Subinvolution of the placental site as an anatomic cause of postpartum uterine bleeding: a review

Secondary postpartum hemorrhage: Incidence, etiologies, and clinical courses in the setting of a high cesarean delivery rate

OBJECTIVES

To evaluate the incidence, etiologies, and clinical outcomes of secondary postpartum hemorrhage in a hospital with a high cesarean section rate and to compare the etiologies of secondary postpartum hemorrhage following cesarean delivery versus vaginal delivery.

MATERIALS AND METHODS

This retrospective study included 123 women with secondary postpartum hemorrhage who were treated at a tertiary-level hospital between January 2004 and June 2018. Descriptive statistics and the chi-square test were used for data analysis.

RESULTS

The incidence of secondary postpartum hemorrhage was 0.21%. The median onset of bleeding was 12 days after delivery. Fifty-two percent of the deliveries were by cesarean section. The most common etiology of secondary postpartum hemorrhage was endometritis (67.5%), followed by retained placental tissue (21.1%). Women who delivered by cesarean section had a higher rate of endometritis (80.0% vs 53.4%) and a lower rate of retained placental tissue (10.8% vs. 32.8%) than those who delivered vaginally. Surgical intervention included uterine evacuation in 29.3% and hysterectomy in 8.1% of the patients. Five percent of women were treated by embolization.

CONCLUSIONS

Endometritis was the most common cause of secondary postpartum hemorrhage. Women who delivered by cesarean section were less likely to have retained placental tissue but were at higher risk for endometritis and uterine pseudoaneurysm than those who delivered vaginally.

Comparative matrix metalloproteinase-2 and -9 expression and activity during endotheliochorial and hemochorial trophoblastic invasiveness

To establish a functional placenta, its development needs adequate trophoblastic invasiveness. The intricate and complex morphological and molecular aspects regulating trophoblastic invasion during endotheliochorial placentation of domestic carnivores and their similarities and differences with the hemochorial placenta are still poorly understood. During placentation processes, from the time of implantation, trophoblast cells invade the uterine endometrium where they achieve extensive degradation and remodeling of extracellular matrix components; in this process, matrix metalloproteinases (MMPs), particularly MMP-2 and 9, have an essential role in rebuilding, cell migration, and invasiveness. This review provides an overview of comparative trophoblast invasive events and the expression and activity of MMP-2 and 9 during endotheliochorial and hemochorial placentation, emphasizing dog and mouse placental models. Understanding of trophoblastic invasiveness in two models of placentation, the intermediately invasive domestic carnivore endotheliochorial placenta, and the more highly invasive mouse hemochorial placenta, contributes to deepen knowledge of the trophoblast invasive processes and their diverse and complex human placental alterations, such as preeclampsia.

Vessel Subinvolution of the Placental Implantation Site: A Case Report and Review of Supportive Literature

Subinvolution of the implantation site is a significant contributor to delayed postpartum hemorrhage (PPH). There is immense literature documenting the histologic features, development, and involution of the uteroplacental site; however, practice-oriented literature on subinvolution of the implantation site is sparse. In the present study, we briefly review the physiologic characteristics associated with the normal development and involution of uteroplacental arteries and the proposed pathophysiologic attributes of subinvolution. Furthermore, we engage in a comparison of the condition with preeclampsia. Herein, we report a case of postpartum vaginal bleeding that persisted for two weeks following cesarean delivery. The bleeding was nonresponsive to conservative treatment. Sonography performed revealed that a heterogeneous intrauterine vascular mass measuring 14.6 × 9.2 × 10.4 cm was present, distending the uterine cavity. The presence of retained products of conception could not be ruled out. Therefore, to further confirm the condition, the patient underwent an emergency hysterectomy. Gross examination showed an enlarged and boggy uterus with numerous dilated and ecstatic thrombosed blood vessels in the implantation site of the endomyometrium. Histologic and immunohistochemical examination of the implantation site revealed the presence of persistently patent uteroplacental arteries with variable degrees of thrombosis adjacent to normally involuted vessels. Hence, a diagnosis of placental site vessel subinvolution (VSI) was established in this case. We also reviewed the related literature to illustrate the informative histologic findings of subinvolution. Preparing the ground for diagnosing subinvolution is important as this process defines that the cause of delayed postpartum uterine bleeding is idiopathic, rather than iatrogenic.

Abundance of insulin-like growth factors 1 and 2, and type 1 insulin-like growth factor receptor in placentas of dogs

Insulin-like growth factors (IGFs) are among the primary compounds regulating placental development. In bitches, relative abundance of IGF1, IGF2 and IGFR1 mRNA transcripts have been studied in the pre-implantation uterus and early endotheliochorial placentas. The IGF2 and IGFR1 distribution has also been previously described in the uterus before embryo implantation. The aim of this study was to detect, characterize, and localize the presence of IGF1, IGF2, and IGFR1 in early-developing and mature placentas of dogs. Placentas of 15 bitches were analyzed using immunohistochemistry. The IGFs were located in endometrial epithelium and glands, with the staining pattern and intensity being less in mature placentas. Cytotrophoblast cells (CTB) and syncytiotrophoblast (STB) cells contained both IGFs; the labeling was greater in CTB of the early-developing than mature placentas. The maternal endothelium was positively stained for both IGFs, while the vascular endothelium of the chorioallantoic membrane were only stained for IGF2. The IGFR1 was detected in all cell populations evaluated. Results regarding trophoblastic IGF are quite consistent with those reported in human placentas. Spatiotemporal IGFs/IGFR1 pattern might reflect the occurrence of autocrine and paracrine signaling during placentation in bitches, and the involvement in early placental developmental processes. Furthermore, it is hypothesized that, besides hemotrophic actions of plasma IGFs, endometrial secreted IGFs may promote early placental development through histotrophic signaling.

Placenta Increta Presenting as Retained Placenta: A Report of 3 Cases

OBJECTIVES

Morbid adherence is a risk factor for retained placenta (RP). We encountered three cases of placenta increta presenting clinically as delayed postpartum hemorrhage.

METHODS

This was a retrospective study of three cases of placenta increta presenting as RP.

RESULTS

One "routine" term placenta had heavy bleeding 2 weeks later; one missed abortion at 16 weeks with fetal and placental tissue submitted, had heavy bleeding 6 weeks later; and one elective abortion (no tissue submitted), had delayed postpartum bleeding leading to a curettage with blood only, then 6 weeks later a hysterectomy for menorrhagia. All 3 pathology specimens showed necrotic villi. However, all three also showed myometrium with keratin-positive interstitial trophoblasts in a zone of damaged myometrium, consistent with increta. All three cases had basal plate myofibers (BPMF) in the placenta, with BPMF recurrence in the two cases with another pregnancy.

CONCLUSION

RP may be a presenting clinical manifestation of placenta increta.

Multimodality imaging in secondary postpartum or postabortion hemorrhage: retained products of conception and related conditions

Secondary postpartum hemorrhage (PPH) and postabortion hemorrhage are rare complications. Retained products of conception (RPOC) is among the most common causes of both secondary PPH and postabortion hemorrhage. Other less common causes of secondary PPH are uterine vascular abnormalities such as arteriovenous malformations and pseudoaneurysms. These are usually related to a history of a procedure such as dilation and curettage or cesarean delivery. Subinvolution of the placental site is an idiopathic cause of secondary PPH; this condition may be underrecognized and therefore could have a higher incidence than currently reported. Gestational trophoblastic disease is rare but commonly presents as secondary PPH and resembles RPOC in radiologic appearance. The first-line imaging modality for secondary PPH is ultrasound, but computed tomography and magnetic resonance imaging may be used if the ultrasound findings are indeterminate. Angiography is an important tool for the definitive diagnosis of uterine vascular abnormalities. Appropriate management requires radiologists to be familiar with the multimodality imaging features of secondary PPH or postabortion hemorrhage.

Cellular localization, expression and functional implications of the utero-placental endothelin system during maintenance and termination of canine gestation

Utero-placental (Ut-Pl) angiogenesis and blood flow are fundamental for successful outcome of pregnancy. They are controlled by numerous vasodilator and vasoconstrictor systems such as endothelins (EDNs) and the renin angiotensin system. Dogs possess an invasive type of placentation, classified as endotheliochorial. Despite increasing knowledge regarding canine Ut-Pl function, little information exists on uterine and placental vascular activity during initiation, maintenance and termination of pregnancy in this species. The current study investigated expression of EDNs and their receptors (EDNRA and EDNRB) in the pre-implantation uterus and Ut-Pl compartments during gestation and at normal parturition, as well as in mid-pregnant dogs treated with the antigestagen aglepristone. The Ut-Pl mRNA expression of EDN1 and EDNRA was constant until mid-gestation and increased significantly during prepartum luteolysis. In contrast, EDN2 was highest pre-implantation and decreased following placentation, remaining low thereafter. Expression of the EDN-activating enzyme ECE1 and mRNA of EDNRB increased towards mid-gestation and was further elevated at prepartum luteolysis. Antigestagen treatment resulted in increased levels of EDN1 and EDNRA. At the cellular level, the uterine expression of EDN1, ECE1 and EDNRB was found predominantly in the endometrial surface and glandular epithelial cells; uterine signals for EDNRA were weak. In Ut-Pl all targets were mainly localized in the placenta fetalis, with syncytiotrophoblast staining stronger for ECE1 and EDNRB. In contrast, EDNRA stained strongly at the base of the placental labyrinth. Expression and localization of EDNs (EDN1, -2), EDN receptors and ECE1 in the placenta fetalis suggests their involvement in the trophoblast invasion and proliferation.

Severe secondary postpartum hemorrhage: a historical cohort

OBJECTIVES

The principal objective of our study was to describe the frequency of severe secondary postpartum hemorrhages (PPH). Our secondary objectives were to describe the different causes of PPH and to assess if the PPH etiologies varied by parity.

METHODS

This is a historical cohort study covering the period from January 1, 2004, through February 13, 2013, in a level III maternity ward. Women were eligible if they were treated for severe secondary PPH during their postpartum hospitalization or were admitted for it after discharge but before the 42nd day postpartum, regardless of the type of delivery. Women were excluded if they gave birth before 22 weeks of gestation or if they had experienced only an immediate PPH (≤ 24 hours after delivery). Eligible patients were identified by the hospital's administrative software. Primiparas and multiparas were compared with Student's t test and a chi-squared or Fisher's exact test.

RESULTS

The incidence of severe secondary PPH was 0.23 percent (n = 60/26,023). The mean time between delivery and PPH onset was 13.4 ± 10.8 days. The women's mean age was 30.4 ± 5.7 years and their mean body mass index was 23.4 ± 5.7 kg/m². Placental retention was the cause to which these hemorrhages were most frequently attributed (30.0%). Subinvolution of the placental bed was noted in 13.3 percent of the patients, endometritis in 10.0 percent, pseudoaneurysm of the uterine artery in 3.3 percent, and excessively strong resumption of menses in 3.3 percent; no cause could be determined for 16.7 percent of the cases. Neither clinical signs nor causes differed by parity.

CONCLUSION

Secondary PPH is rare. Accurate diagnosis is based most often on histopathologic findings.

Novel pathophysiological cause for post-partum hemorrhage: Case report of post-partum hemorrhage with occult abnormal artery diagnosed on pelvic angiography

To the best of our knowledge, this is the first report of post-partum hemorrhage (PPH) caused by an occult abnormal artery detected shortly after delivery on pelvic angiography (PAG). Initially, a diagnosis of uterine atony was made because the apparent cause of hemorrhage was not detected via the usual obstetrical examination. An abnormal artery, however, was suspected on PAG and confirmed on pathology. This case suggests a novel cause of persistent PPH resistant to obstetric management. Obstetricians should be aware that an abnormal artery may cause PPH, and that radiology may be required for diagnosis.

Uterine artery impedance during the first eight postpartum weeks

The aim of this study was to construct reference ranges for the uterine artery (UtA) mean pulsatility (PI) and resistance (RI) indices from 1–8 weeks postpartum. A prospective, cross-sectional, and observational study was performed with 320 healthy women from week 1 through week 8 postpartum. UtAs were examined transvaginally using colour and pulsed Doppler imaging, and the means of the right and left values of the PI and RI, as well as the presence or absence of a bilateral protodiastolic notch, were recorded. The 5^th, 50^th and 95^th reference percentile curves for the UtA-PI and UtA-RI were derived using regression models. The adjusted reference intervals uncovered a convergence trend at the week 8 time-point, although impedance was lower at the week 1 time-point in multiparous women compared with primiparous women. The notching prevalence was 22.5% (9/40) at week 1 and 95.0% (38/40) at week 8. The study revealed consistent evidence of a progressive increase of postpartum uterine impedance and provided new average UtA-PI and UtA-RI reference charts for weeks 1 through 8. Multiparity does not change the trend but does impart a lower rate of increase, likely as a consequence of previous vascular structural and functional differences.

Post-partum hemorrhage and malpractice claims: what can we learn from the findings of placental examination and endometrial curettage? A retrospective analysis of surgical pathology reports

OBJECTIVE

This study reviews the surgical pathology reports of post-partum hemorrhages to support clinicians in malpractice litigation and, potentially, to enhance pregnancy-related diagnoses.

STUDY DESIGN

This work is a retrospective study of surgical pathology reports of term pregnancies between January 2000 and January 2012 selected from the Surgical Pathology database of the I.R.C.C.S Azienda Ospedaliera Universitaria San Martino-IST (Istituto Nazionale per la Ricerca sul Cancro, Genoa).

RESULTS

Ninety-five revision reports were identified (0.22% "placenta accrete," 0.46% "non-accreta placental tissue retention," and 0.31% "no placental fragments retention"). Secondary post-partum hemorrhages occurred in 0.3%, and primary PPH occurred in 0.05%, regardless of the group examined. Both types of PPH were most often associated with vaginal deliveries (58%). The most frequent endometrial finding was post-partum endometritis (43%). The entire placenta was submitted to the pathologist in 22/95 cases (23%). Hypermaturity and/or villous immaturity were the main histological patterns.

CONCLUSIONS

This review supports the hypothesis that the pathological placenta abnormalities observed, rather than underlying myometrium abnormalities, may underlie the contractile failure and the incomplete removal of the placenta. For these reasons, the authors emphasized the importance of investigating the placenta in cases of complicated deliveries not associated with PPH to support clinicians in malpractice claims.

Recurrent secondary postpartum hemorrhages due to placental site vessel subinvolution and local uterine tissue coagulopathy

Background

Postpartum hemorrhage (PPH) represents a serious problem for women and obstetricians. Because of its association with hemorrhagic shock and predisposition to disseminated coagulopathy, it is a leading cause of maternal deaths worldwide. Furthermore, the jeopardy of PPH is rising with the secondary form of PPH occurring between 24 hours and 6 weeks postpartum, when women are already discharged home. The causes of this pathology are severe inflammation (endometritis), inherited coagulation disorders, consumptive coagulopathy, and retained products of conceptions. Others are of rare occurrence, such as vessel subinvolution (VSI) of the placental implantation site, uterine artery pseudoaneurysm, or trauma.

Case presentation

We present a rare form of recurrent secondary postpartum hemorrhage in a woman after uncomplicated cesarean delivery, with review of the literature linked to the management of this situation originating in the rare local VSI in the placental implantation site, defective decidual homeostasis, and coagulopathy confined to the uterus.

Conclusion

The placental site VSI is one of the rare causes of secondary PPH, and this situation is frequently underdiagnosed by clinicians. The histological confirmation of dilated “clustered”-shaped myometrial arteries partially occluded by thrombi of variable “age” together with the presence of endovascular extravillous trophoblasts confirms the diagnosis.

Cross-species withdrawal of MCL1 facilitates postpartum uterine involution in both the mouse and baboon

A successful postpartum involution permits the postnatal uterus to rapidly regain its prepregnancy function and size to ultimately facilitate an ensuing blastocyst implantation. This study investigates the molecular mechanisms that govern the initiation of the involution process by examining the signaling events that occur as the uterus transitions from the pregnant to postnatal state. Using mouse and baboon uteri, we found a remarkable cross-species conservation at the signal transduction level as the pregnant uterus initiates and progresses through the involution process. This study originated with the observation of elevated levels of caspase-3 activation in both the laboring mouse and baboon uterus, which we found to be apoptotic in nature as evidenced by the concurrent appearance of cleaved poly(ADP-ribose) polymerase. We previously defined a nonapoptotic and potential tocolytic role for uterine caspase-3 during pregnancy regulated by increased antiapoptotic signaling mediated by myeloid cell leukemia sequence 1 and X-linked inhibitor of apoptosis. In contrast, this study determined that diminished antiapoptotic signaling in the postpartum uterus allowed for both endometrial apoptotic and myometrial autophagic episodes, which we speculate are responsible for the rapid reduction in size of the postpartum uterus. Using our human telomerase immortalized myometrial cell line and the Simian virus-40 immortalized endometrial cell line (12Z), we demonstrated that the withdrawal of antiapoptotic signaling was also an upstream event for both the autophagic and apoptotic processes in the human uterine myocyte and endometrial epithelial cell.

Subinvolution of placental bed vessels: case report and review of the literature

Subinvolution of placental bed vessels, a well-recognized cause of postpartum and postabortal hemorrhage, is defined with prolonged or excessive uterine hemorrhage beginning after the delivery or abortion. Although physiological changes in uteroplacental parts of spiral arteries are well known, the sequence of events in involution of these vessels is not yet clearly understood. In this article we present two cases of subinvolution of placental bed vessels in which we were able to demonstrate the presence of extravillous trophoblast in and around the placental bed vessels. The disease is supposed to be the result of abnormal interaction between maternal uterine cells and fetal trophoblast.

Secondary post-partum haemorrhage: challenges in evidence-based causes and management

Secondary postpartum haemorrhage (SPPH) is an important post-natal issue, whose significance is perceived differently between practices, settings and probably within cultures. It is generally less focussed upon, in contrast to its primary counterpart. Patients prefer that it is treated promptly, even when it is not life-threatening. Intensity of blood loss, and the lesser popularity of conservative management drive clinicians towards the active options. Remarkably, none of the current treatment options is based on any evidence. Suction evacuation of the uterus may be complicated by life-threatening complications and blood transfusion. There are a few guidelines, and probably no protocols. In this review, we highlight salient factors to take into consideration, and propose a locally adaptable flowchart, which may be of use to General Practice doctors, Community Midwives and Obstetricians.

A death due to subinvolution of the uteroplacental arteries

A 19-year-old G1P0 Caucasian woman died 8 days postpartum because of the subinvolution of the uteroplacental arteries. Microscopic examination of the placental implantation site revealed large, dilated spiral arteries containing partially occluding thrombi in the superficial myometrium. The presence of cytotrophoblasts within and surrounding the spiral arteries was confirmed by low molecular weight cytokeratin immunohistochemistry. Infection of the Cesarean section incision site was demonstrated by the growth of Staphylococcus aureus and Streptococcus agalactiae Group B in the wound as well as the intrauterine blood clot. Although subinvolution of the placental site may be a cause of delayed postpartum hemorrhage and significant morbidity, the underlying pathophysiologic mechanism is unknown.