Atypical amniotic fluid embolism presenting with isolated coagulopathy: a case report

Abstract

Background

Amniotic fluid embolism (AFE) is a rare but catastrophic obstetric complication characterised by the sudden entry of amniotic fluid or fetal components into the maternal circulation, triggering severe cardiorespiratory collapse, coagulopathy, or both. While most patients exhibit abrupt hypotension and hypoxia, a coagulopathy-dominant subtype has increasingly been recognised but remains easily overlooked. Its insidious onset and absence of overt cardiopulmonary signs often delay recognition and appropriate intervention.

Case presentation

We report a 30-year-old Chinese woman (gravida 2, para 1) who developed severe coagulopathy-dominant AFE shortly after the vaginal delivery of a term singleton infant at a tertiary comprehensive hospital. She presented exclusively with massive postpartum bleeding and precipitous drops in fibrinogen (3.21→ 0.37 g/L within 15 min) and platelets (96→46 × 10⁹/L), without hypoxia or cardiopulmonary compromise. Recognising the disproportionate coagulopathy, clinicians rapidly initiated a protocol involving massive transfusion emphasising early fibrinogen supplementation, followed by timely surgical intervention. Despite profound disseminated intravascular coagulation and recurrent haemorrhage, coordinated multidisciplinary management resulted in complete recovery without sequelae.

Conclusions

This case highlights an atypical, coagulopathy-dominant case of AFE in which rapid recognition of isolated coagulopathy and early fibrinogen-guided transfusion likely avoided a fatal outcome. Vigilant monitoring and prompt, team-based intervention are essential to improving survival in such non-classical AFE presentations.

Background

Amniotic fluid embolism (AFE) is a rare but life-threatening obstetric complication that poses a serious threat to both maternal and fetal survival. Although its global incidence is extremely low—recent population-based data estimate approximately 6 cases per 100,000 deliveries [1]—AFE remains a leading cause of maternal morbidity and mortality because of its abrupt onset and rapidly progressive haemodynamic and coagulopathic collapse [2, 3]. While classical AFE is often promptly diagnosed based on its hallmark triad of sudden cardiopulmonary collapse, hypoxia, and disseminated intravascular coagulation (DIC), atypical forms of AFE are far more insidious and diagnostically challenging, as they may lack the hallmark respiratory or cardiovascular manifestations, leading to delayed recognition and missed opportunities to intervene in a timely manner.

Recent studies have suggested that AFE represents not merely a mechanical embolic event but rather a complex immunologic and haemostatic reaction involving the activation of inflammatory and coagulation cascades [4]. Among its variants, the coagulopathy-dominant type – characterised by early and profound consumptive coagulopathy – remains particularly rare and difficult to recognise [5]. Successful management is highly reliant on clinical vigilance, rapid multidisciplinary coordination and decision-making tailored to the particular case.

Here, we report a case of atypical, coagulopathy-dominant AFE occurring after vaginal delivery, in which the patient developed abrupt and severe coagulopathy with massive postpartum haemorrhage but no cardiopulmonary collapse. Prompt recognition of the severity of the condition and initiation of a protocol involving massive transfusion emphasising early fibrinogen replacement, combined with immediate surgical intervention and multidisciplinary management, led to full recovery. This case highlights the importance of early diagnosis and team-based management in improving outcomes in atypical presentations of AFE.

Case presentation

A 30-year-old Chinese woman, gravida 2 para 1, at 40 weeks of gestation was admitted to our hospital—a tertiary general hospital in China—because of a 2-day history of slightly decreased fetal movement. On admission, her vital signs were stable (temperature 36.6 °C, pulse 78 beats/min, respiratory rate 20 breaths/min and blood pressure 109/78 mmHg). Her body mass index was 24.2 kg/m². The antenatal course had been uneventful, with no hypertensive disorders, diabetes or other complications. She was diagnosed with decreased fetal movement, suspected nuchal cord, and intrauterine singleton pregnancy at term with signs of impending labour. Routine examinations revealed no abnormalities.Labour was induced with a conventional protocol of intravaginal dinoprostone (Cervidil) followed by intravenous oxytocin for cervical ripening and augmentation of uterine contractions. On the third day of induction, owing to minimal labour progress, artificial rupture of membranes was performed at 13:20, releasing clear amniotic fluid. Uterine contractions intensified within 20 min, and labour progressed rapidly. The cervix became fully dilated at 17:48, and the patient delivered a healthy live infant vaginally at 18:29. The neonate had Apgar scores of 9, 10, and 10 at 1, 5, and 10 min, respectively, and the labour and delivery progressed smoothly without complications.

Onset of event and initial management

Six minutes after fetal delivery, the placenta and membranes were expelled spontaneously but appeared slightly incomplete, and uterine curettage was performed to remove residual tissue. Within 15 min postpartum, the total estimated blood loss reached approximately 400 ml. During this period, the patient experienced sudden chest tightness without oxygen desaturation, which resolved quickly with supplemental oxygen. Uterine atony was initially suspected, and uterotonic agents—including oxytocin (20IU intravenously), carboprost tromethamine (250 µg intramuscularly), and methylergometrine (0.2 mg intramuscularly)—were administered according to institutional postpartum haemorrhage protocols. Laboratory tests, including complete blood count, coagulation profile and blood cross-matching, were ordered, and two intravenous lines were established. Cervical and vaginal lacerations were identified and promptly sutured.

Despite these interventions, bleeding persisted, reaching approximately 1200 mL by 19:00 and increasing to about 1500 mL by 19:21. Uterine balloon tamponade was applied, accompanied by the transfusion of 4 units of packed red blood cells and 400 mL of fresh frozen plasma. Approximately 1 h after delivery, the patient developed progressive pallor, decreased responsiveness, thready pulse and hypotension, indicating worsening haemodynamic instability. By 20:18, the cumulative blood loss exceeded 3000 mL, and the patient was transferred to the operating room for surgical management. At that time, laboratory results from the initial 400 mL bleeding episode became available, revealing marked thrombocytopenia and hypofibrinogenaemia, indicating severe coagulopathy. Apart from vaginal bleeding, no cutaneous bleeding from intravenous or cannulation sites, mucocutaneous hemorrhage, or oozing from puncture sites was observed. According to the International Society on Thrombosis and Hemostasis (ISTH) criteria, the laboratory profile was consistent with overt consumptive coagulopathy that appeared disproportionate to the degree of blood loss.

Intraoperative management and outcome

Owing to persistent vaginal bleeding and rapidly worsening coagulopathy, the patient was taken for an emergency exploratory laparotomy at 20:18. Given the uncontrolled haemorrhage and severe coagulation dysfunction, a total hysterectomy was performed to achieve haemostasis. The patient received massive transfusion, including packed red blood cells, fresh frozen plasma, cryoprecipitate, and fibrinogen concentrate, with detailed transfusion volumes provided in Fig. 1. After surgical intervention and aggressive correction of coagulopathy, the bleeding was brought under control and the patient was transferred to the intensive care unit (ICU) for close postoperative monitoring. The first operation concluded at 01:00 the next day.

Fig. 1.

Clinical timeline of haemorrhage progression, laboratory changes, and key interventions in the patient with suspected coagulopathy-dominant amniotic fluid embolism

Following the initial hysterectomy, the patient remained haemodynamically unstable and required vasoactive support, with endotracheal intubation maintained in the ICU.

However, at 05:00, ICU staff noted a large volume of fresh blood in the abdominal drainage bag. Bedside ultrasound and urgent computed tomography revealed massive intra-abdominal and pelvic bleeding(Fig. 2), accompanied by a sharp drop in haemoglobin, falling from 58 g/L on postoperative assessment to 44 g/L despite ongoing transfusion (4 units of packed red blood cells and 400 mL of fresh frozen plasma). The patient was immediately returned to the operating room for re-exploration. Intraoperatively, diffuse oozing from the vascular plexus of the ovarian ligament and adjacent pelvic peritoneum was identified, while the hysterectomy stump remained haemostatic. Vascular ligation and extensive compression suturing were performed, along with additional massive transfusion and haemostatic therapy. The total cumulative blood loss reached approximately 6500 ml. The clinical course, key interventions and corresponding laboratory results are summarised in Fig. 1. whereas Fig. 3 illustrates the dynamic changes in key coagulation parameters characteristic of coagulopathy-dominant amniotic fluid embolism.

Fig. 2.

Abdominal computed tomography performed prior to the second surgical intervention in the intensive care unit, demonstrating massive intra-abdominal and pelvic bleeding. Arrowheads indicate areas of free intraperitoneal fluid

Fig. 3.

Dynamic changes in key coagulation parameters in a patient with coagulopathy-dominant amniotic fluid embolism. Panel (A) shows fibrinogen levels (g/L); Panel (B) shows platelet counts (×10⁹/L); Panel (C) shows INR; and Panel (D) shows APTT (s). Timepoints (T0–T8): T0–Admission; T1 – Delivery (18:29); T2 – 15 min postpartum; T3 – Before surgery (massive haemorrhage >3000 mL); T4 – Intraoperative laboratory results (during hysterectomy); T5 – Postoperative laboratory results on ICU admission; T6 – Re-bleeding at 05:00; T7 – Post-second surgery (ICU stage); T8 – Postoperative Day 2

Following the second surgery, haemostasis was successfully achieved, and the patient was returned to the ICU for continued monitoring and supportive care. Her clinical condition gradually stabilised, allowing discontinuation of vasoactive agents and successful extubation on postoperative day 1 after the reoperation. Over the following days, coagulation parameters and haemoglobin levels progressively normalised, with no further bleeding episodes observed. The total length of stay in the ICU was 5 days, after which the patient was transferred to the general ward. During the recovery phase, serial assessments including cardiac biomarkers, serum lactate levels, and multi-organ function tests demonstrated continued improvement without evidence of organ dysfunction, and she was discharged in good condition without complications 2 weeks after surgery.

Discussion

While AFE is classically associated with sudden cardiopulmonary collapse, this case exemplifies an atypical, coagulopathy-dominant phenotype. The earliest and most striking feature was a precipitous drop in fibrinogen within minutes of delivery, which was markedly disproportionate to the observed blood loss. Recognising this pattern is clinically crucial, as it may prompt earlier consideration of AFE-associated coagulopathy and timely correction of coagulopathy, even in the absence of overt respiratory or haemodynamic compromise.

Given the diagnostic complexity of AFE and the absence of a definitive “gold-standard” confirmatory test [6], we evaluated this case against established diagnostic frameworks. Specifically, the 2016 uniform diagnostic criteria proposed by Clark et al. [7]were employed to delineate areas of concordance and divergence.

Strictly speaking, the case did not meet the first criterion, as no sudden cardiorespiratory arrest, hypotension, or overt respiratory compromise was observed at the time of delivery. However, the remaining key components were satisfied. Overt coagulopathy consistent with a DIC-like process was identified early, with a precipitous decline in fibrinogen from 3.21 g/L to 0.37 g/L and thrombocytopenia (platelets from 96 × 10⁹/L to 46 × 10⁹/L) documented on blood tests obtained approximately 15 min postpartum.Notably, the initial volume of haemorrhage was insufficient to account for such profound coagulation derangement, thereby fulfilling the requirement that coagulopathy be detected before blood loss sufficient to explain dilutional or consumptive coagulopathy [8]. In addition, symptom onset occurred within 30 min of placental delivery, and no intrapartum fever was documented.

Overall, although the present case does not strictly fulfill the cardiorespiratory component of the 2016 research reporting criteria, its concordance with the temporal, afebrile, and early overt coagulopathy components supports consideration of AFE within an established diagnostic framework.

Given that amniotic fluid embolism remains a diagnosis of exclusion, a systematic differential diagnostic evaluation was undertaken in this case [6]. Major obstetric conditions known to cause acute postpartum disseminated intravascular coagulation—including placental abruption, hypertensive disorders of pregnancy such as HELLP syndrome, acute fatty liver of pregnancy, sepsis-associated DIC, and massive postpartum haemorrhage-were carefully considered and excluded based on the clinical presentation, laboratory findings, and temporal characteristics, in accordance with established diagnostic criteria and previous reports [4, 6, 9–11]. The key differential diagnoses and the rationale for exclusion are summarized in Table 1.

Table 1.

Differential diagnosis of acute postpartum disseminated intravascular coagulation and rationale for exclusion in the present case

Condition	Typical timing	Key features	Rationale
Placental abruption	Antepartum / intrapartum	Abdominal pain; uterine hypertonicity; vaginal bleeding; fetal distress; DIC secondary to hemorrhage	No abdominal pain; no uterine hypertonicity; no abnormal findings on postpartum placental examination
HELLP syndrome	Late pregnancy / ≤48 h postpartum	Hypertension; proteinuria; epigastric pain; hemolysis; elevated liver enzymes; thrombocytopenia	No hypertensive disorder; laboratory criteria for HELLP not met
Acute fatty liver of pregnancy	Third trimester / early postpartum	Progressive liver dysfunction; jaundice; encephalopathy; hypoglycemia; secondary DIC	No hypoglycemia or liver failure; coagulopathy predominated early
Sepsis-associated DIC	Variable; progressive	Fever or hypothermia; infection focus; elevated inflammatory markers; secondary DIC	No identifiable source of infection; no fever or clinical signs of infection
Massive postpartum hemorrhage	Postpartum	Profuse bleeding; hemodynamic compromise; dilutional or consumptive coagulopathy	Early coagulopathy disproportionate to hemorrhage
Amniotic fluid embolism	During / shortly after delivery	Abrupt onset; severe early coagulopathy; cardiopulmonary collapse may be absent	Clinical course, timing, and laboratory findings most consistent

Recent evidence suggests that AFE encompasses two major clinical phenotypes with distinct pathophysiological mechanisms: a cardiopulmonary-collapse type, characterised by sudden hypoxia, hypotension and cardiac arrest caused by pulmonary vasospasm and right ventricular failure [12],and a coagulopathy-dominant type, in which disseminated intravascular coagulation and massive obstetric haemorrhage are the predominant manifestations [13, 14]. Although the precise pathogenesis of AFE remains unclear, Weiner et al. [15] demonstrated in vitro that amniotic fluid possesses strong procoagulant activity. Subsequent experimental studies have shown that amniotic fluid can directly activate factor X through the extrinsic coagulation pathway and induce platelet–neutrophil aggregation and activation, supporting its potential role in triggering systemic coagulation dysfunction [16, 17].

In the coagulopathy-dominant pattern, bioactive components of amniotic fluid—such as tissue factor, cytokines, and complement factors—are thought to initiate widespread activation of the coagulation cascade and secondary fibrinolysis, leading to rapid consumption of clotting factors and platelets [18]. This cascade may result in abrupt hypofibrinogenaemia and thrombocytopenia, occasionally preceding any overt cardiopulmonary compromise [19].

In clinical practice, coagulopathy-dominant AFE may initially be indistinguishable from routine postpartum haemorrhage, particularly when laboratory results are pending and uterine atony is presumed as the primary aetiology. However, the prompt availability of early laboratory data revealing abrupt and disproportionate coagulation failure represents a critical diagnostic inflection point. Recognition of AFE-associated coagulopathy at this stage is clinically important, as management considerations may differ from those for postpartum haemorrhage–related disseminated intravascular coagulation. This distinction has implications for subsequent therapeutic planning, including haemostatic resuscitation strategies and the consideration of surgical interventions.

To further enhance early recognition of coagulopathy-dominant AFE, the role of rapid coagulation assessment deserves consideration. Conventional laboratory coagulation tests are often limited by processing delays, which may hinder timely diagnostic reassessment during acute obstetric crises. In this context, point-of-care viscoelastic testing, such as rotational thermoelectrometry (ROTEM) or thromboelastography (TEG), has been increasingly advocated as a useful adjunct for the early detection and characterization of severe coagulopathy [20, 21].

These point-of-care viscoelastic techniques provide rapid, dynamic assessment of clot initiation, propagation, strength, and fibrinolysis, offering clinically actionable information in real time [22]. Such early characterization of disproportionate coagulation failure may facilitate earlier diagnostic reconsideration and more timely initiation of targeted haemostatic management [23].

Although viscoelastic testing was not available in the present case, its potential role underscores an important opportunity to bridge early recognition with prompt therapeutic decision-making, particularly in guiding haemostatic resuscitation strategies and anticipating the need for surgical intervention in similar clinical scenarios [24].

The management of coagulopathy-dominant AFE differs in several important respects from that of disseminated intravascular coagulation secondary to routine postpartum haemorrhage. In typical postpartum haemorrhage, coagulation abnormalities are usually secondary to progressive blood loss and dilution, and initial management primarily focuses on uterotonic agents, mechanical or surgical control of bleeding, and volume replacement. In contrast, accumulating evidence suggests that AFE-associated coagulopathy is characterised by abrupt and primary consumption of coagulation factors, often occurring early and disproportionate to the degree of haemorrhage [25].

Accordingly, once AFE-associated coagulopathy is suspected, early escalation of haemostatic resuscitation should be considered rather than a purely stepwise approach based on blood loss alone. Prompt activation of massive transfusion protocols and early multidisciplinary involvement are particularly important, as conservative measures directed solely at uterine tone may be insufficient to achieve haemostasis [7]. In such cases, surgical intervention may need to proceed in parallel with correction of coagulopathy to control ongoing bleeding.

From a transfusion perspective, routine postpartum haemorrhage–related DIC is commonly managed with component replacement guided by cumulative blood loss. By contrast, recent literature emphasises the importance of early and targeted fibrinogen replacement in AFE-related DIC, given that hypofibrinogenemia is often an early and prominent feature of this condition [25, 26]. Because physiological fibrinogen concentrations during pregnancy are substantially higher than in non-pregnant individuals, resuscitation targets may need to remain within the normal pregnancy range of approximately 4–6 g/L [25]. Cryoprecipitate or fibrinogen concentrate provides a concentrated source of fibrinogen and allows rapid correction in this setting [7].

This case illustrates that recognition of these therapeutic differences is essential. In coagulopathy-dominant AFE, a treatment strategy that prioritises early fibrinogen-centred resuscitation, continuous laboratory-guided reassessment, and timely definitive surgical control, when indicated, may be necessary to achieve haemostasis and improve maternal outcomes, even in the absence of early cardiopulmonary collapse [27].

Conclusion

This case demonstrates that coagulopathy-dominant AFE can manifest primarily as acute disseminated coagulopathy without cardiopulmonary collapse. Early recognition of disproportionate coagulation dysfunction, rapid activation of a multidisciplinary team and implementation of a protocol involving massive transfusion emphasising early fibrinogen replacement together with timely surgical intervention were pivotal to maternal survival. Heightened awareness of this atypical presentation and prompt decision-making and coordinated team management remain essential to improving outcomes in this rare but life-threatening obstetric emergency.

Abbreviations

AFE

Amniotic fluid embolism

APTT

Activated partial thromboplastin time

Cryo

Cryoprecipitate

DIC

Disseminated intravascular coagulation

Fbg

Fibrinogen

Fbg concentrate

Fibrinogen concentrate

FFP

Fresh frozen plasma

ICU

Intensive care unit

INR

International normalised ratio

ISTH

International Society on Thrombosis and Haemostasis

MTP

Massive transfusion protocol

Plt

Platelets

PT

Prothrombin time

RBC

Red blood cells

ROTEM

Rotational thromboelastometry

TEG

Thromboelastography

TXA

Tranexamic acid

Authors’ contributions

Huang X was primarily responsible for the conception and design of the study, data acquisition, analysis, and drafting of the manuscript. Zhong XL contributed to clinical data collection and assisted with the interpretation of clinical findings. Long JJ assisted in manuscript revision and provided important clinical insights. Liu XY supervised the project, ensured adherence to reporting standards, and provided overall guidance throughout the research and manuscript preparation process. All authors have read and approved the final manuscript.

Funding

This work was supported by the Technological Innovation and R&D Project of the Chengdu Science and Technology Bureau (No. 2024-YF05-02147-SN).

Data availability

All data generated or analyzed during this study are included in this published article. No additional datasets are available.

Declarations

Ethics approval and consent to participate

Ethical approval for this case report was waived by the Ethics Committee of The First People’s Hospital of Shuangliu District, Chengdu (West China Airport Hospital, Sichuan University) in accordance with institutional policy. Written informed consent for participation was obtained from the patient.

Consent for publication

Written informed consent for publication of this case report and any accompanying images was obtained from the patient.

Competing interests

The authors declare no competing interests.