PLACENTA - ACCRETA, INCRETA, PERCRETA

Of all the body's organs, perhaps the one that best typifies selfless service is the placenta. Most people give little thought to the placenta, and few appreciate the marvelous complexity and profound importance of this organ that is discarded and forgotten after birth. While parents and loved ones rejoice at the safe arrival of their newborn, few think of essential services rendered by the placenta.
Until things go wrong.

Placental Attachment

During a normal pregnancy the placenta attaches to the surface of the endometrium and uterine wall. However a severe obstetric complication occurs when there is abnormally deep attachment of the placenta to the uterine wall. This condition is called placenta accreta, increta, or percreta, depending on the severity and deepness of the placental penetration. During Birth the placenta usually separates from the uterine wall relatively easily, however with placenta accreta, increta or percreta there is a great risk of haemorrhage during manual attempts to remove the placenta. Severe hemorrhaging can be life threatening. Other concerns for placenta percreta involve damage to the uterus or other organs during removal of the placenta. Hysterectomy is a common surgical intervention, but the results involve the loss of the uterus and the ability to conceive. Premature delivery and its complications is the primary risk factor for the baby.

Causes

The specific cause of placenta accreta is unknown, but it has been related to:

  • placenta previa
  • Previous cesarean deliveries: The risk of placenta accreta increases with the number of cesareans.
  • Scar tissue

Diagnosis

Placenta accreta is diffcult to diagnose and is rarely identified before birth. A Doppler ultrasound and MRI can lead t o the diagnosis of a suspected accreta. However, placenta accreta is rarely confirmed with certainty. Placenta accreta can cause some vaginal bleeding during the third trimester and elevated maternal serum alpha-fetoprotein levels in the second trimester, 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 placental traction is attempted but can cause haemorrhage.

Treatment

The safest treatment is a planned caesarean section and abdominal hysterectomy if placenta accreta is diagnosed before birth. If it is important to save the woman's uterus for future pregnancies then resection around the placenta may be successful.

VARIANTS

There are multiple variants, defined by the depth of their attachment to uterine wall:

Placenta accreta Placenta attaches too deeply to the uterine wall and invades the myometrium but does not penetrate the entire thickness of the muscle.
Placenta increta Occurs when the placenta further extends into the myometrium.
Placenta percreta The worst form of the condition is when the placenta penetrates the entire through entire uterine wall. This variant can lead to the placenta attaching to other organs such as the rectum or bladder.
  • XXVI : III :6: Placenta percreta


    This is half the uterus and attached placenta removed at caesarian section from a 30 year old coloured woman who was 28 weeks pregnant and presented with massive intra-abdominal haemorrhage. Note the abnormal attachment of the placenta to the uterine wall with no defined line of cleavage between the two. To the right of the umbilical cord, the placenta has penetrated through the uterine wall and appears on the serosal side as a roughened area. The haemorrhage necessitated a caesarean and hysterectomy.

  • XXVI: III: 13 Placenta accreta


    The specimen is from a woman aged 28 who gave a history of 7 previous births during which manual removal of the placenta was necessary. On this occasion a Caesarean section was performed. At operation it was found that although the placenta could be removed from the uterine wall at some areas, considerable portions were too rmly attached to be removed. A hysterectomy was performed. Placenta accreta can be complete or partial - in this case it was partial. The specimen shows a portion of the uterine wall at the site of placental attachment. There is no recognisable plane of cleavage between the grey-white myometrium and placental tissue. Note that the specimen was everted prior to fixation which situates the placenta external to the myometrium.

  • XXVI: III: 14 Placenta accreta


    This is another example of placenta accreta. The placenta is attached to the lower uterine segment (placenta praevia) and in many areas there is no readily recognisable plane of cleavage. Histological examination confirms the diagnosis. The striking change is that the deciduas basalis is virtually absent being represented only by a few groups of cells. Placenta accreta is due to focal or difuse lack of deciduas basalis between the placental trophoblast and myometrium.