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OB Definitions

Ch. 15 L&D

acceleration An increase of at least 15 beats per minute over the baseline fetal heart rate that lasts at least 15 seconds, often associated with fetal activity.
acme The peak of a uterine contraction.
active labor The second part of the first stage of labor, with cervical dilatation from 4 to 7 cm.
afterbirth The expelled placenta and membranes following birth of a baby.
attitude The relationship of the fetal parts to one another. Attitudes are described as being in a state of flexion or extension.
baseline bradycardia A baseline fetal heart rate less than 120 bpm.
baseline tachycardia A baseline fetal heart rate greater than 160 bpm.
baseline variability The rhythm or beat-to-beat interval changes in the fetal heart rate. Long-term variability refers to oscillations or undulations of the baseline fetal heart rate.
Bishop score A system for rating the readiness of the cervix for labor based on assessment of cervical position, consistency, effacement, and dilatation, as well as the fetal station.
bloody show Pinkish-tinged vaginal discharge, often mixed with mucus, caused by rupture of capillaries in the cervix as it begins to efface and dilate.
Braxton-Hicks contractions Intermittent uterine contractions throughout pregnancy beginning approximately the fourth month; they may be painful or painless; also called “false labor.”
bregma The area of the fetal head that includes the anterior fontanel.
contraction Intermittent tightening of the uterine muscles during labor, which accomplishes cervical effacement and dilation and facilitates fetal descent through the pelvis.
contraction duration The length of a uterine contraction, measured from the beginning to the end of the contraction and recorded in seconds.
contraction frequency Measurement of the interval of labor contractions, lasting from the beginning of one contraction to the beginning of the next, and recorded in minutes.
contraction intensity The increase in uterine pressure during a contraction.
crowning Encircling of the widest part of the fetal head by the vaginal opening before birth.
deceleration A deviation of the fetal heart rate below baseline that persists for at least 10 to 15 seconds but for less than 2 minutes.
denominator The arbitrarily chosen landmark on the fetal presenting part used to describe position.
dilation The opening of the cervical canal, measured from 0 to 10 cm.
doula A Greek word meaning woman's servant. In labor, it refers to a supportive companion professionally trained to provide continuous support to a woman throughout the process.
early deceleration A decrease in fetal heart rate that begins and ends at the same time as the uterine contraction, causing a consistent U-shaped waveform that mirrors the contraction on an electronic fetal monitor; thought to be caused by compression of the fetal head.
early labor The first phase of first-stage labor, with the cervix dilating from 0 to 3 cm; also called the latent phase.
effacement Thinning or flattening of the edge of the cervical os, measured from 0% to 100%.
electronic fetal monitoring (EFM) Continuous recording of the fetal heart rate and uterine contractions by an electronic fetal monitor using external or internal modes.
engagement Entry of the widest part of the fetal presenting part at the maternal pelvic inlet, with the presenting part at 0 station.
episiotomy A surgical incision of the perineum made just prior to the birth of a baby.
first stage of labor Labor from the onset of regular contractions to 10 cm of cervical dilatation; this stage is further divided into early, active, and transition phases.
fontanelles Soft spots at the top (anterior) and back (posterior) of the fetal head, covered with strong connective tissue where the unfused bones of the fetal skull intersect at the suture lines.
fourth stage of labor The period from delivery of the placenta until 1 hour after birth.
labor The series of events by which the products of conception are expelled from the mother's body.
late deceleration A deceleration of the fetal heart rate that begins after the peak and finishes after the end of the contraction; it is associated with compromised uteroplacental perfusion.
lie The relationship of the fetal long axis (spine) to the maternal long axis (spine).
lightening A lay term describing settlement of the fetal presenting part into the maternal pelvis.
mechanisms of labor The movements the fetus must accomplish to negotiate passage through the maternal pelvis and be born, including engagement, descent, flexion, internal rotation, extension, restitution, external rotation, and expulsion; also called cardinal movements.
molding The elongated shaping of the fetal head as it moves through the bony pelvis during labor and birth; caused by the normal overriding of the unfused fetal cranial bones.
occiput Head.
pelvic inlet The upper border of the true pelvis; also called the pelvic brim or linea terminalis.
pelvic outlet The lower border of the true pelvis.
position The relationship of a landmark on the presenting part of the fetus to the front, back, or side of the maternal pelvis.
presentation The part of the fetal body that appears at the pelvic outlet first; also called the presenting part.
presenting part The part of the fetal body that appears at the pelvic outlet first; also called presentation.
prodromal labor A period of regular or irregular contractions toward the end of pregnancy that does not result in progressive cervical dilatation.
second stage of labor The period of labor from 10 cm of cervical dilatation to the birth of the baby; also called expulsion.
spontaneous rupture of membranes (SROM) The natural breaking of the bag of waters, or amniotic sac, either before or during labor.
station The relationship of the presenting part of the fetus to an imaginary line drawn at the level of the ischial spines within the maternal pelvis.
third stage of labor Separation and expulsion of the afterbirth.
transition phase The last part of first-stage labor with cervical dilatation between 8 to 10 cm.
variable deceleration A rapid decrease in the fetal heart rate followed by a rapid return to baseline during or between contractions (with a characteristic V shape). Variable decelerations usually are associated with compression of the umbilical cord.
vertex The top portion of the fetal head between the anterior and posterior fontanelles.
amnioinfusion Infusion of a volume of warmed, sterile, Ringer's lactate solution or normal saline through a catheter to increase amniotic fluid volume, thus improving fetal and placental oxygenation, helping to cushion the umbilical cord, and diluting any meconium.
amniotic fluid embolism An embolism that results when a tear in the amnion and chorion provides a mechanism by which amniotic fluid can enter the maternal circulation and reach the pulmonary capillaries.
arrest disorder Dystocia that develops during active labor and is characterized by a prolonged deceleration phase (at least 3 hours in a nullipara and 1 hour in a multipara); secondary arrest of cervical dilation (none for more than 2 hours).
breech presentation A fetus whose presenting part is the buttocks.
cephalopelvic disproportion (CPD) A term used when the size or shape of the fetal head or the maternal pelvis does not allow passage of the fetus through the maternal pelvis.
constriction rings Rare rings in the uterus that usually conform to a fetal depression and do not extend all the way around the uterus. The area of spasm is thick, but the lower uterine segment does not become stretched or thinned.
cord prolapse Term used when a portion of the umbilical cord falls in front of, lies beside, or hangs below the fetal presenting part.
dystocia Abnormal or dysfunctional labor.
external cephalic version A procedure in which a fetus is turned in utero from noncephalic (usually breech) to cephalic presentation.
failure to progress Labor in which the cervix does not dilate normally despite normal uterine contractions and no cephalopelvic disproportion.
forceps Stainless-steel instruments that can fit around the head of the fetus to help pull him or her through the vaginal outlet.
hydrocephalus Excess accumulation of cerebrospinal fluid in the brain ventricles and subsequent cranial enlargement.
hyperstimulation Either a series of single contractions lasting 2 minutes or more or a contraction frequency of five or more in 10 minutes. Contractions of normal duration within 1 minute of each other would also be included.
hypertonic uterine contractions Contractions in which the uterine midsegment contracts with more force than the fundus or the impulses in each upper uterine corner are not synchronized.
hypotonic uterine contractions Contractions that have no basal tone, are infrequent, and fail to dilate the cervix satisfactorily.
macrosomia Term used to indicate an infant whose birth weight is 9 lbs (4000 g) or more; also called a high birth weight infant.
molding The elongated shaping of the fetal head as it moves through the bony pelvis during labor and birth; caused by the normal overriding of the unfused fetal cranial bones.
occipitoposterior (OP) positioning Fetal position in which the fetal occiput is found in the posterior part of the maternal pelvis.
pathologic retraction ring An exaggeration of the normal physiologic retraction ring found at the junction of the upper and lower uterine segments.
Piper forceps A special type of forceps used in breech presentations with an aftercoming head.
postterm pregnancy Gestation that has reached 42 weeks from the first day of the last menstrual period in the woman with a 28-day menstrual cycle.
precipitous labor Labor that lasts less than 3 hours, caused by uterine contractions that are more frequent, intense, or both than normal.
preterm labor Uterine contractions between 20 to 37 weeks' gestation that cause progressive cervical changes (dilatation, effacement, or both).
protraction disorder A classification of dysfunctional labor characterized by delayed cervical dilation and slowed descent of the fetal head.
shoulder dystocia Failure of the fetal shoulders to traverse the pelvis spontaneously after birth of the fetal head.
uterine rupture Separation of the uterine wall with or without fetal expulsion.
vacuum extractor A cup-shaped device attached to a suction pump and applied to the fetal head to remove it from the vaginal outlet.
vaginal birth after cesarean (VBAC) The term used for a vaginal birth to a woman who has undergone at least one previous cesarean birth.
Created by: amykswisher