Classification of umbilical cord anomalies
Umbilical cord pathology in obstetrics encompasses a spectrum of structural and functional deviations. The main anomalies include:
- Changes in normal length (formation of a short or long umbilical cord).
- Changes in thickness (the so-called "skinny" cord).
- Formation of knots (true and false).
- Pathological insertion into the placenta.
- Abnormal development of blood vessels.
- Appearance of various mass lesions and localized fluid collections (including hematomas, cysts, hemangiomas, and teratomas).
Special attention in the context of obstetric pathology is deserved by chorioamnionitis. This infectious process often acts as a triggering factor for the onset of labor. If chorioamnionitis is diagnosed and spontaneous labor activity is absent, the decision regarding the need for labor induction is made by the physician on a strictly individual basis.
Length pathology: short umbilical cord
Anomalies of the umbilical cord length are classified into two major groups: absolutely and relatively short umbilical cord.
1. Absolutely short umbilical cord The diagnosis is established if at term pregnancy the cord length is less than 40 cm. This pathology is usually combined with other serious abnormalities: placental hypoplasia, intrauterine growth restriction (IUGR), and carries the risk of premature placental abruption and preterm labor. A specific and extremely dangerous risk in this case is the potential rupture of the excessively short cord.
2. Relatively short umbilical cord This form is encountered in clinical practice much more frequently than the absolute one. Initially, the umbilical cord has a normal length (within 40–70 cm), but becomes functionally shortened. The main causes of such shortening are nuchal entanglement around fetal body parts or the formation of true knots.
Complications associated with a short umbilical cord:
- During pregnancy: contributes to abnormal fetal presentations in the uterine cavity.
- During the second stage of labor (expulsion): causes delayed descent of the fetus through the birth canal. Due to severe tension, placental abruption or rupture of the cord itself may occur, accompanied by bleeding from the umbilical vessels.
The consequence of all listed complications is acute fetal hypoxia.
Long umbilical cord and its risks
A long umbilical cord is considered to be one whose size exceeds 70 cm. In obstetrics, this anomaly is recorded more frequently than cord shortening.
The clinical significance of a long umbilical cord is that it creates conditions for entanglement around fetal parts. Entanglement can be complex, including multiple loops (e.g., in a specific "cross-body" pattern). In addition, excessive length contributes to the formation of true knots.
The most formidable complication for the fetus with a long umbilical cord is cord prolapse. As a rule, this critical situation occurs at the time of amniotic fluid rupture.
Umbilical knots: true and false
During intrauterine development, knots can form on the umbilical cord, which differ radically in their origin and degree of danger.
True umbilical knot Occurs in approximately 0.5% of all deliveries and is most often associated with a long umbilical cord. The pathogenesis of its formation is linked to early gestation: while the fetus is small, it can accidentally slip through a loop formed by the umbilical cord. The clinical significance of a true knot is enormous. If it tightens (which can happen both during pregnancy and directly during labor), it leads to acute fetal hypoxia and can cause fetal demise.
False umbilical knot Represents only localized thickenings on the umbilical cord. Their etiology lies in varicose dilation of the umbilical vein or localized accumulation of Wharton's jelly. Unlike true knots, false knots are completely safe and do not have a negative impact on the fetal condition.
Pathological insertion
In addition to changes in length and knot formation, obstetrics distinguishes anomalies in the fixation of the umbilical cord to the placenta. There are two main types of pathological cord insertion:
- Marginal insertion.
- Velamentous insertion.
Briefly: answers to topical questions
What specific developmental anomalies of umbilical blood vessels are encountered in clinical practice?
In clinical practice, the following developmental and numerical anomalies of umbilical blood vessels are encountered:
- Single umbilical artery — forms as a result of aplasia of one of the umbilical arteries, often combined with fetal malformations and chromosomal abnormalities.
- Vasa previa (vasa praevia) — a condition in which a portion of the fetal membranes with blood vessels traversing them is located over the internal cervical os.
Why is velamentous cord insertion dangerous in labor upon amniotic fluid rupture?
Upon rupture of membranes, velamentous cord insertion (insertio velamentosa) is hazardous due to the high risk of rupture of the presenting vessels (vasa praevia). The umbilical vessels running along the fetal membranes are not protected by Wharton's jelly and are therefore easily subjected to compression and rupture. This complication leads to fetal hemorrhage, acute hypoxia, and fetal demise.
What is the obstetric management for diagnosed umbilical cord prolapse?
In cases of umbilical cord prolapse following rupture of membranes, a vaginal examination is mandatory. If conditions for rapid vaginal delivery are absent, an emergent cesarean section is performed.
What is the complete clinical management for chorioamnionitis in the absence of spontaneous labor activity?
Complete clinical management for chorioamnionitis includes drug therapy and accelerated delivery, with the decision on labor induction in the absence of labor activity determined on a strictly individual basis. Drug therapy depends on the gestational age:
- Under 24 weeks — antibiotic therapy and paracetamol.
- From 24 to 33 weeks — antibiotic therapy, paracetamol, magnesium sulfate, and glucocorticoids (for the prevention of fetal respiratory distress syndrome).
- 34 weeks and more — antibiotic therapy and paracetamol.
Following the initiation of therapy for all gestational ages, accelerated delivery is indicated.
How to distinguish knots: True — Trial for the fetus (risk of hypoxia and demise upon tightening), False — Fat or localized thickening only (completely safe).
Class and exam questions
What are the risks of a long umbilical cord upon amniotic fluid rupture?
The most formidable complication at this moment is cord prolapse, which requires emergency obstetric care.
Can a false knot tighten and cause hypoxia?
No, a false knot is not a loop, but merely a localized thickening due to the accumulation of Wharton's jelly or vein varicosity. It is completely safe.
Why can a normal-length umbilical cord behave like a short one during labor?
This occurs with relative shortening of the umbilical cord. An initially normal cord (40–70 cm) becomes functionally shortened due to entanglement around fetal parts or the formation of true knots.
What umbilical cord length is considered absolutely short?
An absolutely short cord is considered to be one less than 40 cm in length at term pregnancy. This condition threatens cord rupture during labor.
What else to study on this topic
- Umbilical cord mass lesions: hematomas, cysts, hemangiomas, and teratomas
- Marginal and velamentous cord insertion: biomechanics and risks
- Abnormal development of umbilical cord vessels
- Chorioamnionitis: criteria for individual decision-making on labor induction
- Pathomechanisms of acute fetal hypoxia in umbilical cord anomalies
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