Threatened abortion is a term that comprises of spotting within the first 20 weeks of gestation without cervical dilation, and may lead to spontaneous miscarriage. It occurs in 10-25% of all pregnancies, and the cause often remains unknown. Vaginal bleeding may be accompanied by abdominal pain, and the diagnosis is made clinically and by ultrasonography. Therapy consists of treating the underlying cause, observation, and the management of accompanying diseases.
The main feature of threatened abortion is the presence of vaginal bleeding, or sometimes spotting may be encountered as well. Other symptoms include abdominal pain or cramping, back aches, or period pains, which may be overlooked, as they commonly appear during regular pregnancy. Not all threatened abortions progress to miscarriage. However, the chances are high in women that present with threatened abortion with an open cervix.
The diagnosis of threatened abortion is made during a clinical examination when the absence of cervical dilation is observed in the setting of vaginal bleeding. Other forms of abortion (incomplete, inevitable) almost always include the presence of cervical dilation. However, ultrasonography (either abdominal or vaginal) is a recommended diagnostic procedure to evaluate the status of the fetus (the fetus may be expelled in the case of missed abortion, which can also present without cervical dilation) . Additionally, levels of beta-hCG should be measured, but results may be inconclusive. It is important to obtain a diagnosis early so that appropriate steps can be taken in terms of therapy, and in the case of recurrent miscarriage, several diagnostic tools should be included, such as genetic testing, evaluation of hormonal status, and other tests .
The main therapeutic principle in threatened abortion is observation and treatment of the underlying cause, in order to prevent the development of miscarriage. Several factors, such as bed rest and avoidance of sexual intercourse have been recommended by certain studies, but with inconclusive results .
Management of accompanying illnesses, such as diabetes mellitus, hypothyroidism, is vital in minimizing the risk of pregnancy loss. Infections in early pregnancy should be treated appropriately, and screening of bacterial vaginosis with proper antibiotic therapy has resulted in reduced rates of miscarriages . The Antiphospholipid syndrome has also been established as a potential cause of pregnancy loss, and therapy consists of heparin combined with aspirin. Environmental factors, such as alcohol consumption and cigarette smoking, should be ceased or avoided, as well as drug abuse and increased caffeine intake.
Supplemental therapy with progesterone is a topic of debate across the world since numerous studies have implicated progesterone, as well as dydrogesterone (a synthetic analog of progesterone) supplementation to be beneficial for threatened miscarriage . However, more evidence is necessary to prove that it is beneficial and that it can be used in general practice.
About 30% of all threatened abortions end in eventual miscarriage and pregnancy loss, which is why it is of vital importance to establish the diagnosis promptly, and identify possible factors which may contribute to pregnancy loss. Inevitable, incomplete or complete abortion can be emotionally debilitating for couples, especially for women who experience recurrent miscarriages.
The exact causes of threatened abortion are not always identified, and it may commonly remain unknown. However, several theories have been proposed:
Numerous maternal factors have been proposed to be of influence to the fetus, including genital tract and uterine abnormalities, endocrine factors (reduced levels of progesterone and human chorionic gonadotropin (beta - hCG), poorly controlled diabetes mellitus, disorders of the thyroid gland, as well as other conditions, such as antiphospholipid syndrome, both acquired and hereditary thrombophilias, and trauma.
It is estimated that threatened abortion occurs in about 20-25% of all pregnancies, and is associated with an increased rate of fetal loss. Namely, miscarriage rates in women with threatened abortion are much higher (ranging from 15-50%) compared to women in whom this condition did not develop (between 2-7% of pregnancies result in miscarriage).
Risk factors for threatened abortion, but for other types of abortion as well, have been proposed and include:
The pathogenesis of threatened abortion is incompletely understood, as it primarily depends on the underlying cause, but several studies have implicated that progesterone levels are one of the key factors in maintaining a normal pregnancy  . Progesterone maintains the structure and function of the uterus, as well as cervical competency, and it has been established that sufficient levels of progesterone induce lymphocytic production of progesterone-induced blocking factor (PIBF), which shows anti-abortive properties in animal models . PIBF also performs other important functions during pregnancy, such as modulation of maternal immune response to mediate the reaction to the fetus, as well as relaxation of uterine smooth muscles , indicating that progesterone therapy may be a valid approach in women with threatened abortion. However, there is still no concrete evidence for progesterone use in general practice, and more studies need to be performed to solidify these findings .
Prevention of threatened miscarriage is directed at maintaining good prenatal care, which consists of regular check-ups, avoiding toxins that may harm the fetus, including alcohol, cigarettes, and certain drugs that have proven harmful effects to the fetus, while caffeine should be completely avoided, and intake of this compound should be reduced to a minimum; and management of accompanying conditions, such as diabetes, hypothyroidism, or autoimmune disorders should be done.
Threatened abortion is a term that implies vaginal bleeding before reaching 20 weeks of gestation, but without cervical dilation, and may lead to preterm delivery, low birth weight, or it may lead to fetal death and loss of pregnancy . The cause often remains unknown, but several factors have been proposed, including infectious, genetic and environmental. Risk factors for threatened abortion have been proposed, such as cigarette smoking, uterine abnormalities, previous miscarriages, use of certain drugs, reduced levels of progesterone, increased age, as well as other illnesses and conditions. Threatened abortion is estimated to occur in about 20% of early gestations, and about 50% of them will progress to miscarriage, with the majority of threatened miscarriages occurring between 14 and 20 weeks of gestation . Clinical presentation of threatened abortion, in addition to vaginal bleeding, may include abdominal pain and backache . The diagnosis can be made by clinical examination and abortion criteria, while ultrasonography is used to confirm the diagnosis, through recognizing the fetus and evaluation of vital signs. Treatment of threatened abortion includes supportive therapy, correction and proper management of other accompanying illnesses and conditions, and observation. Because of the psychological burden, it carries , proper prenatal care and avoidance of risk factors that may harm the fetus are recommended, to avoid pregnancy loss, and in the case of recurrent miscarriages, extensive evaluation should be conducted to identify the cause.
Threatened abortion is a term used to describe the presence of vaginal bleeding within the first 20 weeks of pregnancy, but without cervical dilation. It is important to note that threatened abortion does not imply pregnancy loss, it is rather a predisposing condition which may lead to miscarriage. Threatened abortion occurs in about a quarter of all pregnancies, and rates of miscarriage range from 15-50%, depending on numerous factors. Smoking, alcohol and drug abuse, age over 35 years, uterine abnormalities, poor monitoring and management of accompanying illnesses (such as diabetes mellitus) and prior miscarriages are all proposed as risk factors. The exact cause of threatened abortion is not known, while several factors have been mentioned. Infection by certain viruses has been proposed as a potential cause, while genetic defects, genital, and uterine abnormalities, as well as environmental factors, are also considered. However, the exact cause often remains unknown.
Symptoms of threatened abortion include spotting (light bleeding from the vagina), abdominal pain or cramping, back aches, while period pains may also be observed. The majority of symptoms are commonly encountered in normal pregnancy, but whenever there is the presence of bleeding, an immediate visit to the physician is necessary to identify the possible case, because threatened abortion may lead to pregnancy loss.
The diagnosis can be made during clinical examination, while ultrasound can be performed (either abdominal or vaginal) to assess the status of the fetus. In the case of recurrent pregnancy loss, a detailed diagnostic workup should be performed, including genetic testing, and evaluation of hormonal status. Treatment of threatened abortion should be directed at the underlying cause, if discovered, while supportive measures, such as bed rest and avoidance of sexual intercourse have been proposed, but a clear benefit has not been established. Supplemental use of progesterone is a topic of many discussions, because of the key roles this hormone has during pregnancy, but more evidence is necessary for this method to be used in everyday practice. Management of underlying illnesses, such as diabetes, hypothyroidism, or autoimmune diseases, should be performed, while prevention measures include proper prenatal care with regular check-ups, avoidance of risk factors that may harm the fetus, and proper management of accompanying illnesses.