In this study we investigated and discussed umbilical cord knot prediction by color Doppler and related placental insufficiency as one of the most serious morbidities that threaten pregnancy in its different stages. It may relate to many co-morbidities such as diabetes mellitus, maternal blood diseases, etc. Intrauterine fetal death is considered the worst fate for any pregnancy. It occurs frequently and suddenly in diabetic pregnant women with no significant warning signs. Color Doppler is a commonly used tool for the assessment of placental blood flow and prediction of early placental insufficiency changes.

Case: A 25-year-old pregnant female with a history of gestational diabetes mellitus in the previous and current pregnancy is presented to an obstetric clinic in Muli regional hospital, Maldives for pregnancy followed up at gestational age of 36 weeks to ER with Left lower abdominal pain. Abdominal US and urgent obstetric Doppler was done and findings analyzed in correlation to co-existing morbidity. Color Doppler was showing an intermittent unexplained significant irregularity of Color Doppler wave form mainly involving EDV. Follow-up was done the next day and revealed worse of the changes. The decision to end the pregnancy by caesarian section was made for fear of the baby. A true umbilical cord knot was discovered and explained the cause of the described color Dopler fluctuant flow. Placental insufficiency is a dangerous morbidity and a direct leading cause of intrauterine fatal death. It is more suspected with diabetes mothers with no sufficient or clear warning signs. Color Doppler is a good tool for assessment of placental blood flow and prediction of early placental insufficiency, but unexpected cause as cord knot may be non-discovered in color, especially when expected with associated certain co-morbidity as diabetes. UA artery flow irregularity is a described sign of many causes of placental insufficiency, but cord knot must be in mind as a cause of intermittent waveform irregularity and variable indices.