When the presenting part is at the ischial spines the station is 0 (synonymous with engagement). If the presenting fetal part is above the spines, the distance is measured and described as minus stations, which range from −1 to −4 cm. If the presenting part is below the ischial spines, the distance is stated as plus stations ( +1 to +4 cm). At +3 and +4 the presenting part is at the perineum and can be seen.The fetal head may temporarily change shape (becoming more elongated or cone shaped) as it moves through the birth canal. This change in the shape of the fetal head is called molding and is much more prominent in women having their first vaginal delivery.Cervical ripening is the physical and chemical changes in the cervix to prepare it for the stretching that will take place as the fetus moves out of the uterus and into the birth canal. A scoring system called a Bishop score can be used to judge the degree of cervical ripening in order to predict the timing of labour and delivery of the infant or for women at risk for preterm labour. It is also used to judge when a woman will respond to induction of labour for a postdate pregnancy or other medical reasons.
A bronchocele is a segment of bronchus that is filled with mucus and completely enclosed so the mucus cannot drain out. This segment is usually dilated. It is also called bronchial mucocele. If there is no obstruction to the flow of mucus, it is called mucoid impaction of bronchus. A bronchocele results from obstruction of the bronchus. Overproduction of mucus can also contribute. Obstruction may occur due to scarring, a tumor, or congenital atresia.