Prenatal ultrasound diagnosis of velamentous cord insertion: a case report and review of the literature

Abstract

Purpose

The velamentous cord insertion is a rare pathology in which the umbilical blood vessels branch before reaching the placenta; by varying its structure, the cord becomes prone to spontaneous internal ruptures. This pathology is an obstetric emergency, so its early diagnosis is essential.

Methods and results

We present a 27-year-old pregnant woman who attends an antenatal check-up for a routine third-trimester examination. Ultrasound reveals grade I polyhydramnios and suggestive findings of a trivascular umbilical cord with velamentous insertion 35 mm from the nearest placental border. The ultrasound diagnosis allowed a term delivery by elective cesarean section, avoiding severe complications of the maternal–fetal binomial.

Conclusion

Velamentous cord insertion can and should have an early prenatal diagnosis, even from the second trimester, through imaging techniques such as transabdominal ultrasound or color Doppler. Early detection and appropriate peripartum management will highly reduce complications during labor.

Introduction

Velamentous cord insertion (VCI) is an unusual pathology present in 1% of singleton pregnancies, implying a high rate of perinatal morbidity [1]. It consists of the abnormal insertion of the umbilical cord into the ovular membranes (the amnion and the chorion) before reaching the placental margin so that the chorioamniotic membrane covers it but without Wharton's jelly [2]. This lack of protection leads to a high risk of spontaneous intrapartum rupture, resulting in intrauterine fetal death and obstetric emergencies during delivery [3].

Thirty-five percent of spontaneous abortions are due to VCI [4]. Regarding its pathogenesis, the mechanisms that produce the irregular insertion are still unknown; one theory proposed in the literature is the placental trophotropism process, a phenomenon in which the placenta, in search of a better blood supply, tends to migrate to different areas as gestation progresses [5]. In vitro fertilization, nulliparity, and maternal obesity have been mentioned as risk factors for VCI [6]. Additionally, VCI is associated with conditions such as spina bifida, intrauterine growth retardation, and ventricular septal defect [7]. Diagnosis can be made prenatally by abdominal ultrasound or Doppler, reducing the fetal mortality rate as much as possible [8]. This article will describe a case of a pregnant woman with VCI, diagnosed by ultrasound findings.

Case history

A 27-year-old pregnant woman in her fourth pregnancy begins her antenatal check-up at week 7 of gestation at the Departmental Hospital San Antonio de Roldanillo Valle (HDSAR). She was classified as high obstetric risk from the beginning of pregnancy due to morbid obesity (Body mass index: 40 kg/m²), risk of isoimmunization (maternal blood group B −, partner O + , receiving a dose of anti-D immunoglobulin at 28 weeks), toxo-susceptibility, history of two abortions (last one year prior to final gestation), the long inter-gestational period between births (nine years), and gestational anemia (hemoglobin: 10. 2 g/dl).

The pregnancy initially progresses without alterations, with a normal nuchal sonolucency ultrasound, CTOG 75 gr in normal values, a normal ultrasound vaginal cervicometry at week 24 with low risk for preterm delivery, without placenta on internal cervical os, anatomy ultrasound with fetal wellbeing, thyroid panel within normal ranges, and STORCH (syphilis, toxoplasmosis, rubella, cytomegalovirus, and herpes simplex) test without alteration. At 31 weeks of gestation, a transabdominal obstetric ultrasound was performed, which identified grade I polyhydramnios with an amniotic fluid index greater than 9 cm, in addition to findings suggestive of a trivascular umbilical cord with velamentous insertion at 35 mm from the nearest placental border with preserved fetal wellbeing (Fig. 1).

Fig. 1.

a Transabdominal ultrasound scan by color Doppler at 31 weeks of gestation. Velamentous insertion of the UC is observed 3.5 cm from the nearest placental border. b and c Umbilical Vessels (Arrows) are observed running along the uterine surface from the UC Velamentous Insertion to the nearest placental border. UC umbilical cord

A close follow-up of the patient was continued with a general practitioner and a gynecologist-obstetrician. In the last check-up, the gynecologist-obstetrician indicated the termination of pregnancy at 38 weeks via cesarean because of the risk of umbilical cord rupture and severe hemorrhage. Finally, cesarean section was performed at 38.5 weeks of gestational age, without maternal or fetal complications, obtaining a male newborn, weight 3170 g, height of 50 cms, and APGAR 8 of 10 at min 5. The morphology of the placenta was reviewed, and the findings described in the transabdominal obstetric ultrasound were observed (Fig. 2). The mother and newborn were discharged from the hospital after 48 h of follow-up without abnormalities.

Fig. 2.

Macroscopic examination of placenta. There is a CU insertion site (☆) on amniotic membranes, loss of Wharton’s jelly and path of Free Umbilical Vessels (Arrows) on membranes up to the Placental disc. CU Umbilical cord

Discussion

The described case shows that an adequate evaluation of the placenta and the umbilical cord during obstetric ultrasound allows timely identification of the velamentous cord insertion, contributing to the decision-making for pregnancy follow-up and termination of pregnancy, reducing the risk of maternal and perinatal complications associated with this entity.

In normal pregnancy, the umbilical vessels run in isolation to insert into the placental disc. However, in velamentous cord insertion, these vessels insert into the amniotic membranes and branch before reaching the placental disc [9]; this makes the vascular bundle more vulnerable to compression and rupture before or during pregnancy delivery [3, 10]. The underdiagnosis of this entity represents a critical clinical problem, given its high fetal mortality rate, which is as high as 44% in women with undiagnosed VCI. In contrast, the fetal mortality rate is about 3% in women with a prenatal diagnosis of VCI [11].

The classification of VCI varies according to the distance between the insertion of the umbilical vessels and the placenta: (1) complete velamentous insertion, where the umbilical vessels insert into the fetal membrane at a significant distance from the placenta, (2) partial velamentous insertion, the umbilical vessels insert into the fetal membrane but are close to the placenta and (3) marginal velamentous insertion, the umbilical vessels insert at the edge of the placenta [1, 12].

Health professionals performing prenatal ultrasounds must be trained to detect a VCI and assess its severity accurately. In case of an unconfirmed suspicion, additional tests, such as a fetal MRI, are available to confirm the diagnosis and assess the fetus's health [13]. Ultrasound findings of VCI include:

1. The insertion of the umbilical cord into the fetal membrane rather than being directly connected to the placenta.

2. The presence of blood vessels in the fetal membranes that branch toward the fetus.

3. Visualization of the umbilical cord outside the placental insertion.

4. The identification of an avascular zone in the placenta near the insertion of the umbilical cord [14, 15].

Evaluating umbilical cord blood flow using the Doppler technique is a noninvasive method of assessing fetal health. Doppler uses sound waves to measure intrauterine flow velocity and determine abnormalities. In some cases, it can be used for monitoring during labor to take measures to minimize cord compression and prevent health problems for the fetus [16].

Conclusion

Early diagnosis of velamentous cord insertion by ultrasound is feasible, accurate, and essential for proper pregnancy management. Ultrasound can detect this complication and assess its severity. Ultrasound findings may include visualization of the umbilical vessels emerging from the fetal membrane rather than the placenta, as well as the measurement of the level of insertion and the distance between the vessels and the internal cervical os.

If VCI is diagnosed, measures can be taken to reduce the risk of complications, such as frequent fetal monitoring and planning an elective cesarean section. Patients must inform their physician if they have experienced any symptoms, such as bleeding or abdominal pain, as these may be signs of a severe complication. In addition to closely monitoring prenatal check-ups for signs such as anemia, in this case.

Author contributions

JAPG, JHVV, RHMB and JVT contributed to the material preparation, data collection, and draft of the manuscript. EEPZ and MFEV contributed to the revision and finalization of the manuscript. All authors commented on previous versions of the manuscript. All authors read and approved the final version of the manuscript.

Funding

The authors declare that no funds, grants, or other support were received during the preparation of this manuscript.

Data availability

The data that support the findings of this study are available from the corresponding author, [MFE], upon reasonable request.

Declarations

Conflict of interest

The authors have no relevant financial or non-financial interests to disclose.

Ethical approval

This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Ethics Committee of Hospital Departamental San Antonio de Roldanillo E.S.E (February 24, 2023. Act No. 1).

Consent to participate

Written informed consent was obtained from the patient described in the above case.

Consent for publication

The authors affirm that the patient described in the above case provided written informed consent for submission of the case report for publication, including the publication of the figures.