Doppler ultrasound showing a<unk>  In 1962, J. Selwyn Crawford MD from the British Research Council defined a<unk>  as one that is wrapped 360 degrees around the fetal neck. Crawford commented "It is all the more remarkable, therefore, that little work has been done. to analyze its effects during labor and delivery". To date, there is no prospective case control double-blind study looking at<unk> s and observational studies vary in opinion as to the degree of poor outcomes. Also not included in these studies is which umbilical<unk>  form (of the 8 different possible structures) was considered a<unk> . Ultrasound diagnosis of a<unk>  around the neck was first described in 1982. “Coils occur in about 25% of cases and ordinarily do no harm, but occasionally they may be so tight that constriction of the umbilical vessels and consequent hypoxia result.” Williams Obstetrics 16th Edition, has only one single sentence in the entire textbook regarding<unk> s around the neck. By contrast, the First Edition of the Encyclopædia Britannica from 1770 had 20 pages of information about Umbilical<unk>  Pathology with drawings of Umbilical<unk>  Entanglement. The Royal College of Obstetricians and Gynaecologists has these images on its brochure. There are currently three recent texts on ultrasonography which demonstrate the ability of ultrasound to identify umbilical<unk>  issues with reliability as of 2009. A study published in 2004 was done to establish the sensitivity of ultrasound in the diagnosis of a<unk> . Each of 289 women, induced the same day, underwent a transabdominal ultrasound scan with an Aloka 1700 ultrasound machine with a 3.5 MHz abdominal probe, using gray-scale and color Doppler imaging immediately prior to induction of labor. Presence of the<unk>  was sought in the transverse and sagittal plane of the neck. A<unk>  was diagnosed if the<unk>  was visualized lying around at least 3 of the 4 sides of the neck. A<unk>  was actually present at delivery in 52 of the 289 women. Only 18 of the 52<unk> s or 35% of the<unk> s were detected on ultrasound done immediately before delivery, and 65% of<unk> s were not detected. Of the 237 cases where there was no<unk>  at delivery, ultrasound had false positive results, i.e. diagnosed a<unk>  in 44 of the 237 cases (19%) in which there was no<unk>  present at all. In this study, ultrasound was only 35% accurate at finding a single loop, and only 60% accurate at detecting a<unk>  wrapped multiple times around the neck. In no study was it possible by ultrasound to distinguish between a loose or a tight<unk> , although at least 3 attempted to do so. Peregrine concludes that ultrasound diagnosis of<unk> s will only be useful if doctors are able to do so reliably and predict which of those fetuses are likely to have a problem., However, perinatologists routinely look for umbilical<unk>  issues in monoamniotic twins. Studies have shown an improvement in outcomes where<unk>  entanglement was prenatally identified in these cases. Ultrasound measurement of the velocity of flow in the<unk>  may be useful in the management of twins and chronically growth-retarded fetuses. Of course this depends on the training of the sonographer. To date there are no ultrasound courses which teach the identification of<unk>  to physicians or technicians. A recent review by Wilson of the American Academy of Ultrasonography Technicians recommends the documentation of umbilical<unk>  issues. Classification * A "Type A"<unk>  is wrapped around the neck but is free sliding * A "Type B" pattern is described as a hitch which cannot be undone and ends up as a true knot. File:NuchalFree.Nuchal<unk>  - free sliding File:NuchalLocked.Nuchal<unk>  - locked pattern
Nuchal cord
Perinatal asphyxia
Posterior cord
Oblique cord
Rhomboid fossa
Medial cord
Nicomachus 
Adina