Bag of waters

The membrane (amnion) surrounding the fetus and the amniotic fluid.

Banana Sign Curvature of the cerebellum (the part of the brain that controls balance) around the midbrain giving the cerebellum the shape of a banana. Caused by Arnold-Chiari II malformation.  In 95% percent of cases the Arnold-Chiari II malformation is accompanied by hydrocephalus and myelomeningocele (open spina bifida).

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Bicornuate uterus

Two separate single horn uterine bodies sharing one cervix. 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' . Partial failure of the ducts to unite results in two separate single horn uterine bodies sharing one cervix. Bicornuate uterus is associated with increased risk for miscarriage, preterm labor, breech presentation, and fetal growth restriction.

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Bilirubin

Bilirubin is a yellowish pigment produced from the breakdown of hemoglobin the protein that carries oxygen in the red blood cells). Bilirubin is removed from the body largely by the liver. The liver of many newborns may not be mature enough to remove bilirubin from the blood stream quickly enough. The excess bilirubin may build up giving the the infant's skin and membranes a yellow color a condition called jaundice.

Biophysical profile (BPP)

An assessment of the well being of the fetus that uses the nonstress test (NST)  and ultrasound to examine fetal breathing movements, tone, and amniotic fluid amounts. A score of 2 is given for each component present. A score of 8 or greater is reassuring.
 

Component	Score 2	Score 0
Reactivity (NST)	Two or more fetal heart rate accelerations of at least 15 beats/min and lasting at least 15 seconds during  30 minutes of observation	No accelerations or less than two accelerations of fetal heart rate in 30 minutes
Breathing	30 seconds of sustained fetal breathing during a 30 minute period of observation. (Hiccups are included as breathing activity)	Less than 30 seconds of fetal breathing movements in 30 min
Movement	3 or more discrete gross body/limb movements in 30 minutes, simultaneous limb and trunk movements	2 or less gross body/limb movements in 30 minutes
Tone	One episode of motion of a limb from position of flexion to extension and rapid return to flexion (opening and closing of hand considered normal tone)	Position of semi or full limb extension with no return or slow return to flexion with movement;absence of fetal movement
AFI	At least 1 pocket of fluid that measures at least 2 cm in two perpendicular planes	Largest pocket of amniotic fluid measures < 2 cm in two perpendicular planes

 

Biparietal diameter (BPD The distance between the parietal eminences on each side of the skull. The distance is measured by sonogram from the outer surface of the skull to the opposite inner surface of the skull. The appropriate transverse plane for measurement of the fetal biparietal diameter (BPD) and head circumference (HC) should include the thalamic nuclei (structures deep in the brain) and the cavum septum pellucidum (a space between the thin membranes that separate the lateral ventricles). Both structures are inferior to the corpus callosum
	T = Thalamus   C= Cavum septum pellucidum

Bishop score