The significance of clinical symptoms of subchorionic hematomas, “bleeding first”, to stratify the high-risk subgroup of very early preterm delivery

Potential mechanisms for chorioamniotic membrane rupture after subchorionic hematoma

BACKGROUND

Subchorionic hematoma is a risk factor for preterm prelabor rupture of membranes and preterm birth. A small proportion of persistent subchorionic hematoma leads to a chronic abruption-oligohydramnios sequence.

OBJECTIVE

To determine the mechanism by which subchorionic hematomas may damage chorioamniotic membranes.

STUDY DESIGN

1) The number and subtype of macrophages were determined by immunohistochemistry in chorioamniotic membranes from 8 subchorionic hematoma patients who delivered preterm (25.5 (24-32) weeks of gestation (median and range)) and 6 gestational age-matched control patients (25.5 (25-28) weeks of gestation (median and range)). Further, the thickness and fibrosis of the membranes were quantified. 2) We also developed an intrauterine hematoma model in pregnant mice, and the effects of hematoma on the amnion were analyzed by histology and immunofluorescence. 3) In vitro, primary human amnion mesenchymal cells were cocultured with M2-differentiated macrophages, and changes in mesenchymal cells were analyzed.

RESULTS

1) Subchorionic hematoma increased the number of iron-laden macrophages in the human amnion. These macrophages were CD206+, a marker of macrophages required for the maintenance of homeostasis, tissue remodeling, and metabolic adaptations. The collagen layer of the amnion tended to be thickened in patients with subchorionic hematoma. Interestingly, α-smooth muscle actin+ myofibroblasts were increased in the amnion mesenchymal layer in patients with subchorionic hematoma. Vimentin, a mesenchymal marker, was expressed in the epithelial layer of the hematoma amnion. Together, these findings indicate epithelial-mesenchymal transition in the amnion of membranes from pregnancies with subchorionic hematomas. 2) These findings in human amnion were confirmed in a mouse model of intrauterine hematoma. 3) Further, in vitro, coculture of human amnion mesenchymal cells with M2-differentiated human macrophages resulted in transformation of these cells into α-smooth muscle actin-expressing myofibroblasts via the TGF-β‒Smad3 pathway.

CONCLUSION

Subchorionic hematoma induces migration of macrophages to chorioamniotic membranes which activate the transition of amnion mesenchymal cells to myofibroblasts. These myofibroblasts may contribute to fibrosis of the amnion and damage chorioamniotic membranes.

Prediction of antenatal bleeding and preterm deliveries using placental magnetic resonance imaging in patients with placenta previa

PURPOSE

This study aimed to clarify associations between subacute hematoma on placental magnetic resonance imaging (MRI), antenatal bleeding, and preterm deliveries in patients with placenta previa (PP) without placenta accreta spectrum (PAS).

MATERIALS AND METHODS

This retrospective study investigated 78 consecutive patients with PP (median age, 34.5 years; interquartile range [IQR], 31-37 years) who underwent placental MRI in the third trimester. Patients with PAS detected intraoperatively or pathologically were excluded. Two radiologists evaluated the presence of subacute hematomas and their locations on placental MRI. We examined associations between presence of subacute hematoma and antenatal bleeding, emergency cesarean section (CS), hysterectomy, gestational age (GA) at delivery, birth weight, and amount of blood loss at CS. We also examined the association between perinatal outcome and subacute hematoma location: marginal, retro-placental, or intra-placental. Inter-observer agreement for the detection of subacute hematoma was calculated using kappa analysis.

RESULTS

Subacute hematomas were identified on MRI in 39 of the 78 patients (50.0%). Antenatal bleeding and emergency CS were more prevalent in patients with subacute hematoma on MRI (20 patients [51.3%] and 18 patients [46.2%], respectively) than in patients without (7 patients [17.9%], Fisher's exact test, p = 0.004 and 7 patients [17.9%], p = 0.014, respectively). GA at delivery was significantly lower in patients with subacute hematoma (median 36w3d, IQR 35w4d-37w1d) than in patients without (median 37w1d, IQR 36w4d-37w2d; Mann-Whitney test: p = 0.048). Marginal hematoma was significantly associated with antenatal bleeding and emergency CS. Inter-observer agreement for the presence of subacute hematoma was moderate (κ = 0.573).

CONCLUSION

Subacute hematoma on placental MRI was associated with antenatal bleeding, emergency CS and shorter GA at delivery in patients with PP. Marginal hematoma was also associated with antenatal bleeding and emergency CS. Placental MRI appears useful for predicting antenatal bleeding and preterm delivery in patients with PP.

The prognosis of neonatal respiratory status within three years after birth in chronic abruption-oligohydramnios sequence

AIM

Chronic abruption-oligohydramnios sequence (CAOS), which is characterized by vaginal bleeding and oligohydramnios, adversely affects the lungs of fetuses due to bloody amniotic fluid and oligohydramnios. The criteria for termination of pregnancy remain controversial. This study aimed to examine respiratory function in infants within 3 years after birth and risk factors for respiratory prognosis, and to clarify the management of CAOS.

METHODS

This study is a case series of patients with CAOS managed at our institution between 2010 and 2020. The clinical data of the patients and their infants within 3 years after birth were reviewed. The amniotic fluid volume was measured using the maximum vertical pocket (MVP).

RESULTS

Six of 17 neonates (35.3%) used inhaled nitric oxide (iNO) to improve oxygenation. Women with longer periods of MVP <1 cm delivered more neonates using iNO; however, periods of MVP <2 cm were not associated with iNO use. Almost half of the infants required home oxygen therapy when discharged, regardless of amniotic fluid volume. At 18 months corrected age, only one child needed respiratory support, and the others discontinued. Two neonates, both born at 23 weeks of gestational age, died within 1 month after birth because of extremely preterm birth.

CONCLUSIONS

The amniotic fluid volume could predict the use of iNO in neonates, but it did not affect the child's respiratory function after the newborn period. Almost all children born to women with CAOS can improve their respiratory function as they grow up.

Associations between the size and duration of asymptomatic subchorionic hematoma and pregnancy outcomes in women with singleton pregnancies

BACKGROUND

The purpose of this study was to investigate the relationship between the size and duration of asymptomatic subchorionic hematoma and pregnancy outcomes in women with singleton pregnancies.

METHODS

This was a retrospective study that enrolled 701 singleton pregnant women who were diagnosed with asymptomatic subchorionic hematoma by ultrasound at 5-10 gestational weeks. The control group recruited 640 normal pregnant women without subchorionic hematoma who were matched with subchorionic hematoma group on baseline characteristics. The pregnancy outcomes were compared between the two groups, and the associations of the size and duration of subchorionic hematoma with pregnancy outcomes were analyzed by logistic regression model.

RESULTS

Compared with the normal pregnancy group, the incidence of, gestational diabetes mellitus, gestational thrombocytopenia, placenta adhesion, fetal growth restriction, macrosomia in subchorionic hematoma group were higher (all P < 0.05). After adjusting for confounding factors, the hematoma size was positively associated with the occurrence of gestational hypothyroidism (adjusted OR[95%CI]: 1.029[1.004-1.054]), intrahepatic cholestasis of pregnancy (adjusted OR[95%CI]: 1.095[1.047-1.146]), term premature rupture of membranes (adjusted OR[95%CI]: 1.044[1.005-1.085]), hypertensive disorders of pregnancy (adjusted OR[95%CI]: 1.030[1.0004-1.060]), gestational thrombocytopenia (adjusted OR[95%CI]: 1.078 [1.045-1.113]), placenta adhesion (adjusted OR[95%CI]: 1.054 [1.027-1.082]), and the duration of hematoma was positively associated with the incidence of term premature rupture of membranes (adjusted OR[95%CI]: 1.070[1.027-1.115]), gestational diabetes mellitus (adjusted OR[95%CI]: 1.938 [1.886-1.993]) and fetal growth restriction (adjusted OR[95%CI]: 1.194 [1.124-1.268]).

CONCLUSIONS

The presence, size and duration of a first-trimester asymptomatic subchorionic hematoma may be associated with adverse pregnancy outcomes at later gestations such as term premature rupture of membranes and fetal growth restriction.

Subchorionic hematoma and risk of preterm delivery: a systematic review and meta-analysis

OBJECTIVE

This study aimed to investigate the association between early pregnancy with subchorionic hematoma and preterm delivery and other adverse pregnancy outcomes in singleton pregnancies.

DATA SOURCES

English studies published from 2000 to July 15, 2022 were retrieved from PubMed, Web of Science, and the Cochrane Library.

STUDY ELIGIBILITY CRITERIA

The inclusion criteria were: singleton pregnancy, subchorionic hematoma, and perinatal outcomes. Studies including multiple pregnancy, basic molecular studies, case reports (series), and conference reviews were excluded.

METHODS

Data analysis was mainly conducted with Review Manager (RevMan) and Stata, and the results were represented with odds ratios and 95% confidence intervals. The methodological quality of the included studies was evaluated by the Cochrane risk assessment scale.

RESULTS

In total, 370 studies were retrieved from the above databases. Our review included 16 studies and divided them into 2 subgroups: natural pregnancy (12 studies) and assisted reproductive pregnancy (4 studies). The relevant characteristics of each study were analyzed in detail. The primary outcome was preterm delivery. The secondary outcomes were miscarriage, fetal growth restriction, cesarean delivery, and preeclampsia. We found that subchorionic hematoma in the first trimester was not significantly associated with preterm delivery (odds ratio, 1.11; 95% confidence interval, 0.82-1.51) or other adverse outcomes in singleton pregnancy. Regression analysis found that the large heterogeneity of the included studies might be related to whether the included study population (early pregnancy with subchorionic hematoma) was complicated with threatened abortion (P<.05). However, no studies caused large heterogeneity according to sensitivity analysis. Finally, 15 studies related to preterm delivery did not have publication bias (Egger test: P=.26). However, subchorionic hematoma in the first trimester was associated with miscarriage in single pregnancies (natural pregnancy: odds ratio, 3.07; 95% confidence interval, 1.98-4.75; assisted reproductive pregnancy: odds ratio, 1.45; 95% confidence interval, 1.1-1.90).

CONCLUSION

In singleton pregnancy, we found no association between subchorionic hematoma in the first trimester and preterm delivery. Although there was a correlation with miscarriage, the possible gestational age of miscarriage was not stated. More studies are needed to further address the herein posed research questions.