Current opinionPlacenta accreta: Pathogenesis of a 20th century iatrogenic uterine disease
Introduction
Placenta accreta is a novel pathological entity. Unlike many other placental disorders, such as hydatidiform mole, which have been known for centuries, placenta accreta was first described in the 20th century. In 1937, Irving and Hertig defined placenta accreta as “the abnormal adherence, either in whole or in part, of the afterbirth to the underlying uterine wall [1]. The fact that it was not described by the anatomists and pathologists of the 18th and 19th century who describe most of the pathological lesions that we know today, suggests that the condition did not exist or was so rare that it was not diagnosed before the 1930s. Within this context and due to the severe clinical complications associated with the abnormal adherence of the placenta at birth, it is very unlikely that placenta accreta would have avoided detection for so long.
The general term “placenta accreta” refers to different grades of abnormal placental attachment to the uterine wall, which are characterised by invasion of trophoblast into the myometrium (Fig. 1). The term placenta increta is sometimes used to describe deep myometrial invasion of trophoblast villi and placenta percreta refers to accreta villi perforating through the full thickness of the myometrium and uterine serosa with possible involvement of adjacent organs [2], [3]. Placenta increta and percreta are rare representing less than 20% of the cases of placenta accreta [4]. Before the development of imaging techniques, it was not often easy to assess clinically the exact depth of placental invasion and the term placenta accreta has been used to describe all types of abnormally adherent placentae. Placenta accreta has also been subdivided into total, partial or focal, depending on the amount of placental tissue involved. This sub-classification is rarely used on the basis that in case of placenta accreta the microscopic examination of the hysterectomy specimen is rarely complete and that attempts at manual removal often distort the placental anatomy [2].
Where placenta accreta is present, the failure of the placenta to separate normally from the uterus after delivery is typically accompanied by severe post-partum haemorrhage. Attempts to remove the adherent tissue may provoke further bleeding and a cascade of ongoing haemorrhage, shock and coagulation disorders requiring complex clinical management. Not surprisingly, a recent study has shown that women managed by a multidisciplinary care team are less likely to require large-volume blood transfusion, re-operation within seven days of delivery for bleeding complications and to experience prolonged maternal admission to the intensive care unit, large-volume blood transfusion, coagulopathy, urethral injury and early re-operation than women managed by standard obstetric care [5].
There has been a substantial increase in the occurrence of placenta accreta over the last 50 years with as much as a 10 fold rise in the prevalence to around 1 in 2500 deliveries in many Western countries [11], [12], [13], [14], [15], [16], [17]. Thus placenta accreta can be no longer considered as a rare obstetric pathology and has become a complication that an average obstetrician is likely to encounter several times during a practicing lifetime. It is rapidly becoming recognised as a major cause of obstetric complications worldwide, including in developing countries. With the development of high quality ultrasound and colour Doppler imaging it is now possible to diagnose abnormal trophoblast invasion into the myometrium early in the first trimester of pregnancy As most cases of placenta accreta continue to be diagnosed during the second and third trimester of pregnancy little is known about the natural evolution of this placentation disorder. We have reviewed current literature on the aetiology, pathophysiology and early prenatal diagnosis of this placental abnormality which is rapidly becoming one of the main placental-related obstetric problems around the world.
Section snippets
Epidemiology
A prior caesarean section and a history of previous intrauterine surgical procedures are the two most important risk factors for placenta accreta [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11]. Large studies in the US, have suggested a prevalence of 1 in 540 to 1 in 2500 deliveries [6], [11]. The reason for this difference in prevalence is mainly due to variations in clinico-pathological definitions and local caesarean section rates. The gold standard of reference for the diagnosis of
Pathology
Although the risk factors for placenta accreta are well established, the underlying mechanisms leading to abnormal placentation are less well understood. Human placentation is almost unique amongst mammals in that it is highly invasive and the conceptus embeds itself completely within the maternal uterine decidua and superficial myometrium [21], [22]. During the process of implantation, cytotrophoblast cells detach from the anchoring villi and invade the maternal decidual stroma. These cells
In vivo imaging
Most early in utero studies of placenta accreta have focussed on identifying reliable ultrasound and other radiological markers of a defect in the deciduo-placental interface in order to facilitate antenatal detection and improve management at delivery [4], [6], [63], [64], [65], [66], [67]. These studies are largely retrospective, collating data from the second half of pregnancy and providing little information on the natural evolution of a placentation disorder which takes during the first
References (98)
- et al.
Clinical risk factors for placenta previa-placenta accreta
Am J Obstet Gynecol
(1997) - et al.
Risk factors for placenta accreta
Obstet Gynecol
(1999) - et al.
Abnormal placentation
Semin Perinatol
(2009) - et al.
Abnormal placentation: twenty-year analysis
Am J Obstet Gynecol
(2005) - et al.
Multiple repeat cesareans and the threat of placenta accreta: incidence, diagnosis, management
Clin Perinatol
(2011) The technique of cesarean section, with special reference to the lower uterine segment incision
Am J Obstet Gynecol
(1926)- et al.
The history of cesarean technique
Am J Obstet Gynecol
(2003) - et al.
Trophoblastic invasion of human decidua from 8 to 18 weeks of pregnancy
Placenta
(1980) - et al.
Rheological and physiological consequences of conversion of the maternal spiral arteries for uteroplacental blood flow during human pregnancy
Placenta
(2009) - et al.
Placenta creta and placenta praevia creta
Placenta
(1987)
Pathophysiology of placenta creta: the role of deciduas and extravillous cytotrophoblast
Placenta
Invasion of the trophoblasts
Cell
Accreta complicating complete placenta previa is characterized by reduced systemic levels of vascular endothelial growth factor and by epithelial-to-mesenchymal transition of the invasive trophoblast
Am J Obstet Gynecol
Implantation site intermediate trophoblast in placenta cretas
Mod Pathol
Expression of epidermal growth factor receptor and c-erbβ-2 oncoprotein in trophoblast populations of placenta accrete
Am J Obstet Gynecol
Differential expression of vascular endothelial growth factor, placental growth factor and their receptors in placentae from pregnancies complicated by placenta accreta
Placenta
Differential expression of angiopoietin-1, angiopoietin-2 and Tie receptors in placentas from pregnancies complicated by placenta accreta
Am J Obstet Gynecol
Maternal arterial connections to the placental intervillous space during the first trimester of human pregnancy: the Boyd collection revisited
Am J Obstet Gynecol
Onset of placental bloodflow and trophoblastic oxidative stress: a possible factor in human early pregnancy failure
Am J Pathol
Regulation of placental vascular endothelial growth factor (VEGF) and placenta growth factor (PIGF) and soluble Flt-1 by oxygen–a review
Placenta
Differential expression of growth-, angiogenesis- and invasion-related factors in the development of placenta accreta
Taiwan J Obstet Gynecol
Accreta complicating complete placenta previa is characterized by reduced systemic levels of vascular endothelial growth factor and by epithelial-to-mesenchymal transition of the invasive trophoblast
Am J Obstet Gynecol
Population-based ectopic pregnancy trends, 1993-2007
Am J Prev Med
Tubal pregnancy. Associated histopathology
Obstet Gynecol Clin North Am
Effect of cesarean delivery on the endometrium
Int J Gynaecol Obstet
Sonographic detection of placenta accreta in the second and third trimesters of pregnancy
Am J Obstet Gynecol
Ultrasonographic investigation of placental morphologic characteristics and size during the second trimester of pregnancy
Am J Obstet Gynecol
Prenatal diagnosis of placenta previa accreta with power amplitude ultrasonic angiography
Am J Obstet Gynecol
MRI appearance of placenta percreta and placenta accreta
Magn Reson Imaging
Assessing the role of magnetic resonance imaging in the management of gravid patients at risk for placenta accreta
Acad Radiol
The myometrial junctional zone spiral arteries in normal and abnormal pregnancies
Am J Obstet Gynecol
Shunting the intervillous space: new concepts in human uteroplacental vascularization
Am J Obstet Gynecol
Use of three-dimensional ultrasonography in the evaluation of uterine perfusion and healing after laparoscopic myomectomy
Fertil Steril
A study of placenta accreta
Surgery Gynecol Obstet
Evaluation of sonographic diagnostic criteria for placenta accreta
J Clin Ultrasound
Maternal morbidity in cases of placenta accreta managed by a multidisciplinary care team compared with standard obstetric care
Obstet Gynecol
Placenta percreta: ultrasound diagnosis and conservative surgical management
Obstet Gynecol
The influence of both individual and area based socioeconomic status on temporal trends in Caesarean sections in Scotland 1980-2000
BMC Public Health
The risk of caesarean section in obese women analysed by parity
Eur J Obstet Gynecol Reprod Biol
The effect of cesarean delivery rates on the future incidence of placenta previa, placenta accreta, and maternal mortality
J Matern Fetal Neonatal Med
Placenta accreta and myotonic dystrophy: two cases
BJOG
A pregnancy after planned partial endometrial resection
Aust NZJOG
Placenta accreta is associated with IVF pregnancies: a retrospective chart review
BJOG
Is endomyometrial injury during termination of pregnancy or curettage following miscarriage the precursor to placenta accreta?
J Clin Pathol
The human placenta
Anatomy and Genesis of the placenta
A clinical and pathology study of placenta accreta
J Obstet Gynaecol Br Emp
Cited by (305)
Ultrasound-guided suction curettage followed by cervico-isthmic placement of foley threeway catheter for cesarean scar pregnancy's treatment. Retrospective study
2024, Journal of Gynecology Obstetrics and Human ReproductionRisk factors for placenta accreta spectrum in pregnancies conceived after frozen–thawed embryo transfer in a hormone replacement cycle
2024, European Journal of Obstetrics and Gynecology and Reproductive BiologyAssisted reproductive technology-associated risk factors for retained products of conception
2024, Fertility and SterilityRisk of placenta accreta spectrum following myomectomy: a nationwide cohort study
2024, American Journal of Obstetrics and GynecologySubsequent pregnancy outcomes and risk factors following conservative treatment for placenta accreta spectrum: a retrospective cohort study
2023, American Journal of Obstetrics and Gynecology MFM