A misdiagnosed case of a 150-cm umbilical cord coiled twice around the fetal neck with a true cord knot: A rare Syrian case report

Abstract

The normal umbilical cord is a crucial component during pregnancy, but sometimes it could become compromised due to some abnormalities such as excessive long umbilical cord, and though they usually end up with a healthy baby, they may lead to severe consequences. Excessive long umbilical cords are found in 4% of pregnancies and represent a risk factor for nuchal cords and true knots. We report a case of a 37-year-old Syrian pregnant woman who presented to the hospital at 37 weeks of gestation asking for a C-section for a fear of ambiguous ultrasound findings that have been interpreted as fetal malformation. At delivery, a healthy baby was born with a 150-cm umbilical cord, a true knot, and double-looped nuchal cords; the formation of the loops and the knot had been attributed to the elongated cord. Besides, ultrasound imaging could sometimes be deceptive and lead to unnecessary interventions; therefore, cord anomalies should always be kept in mind because they do not always represent a justification for a C-section.

Introduction

The umbilical cord (UC) is the vital connection between the fetus and the placenta. Placenta provides the crucial resources needed for fetus development. ¹ The UC begins to develop in the embryologic period between Week 3 and Week 7 gestation. ¹ It contains umbilical vessels, two arteries carry deoxygenated blood and a single vein carries the oxygenated blood. ² Elongated UCs may affect cardiac dynamics and increase peripheral vascular resistance; excessive long umbilical cords (ELUCs) predispose to stasis which is a risk factor for thrombosis (Virchow’s triad). ³ Generally, UC abnormalities such as short cord, long cord, knots, hyper-coiling, hypo-coiling, stricture and single umbilical artery can lead to increased morbidity and mortality of the fetus. ⁴ To consider the cord abnormally long, it must be longer than 100 cm. ⁵ And it presents in 4% of placentae, increasing the risk of cord entanglement. ⁶ The incidence of true knots of the UC is not only very low but also the majority of them did not present distinct symptoms. However, several fetuses can present with serious complications, given the possibility of circulatory alteration (low perfusion) and subsequent intrauterine growth restriction (IUGR), increased incidence of premature birth, or even death. A true UC knot has been described in 0.3%–2.1% of all births worldwide, and its prenatal diagnosis is extremely difficult and rarely described in the literature. ⁷ Especially, the presence of one single true knot in the navel string is a rare disorder occurring in roughly 0.3%–2% of pregnancies. ⁵ In our case, we report a rare condition of a 150-cm UC with two nuchal cords and a rare true knot.

Case presentation

A 37-year-old woman at 37 weeks of gestation, gravida 4 para 2, presented to our hospital to perform a selective C-section delivery, a private OB/GYN clinician interpreted the woman’s ambiguous findings on ultrasound in the third trimester as an undefined malformation. The patient had a history of two cesarean deliveries and one spontaneous complete abortion in the first trimester. She does not suffer from any illnesses or allergies and does not take any prescribed medications. On the first day of arrival at our hospital, the woman had undergone a full clinical examination; her vital signs were as follows: blood pressure = 110/80, heart rate = 82 bpm and temperature = 37°C; a series of laboratory tests were performed and the findings were as follows: complete blood count (hemoglobin = 12.2 g/dL, white blood cells = 10.8 × 10⁹ cells/L, 168,000 platelets/µL), body mass index (BMI) = 28 kg/m² and her blood type is O positive. An ultrasound imaging showed normal findings; the placenta was positioned anteriorly and the fetus measurements were suitable for gestational age (biparietal diameter = 38W and femur length = 37W + 6D). The non-stress test (NST) results were normal. On the second day of hospitalization, cesarean delivery was performed on the request of the patient. A male infant was delivered. Apgar’s score was 8 at 1 min, and the newborn weighed 3500 g. Examination of the placenta showed an ELUC measuring 150 cm, with a double loop of the nuchal cord and a true knot (Figure 1).

Figure 1.

The placenta (star), the excessive long umbilical cord measuring 150 cm (thin arrow) and the true cord knot (thick arrow).

The patient was monitored at regular intervals and was later discharged with normal vital signs and no bleeding. No complications were observed.

Discussion

For a healthy fetus development, a normal UC is critical. It is a three-vessel cord, one vein responsible for supplying the fetus with nutrients and oxygen from the placenta, and two arteries through which deoxygenated blood and waste products get removed. This conduit begins to form at 5 weeks and elongates until it reaches full length by the 28th week of gestation, with an average length of 50–60 cm. ⁸ The blood flows through the cord vessels at a speed of 35 mL/min at 20 weeks of gestation and 240 mL/min at 40 weeks of gestation. Several abnormalities can affect the UC, including single artery, prolapse, knots, ELUCs and entanglements, all can lead to severe outcomes such as intrauterine growth retardation and stillbirth which is defined as fetal death inside the womb during labor and birth or after 20 weeks of gestation, about 2.5%–30% of abnormalities are associated with stillbirth.^9,10 In our case, we will discuss a cord with a length of 150 cm, double-loop nuchal cords and a true cord knot.

ELUCs are defined as cords longer than 100 cm occurring in 4% of placentae.^5,6 Increased parity, high BMI, increased placental weight and a history of chronic diseases such as hypertension and diabetes mellitus increase the risk of an elongated cord; gender plays a big role as well where male fetuses tend to develop longer cords than female ones, and this difference is observed after gestational week 28. ¹¹ ELUC leads to very dangerous outcomes for the mother and the fetus, that is, pre-eclampsia, preterm premature rupture of membranes (PPROM), intrauterine and perinatal death, low 5-min Apgar score and even transfer to the neonatal intensive care unit (NICU). ¹¹ The mechanism of pre-eclampsia as a result of prolonged UC is still not fully understood, but abnormal vascular endothelial growth factor (VEGF) family protein and messenger ribonucleic acid (mRNA) expression were observed in both pre-eclampsia and the UC anatomical abnormalities (UCAA), which may be the reasons for severe maternal outcomes. ¹²

ELUC is considered a strong risk factor for entanglements, which is the most observed abnormality with an incidence of 6% at 20 weeks of gestation and increased with advancing gestational age till peaking at 29% at 42 weeks of gestation. ¹² Entanglement is a feature in which one or more loops are encircled around any part of the fetus’ body due to random fetal movements and when that part is the neck it is called the nuchal cord; it is the most common kind of entanglement occurring in 15%–34% of all pregnancies. ⁶ In addition to ELUC, oligohydramnios and low birth weight increase the risk of nuchal cord formation. Nuchal loops could be loose or tight. Tight ones are more severe for the fetus because they could lead to the obstruction of blood flow causing hypoxia or even death, but, fortunately, most nuchal loops are benign, the frequency of a single loop is estimated to be 24%–28%, while the frequency of multiple loops is 0.5%–3.3%. Moreover, three loops or more are needed to cause adverse outcomes. ⁶

Besides these abnormalities, true cord knots in which the UC loops upon itself and can be physically untied represent a very rare condition occurring in roughly 0.3%–2% of all deliveries, unlike false knot which is varicosity or redundancy of an umbilical vessel (usually the vein) within the cord substance and cannot be physically released. Risk factors influencing the formation of cord knots include polyhydramnios, gestational diabetes, chronic hypertension, mono-amniotic twins, male and small fetuses, long cord and multi-parity. ¹³ Knots can cause either severe outcomes or benign due to their level of tightness just like nuchal loops. ¹⁴ A rare but classic radiological finding used to diagnose a true knot is the “hanging noose sign,” and it shows a cross-section of the UC surrounded by one of the UC loops. ¹⁵ Maybe this sign was interpreted as a malformation by the private doctor in our case.

In addition to our case, which describes a cord with a length of 150 cm and two loops, two special cases about ELUC with entanglements were reported in the medical literature. One with a 160-cm cord coiled eight times around the fetal neck causing IUGR and fetal distress, ¹⁶ and another one with a longer cord but fewer loops, a 190-cm cord wrapped six times around the neck with no complications at all. ¹⁷

The studies regarding UC length—besides the two previous cases—are controversial. Some showed poor perinatal outcomes such as asphyxia and fetal demise,^17,18 while others showed otherwise; a Japanese study published in March 2019, which was conducted on 32,315 women, concluded that ELUC may contribute to the decreased risk factors of intrauterine fetal demise in singleton pregnancies delivered at >34 weeks’ gestation and suggested that ELUC could be a preventive factor of miserable outcomes when combined with true knots by explaining that ELUCs decrease the probability of knots being tightened and closed whenever the fetus moves inside the womb. ¹⁹ This study could interpret the result of our case, a baby with two entanglements and a knot could survive with no complications, the 150-cm cord represents a logical reason for that. However, a case similar to ours reported a 93-cm cord with four loops and a true knot suffered from IUGR and needed an emergency delivery. ⁶ This case ensures that more research is needed to be done about the combined effects of multiple UC abnormalities.

In this case, the entanglements and the true cord knot were interpreted as a result of ELUC, and the reason behind the survival of the baby is also “ELUC.”

Our patient requested to deliver her baby by C-section though all other investigations were normal because she thought that would be the best for her baby’s health as the echo image finding was wrongly diagnosed as a fetal malformation by a private OB/GYN. According to studies, the decision of pregnant women to choose the mode of birth (MOB) is still debatable and there are no standards that prevent women from that, and sometimes all doctors can do is give the pros and cons of each MOB. ²⁰

Conclusion

Ultrasound images could sometimes be misleading due to UC abnormalities, leading to confusion about whether it is a malformation or not and consequently resulting in unnecessary surgical interventions. So as doctors, we have to bear in mind all of the cord abnormalities for such unclear ultrasound findings because knots and nuchal loops unlike malformation are not a cause for concern and do not represent a justification for a C-section, especially when every another aspect of the mother and fetus health is normal not all cord abnormalities end up with devastating results even when two or more abnormalities are combined.