Adherent Placenta and Placenta Accreta Spectrum: An Overview

What is Adherent Placenta?

An adherent placenta is a condition where the abnormally attached placenta does not detach after the delivery of the baby. An adherent placenta might be of two types:

• Partial Adherence - Partially adherent placenta is diagnosed during the delivery. Bleeding might be present with a partial separation.

• Complete Adherence - In a completely adherent placenta, there will not be bleeding since there is no placental separation at all.

What Are the Causes and Management of an Adherent Placenta?

It occurs due to a previous uterine manipulation during previous delivery or abortion, causing uterine infections. This leads to the adhesion of the placenta.

Management of Adherent Placenta:

Manual removal of the placenta is the main choice of treatment. The steps of this technique are listed below:

• It is a procedure done in the operation theater under general anesthesia.

• One hand of the doctor is placed on the abdomen, and the other hand is made into the shape of a cone and is placed in the vagina to locate the lower end of the placenta.

• Fingers are kept below the placenta, and the placenta is removed with the help of a sweeping movement.

• Meanwhile, the abdomen hand gives counter pressure.

• Continuous bladder drainage should be done.

• Blood and blood products are kept ready, and transfusion is done if necessary.

• Meanwhile, intravenous oxytocin (to help in the contraction of the uterus) and antibiotics (to prevent infection) are given.

• The placenta accreta spectrum is one of the causes of the adherent placenta.

What Is Placenta Accreta Spectrum?

Placenta accreta spectrum is a serious condition in pregnancy that includes a group of disorders with abnormal placentation that means abnormal attachment of the placenta with the uterus.

Is the Placenta Accreta Spectrum a Concern?

Normally after the delivery of the baby, the placenta separates from the uterus and is expelled within 15 to 20 minutes. However, in cases where the placenta is abnormally attached to the uterus, as in the placenta accreta spectrum, the placenta is not expelled and may result in

• Excessive bleeding (one of the causes of postpartum hemorrhage).

• Infections.

• Interference with the return of the uterus to its pre-pregnant size.

How Does the Placenta Accreta Spectrum Develop?

In a normal pregnancy, the placenta attaches to the wall of the uterus on one side and to the umbilical cord connecting the baby on the other side. It attaches to that part of the uterus called the endometrium (which sheds as periods in a non-pregnant state). Endometrium in pregnancy is called decidua. Ideally, there is a layer of separation between this placenta and the decidua called the nitabuch's membrane. In the placenta accreta spectrum, there is an absence of this nitabuch's membrane hence allowing the attachment of the placenta deep into the muscular layer of the uterus called the myometrium and thus making it difficult for the uterus to expel it after childbirth.

What Conditions Does the Placenta Accreta Spectrum Include?

The Placenta accreta spectrum includes the following conditions:

• Placenta Accreta - There is just an attachment of the placenta to the muscle layer of the uterus.

• Placenta Increta - Placenta invades the muscle layer of the uterus.

• Placenta Percreta - Placenta penetrates the muscle layer and comes out via the outer layer.

What Are the Risk Factors Associated with the Placenta Accreta Spectrum?

Associated conditions that increase the risk of placenta accreta spectrum include:

• Previous Cesarean Section - Placenta attaches to the previous cesarean section scar in the lower uterine segment.

• Placenta Previa - Growth of the placenta in the lowest part of the womb.

• Previous Uterine Surgery - Causing a scar in the uterus.

• Previous Uterine Curettage - Scraping of the uterus done for conditions like abortion.

How Is Placenta Accreta Diagnosed?

Even though ultrasonography is done routinely for all pregnant women, diagnosis of accreta is made most of the time during the delivery of the baby when the placenta is not expelled on its own and manual removal of the placenta is not successful. The diagnosis of placenta accreta is made in the ways listed below:

1. Ultrasound - Placenta accreta can be identified during pregnancy by ultrasound. The findings in the ultrasound of the placenta accreta patient are listed below:

• The moth-eaten appearance of the placenta (due to bleeding of blood vessels due to invasion).

• Irregularly spaced placental lacunae.

• Thinning of the muscle layer of the uterus overlying the placenta.

• Loss of clear space behind the placenta.

• Disruption of the bladder lining.

2. Doppler - Findings in doppler of the patient are listed below:

• Abnormal blood vessels go from the placenta to the myometrium (muscular outer layer of the uterus).

• Turbulent blood flow through placental lacunae (highly vascular areas of the placenta).

3. MRI (Magnetic Resonance Imaging) - It is not done routinely but is done due to the following reasons:

• Uncertainty in ultrasound

• When the depth of invasion of the placenta is to be assessed.

How Is Placenta Accreta Managed?

Placenta accreta is managed in the ways listed below:

• If only a small part of the placenta is attached abnormally, then it may be torn and removed. The bleeding which follows the removal of the placenta can be controlled by the drug Oxytocics.

• If a large part of the placenta is attached abnormally, then it can't be removed manually since doing so might lead to severe bleeding, which can be life-threatening (known as postpartum hemorrhage).

• So, in such cases, a hysterectomy is always preferred (removal of the uterus along with the placenta) to save the life of the mother.

• If a diagnosis is made during pregnancy in the antenatal period, then an elective classical cesarean section (in all the other conditions, a c-section is done in the lower segment, here upper segment of the uterus is opened to avoid cutting the placenta which leads to severe bleeding) is planned along with hysterectomy (removal of the uterus).

• Leaving the placenta inside the uterus might be an option that is not usually suggested because of the complication of infection but might be rarely suggested in case a patient wants to preserve fertility. A drug called Methotrexate is given, but the outcome cannot be predicted.

What Are the Consequences of Adherent Placenta?

The consequences of an adherent placenta are listed below:

• Puerperal Infection - Infection of the genital tract that occurs after the baby's birth.

• Improper Involution of Uterus - Uterus that is not decreasing in size.

• Postpartum Hemorrhage - Bleeding that does not cause stop after childbirth.

• Formation of Placental Polyps - Polypoidal mass after retained placental tissue in the uterus.

Conclusion:

Advancement in technology has made it possible to identify this condition well in advance during pregnancy, but most of the time, it is observed that this condition is diagnosed during the third stage of labor i.e., after the delivery of the baby during labor. Also, the rising cesarean section rates have led to an increase in the incidence of the placenta accreta spectrum. Getting timely routine medical checkups during pregnancy may help diagnose this condition and prevent any emergency.