|Year : 2015 | Volume
| Issue : 2 | Page : 136-138
True umbilical cord knot
S Santhosh Kumar1, B Anandha Priya2
1 Department of General Surgery, Composite Hospital, GC CRPF, Chennai, Tamil Nadu, India
2 Department of Obstetrician and Gynecologist, Composite Hospital, GC CRPF, Chennai, Tamil Nadu, India
|Date of Web Publication||17-Jan-2016|
S Santhosh Kumar
S-1, Block-4, Plot No. 76, Habitat Apartments, Sekaran Street, Krishnapuram, Ambattur, Chennai - 600 053, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Umbilical cord is the lifeline of the fetus connecting it to the mother. It provides nutrition, oxygen, various trophic factors, and hormones from the mother to the fetus. Knotting of the umbilical cord is relatively a rare occurrence and is of two types. True knot of the umbilical cord is a serious condition which can result in fetal distress and catastrophic neonatal complications. We report a case of true umbilical cord knot, in a 28-year-old second gravida, which was diagnosed after elective cesarean section. The knotting was not found during her routine ante-natal scans. The newborn did not have any complications due to the knotting. Although prenatal diagnosis of a true knot is challenging, newer imaging techniques are promising.
Keywords: Cesarean section, true knot, umbilical cord
|How to cite this article:|
Kumar S S, Priya B A. True umbilical cord knot. Indian J Health Sci Biomed Res 2015;8:136-8
| Introduction|| |
Umbilical cord true knots are quite common in occurrence, with the incidence rates ranging from 0.3% to 2.1% of all the deliveries, but, unfortunately, the associated perinatal mortality rate is as high as 11%.  Known risk factors are long cord, small fetus, polyhydramnios, and mono-amniotic twin pregnancies. Most knots are loose and are detected only after delivery of the baby. However, knots can cause severe fetal distress and fetal losses, if it gets tightened during active fetal movements by obstructing the fetal circulation. In order to reduce these catastrophes, it is better to have an ante-natal diagnosis of knots, which is quite challenging.
| Case Report|| |
A 28-year-old North Indian woman, gravid-2, para-1, live-1, booked and immunized case belonging to a higher socioeconomic status was planned for an emergency repeat lower segment cesarean section, indication being decreased fetal movements, as perceived by the patient. The patient was admitted and nonstress test was done, the findings of which were equivocal. The patient was prepared for surgery after doing basic hematological and biochemical investigations. There was no preceding history of bleeding per vagina, vaginal discharge or leakage. There was no significant medical history and her previous menstrual cycles were regular. She had completed 38 weeks of gestation by menstrual dating method and her previous cesarean section was un-eventful which had an indication of nonprogression of labor. The first child is 7 years old and is healthy.
Her general examination was normal and her vitals were stable with normal cardiovascular and respiratory system examinations. Abdominal examination revealed a gravid uterus consistent with term gestation with cephalic presentation and audible fetal heart sounds. She was not in labor. Her basic laboratory investigations reports were within normal limits. Her blood group was B-positive. Preanesthetic check-up was done by the anesthetist and she was categorized into the American Society of Anesthesiologists I-E category. She was under regular ante-natal check-ups, and routine ante-natal scans were done at 8, 20, 28, and 37 weeks which revealed no abnormalities. The last abdominal ultrasonogram (USG) revealed a 37 weeks single live fetus in cephalic presentation.
The patient was operated under spinal anesthesia, and a Pfannensteil's incision was made over the old scar. A healthy male baby weighing 3.2 kg was delivered, which cried immediately after birth with APGAR score of 8/10 and 9/10 at 0 and 1 st min, respectively. A true umbilical cord knot was identified at around 25 cm from the umbilical end [Figure 1]. It was a complex knot, with almost like a "figure of eight" configuration [Figure 2]. The umbilical cord was 75 cm long, and normal without any ecchymoses or gangrene. The placenta was examined and found to be normal without any evidence of retro-placental clots. Her postoperative period was un-eventful and she was discharged on the 4 th postoperative day.
| Discussion|| |
True umbilical cord knots fall under an entity called umbilical cord accidents, which includes, more than 30 conditions resulting in compromised blood flow to the fetus.  The compromise could prove fatal to the fetus, if it is a complete obstruction. Approximately, 4% of all the complications of umbilical cord are due to true knots. 
Umbilical cord knots are classified into true knots or loose knots.  Although only true knots are associated with increased tension and higher risk, loose knots can still become true knots by tightening during fetal movements or labor. Another classification found in literature is true knots and pseudo-knots. In true knots, actual knotting occurs, whereas in pseudo-knots, there is a twisting of umbilical vein around the artery, which results in localized thickening of Wharton's jelly. 
True knots are caused by the rotation of the fetus in the uterus, mostly in the first and second trimester (especially between 9 and 28 weeks of gestation).  This is supported by the fact that the frequency of true knots is same in the aborted fetuses and at term, and also, the cord length does not increase significantly after 28 weeks.  Technically, it is easier to make a knot in a thread (with one end fixed and an object attached at the other end, akin to umbilical cord), if the distance between the two ends is longer, the object attached at the end is smaller, and there is enough space for rotation or revolution of the object around the cord. This is reflected in the associated maternal and fetal factors which are polyhydramnios, small fetus, long cord, mono-amniotic twin pregnancy, prolonged pregnancy, advanced maternal age, history of miscarriages, obesity, anemia, chronic hypertension, and gestational diabetes mellitus.  It is commonly observed in male fetuses. Our case too is a male child, but neither risk factors were present nor there were any fetal complications. Probably, in our case, the knotting was not tight enough to cause any vascular obstruction, although it was a true knot.
Prenatal diagnosis through routine ante-natal USG scanning is very difficult, because ultrasonic image is a two-dimensional image of a knot, which is a three-dimensional event. Moreover, inter-position of fetal parts makes it much more difficult to be diagnosed by USG. Hence, most of the knots are diagnosed after birth. Hanging-noose sign and four-leaf-clover are characteristic findings in USG, which are suggestive of true umbilical cord knots.  In case of suspected cord knots, four-dimensional USG helps in differential diagnosis and the Doppler flow velocimetry can help in the diagnosis of loose knots, which may tighten later on to become true knots.  The most sensitive imaging modality among all is the three-dimensional USG, which gives better functional and anatomical characterization. 
True umbilical cord knots are associated with an increased risk of small for gestational age infants, premature births, need for neonatal intensive care, and fetal deaths.  Airas and Heinonen conducted a population-based analysis and published results in 2002.  They found that when compared to the general obstetric population, fetuses with true umbilical cords frequently had low APGAR score at 1 min and they also had a four-fold increased risk of stillbirth. Surviving fetuses born with true umbilical cord suffer temporary distress during delivery but recover soon after birth. 
If the true knot or even a loose knot is diagnosed in the ante-natal scans, close monitoring of the pregnancy, through Doppler velocimetry and continuous cardiotocography during labor is mandatory, in view of the serious and potentially fatal complications associated with the condition.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]