Long umbilical cord and its mysterious demeanour: A case report

Introduction

An umbilical cord of length >70 cm is deemed long.^1,2 True knotting of such is reported in 0.3–3.5% of pregnancies.^3–5 Cord length is usually shorter in multiple compared to singleton pregnancy. ⁶ True knotting is defined as the entwining of a segment of umbilical cord and commonly results from foetal slippage through a loop of the cord. Predisposing factors include the long umbilical cord, advanced maternal age, ³ polyhydramnios, small foetus, gestational diabetes mellitus, ⁷ mono-amniotic twin and multiparity. When associated with singleton foetus, the stillbirth risk is increased 4–10 times.^3,4,7 Abnormal foetal heart rate tracings are more often encountered during labour. However, acid-base values in cord blood are normal with no increase in Caesarean delivery rates.^3,8

In a retrospective study of 18 cases where true knot was found at delivery, the authors found that true knots of the umbilical cord are easily missed at routine ultrasound scan and there is no characteristic appearance. ⁹ However, if diagnosed prenatally, the unforeseen and sudden complications associated can be prevented by vigilant foetal monitoring and elective induction of labour.

Case report

A 23-year old primigravida with a full term pregnancy with no associated risk factors presented at our emergency department with decreased foetal movements noted for the last 24 h. Her antenatal course was uneventful. Her general and systemic examination were within normal limits. The uterus was full term in size, with a cephalic presentation. Vaginal examination demonstrated a cervix 50% effaced with an internal os 1 finger dilated and vertex was at station 3. She was induced with dinoprostone gel (prostaglandin E2). The first stage of labour and her cardiotocography (CTG) were pathological and so an emergency lower segment Caesarean section was undertaken in view of her foetal distress. We delivered a 3.5 kg healthy male baby. The length of the umbilical cord was 92 cm (Figures 1 & 2) with three tight loops of cord around the neck and one loop around the body. One true knot (Figure 3) was present. The placenta was found to be normal in appearance on examination. The mother and the baby were discharged on the second post-operative day. She provided consent for publication of this case report.

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Figure 1.

Length of umbilical cord from the placental end.

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Figure 2.

Length of umbilical cord from the foetal end.

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Figure 3.

A true knot in the umbilical cord (arrow).

Discussion

The diagnosis of knotting of the umbilical cord is not commonly reported antenatally in routine practice. ¹⁰ In a recent population-based cohort study involving 243,639 newborns with 1.1% incidence of true knots, a significant higher rate of intrauterine foetal death was noted. However, the incidence of neurological events and hospitalization were similar in newborns who were exposed to true knots when compared to newborns not having true knots. ¹² It is still unclear at which gestational age true knots actually occur as they are found during all three trimesters. ⁸ During routine ultrasonography, the whole length of umbilical cord is not seen and hence it cannot be relied upon for diagnosis of true knot antenatally.

Given the risk of foetal compromise, prudent and timely decision to save the foetus has to be made. ⁷ In our case, an abnormal foetal heart rate mandated the Caesarean section. Clinical management protocols do not include suspected true knotting. ¹¹

In a study conducted among 8 cases of true knots to determine the sensitivity of 3D ultrasound, 62.5% had confirmation of the prenatal diagnosis at delivery. ¹⁰ Another case report from Pakistan made similar observations. ¹³ Colour doppler studies at term may be more effective than conventional ultrasound, and crd compression due to a constricted knot may be displayed on doppler velocimetry of the umbilical vessels. ¹⁴ So, if diagnosed antenatally, foetal monitoring and elective intervention may be introduced. There remains much room for evaluation in this field.