A Case Report of a Postmortem Intrauterine Fetal Magnetic Resonance Imaging That Identified an Umbilical Cord Factor as the Cause of Fetal Death

ABSTRACT

Compared to conventional autopsies, using postmortem fetal imaging techniques to investigate the cause of intrauterine fetal demise (IUFD) allows for shorter analysis times and increased consent rates from parents. We reported a case of IUFD in which postmortem fetal magnetic resonance imaging (MRI) was performed before delivery. We confirmed the umbilical abnormalities on MRI: a true knot, hypocoiled, and entangled with the fetal trunk. Notably, the umbilical cord entanglement observed on MRI had been released at the time of delivery. These MRI findings supported the umbilical cord abnormality as the probable cause of the IUFD. Postmortem intrauterine fetal MRI can identify umbilical cord entanglement before delivery, which could not otherwise be detected by conventional examinations. This case demonstrates the potential utility of postmortem intrauterine fetal MRI for evaluating the placenta and umbilical cord in IUFD cases.

Abbreviations

CT

computed tomography

IUFD

intrauterine fetal demise

MRI

magnetic resonance imaging

1. Background

Unexpected intrauterine fetal demise (IUFD) is devastating for any family. Identifying the cause of death and diagnosing fetal disease are essential for preventing such events and assessing the risk of recurrence in future pregnancies [1]. The examinations recommended for stillbirth include a fetal autopsy, placental histopathology, genetic testing, fetal‐maternal hemorrhage testing, antiphospholipid antibody testing, serologic testing for syphilis, indirect Coombs, glucose screening, and toxicology screening [2]. However, the causes of IUFD are unknown in 25%–40% of stillbirths [3, 4]. Although conventional autopsy is the most established method for identifying the cause of IUFD [5], it is time‐consuming, and it can be difficult to obtain consent from the parents due to concerns about body disfigurement. As an alternative to invasive autopsy, non‐invasive postmortem imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) have emerged. Postmortem imaging techniques allow for shorter analysis times, more accessible data storage, and an increased consent rate from parents compared to conventional autopsy. The reported postmortem imaging studies analyzed images taken after delivery [6, 7]. However, there are several concerns, such as ethical issues with performing postmortem fetal imaging on a clinical MRI machine, the effects of the time since death and delivery, and the difficulty of assessing the placenta and umbilical cord. Therefore, we hypothesized that the fetal images in utero, that is, postmortem “intrauterine” fetal MRI, would avoid artifacts associated with delivery and allow an analysis closer to the time of fetal IUFD. Herein, we present a case in which postmortem intrauterine fetal MRIs provided useful information in identifying the cause of IUFD.

2. Case

A 37‐year‐old primipara who had a prenatal checkup without any maternal complications or fetal abnormalities was referred to our hospital with intrauterine fetal death (IUFD) at 37 4/7 weeks of gestation. At 37 weeks of gestation, the estimated fetal body weight was 2800 g (+0.3 SD), with reassuring fetal status on fetal heart rate monitoring. However, she noticed decreased fetal movement and was diagnosed with IUFD at 37 4/7 weeks. She was referred to our hospital for examination of the cause of IUFD. She was hospitalized and found to be in stable condition with no imminent risk. Ultrasonography was insufficient to determine the cause of IUFD due to the low amniotic fluid. We proposed postmortem intrauterine fetal MRI to investigate the cause of IUFD and explained that it is a non‐invasive method that cannot fully replace autopsy but may provide useful diagnostic information. After this explanation, the parents consented to undergo MRI. MRI was performed with the 1.5‐T MRI system (Signa HDx; GE Medical Systems, Waukesh, WI, USA). The scan sequence included a single‐shot fast spin echo, fast imaging employing steady‐state acquisition, and T2‐weighted images in axial, sagittal, and coronal sections. The total scanning time was approximately 15 min per examination. MRI revealed no obvious fetal malformations, but rather, a hypocoiled umbilical cord (Figure 1A,B, arrowheads) and a true knot (Figure 1A,B, arrows). The cord vessels collapsed on the fetal side from the knot, disrupting blood flow (Figure 1B, arrows). MRI also showed three loops of umbilical cord entanglement around the fetal trunk (Figure 1E, arrowheads), tightly wrapped around the upper extremity (Figure 1F, arrowheads). She was induced for labor and delivered a 2480 g baby at 38 2/7 weeks of gestation. The trunk of the stillborn infant showed a band‐like scar, but no umbilical cord entanglement was observed (Figure 2A, circled). The stillborn infant exhibited no apparent external malformations on examination. The umbilical cord was long (82 cm), hypocoiled, and had a true knot (Figure 2B,C). Pathological examination of the placenta showed no findings of a large infarction, hematoma, or severe chorioamnionitis. We could not obtain consent for autopsy and chromosome testing of the stillborn. We concluded that the umbilical cord factor was the high probability cause of IUFD. One year and 7 months later, she delivered a live baby at 38 5/7 weeks during her subsequent pregnancy.

FIGURE 1.

Postmortem intrauterine fetal MRI Images. (A, B) True knot (arrows) and hypocoiled cord (arrowheads). (C, D) Collapsed umbilical vessels on the fetal side of the true knot (arrows). (E) Three loops of umbilical cord entanglement around the fetal trunk (arrowheads). (F) The umbilical cord is tightly wrapped around the upper limbs of the fetus. rt A, right Arm.

FIGURE 2.

Pictures of the stillborn infant and placenta/umbilical cord. (A) The trunk of the stillborn infant had a band‐like scar (circled). (B, C) The placenta and umbilical cord after delivery are shown. A true umbilical cord knot was observed (C).

3. Discussion and Conclusions

The main causes of IUFD include maternal factors (hypertensive disorder and other medical complications), fetal factors (genetic/structural abnormalities), placental disease (placenta abruption, previa, etc.), and umbilical cord abnormalities. The cause of IUFD is unknown in approximately one‐third of cases [3, 4]. Moreover, low autopsy rates, 20.9% in the United States [8] and only 4.7% in Japan [4], make it even more difficult to attain an accurate diagnosis. Postmortem imaging using MRI [7, 9], CT [10], or ultrasonography [11] is a non‐invasive technique to investigate the cause of IUFD and is more likely to obtain parents' consent. Postmortem MRI is the most studied fetal postmortem imaging technique, and its diagnostic accuracy using autopsy as the gold standard is 77%–94% [9]. Thayyil et al. [7] suggested that the combination of postmortem fetal MRI after delivery, clinical course, and laboratory values of the stillborn infant should have comparable diagnostic accuracy to conventional autopsy.

Previous studies have performed MRI in the stillborn after delivery, whereas we performed MRI prior to delivery. Since it takes several days or more from the time of IUFD diagnosis to the time of delivery to obtain MRI images after delivery, we assumed that taking fetal MRI images in utero would be more informative for identifying the cause of IUFD. Moreover, the delivery process may cause changes in the fetus and its appendages. In fact, intrauterine MRI demonstrated multiple cord entanglements around the fetal trunk and collapse of the umbilical vessels distal to the true knot. These findings were no longer evident after delivery. While a band‐like scar on the trunk remained macroscopically, integration with the MRI findings allowed us to conclude that the severe cord entanglement had occurred in utero. Although three‐dimensional ultrasonography is effective in detecting cord abnormality, [12], absence of cord blood flow and relatively low amniotic fluid in the third trimester make it difficult to detect cord abnormalities. This indicates that postmortem intrauterine fetal MRI is at least more useful for identifying umbilical cord abnormalities compared to conventional examinations. In addition to identifying umbilical cord abnormalities, intrauterine fetal MRI may have broader applications, including the detection of central nervous system anomalies, intrathoracic or intra‐abdominal hemorrhage, and possibly early signs of infection. Tan et al. [13] comprehensively described MRI findings in fetuses after intrauterine death, including thrombotic cord changes and postmortem changes of internal organs, highlighting the diagnostic potential of this technique. While genetic syndromes cannot be diagnosed directly by MRI, certain structural features associated with such conditions may be visualized. These considerations suggest that intrauterine fetal MRI may provide clinically useful information across a wider spectrum of IUFD cases. Maternal movement might have affected fetal MRI image quality when performed before delivery. Although our postmortem intrauterine fetal MRI scans provided sufficient images for clinical diagnosis, further studies are needed to determine whether fetal MRI images in utero are comparable to images of stillbirth in diagnosing the cause of IUFD for fetal factors.

Based on our findings, we concluded that umbilical cord abnormalities were associated with fetal death. However, since we could not obtain the consent to perform an autopsy, we could not fully investigate the cause of fetal death. Although cord abnormalities are associated with fetal death [14] and the rate of umbilical cord abnormalities is higher in the third trimester than in the other trimesters for IUFD causes [3], most of them do not lead to adverse outcomes [15]. In our case, the coexistence of the true knot and strong entanglement of the umbilical cord indicated a high probability of intrauterine fetal death. Further research is needed to show the association between the MRI findings of the umbilical cord and the cause of fetal death.

Identifying the cause of IUFD with intrauterine fetal MRI may provide important benefits for both families and clinicians. For parents, establishing the etiology can offer emotional closure and reduce uncertainty. For clinicians, determining the cause supports counseling, informs recurrence risk assessment, and contributes to management planning in subsequent pregnancies [16]. Although MRI does not alter the mode or timing of delivery, it provides clinically meaningful information that may guide future care. Nevertheless, these benefits must always be balanced with maternal safety. Postmortem intrauterine fetal MRI should not be undertaken to investigate the etiology of IUFD when an acute condition such as placental abruption is suspected or when the maternal condition is unstable.

We consider postmortem intrauterine fetal MRI to be most appropriate in the following situations: (i) unexpected IUFD during an otherwise uncomplicated pregnancy, (ii) when the cause remains unclear on ultrasound, (iii) when the maternal condition is stable and does not require urgent intervention, and (iv) when the parents do not wish for an autopsy and prefer a non‐invasive imaging examination. However, this approach has important limitations. First, it requires that MRI be readily available and that the associated costs be acceptable to the family. Second, it cannot replace the histological information provided by a conventional autopsy. Therefore, MRI should be regarded as a complementary tool rather than a substitute for autopsy, applied selectively according to parental preference and clinical context. In addition, from an ethical perspective, postmortem intrauterine fetal MRI should be performed only with informed parental consent, and careful attention should be paid to the family's values and cultural background. This approach may be more acceptable in settings where conventional autopsy is less frequently performed because of cultural or social factors, particularly in countries such as Japan [17].

In summary, we experienced an IUFD case in which umbilical cord entanglement was identified on postmortem intrauterine fetal MRI, which could otherwise not be detected on conventional examinations. This case demonstrates the potential utility of postmortem intrauterine fetal MRI for evaluating the placenta and umbilical cord in IUFD cases. The advantages of postmortem intrauterine fetal MRI are worth further investigation.

Author Contributions

Kaho Sone: writing – original draft. Takashi Iizuka: writing – review and editing, writing – original draft, project administration. Kotaro Yoshida: methodology, supervision, writing – review and editing. Yuka Tanaka: investigation, data curation. Kyosuke Kagami: investigation, data curation. Kaoru Abiko: writing – review and editing, supervision.

Disclosure

The authors have nothing to report.

Ethics Statement

This case report was conducted in accordance with the principles of Declaration of Helsinki. According to the policy of Kanazawa University Hospital, ethical approval was not required for a single case report.

Consent

Written informed consent was obtained from the patient to publish the present case report and any accompanying images, figures, and clinical details. A copy of the written consent is available for review by the Editor of this journal.

Conflicts of Interest

The authors declare no conflicts of interest.

Sone K., Iizuka T., Yoshida K., Tanaka Y., Kagami K., and Abiko K., “A Case Report of a Postmortem Intrauterine Fetal Magnetic Resonance Imaging That Identified an Umbilical Cord Factor as the Cause of Fetal Death,” Journal of Obstetrics and Gynaecology Research 51, no. 10 (2025): e70097, 10.1111/jog.70097.

Data Availability Statement

The data that support the findings of this study are not publicly available due to privacy and ethical restrictions, as they contain patient‐specific clinical information. Data may be available from the corresponding author upon reasonable request.