This article needs additional citations for verification .(September 2010) |
Antepartum bleeding | |
---|---|
Other names | Antepartum haemorrhage (APH), prepartum haemorrhage |
Specialty | Obstetrics ![]() |
Antepartum bleeding, also known as antepartum haemorrhage (APH) or prepartum hemorrhage, is genital bleeding during pregnancy after the 28th week of pregnancy up to delivery. [1] [2]
It can be associated with reduced fetal birth weight. [3] Use of aspirin before 16 weeks of pregnancy to prevent pre-eclampsia also appears effective at preventing antepartum bleeding. [4]
In regard to treatment, it should be considered a medical emergency (regardless of whether there is pain), as if it is left untreated it can lead to death of the mother or baby.
The total amount of blood loss and signs of circulatory shock due to blood determine the severity of the antepartum haemorrhaging. There are 4 degrees of antepartum haemorrhaging: [5]
Stage | Amount of Blood Loss |
---|---|
Spotting | Stains, streaking, or spotting of blood |
Minor Haemorrhage | Less than 50mL |
Major Haemorrhage | 50-1000mL without signs of circulatory shock |
Massive Haemorrhage | Greater than 1000mL with or without signs of circulatory shock |
Placenta praevia refers to when the placenta of a growing foetus is attached abnormally low within the uterus. Intermittent antepartum haemorrhaging occurs in 72% of women living with placenta praevia. [6] The severity of a patient's placenta praevia depends on the location of placental attachment;
Type | Location of Placental Attachment |
---|---|
Type 1 | Lower segment of uterus, no attachment to the cervix |
Type 2 | Touching but not covering the internal orifice of the cervix |
Type 3 | Partially covering the internal orifice of the cervix |
Type 4 | Completely covering the internal orifice of the cervix |
Types 1 and 2 are classified as minor placental praevia as these typically result in minor antepartum haemorrhaging. Types 3 and 4 are referred to as major placental praevia due to the risk of heavy haemorrhaging in the case of a rupture due to the location of placental attachment. [7] During the third trimester of pregnancy, thinning of the lower uterine segment or contractions caused by cervical dilation can increase the amount of stress placed on the placental attachment to the uterine wall. In patients with placenta praevia, these stresses can cause detachment of the placenta from the uterine wall causing haemorrhaging. To prevent further haemorrhaging patients with major placental praevia are recommended to have a caesarean delivery. [8]
During pregnancy the layer of endometrium that attaches directly to developing blastocyst becomes the maternal portion of the placenta, also known as the decidua basalis. [9] In the absence of a decidua basalis, trophoblast cells on the developing blastocyst form an abnormally deep attachment to the uterine wall, this is known as abnormal placentation. Abnormal placentation can categorised into 3 types, depending on the depth of infiltration of the chorionic villi into the uterine wall: [10]
Type | Depth of Chorionic Villus |
---|---|
Placenta Accreta | Attached to outermost portion of the myometrium |
Placenta Increta | Invading the myometrium |
Placenta Percreta | Invading past the myometrium into the perimetrium |
In placenta percreta, the chorionic villi have grow entirely through the myometrium and invade into the perimetrium. Placenta percreta results in the most intense haemorrhaging that can be expected caused by abnormal placentation. In the event of placental detachment from the uterine wall, the depth of chorionic villi attachment dictates the amount of haemorrhaging that can be expected. [11] The chance of abnormal placentation increases in subsequent pregnancies, if there is scar tissue present from previous pregnancies. For example, previously undergoing a caesarean or placenta previa increases the likelihood of abnormal placentation, therefore increasing the chances of antepartum haemorrhaging. [12]
Placental abruption occurs when the placenta detaches from the endometrium. Detachment causes antepartum haemorrhaging at the location of abruption. Depending on the site of detachment, haemorrhaging may or may not be apparent. If abruption occurs behind the placenta where blood cannot escape through the cervix, blood will pool and form a retroplacental clot. Only when the site of detachment occurs on the side facing the cervical opening can the total amount of haemorrhaging be measured by vaginal bleeding. Using vaginal bleeding as a measurement of the severity of the placental abruption is therefore ineffective. The scale of haemorrhaging depends on the degree to which the placenta has separated from the uterine wall. In the case of partial placental separation, haemorrhaging can be minor. However, in the case of total placental separation haemorrhaging will be major and emergency delivery will typically be the course of action. [13] Placental abruption causes blood loss from the mother and loss of oxygen and nutrients to the placenta occasionally leading to preterm labour. [14] Other causes of placental abruption can be abdominal trauma or sudden decompression of amniotic fluid, however it is not uncommon for the cause of placental abruption to be unknown. [15]
Vasa praevia is the presence of unprotected foetal blood vessels running along the placenta and over the internal cervical opening. Vasa praevia is a very rare, presenting only 4:10,000 cases from the largest study of the condition. [16] Risks of antepartum bleeding due to vasa praevia greatly increase during the third trimester of pregnancy during cervical dilation or placenta praevia. Vessel rupture is very likely in the event of a membranous rupture as foetal blood vessels aren't protected by the umbilical cord of the placenta. In the event of foetal vessel rupture, antepartum haemorrhaging occurs however blood is lost from the foetal blood supply. If the foetus is developed enough caesarean sections are often recommended. [17]
A circumvallate placenta refers to when the foetal membrane wraps twice around, over the foetal side around the edge of the placenta. This is to compensate for an undersized chorionic plate resulting in a decreased nutritional supply to the foetus. Thickening of the placental edge due to a circumvallate placenta can lead to placental abruption, causing antepartum haemorrhaging. [18]
A bilobed placenta has a cleavage in the middle dividing it into two lobes with membranous vessels branching in between. The exposed connecting membranous vessels present risk of rupturing due to limited protection from thrombosis and trauma. Bilobing of the placenta can be caused by placental implantation occurring over areas of uterine fibroid scarring, previous surgery, decreased blood supply or implantation occurring over the internal cervical orifice. Chances of vasa previa and placental abruption increase in the presence of a bilobed placenta due to decreased surface area for attachment to the uterine wall and the exposure of membranous vessels. [19]
When a placenta has multiple lobes which are distal and not of equal size this is referred to as a succenturiate placenta. Distal lobes are connected by a placental artery and vein extending from the main placenta, which tends to be centrally located and is the largest in mass. [20] At the time of contraction or delivery the connecting placental arteries and veins may rupture resulting in significant haemorrhaging. Incidences of vasa previa and haemorrhaging in the presence of a succenturiate placenta are highly increased. [21]
Cervical ectropion
There are 2 types of epithelial cells present within the cervical canal. In the endocervix the epithelia is columnar glandular which transitions into stratified squamous towards the ectocervix and external cervical orifice. During cervical ectropion the epithelial transitional zone (also called the squamo-columnar junction) migrates from the endocervical canal towards the ectocervix exposing some columnar glandular cells on the external cervical orifice. Unlike stratified squamous epithelial cells, glandular cells are columnar and not used to external stresses such as abrasion. The translocation of these cells causes bleeding and mucus secretion. Cervical ectropion can be attributed to rises in oestrogen levels during foetal development. Antepartum haemorrhage caused by cervical ectropion can be expected and is typically harmless. [22]
Vaginal infection
The presence of severe vaginal infections at the time of pregnancy may cause minor antepartum haemorrhaging. For example, the presence of chlamydia, thrush, cervicitis or other infections are all irritants to the vaginal and cervical lining, causing bleeding from those surfaces where the infection is severe. [23]
Cervical canal and distal genital tract
Most cases of Antepartum haemorrhaging originate from within the cervical canal or vagina. The amount of bleeding in these areas are typically limited to spotting or minor antepartum haemorrhaging. Cervical ectropion, dysplasia, polyps or cervical carcinoma may cause lesions in the cervix leading to minor haemorrhaging or spotting. Abrasion or slight trauma caused by intercourse, clinical examinations and pap smear may also cause spotting from the cervix. Vaginal bleeding from atrophy, vaginitis, and ulcers also attribute to minor haemorrhaging. Similarly, varicosities, tumours or inflammation in the vulva can cause minor antepartum haemorrhaging. Non genital tract bleeding caused by haematuria or haemorrhoids can often be mistaken for antepartum haemorrhaging and are typically harmless. [24]
Endometriosis
Estimates of the frequency of endometriosis in women range between 6-15% across several sources. In a 30-year reproductive and pregnancy outcome study of 14,000+ women, those with endometriosis had a significantly increased risk of antepartum haemorrhage during pregnancy. [25]
Obstetrics is the field of study concentrated on pregnancy, childbirth and the postpartum period. As a medical specialty, obstetrics is combined with gynecology under the discipline known as obstetrics and gynecology (OB/GYN), which is a surgical field.
Placenta praevia is when the placenta attaches inside the uterus but in a position near or over the cervical opening. Symptoms include vaginal bleeding in the second half of pregnancy. The bleeding is bright red and tends not to be associated with pain. Complications may include placenta accreta, dangerously low blood pressure, or bleeding after delivery. Complications for the baby may include fetal growth restriction.
Placental abruption is when the placenta separates early from the uterus, in other words separates before childbirth. It occurs most commonly around 25 weeks of pregnancy. Symptoms may include vaginal bleeding, lower abdominal pain, and dangerously low blood pressure. Complications for the mother can include disseminated intravascular coagulopathy and kidney failure. Complications for the baby can include fetal distress, low birthweight, preterm delivery, and stillbirth.
Vaginal bleeding is any expulsion of blood from the vagina. This bleeding may originate from the uterus, vaginal wall, or cervix. Generally, it is either part of a normal menstrual cycle or is caused by hormonal or other problems of the reproductive system, such as abnormal uterine bleeding.
Bloody show or show is the passage of a small amount of blood or blood-tinged mucus through the vagina near the end of pregnancy. It is caused by thinning and dilation of the cervix, leading to detachment of the cervical mucus plug that seals the cervix during pregnancy and tearing of small cervical blood vessels, and is one of the signs that labor may be imminent. The bloody show may be expelled from the vagina in pieces or altogether and often appears as a jelly-like piece of mucus stained with blood. Although the bloody show may be alarming at first, it is not a concern of patient health after 37 weeks gestation.
Obstetrical bleeding is bleeding in pregnancy that occurs before, during, or after childbirth. Bleeding before childbirth is that which occurs after 24 weeks of pregnancy. Bleeding may be vaginal or less commonly into the abdominal cavity. Bleeding which occurs before 24 weeks is known as early pregnancy bleeding.
Complications of pregnancy are health problems that are related to, or arise during pregnancy. Complications that occur primarily during childbirth are termed obstetric labor complications, and problems that occur primarily after childbirth are termed puerperal disorders. While some complications improve or are fully resolved after pregnancy, some may lead to lasting effects, morbidity, or in the most severe cases, maternal or fetal mortality.
Placenta accreta occurs when all or part of the placenta attaches abnormally to the myometrium. Three grades of abnormal placental attachment are defined according to the depth of attachment and invasion into the muscular layers of the uterus:
Uterine atony is the failure of the uterus to contract adequately following delivery. Contraction of the uterine muscles during labor compresses the blood vessels and slows flow, which helps prevent hemorrhage and facilitates coagulation. Therefore, a lack of uterine muscle contraction can lead to an acute hemorrhage, as the vasculature is not being sufficiently compressed. Uterine atony is the most common cause of postpartum hemorrhage, which is an emergency and potential cause of fatality. Across the globe, postpartum hemorrhage is among the top five causes of maternal death. Recognition of the warning signs of uterine atony in the setting of extensive postpartum bleeding should initiate interventions aimed at regaining stable uterine contraction.
Postpartum bleeding or postpartum hemorrhage (PPH) is often defined as the loss of more than 500 ml or 1,000 ml of blood following childbirth. Some have added the requirement that there also be signs or symptoms of low blood volume for the condition to exist. Signs and symptoms may initially include: an increased heart rate, feeling faint upon standing, and an increased breathing rate. As more blood is lost, the patient may feel cold, blood pressure may drop, and they may become restless or unconscious. In severe cases circulatory collapse, disseminated intravascular coagulation and death can occur. The condition can occur up to twelve weeks following delivery in the secondary form. The most common cause is poor contraction of the uterus following childbirth. Not all of the placenta being delivered, a tear of the uterus, or poor blood clotting are other possible causes. It occurs more commonly in those who already have a low amount of red blood, are Asian, have a larger fetus or more than one fetus, are obese or are older than 40 years of age. It also occurs more commonly following caesarean sections, those in whom medications are used to start labor, those requiring the use of a vacuum or forceps, and those who have an episiotomy.
Vasa praevia is a condition in which fetal blood vessels cross or run near the internal opening of the uterus. These vessels are at risk of rupture when the supporting membranes rupture, as they are unsupported by the umbilical cord or placental tissue.
A vaginal delivery is the birth of offspring in mammals through the vagina. It is the most common method of childbirth worldwide. It is considered the preferred method of delivery, as it is correlated with lower morbidity and mortality than caesarean sections (C-sections), though it is not clear whether this is causal.
Uterine inversion is when the uterus turns inside out, usually following childbirth. Symptoms include postpartum bleeding, abdominal pain, a mass in the vagina, and low blood pressure. Rarely inversion may occur not in association with pregnancy.
Velamentous cord insertion is a complication of pregnancy where the umbilical cord is inserted in the fetal membranes. It is a major cause of antepartum hemorrhage that leads to loss of fetal blood and associated with high perinatal mortality. In normal pregnancies, the umbilical cord inserts into the middle of the placental mass and is completely encased by the amniotic sac. The vessels are hence normally protected by Wharton's jelly, which prevents rupture during pregnancy and labor. In velamentous cord insertion, the vessels of the umbilical cord are improperly inserted in the chorioamniotic membrane, and hence the vessels traverse between the amnion and the chorion towards the placenta. Without Wharton's jelly protecting the vessels, the exposed vessels are susceptible to compression and rupture.
A placental disease is any disease, disorder, or pathology of the placenta.
Chorionic hematoma is the pooling of blood (hematoma) between the chorion, a membrane surrounding the embryo, and the uterine wall. It occurs in about 3.1% of all pregnancies, it is the most common sonographic abnormality and the most common cause of first trimester bleeding.
Circumvallate placenta is a rare condition affecting about 1-2% of pregnancies, in which the amnion and chorion fetal membranes essentially "double back" on the fetal side around the edges of the placenta. After delivery, a circumvallate placenta has a thick ring of membranes on its fetal surface. Circumvallate placenta is a placental morphological abnormality associated with increased fetal morbidity and mortality due to the restricted availability of nutrients and oxygen to the developing fetus.
Uterine Tachysystole is a condition of excessively frequent uterine contractions during pregnancy. It is most often seen in induced or augmented labor, though it can also occur during spontaneous labor, and this may result in fetal hypoxia and acidosis. This may have serious effects on both the mother and the fetus including hemorrhaging and death. There are still major gaps in understanding treatment as well as clinical outcomes of this condition. Uterine tachysystole is defined as more than 5 contractions in 10 minutes, averaged over a 30-minute period.
Early pregnancy bleeding refers to vaginal bleeding before 14 weeks of gestational age. If the bleeding is significant, hemorrhagic shock may occur. Concern for shock is increased in those who have loss of consciousness, chest pain, shortness of breath, or shoulder pain.
The anomaly scan, also sometimes called the anatomy scan, 20-week ultrasound, or level 2 ultrasound, evaluates anatomic structures of the fetus, placenta, and maternal pelvic organs. This scan is an important and common component of routine prenatal care. The function of the ultrasound is to measure the fetus so that growth abnormalities can be recognized quickly later in pregnancy, to assess for congenital malformations and multiple pregnancies, and to plan method of delivery.