Glossary V
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Vacuum extraction

Traction to the infant's head through the use of a suction cup applied to the infant's scalp for the purpose of assisting delivery.

Vaginal birth

Delivery of an infant through the birth canal (vagina).

Vaginal birth after cesarean ( VBAC )

Delivery of an infant through the birth canal in a woman who has previously given birth by cesarean delivery.


Fluctuations in the fetal heart rate of more than 2 cycles per minute. Grades of the fluctuation are based on amplitude range (peak to trough):

  • Absent variability = Amplitude range undetectable
  • Minimal = < 5 BPM
  • Moderate = 6 to 25 BPM
  • Marked = > 25 BPM

    The tracing to the right shows an amplitude range of ~ 10 BPM (moderate variability ).

    A sinusoidal pattern has regular amplitude and frequency and is excluded in the definition of variability.

    Variable deceleration

    An abrupt decrease in the fetal heart rate equal to or greater than 15 beats per minute (BPM). The time from onset of the deceleration to the lowest heart rate (nadir) during the event is less than 30 seconds. The deceleration lasts for at least 15 seconds but no longer than 2 minutes

    Varicella-Zoster virus (Chickenpox, shingles)

    A DNA virus of the herpes family.
    Infection with the virus presents as fever followed by small papules evolving into vesicules, pustules and crusts. The rash begins on the face and scalp then spreads to trunk. The incubation period ranges from 10 to 21 days. The patient is contagious for 1 to 2 days before the onset of rash until all lesions are crusted. The crusts are not infectious.

    Varicella pneumonia occurs in approximately 10 % of mothers. Mortality is high in untreated cases.

    Varicella infection up to the 28th week of pregnancy has been associated with limb hypoplasia, cicatricial lesions, psychomotor retardation, cutaneous scars, chorioretinitis, cataracts, cortical atrophy, microcephaly, microphthalmus, and IUGR. The risk of the syndrome is less than 2 %.

    Reactivation of the varicella-zoster virus (shingles) during pregnancy does not appear to result in intrauterine infection.


    The relation of a given portion of a presenting part to the anterior, transverse, or posterior portion of the mother's pelvis.

    Vasa previa

    Unsupported fetal blood vessels running over the cervix and under the presenting part. Vasa previa occurs with velamentous cord insertion and succenturate lobes as the frees fetal vessels cross the membranes.

    Vasa previa occurs about 1 in 3000 to 1 in 5000 pregnancies. Typically, vasa previa presents with painless vaginal bleeding at the time of spontaneous rupture of the membranes or amniotomy (AROM). The infant is usually born pale and limp.Fetal mortality for cases not recognized before the onset of labor is reported to range between 22.5% and 100%.

    The condition can sometimes be identified prior to delivery by the use of color Doppler on ultrasound.

    VATER association

    An abbreviation for the combination of defects  Vertebral defects, Anal atresia, Tracheoesophageal fistula with Esophageal atresia, and Radial dysplasia. Although this pattern of malformations has been reported more frequently in the offspring of diabetic mothers the condition is generally sporadic, and no specific genetic or chromosome problem has been identified.

    Velamentous cord insertion

    Insertion of the fetal blood vessels on the membranes at the periphery instead of directly over the placenta. The vessels then travel unprotected through the membranes before entering the placenta. The condition is eight to nine times more common in twins and is associated with an increased risk for vasa previa, intrauterine growth restriction, preterm birth, and congenital abnormalities in particular esophageal atresia , single umbilical artery, and ventricular septal defects.

    Velamentous vessels within the separating membranes of a twin pregnancy may be diagnosed prenatally using color Doppler on ultrasound.


    A device that mechanically assists or controls breathing continuously through a tracheostomy or by endotracheal tube.

    Vernix (vernix caseosa)

    The white, waxy substance that covers the skin of the fetus and newborn.  Vernix is composed of sebum (a complex mixture of fatlike compounds) and cells that have sloughed off the fetus. Vernix is believed to act as a protective film with anti-infective and waterproofing properties.

    Vertex ( vertex presentation )

    The top of the head just in front of the occipital fontanel. Vertex presentation describes a type of cephalic presentation where the top of the fetal head is felt through the cervix on vaginal examination.

    Very low birth weight (VLBW)

    Birth weight less than 1500 grams (3 pounds 5 ounces).

    VSD ( Ventricular septal defect )

    A hole in the wall that divides the large chambers of the heart  (ventricles) that pump blood.



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