agreement.^[91] NVP may represent a defence mechanism which discourages the mother's ingestion of foods that are harmful to the fetus; according to this model, a lower frequency of miscarriage would be an expected consequence of the different food choices made by women experiencing NVP.^[92]

Chemicals and occupational exposure

Chemical and occupational exposures may have some effect on pregnancy outcomes.^[93] A cause-and-effect relationship can almost never be established. Those chemicals that are implicated in increasing the risk for miscarriage are DDT, lead,^[94] formaldehyde, arsenic, benzene and ethylene oxide. Video display terminals and ultrasound have not been found affect the rates of miscarriage. In dental offices where nitrous oxide is used with the absence of anaesthetic gas scavenging equipment, there is a greater risk of miscarriage. For women who work with cytotoxic antineoplastic chemotherapeutic agents, there is a small increased risk of miscarriage. No increased risk for cosmetologists has been found.^[44]

Other

Alcohol increases the risk of miscarriage.^[35] Cocaine use increases the rate of miscarriage.^[41] Some infections have been associated with miscarriage. These include Ureaplasma urealyticum, Mycoplasma hominis, group B streptococci, HIV-1, and syphilis. Chlamydia trachomatis may increase the risk of miscarriage.^[35] Toxoplasmosis can cause a miscarriage.^[95] Subclinical infections of the lining of the womb, commonly known as chronic endometritis are also associated with poor pregnancy outcomes, compared to women with treated chronic endometritis or no chronic endometritis.^[96]

Diagnosis

In the case of blood loss, pain, or both, transvaginal ultrasound is performed. If a viable intrauterine pregnancy is not found with ultrasound, blood tests (serial βHCG tests) can be performed to rule out ectopic pregnancy, which is a life-threatening situation.^[97][98]

If hypotension, tachycardia, and anaemia are discovered, the exclusion of an ectopic pregnancy is important.^[98]

A miscarriage may be confirmed by an obstetric ultrasound and by the examination of the passed tissue. When looking for microscopic pathologic symptoms, one looks for the products of conception. Microscopically, these include villi, trophoblast, fetal parts, and background gestational changes in the endometrium. When chromosomal abnormalities are found in more than one miscarriage, genetic testing of both parents may be done.^[99]

Ultrasound criteria

A review article in The New England Journal of Medicine based on a consensus meeting of the Society of Radiologists in Ultrasound in America (SRU) has suggested that miscarriage should be diagnosed only if any of the following criteria are met upon ultrasonography visualisation:^[100]

Classificationedit

A threatened miscarriage is any bleeding during the first half of pregnancy.^[29] At investigation, it may be found that the fetus remains viable and the pregnancy continues without further problems.^{[medical citation needed]}

An anembryonic pregnancy (also called an "empty sac" or "blighted ovum") is a condition where the gestational sac develops normally, while the embryonic part of the pregnancy is either absent or stops growing very early. This accounts for approximately half of miscarriages. All other miscarriages are classified as embryonic miscarriages, meaning that there is an embryo present in the gestational sac. Half of embryonic miscarriages have aneuploidy (an abnormal number of chromosomes).^[50]

An inevitable miscarriage occurs when the cervix has already dilated,^[102] but the foetus has yet to be expelled. This usually will progress to a complete miscarriage. The foetus may or may not have cardiac activity.

A complete miscarriage is when all products of conception have been expelled; these may include the trophoblast, chorionic villi, gestational sac, yolk sac, and fetal pole (embryo); or later in pregnancy the foetus, umbilical cord, placenta, amniotic fluid, and amniotic membrane. The presence of a pregnancy test that is still positive, as well as an empty uterus upon transvaginal ultrasonography, does, however, fulfil the definition of pregnancy of unknown location. Therefore, there may be a need for follow-up pregnancy tests to ensure that there is no remaining pregnancy, including ectopic pregnancy.^{[citation needed]}

An incomplete miscarriage occurs when some products of conception have been passed, but some remain inside the uterus.^[103] However, an increased distance between the uterine walls on transvaginal ultrasonography may also simply be an increased endometrial thickness and/or a polyp. The use of a Doppler ultrasound may be better in confirming the presence of significant retained products of conception in the uterine cavity.^[104] In cases of uncertainty, ectopic pregnancy must be excluded using techniques like serial beta-hCG measurements.^[104]

A missed miscarriage is when the embryo or fetus has died, but a miscarriage has not yet occurred. It is also referred to as delayed miscarriage, silent miscarriage, or missed abortion.^[105][106] Zdroj:https://en.wikipedia.org?pojem=Miscarriage
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