True Knot of Umbilical Cord: A Diagnosis and Prognostic Challenge
Thaís Kappel Vieira Dal Pai
Department of Medicine, Universidade Luterana do Brasil (ULBRA), Canoas, Rio Grande do Sul, Brazil.
Camila Pauluci Arcolini
Department of Medicine, Universidade Luterana do Brasil (ULBRA), Canoas, Rio Grande do Sul, Brazil.
Amanda Muriela Gobatto
Department of Medicine, Universidade Luterana do Brasil (ULBRA), Canoas, Rio Grande do Sul, Brazil.
Anna Manoela de Holleben Bicca
Department of Medicine, Universidade Luterana do Brasil (ULBRA), Canoas, Rio Grande do Sul, Brazil.
André Campos da Cunha
Department of Fetal Medicine, Porto Alegre, Rio Grande do Sul, Brazil.
Vinicius Freitas de Mattos
Department of Clinical Genetics, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre, Rio Grande do Sul, RS, Brazil.
Patrícia Trevisan
Graduate Program in Pathology, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre, Rio Grande do Sul, Brazil.
Paulo Ricardo Gazzola Zen
Department of Clinical Genetics, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), and Complexo Hospitalar Santa Casa de Porto Alegre (CHSCPA), Porto Alegre, Rio Grande do Sul, Brazil.
Rafael Fabiano Machado Rosa *
Department of Clinical Genetics, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Complexo Hospitalar Santa Casa de Porto Alegre (CHSCPA) and Hospital Materno Infantil Presidente Vargas (HMIPV), Porto Alegre, Rio Grande do Sul, Brazil.
*Author to whom correspondence should be addressed.
Abstract
Introduction: True knot of the umbilical cord is characterized by a cord loop with increased tension and hence higher risk for obstetric and neonatal outcome intervention. It is a finding observed in 1-2% of births.
Aim: Review the etiology, pathophysiology, diagnosis and prognosis of true knot of the umbilical cord.
Methodology: We carried out a review searching for scientific articles present in the electronic database PubMed, using the descriptors “true knot“, “umbilical cord”, “Doppler sonography” and “prenatal diagnosis”. Articles published until 2013 were included in the review.
Discussion: True knot of the umbilical cord is a relatively common finding at birth. However, its diagnosis in uterus is still quite rare. Several factors have been related to its etiology, including the size of the umbilical cord. Its appearance occurs mostly between 9 and 28 weeks of gestation, in the fetal period of greater mobility. The major part of the true knot of the umbilical cord is not associated to increased risk of obstetric intervention and neonatal outcomes because most are loose. However, true knots can tighten during pregnancy due to fetal movement or during labour, leading to reduced blood flow and consequent fetal asphyxia and death. Thus, the close monitoring of pregnancy in cases of true knot of umbilical cord is required. Prenatal diagnosis of true knot of the umbilical cord can be a challenge. Ultrasound complementary techniques, including color Doppler and Doppler velocimetry can improve the detection rate and help to differentiate true from false knots. And this has important implications for the management and prognosis of pregnancy, and consequences for the fetus and newborn.
Keywords: Umbilical Cord; Fetus, Ultrasound, Prenatal, Prenatal Care, Prognosis