The umbilical artery (UA) impedance indices increase when there is decreased
end-diastolic flow due to reduced placental perfusion and "utero-placental
insufficiency" as is seen in intrauterine growth restriction (IUGR). Absent or reversed UA
end-diastolic flow are particularly ominous findings.
Umbilical cord
The flexible tube that connects the fetus at the
abdomen with the placenta. The umbilical cord contains two umbilical arteries
which carry blood depleted of oxygen from the fetus to the placenta, and one
umbilical vein that carries blood enriched with oxygen from the placenta to the
fetus.
Umbilical vein
The blood vessel that carries oxygen enriched blood from the placenta to the fetus.
Uniparental disomy
Both members of a chromosome pair are
inherited from one parent rather than one from each parent. Uniparental disomy
may be maternal or paternal.
Uterine contractions
Recurrent tightening and relaxation of the uterine wall
(myometrium).
Uterine incision
A cut made into the wall of the uterus.
Uterine rupture
A tear through the entire thickness of the uterine wall.
Opening of a surgical scar on the uterus where the visceral peritoneum stays intact is referred to incomplete rupture or dehiscence.
Uterus (womb)
The pear-shaped reproductive organ in a woman's pelvis. The lower narrow part of the uterus (the cervix) opens into the vagina. The
uppermost part of the uterus is connected on both sides to the uterine
(Fallopian) tubes.
The uterine tubes, uterus, and upper vagina are formed by fusion of the two paramesonephric (Müllerian) ducts beginning at about 10 weeks gestation. Fusion of the ducts with resorption
of the uterine septum is usually completed by about 20 weeks' .