Introduction
Placenta increta is the term used to describe abnormal placental attachment to the uterine wall.1 There are varying degrees of placental attachment, which are classified as placenta accreta, placenta increta and placenta percreta, which come under the umbrella of placenta accreta spectrum (PAS).
Understanding the placenta
The placenta is an organ that forms shortly after conception. It is attached to the wall of the uterus which is situated between the rectum and the bladder.2 Placental tissues are rich in stem cells that can treat certain life-threatening conditions.3 Functions of the placenta include:
- providing oxygen and nutrients for the baby through the umbilical cord
- removing waste products from the baby’s blood
- producing hormones that help the baby to grow
- passing antibodies from the mother to improve the immunity of the baby
Disorders of the placenta
In certain conditions, the placenta can cause complications during pregnancy:2,4,5
- Placenta previa: this is when the placenta completely or partially covers the opening of the uterus (cervix). Normally the placenta is attached to the top or side of the uterus, but in this condition it is attached to the lower part of the uterus. This can cause severe bleeding before, during or after delivery. It can also cause preterm birth6
- Placenta accreta: this is known as the first degree of abnormal attachment of the placenta. In this condition the placenta is attached to the uterus deeper than normal but not deep enough to penetrate the uterine wall1
- Placenta increta: this is known as the second degree of abnormal attachment of the placenta with penetration into the uterine wall. It is almost fully penetrated but does not pass right through the uterine wall
- Placenta percreta: this is known as the third degree of abnormal attachment, the most severe, where the placenta completely penetrates the uterine wall, passes through it and can be attached to other adjacent organs
- Placental abruption: this is a complication where the placenta separates from the uterus before delivery7
- Placental insufficiency: this is when the placenta is not providing the baby with enough nutrients and oxygen
- Retained placenta: this is when parts of the placenta are left in the uterus after delivery
Placenta increta
Placenta increta is a serious condition in pregnancy where the placenta grows into the uterine wall too deeply, although it does not pass right through the wall. Usually, the placenta separates from the uterine wall after childbirth. In this condition, the placenta remains attached to the uterine wall after childbirth and can cause heavy bleeding.8 The condition can cause complications during delivery for both the mother and the baby.3
Risk factors
The exact cause of placenta increta is not fully understood. It can happen spontaneously without any prior signs or symptoms. Factors that can increase the chances of placenta increta include:
- maternal age over 35 years
- prior Caesarean section
- placenta previa in current or previous pregnancy
- previous uterine surgical procedure for the removal of fibroids
- smoking during pregnancy
- pregnancy via in vitro fertilisation (IVF)
- previous dilatation and curettage (D&C)
- multiple pregnancies
Complications
Placenta increta is associated with major complications in pregnancy:
- Vaginal bleeding: severe vaginal bleeding during or after delivery that can lead to shock, and lung and kidney failure; this can be life-threatening8,9
- Intrauterine growth retardation
- Premature birth: this condition may cause bleeding during pregnancy, which is a risk to both mother and baby, and can lead to onset of early labour10
- Blood clotting issues, that can be caused by heavy bleeding
- Emergency hysterectomy: surgical removal of the uterus may be necessary, to control severe bleeding and remove the placenta
Diagnosis
Diagnosis is carried out by a gynaecologist, who will conduct a physical examination to evaluate vaginal bleeding. They may ask about the history of pregnancies and any related complications. Investigations may include:
- a complete blood test to evaluate any infection or deficiencies
- abdominal or vaginal ultrasound scan: this scan uses high-frequency sound waves to produce an image of the person’s internal body structure. This helps in studying the foetus, abdominal and pelvic organs
- MRI scan: magnetic resonance imaging is a type of scan that uses strong magnetic fields and radio waves to produce images of the internal structures of the body
- Doppler ultrasound: a 3D non-invasive scan that is used to evaluate blood flow by use of high-frequency sound waves
Management and treatment
Women with placenta increta should be cared for in a specialist centre. The specialist team (including gynaecologists, obstetricians and anaesthetists) will discuss the treatment options available to the patient:
- Early diagnosis of placenta increta is rare, but if suspected early the doctor may recommend bed rest or hospitalisation for the rest of the pregnancy, to prevent preterm labour11
- Healthcare providers may recommend Caesarean section delivery to decrease the risk of severe bleeding during contractions. They may also be able to save the uterus this way
- In severe cases, where the placenta has deeply penetrated the uterine wall, hysterectomy is suggested as the safest option to save the mother. Some health providers leave parts of the placenta inside the uterus because they can dissolve over time. However, this can result in severe bleeding, infection and blood clots
- Intensive care for the baby, if born preterm
- Blood transfusion in cases of severe bleeding
- Dilatation and curettage (D&C) may be performed to treat heavy bleeding
- Uterine artery ligation, to save the uterus in cases of severe postpartum bleeding
Summary
The placenta is an organ that forms in the uterine wall during pregnancy. It provides nutrients and oxygen to the baby through the umbilical cord and also removes wastes from the baby's blood. Placenta increta is the second degree abnormal placental attachment to the uterus.
It penetrates the uterine wall but does not pass all the way through it. Usually, the placenta separates from the uterine wall after childbirth, but in this condition the placenta remains attached which can lead to heavy bleeding. Early diagnosis of placenta increta is rare, but if suspected early the doctor may recommend bed rest or hospitalisation for the rest of the pregnancy, to prevent preterm labour.
Healthcare providers may recommend Caesarean section delivery to decrease the risk of severe bleeding during contractions. Excessive blood loss can sometimes lead to fatalities.
References
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- Ameer MA, Fagan SE, Sosa-Stanley JN, Peterson DC. Anatomy, Abdomen and Pelvis: Uterus. [Updated 2022 Dec 6]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470297/
- Herrick EJ, Bordoni B. Embryology, Placenta. [Updated 2023 May 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK551634/
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- Thiyagarajan DK, Basit H, Jeanmonod R. Physiology, Menstrual Cycle. [Updated 2022 Oct 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK500020/
- Anderson-Bagga FM, Sze A. Placenta Previa. [Updated 2023 June 12]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539818/
- Schmidt P, Skelly CL, Raines DA. Placental Abruption. [Updated 2022 Dec 19]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482335/
- Jimbo M, Sekizawa A, Sugito Y, Matsuoka R, Ichizuka K, Saito H, et al. Placenta increta: postpartum monitoring of plasma cell-free foetal dna. Clinical Chemistry [Internet]. 2003 Sep 1 [cited 2024 Mar 21];49(9):1540–1. Available from: https://academic.oup.com/clinchem/article/49/9/1540/5641971
- Haseer Koya H, Paul M. Shock. [Updated 2023 July 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK531492/
- Nik-Ahmad-Zuky NL, Seoparjoo A, Husna EIE. Placenta increta presenting with threatened miscarriage during the first trimester in rhesus-negative mother: a case report. Journal of Medical Case Reports [Internet]. 2021 Dec [cited 2024 Mar 21];15(1):448. Available from: https://jmedicalcasereports.biomedcentral.com/articles/10.1186/s13256-021-03030-x
- Fitzpatrick K, Sellers S, Spark P, Kurinczuk J, Brocklehurst P, Knight M. The management and outcomes of placenta accreta, increta, and percreta in the UK : a population‐based descriptive study. BJOG [Internet]. 2014 Jan [cited 2024 Mar 21];121(1):62–71. Available from: https://obgyn.onlinelibrary.wiley.com/doi/10.1111/1471-0528.12405