Placental histopathology lesions and pregnancy outcome in pregnancies complicated with symptomatic vs. non-symptomatic placenta previa☆,☆☆
Introduction
Placenta previa is defined as placental implantation that takes place in the lower uterine segment, partially or completely covering the internal cervical os [1]. The incidence of placenta previa is about 1 in 200 term pregnancies [2], and the rate appears to be rising as a consequence of the increasing rate of cesarean deliveries (CD) [3]. Advanced maternal age (over 35 years), multiparty, smoking and infertility treatment appears to be additional risk factors for placenta previa [3], [4], [5], [6]. Diagnosis is usually done during the second half of pregnancy by vaginal or trans-abdominal ultrasound [7]. Symptomatic (bleeding) placenta previa is associated with increased maternal and neonatal morbidity and mortality [1], [5], [8], [9], [10]. There is a threefold increase in neonatal mortality rate, in comparison with normally positioned placenta [11].
Studies on placental histopathology evaluation in cases of placenta previa are scarce, although abnormal placental implantation may be associated with different placental developmental abnormalities, that may provide specific explanations for adverse neonatal outcome [12]. Histopathology evaluation of placental bed biopsies revealed that placenta previa is associated with normal physiological changes in the spiral arterioles [13]. Stereological analysis has been shown that the volume of blood vessels of the placental villi is significantly increased as compared to controls [14]. Moreover, the mechanism that involve in bleeding is unclear. It is usually, but not always, related to uterine contractions, cervical effacement and dilation leading to separation of the placenta from the underlying decidua [14].
We aimed to compare pregnancy outcome and placental histopathology lesions in pregnancies with placenta previa, with and without bleeding events requiring emergent CD. We hypothesized that in cases of symptomatic placenta previa, due to abnormal placentation, higher rates of placental pathological lesions will be observed, as compared to non-symptomatic placenta previa. Additionally, we aimed to study the consequences of the existence of retro-placental hemorrhage in symptomatic placenta previa on neonatal and maternal outcomes.
Section snippets
Materials and methods
The medical records of all women diagnosed with placenta previa (complete or partial), who underwent CD, and their placentas were sent to histology evaluation, at 24 to 42 gestational weeks, between January 2009 to December 2015, were reviewed. The study was conducted in a single university hospital, with an annual volume of approximately 5000 deliveries and a total cesarean delivery rate of approximately 22.5%. In all cases diagnosis of placenta previa was confirmed by trans-vaginal ultrasound
Results
During the study period 32,246 deliveries occurs in our institute. Of them, 137 CD (0.42%) for placenta previa were performed and met the inclusion criteria for the study (after excluding 11 cases of multiple pregnancy and 10 cases of concomitant placenta accreta). The mean gestational age at the initial diagnosis of placenta previa was 27.1 ± 3.1 gestational weeks.
Out of those CDs 74 (54%) underwent non-elective CDs due to vaginal bleeding (symptomatic previa group) and 63 (46%) underwent
Comment
The present study demonstrates that pregnancies complicated with symptomatic placenta previa differ in maternal and pregnancy characteristics and placental histopathology lesions, as compared to pregnancies complicated with non- symptomatic placenta previa, without bleeding episodes.
The etiology of placenta previa is multifactorial and it is associated with adverse maternal and neonatal outcomes [1], [5], [8], [9], [10]. Possible etiopathogenesis of placenta previa is injured endometrium and
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2020, Obstetrics and Gynecology Clinics of North AmericaCitation Excerpt :The authors have suggested that the endometrium thickness could influence fundus-to-cervix uterine peristalsis, explaining the increased risk of implantation in the lower uterine segment in women with thicker endometrium.18 Some authors have hypothesized that placentation in the lower segment of the uterus could be associated with suboptimal vascular development of the utero-placental and the umbilico-placental circulations.28,29 These studies were poorly controlled for the number of active smokers and medical disorders such as thrombophilia, and the women in the placenta previa group were delivered on average 3 weeks before their nonprevia controls, making the evaluation of placental weight and fetal birthweight inaccurate.
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This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
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All authors have no conflicts of interest to report.
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First two authors, EW and HM, contributed equally to the article.