True knot-diagnostic dilemma -CTG change & Abnormal diastolic waves in Umb a may suggest in low risk women

True knot-diagnostic dilemma -CTG change & Abnormal diastolic waves in Umb a may suggest in low risk women

True knot-diagnostic dilemma -CTG change & Abnormal diastolic waves in Umb a may suggest in low risk women .Why diagnosis of true knot is missed sometimes?? Do you know that that the majority of knots are formed during labor, and thus antepartum diagnosis is not possible? How many of you will believe this?? This may an cause of sudden changes of CTG in a seemingly uncomplicated booked young gravida .      Ans:   Wharton’s jelly cushions umbilical blood vessels, thus preventing disruption of flow due to compression or bending of the umbilical cord. It has been shown that true umbilical cord knots may be responsible for fetal compromise due to cord blood flow alternations. Constriction of the umbilical cord by a true knot may lead to obstruction of the fetal circulation with subsequent intrauterine growth restriction or fetal death However, in most cases,

failure to identify umbilical cord knots prenatally may be attributed to several factors. Firstly , the umbilical cord is a complex vascular structure with different patterns of twisting and displays an erratic spatial configuration within the amniotic cavity. Secondly , even though early observations suggested that cord knots are formed early in gestation when the fetus is extremely mobile and there is enough amniotic fluid surrounding it, later observations suggest that the majority of knots are formed during labor, and thus antepartum diagnosis is not possible.

What are the various sonographic patterns  of true knot?? Various sonographic patterns have been described as characteristic of true knots, including A) ‘cloverleaf’ pattern ,B)  ‘four-leaf clover’ or C)  ‘hanging noose’ However, none of these signs is specific, and other cord complications can generate a sonographic image that can be indistinguishable from a true knot, including false knots, the presence of multiple loops of cord a small pocket of fluid, and situations in which two or more segments of the cord are in close opposition to each other In addition, the sensitivity of these findings is limited. The case described above had neither of these patterns. Recently, 3-dimensional Doppler sonography had been suggested to be helpful in the diagnosis true knots, especially in second trimester

The presence of a true knot was suspected by the presence of a bulging of an umbilical cord segment anterior to the fetal abdomen. Color Doppler sonography assisted in making the diagnosis by providing additional information on the direction of blood flow and was essential for the accurate diagnosis of the knot. The deterioration in the diastolic flow in the umbilical artery, in some uncomplicated cases may be attributed to such true knot. Which may be  – from intermittent to persistent absence of diastolic flow - could be attributed to some degree of tightening of the true knot..

The appropriate management of patients with a suspected true knot in the umbilical cord identified by ultrasonography during the antepartum period is unclear. Once the prenatal diagnosis of a true knot is suspected, further fetal surveillance is required, including Doppler flow velocity and fetal CTG. The optimal management of cases of true knot of the umbilical cord and abnormal flows which are diagnosed earlier during gestation is a true dilemma and should be tailored to each patient following proper patient counseling.

Nevertheless, our ability to diagnose antepartum problems continues to outstrip our ability to treat them. Although frustrating, it should be viewed merely as a necessary step in the evolution of diagnostic testing.