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Case Study 1 - Prenatal Diagnosis Of A Double Nuchal Cord With A True Knot Resulting In Live Birth

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We previously reported two cases of stillbirth secondary to multiple umbilical cord abnormalities. (American Journal OB/GYN volume 168, number 1, January 1993, page 125-128). Unltrasonographic and fetal heart rate characteristics were described which were specific to those two occurances. We now describe how those observations assisted us in identifying a similar case which resulted in live birth. This case suggests that entanglement mechanisms repeat themselves. It is this repetition which points to a solution to umbilical cord accidents and why umbilical cord accidents can repeat themselves in the same patient.


A twenty five year old woman, gravida 3, stillborn 1, abortus 1, related that her first pregnancy resulted in a stillbirth at 38 weeks secondary to a double nuchal cord. She recalled decreased fetal movement and hiccups several days prior to discovery of no movement. Delivery confirmed a term fetus with a tight double nuchal cord. After a miscarriage, pregnancy was again achieved. She agreed to join the Perinatal Umbilical Cord Project (previously reported). Fetal nuchal cord entanglement was identified at twenty four weeks and she was cleared at twenty six weeks. At twenty eight weeks cord bunching was noticed next to a double nuchal cord. (fig. 1). A fetal heart rate recording showed a baseline of 150 BPM with some variability, spike variables and W signs. (fig. 2). The patient reported decreased fetal movement of about 25%. Fetal heart rate monitoring was instituted at home every night for 30 minutes by means of FHR telemetry (Corometrics Monitor 115/410 Modem/Spectratel TM).

Figure 1a


Figure 1b


Figure 2


At 33-34 weeks the patient again reported decreased fetal movement of 50%. A decrease in fetal heart rate baseline was also noted to 100 to 110 BPM. She was hospitalized for observation, NST, and fetal profiling by ultrasound. A double nuchal cord with neck skin indentation was seen. A doppler ratio was normal at two sites of the umbilical cord, 2.3/2.6 respectively. A true knot was confirmed visually. (fig. 3-4). After advising the patient, she was scheduled and consented for betamethasone (12mg) every 12 hours for 2 doses followed by an OCT in 24 hours. Over a six hour period she reported 4 episodes of hiccups lasting greater than 15 minutes each. An OCT was initiated. After three hours of uterine contractions every 3 to 4 minutes late decelerations developed. Five repetitive late deceleration episodes of more than 30 BOM resulted in a C/Section. A viable male infant appeared 9/10 with an umbilical vein ph of 7.23 (BE-3), hematocrit 56%, NRBC's of 9 was delivered. Placental microscopic exam revealed villous congestion with edema and hypervascularity. Some areas met the definition of chorangiosis. Central know sections showed a decreased diameter of .9mm from a normal of 2.1 cm. Also noticed was the second nuchal loop was a type B patter and the first was type A (as described by Giocomelli). This essentially means a second know was about to form. The infant did well requiring oxihood and ventilation for 24 hours after one dose of Exosurf-TM. At 48 hours the infant was stable on room air. The mother intends to breast feed.

Figure 3


Figure 4



Prenatal observations of cord entanglement and knots have been reported. This is our third case observed, the original having been reported. The PUCP has demonstrated prospectively that this is possible and to date no knots have been missed. Ultrasound is necessary to find these cases. (1) Several observations can assist in their discovery. First: There are two types of nuchal cord patterns. Type A is unlocked and crossed over. Type B is locked, crossed under and forms knots. (2) If type B is observed on ultrasound and it later disappears it means the loop has passed over the fetal body. Subsequent ultrasounds should look for a knot in these fetuses. Second: Knots seem to form at any time and may position near the fetal neck included with additional nuchal cords. Third: True knots when viewed tangenetically have a specific pattern similar to a clover leaf. Ultrasoud of the umbilical cord in water with a post partial cord segment knotted will demonstrate this. The addition of cord entanglement with knots increases the risk of stillbirth in our opinion. Fetal heart rate patters of cord compression should be carefully evaluated. The best example is with monoamniotic twins. (3) What holds for monoamniotic twins with cord entanglement should hold for singletons. Delivery should be considered when evidence exists that the fetus is compromised. Finally, placental changes may be present which when viewed pathologically may add to the explanation of fetal heart rate changes. Villous congestion, hypervascularity and NRBC's may be valuable to document. We continue to recommend that cord entanglement identification be part of prenatal care. Especially in a patient with a previous umbilical cord accident.

Figure 5


1) Jauniax E., M.D., Ramsay B. M.D., Peellaerts C.M.D., Scholler Y., M.D., Perinatal Features of Pregnancies Complicated by Nuchal Cord. Amer J Perinat, 1995; 12: 255-58.

2) Collins, J.H., M.D., Giacomello's Observation and Nuchal Cords, Amer J Obstet Gynecol, 1991; 165: 1895

3) Aisenbrey G., M.D., Catanzarite V., M.D., PhD, Hurley T., M.D., Spiegel J., M.D. Schrimmer D., M.D., Mendoza A., M.D. Monoamniotic and Pseudomonoamniotic Twins: Sonographic Diagnosis, Detection of Cord Entanglement, and Obstetric Management. Obstet Gynecol, 1995; 86: 218-22

Fig. 1:


28 weeks untrasound showing double nuchal cord and cord bunching.


Fig. 2:


Fetal heart rate recording at 28 weeks with spike variable and W sign suggesting cord compression.


Fig. 3:


Double nuchal cord as seen by color doppler.


Fig. 4:


True knot by color doppler.


Fig. 5:


Placenta with true knot.

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