Placenta accreta
Encyclopedia
Placenta accreta is a severe obstetric
complication involving an abnormally deep attachment of the placenta
, through the endometrium
and into the myometrium
(the middle layer of the uterine wall
). There are three forms of placenta accreta, distinguishable by the depth of penetration.
The placenta usually detaches from the uterine wall relatively easily, but women who encounter placenta accreta during childbirth
are at great risk of haemorrhage
during its removal. This commonly requires surgery
to stem the bleeding and fully remove the placenta, and in severe forms can often lead to a hysterectomy
or be fatal.
Placenta accreta affects approximately 1 in 2,500 pregnancies
.
can lead to the diagnosis of a suspected accreta and an MRI will give more detail leading to further suspicion of such an abnormal placenta. However, both the ultrasound and the MRI rarely confirm an accreta with certainty. While it can lead to some vaginal bleeding during the third trimester, this is more commonly associated with the factors leading to the condition. In some cases the second trimester can see elevated maternal serum alpha-fetoprotein
levels, though this is also an indicator of many other conditions.
During birth, placenta accreta is suspected if the placenta has not been delivered within 30 minutes of the birth. Usually in this case, manual blunt dissection or placenta traction is attempted but can cause haemorrhage in accreta.
, and is increased in incidence by the presence of scar tissue
i.e. Asherman's syndrome
usually from past uterine surgery, especially from a past Dilation and curettage
, (which is used for many indications including miscarriage, termination, and postpartum hemorrhaging), myomectomy, or caesarean section
. A thin decidua
can also be a contributing factor to such trophoblast
ic invasion. Some studies suggest that the rate of incidence is higher when the fetus
is female.
and abdominal hysterectomy
if placenta accreta is diagnosed before birth.
Obstetrics
Obstetrics is the medical specialty dealing with the care of all women's reproductive tracts and their children during pregnancy , childbirth and the postnatal period...
complication involving an abnormally deep attachment of the placenta
Placenta
The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. "True" placentas are a defining characteristic of eutherian or "placental" mammals, but are also found in some snakes and...
, through the endometrium
Endometrium
-Function:The endometrium is the innermost glandular layer and functions as a lining for the uterus, preventing adhesions between the opposed walls of the myometrium, thereby maintaining the patency of the uterine cavity. During the menstrual cycle or estrous cycle, the endometrium grows to a...
and into the myometrium
Myometrium
The myometrium is the middle layer of the uterine wall, consisting mainly of uterine smooth muscle cells , but also of supporting stromal and vascular tissue...
(the middle layer of the uterine wall
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
). There are three forms of placenta accreta, distinguishable by the depth of penetration.
The placenta usually detaches from the uterine wall relatively easily, but women who encounter placenta accreta during childbirth
Childbirth
Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...
are at great risk of haemorrhage
Obstetrical hemorrhage
Obstetrical hemorrhage refers to heavy bleeding during pregnancy, labor, or the puerperium. Bleeding may be vaginal and external, or, less commonly but more dangerously, internal, into the abdominal cavity...
during its removal. This commonly requires surgery
Surgery
Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...
to stem the bleeding and fully remove the placenta, and in severe forms can often lead to a hysterectomy
Hysterectomy
A hysterectomy is the surgical removal of the uterus, usually performed by a gynecologist. Hysterectomy may be total or partial...
or be fatal.
Placenta accreta affects approximately 1 in 2,500 pregnancies
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
.
Variants
There are multiple variants, defined by the depth of their attachment to uterine wall:| Type | Description | Percent |
|---|---|---|
| placenta accreta | An invasion of the myometrium which does not penetrate the entire thickness of the muscle Muscle Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to... . This form of the condition accounts for around 75% of all cases. |
75-78% |
| placenta increta | Occurs when the placenta further extends into the myometrium, penetrating the muscle. | 17% |
| placenta percreta | The worst form of the condition is when the placenta penetrates the entire myometrium to the uterine serosa (invades through entire uterine wall). This variant can lead to the placenta attaching to other organs such as the rectum or bladder Urinary bladder The urinary bladder is the organ that collects urine excreted by the kidneys before disposal by urination. A hollow muscular, and distensible organ, the bladder sits on the pelvic floor... . |
5-7% |
Diagnosis
Placenta accreta is very rarely recognised before birth, and is very difficult to diagnose. A Doppler ultrasoundUltrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
can lead to the diagnosis of a suspected accreta and an MRI will give more detail leading to further suspicion of such an abnormal placenta. However, both the ultrasound and the MRI rarely confirm an accreta with certainty. While it can lead to some vaginal bleeding during the third trimester, this is more commonly associated with the factors leading to the condition. In some cases the second trimester can see elevated maternal serum alpha-fetoprotein
Alpha-fetoprotein
Alpha-fetoprotein is a protein that in humans is encoded by the AFP gene....
levels, though this is also an indicator of many other conditions.
During birth, placenta accreta is suspected if the placenta has not been delivered within 30 minutes of the birth. Usually in this case, manual blunt dissection or placenta traction is attempted but can cause haemorrhage in accreta.
Risk factors
The condition affects around 10% of cases of placenta praeviaPlacenta praevia
Placenta praevia is an obstetric complication in which the placenta is attached to the uterine wall close to or covering the cervix. It can sometimes occur in the later part of the first trimester, but usually during the second or third. It is a leading cause of antepartum haemorrhage...
, and is increased in incidence by the presence of scar tissue
Scar
Scars are areas of fibrous tissue that replace normal skin after injury. A scar results from the biological process of wound repair in the skin and other tissues of the body. Thus, scarring is a natural part of the healing process. With the exception of very minor lesions, every wound results in...
i.e. Asherman's syndrome
Asherman's syndrome
Asherman's syndrome , also called "uterine synechiae" or intrauterine adhesions , presents a condition characterized by the presence of adhesions and/or fibrosis within the uterine cavity due to scars...
usually from past uterine surgery, especially from a past Dilation and curettage
Dilation and curettage
Dilation and curettage refers to the dilation of the cervix and surgical removal of part of the lining of the uterus and/or contents of the uterus by scraping and scooping . It is a diagnostic gynecological procedure.D&C normally is referred to a procedure involving a curette, also called sharp...
, (which is used for many indications including miscarriage, termination, and postpartum hemorrhaging), myomectomy, or caesarean section
Caesarean section
A Caesarean section, is a surgical procedure in which one or more incisions are made through a mother's abdomen and uterus to deliver one or more babies, or, rarely, to remove a dead fetus...
. A thin decidua
Decidua
Decidua is the term for the uterine lining during a pregnancy, which forms the maternal part of the placenta. It is formed under the influence of progesterone and forms highly-characteristic cells.-Etymology:...
can also be a contributing factor to such trophoblast
Trophoblast
Trophoblasts are cells forming the outer layer of a blastocyst, which provide nutrients to the embryo and develop into a large part of the placenta. They are formed during the first stage of pregnancy and are the first cells to differentiate from the fertilized egg...
ic invasion. Some studies suggest that the rate of incidence is higher when the fetus
Fetus
A fetus is a developing mammal or other viviparous vertebrate after the embryonic stage and before birth.In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age, which is the 9th week after fertilization.-Etymology and spelling variations:The...
is female.
Treatment
The safest treatment is a planned caesarean sectionCaesarean section
A Caesarean section, is a surgical procedure in which one or more incisions are made through a mother's abdomen and uterus to deliver one or more babies, or, rarely, to remove a dead fetus...
and abdominal hysterectomy
Hysterectomy
A hysterectomy is the surgical removal of the uterus, usually performed by a gynecologist. Hysterectomy may be total or partial...
if placenta accreta is diagnosed before birth.