Retained Placenta After Vaginal Delivery: Risk Factors and Management
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International Journal of Women's Health Dovepress open access to scientific and medical research Open Access Full Text Article REVIEW Retained placenta after vaginal delivery: risk factors and management This article was published in the following Dove Press journal: International Journal of Women's Health Nicola C Perlman Abstract: Retained placenta after vaginal delivery is diagnosed when a placenta does not Daniela A Carusi spontaneously deliver within a designated amount of time, variably defined as a period of 18–60 mins. It may also be diagnosed if a patient experiences significant hemorrhage prior to Department of Obstetrics and Gynecology, Brigham and Women’s delivery of the placenta. Normal placenta delivery requires adequate uterine contractions, Hospital, Harvard Medical School, with shearing of the placenta and decidua from the uterine wall and expulsion of the tissue. Boston, MA, USA Thus, retained placenta can occur in the setting of significant uterine atony, abnormally adherent placenta, as with placenta accreta spectrum (PAS), or closure of the cervix prior to placental expulsion. Risk factors for retained placenta parallel those for uterine atony and PAS and include prolonged oxytocin use, high parity, preterm delivery, history of uterine surgery, and IVF conceptions. History of a prior retained placenta and congenital uterine anomalies also appear to be risk factors. Management entails manual removal of the placenta with adequate analgesia, as medical intervention alone has not been proven effective. For personal use only. Complications can include major hemorrhage, endometritis, or retained portions of placental tissue, the latter of which can lead to delayed hemorrhage or infection. Prophylactic antibiotics can be considered with manual placenta removal, though evidence regarding effectiveness is inconsistent. If hemorrhage is encountered, deployment of a massive transfu- sion protocol, uterine evacuation with suction, and use of intrauterine tamponade, as with an intrauterine balloon, should be initiated immediately. When a separation plane between the placenta and uterus is particularly difficult to create, PAS should be considered, and preparations should be made for hemorrhage and hysterectomy. Patients with risk factors for retained placenta should have a laboratory sample sent for blood type and antibody screening on admission to labor and delivery, and plans should be made for appropriate analgesia and preparations for hemorrhage if a retained placenta is encountered. Keywords: retained placenta, manual removal of the placenta, postpartum hemorrhage, International Journal of Women's Health downloaded from https://www.dovepress.com/ by 54.70.40.11 on 18-Jul-2021 placenta accreta spectrum Introduction Retained placenta after vaginal delivery, which occurs in around 1–3% of deliv- eries, is a relatively common cause of obstetrical morbidity. This is typically diagnosed when the placenta fails to spontaneously separate during the third stage of labor when a patient experiences excessive bleeding in absence of placenta Correspondence: Daniela A Carusi fi Department of Obstetrics and separation or if there is con rmation of placenta tissue remaining after the Gynecology, Brigham and Women’s majority of the placenta delivers spontaneously.1–3 Placentas that fail to sponta- Hospital, Harvard Medical School, 75 Francis St, Boston, MA 02115, USA neously separate can be a cause of significant surgical and hemorrhagic Tel +1 617 732 5452 morbidity.4,5 Untreated, retained placenta is considered the second leading cause Fax +1 617 232 6346 5,6 Email [email protected] of postpartum hemorrhage (PPH). submit your manuscript | www.dovepress.com International Journal of Women's Health 2019:11 527–534 527 DovePress © 2019 Perlman and Carusi. This work is published and licensed by Dove Medical Press Limited. 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Powered by TCPDF (www.tcpdf.org) Perlman and Carusi Dovepress Although retained placenta is an obstetrical complica- Table 1 Risk factors for retained placenta tion encountered relatively infrequently on the labor and Risk factors related to poor uterine contraction delivery floor, recognizing patient risk factors and under- High parity standing management are important steps in mitigating Prolonged use of oxytocin this morbidity. Risk factors related to abnormal placentation Pathophysiology History of uterine surgery Normal placentation begins with blastocyst implantation into IVF conception the maternal endometrium. In preparation for this implanta- Other risk factors tion, the endometrium develops the decidua under the influ- Preterm delivery ence of progesterone and estrogen in early pregnancy. As the Congenital uterine anomaly blastocyst invades this decidua, the layer of cells forming the Prior history of retained placenta surface of the blastocyst develops into the chorionic mem- brane. Cytotrophoblast cells proliferate from the chorionic membrane and form multinucleated aggregates called syncy- risk factors include prior retained placenta, preterm deliv- tiotrophoblast cells. These cells form the placental villi, ery, prior uterine surgery, previous pregnancy termination, allowing fetal–maternal interchange between the villi–decid- miscarriage or curettage, grand multiparity (greater than ual interaction. With delivery of the infant, both a hormonal five prior deliveries), and congenital uterine anomalies cascade and uterine contractions allow for separation of these (often unrecognized prior to delivery).3,5,11 layers and expulsion of the placenta.7 Some studies have suggested that prolonged oxytocin Retained placenta is generally attributed to one of three use could be a potentially modifiable risk factor for pathophysiologies. First, an atonic uterus with poor con- retained placenta, with one study reporting that oxytocin traction may prevent normal separation and contractile use for over 195 mins increased the odds ratio of the For personal use only. expulsion of the placenta.2,8,9 Second, an abnormally retained placenta by 2.0, and oxytocin use over 415 mins adherent or invasive placenta, as seen with placenta increased the odds ratio by 6.5.5 It is less clear whether accreta spectrum (PAS), may be incapable of normal oxytocin is directly involved in placental retention, or if separation. Finally, a separated placenta may be trapped the association is mediated by uterine atony or infection or incarcerated due to closure of the cervix prior to deliv- due to prolonged labor. ery of the placenta.2,8–10 Placental hypoperfusion disor- Placental under perfusion disorders have been impli- ders, such as with preeclampsia, and infection have also cated as risk factors for retained placenta.11 In a case– been proposed as mechanisms for retained placenta, control study of all singleton primiparous vaginal deliv- although little is known about the specific mechanism.9,11 eries in Sweden between 1997 and 2009, the authors found an increased association between placental under perfusion Epidemiology disorders (such as preeclampsia, small for gestational age, International Journal of Women's Health downloaded from https://www.dovepress.com/ by 54.70.40.11 on 18-Jul-2021 Estimates of retained placenta put the incidence at between and stillbirth) and retained placenta; however, they could 0.1% and 3%.5,8 Prospective investigations of retained pla- not designate a common pathophysiology. centa confirm these estimates, with one study of >45,000 Some research suggests that women may be predis- patients showing that overall for all gestational ages, retained posed to retained placenta. Retained placenta in a prior placenta happened in about 3% of deliveries, with gestational delivery appears to be an important risk factor for recur- ages of <26 weeks and <37 weeks having a significantly rence. In one study of over 280 women in Denmark, increased risk of retained placenta requiring manual prevalence of retained placenta was found to be consistent removal.1 Generally, incidence seems to be higher in devel- with previously reported numbers (approximately 3%) oped countries where practices tend toward earlier manual using strict diagnostic criteria. The authors found that in removal of the placenta in the third stage of labor.8,12 subsequent vaginal deliveries, the risk of recurrence was substantially increased to about 25%.3 There has even Risk factors been some suggestion that tendency toward retained pla- Many studies have attempted to define risk factors for centa may even be inherited. In one study, authors used the retained placenta, which are listed in Table 1. Established Swedish Medical Birth Register to identify women with 528 submit your manuscript | www.dovepress.com International Journal of Women's Health 2019:11 DovePress Powered by TCPDF (www.tcpdf.org) Dovepress Perlman and Carusi retained placenta after 1992 whose mothers’ own birth If the placenta or pieces of the placenta remain in situ records were also in the Register (after