Umbilical cord prolapse is a rare obstetrical emergency that occurs when the umbilical cord descends alongside or beyond the fetal presenting part. It is life-threatening to the fetus since blood flow through the umbilical vessels is usually compromised from compression of the cord between the fetus and the uterus, cervix, or pelvic inlet. There are two types of cord prolapse:
- Overt prolapse, which is the most common, refers to protrusion of the cord in advance of the fetal presenting part, often through the cervical os and into or beyond the vagina. The fetal membranes are invariably ruptured in these cases and the cord is visible or palpable on examination.
- Occult prolapse occurs when the cord descends alongside, but not past, the presenting part. It can occur with intact or ruptured membranes. The diagnosis should be considered in the differential diagnosis of a sudden, prolonged fetal heart rate deceleration. An occult prolapse often cannot be diagnosed with certainty, but is suggested by clinical features (eg, fetal bradycardia) and findings at cesarean delivery.
Cord prolapse occurs in 0.14 to 0.62 percent of deliveries .
RISK FACTORS AND ETIOLOGY
Pregnancy characteristics that increase the risk of cord prolapse are generally not modifiable, but awareness of patients at high risk may help facilitate prompt diagnosis and delivery when prolapse occurs. The two major etiologic categories of cord prolapse are:
- Fetomaternal factors that lead to inadequate filling of the maternal pelvis by the fetus
- Iatrogenic obstetrical interventions