Ultrasound in the delivery room represents a useful diagnostic tool and is used for the assessment of fetal presentation, fetal malpresentation/malposition, and prior to any operative delivery. Transperineal ultrasonography, performed by placing the ultrasound probe covered by a sterile glove at the level of the labia majora, has proven useful in providing information on the progression of the presented fetal part in the birth canal and in predicting birth outcomes. Many studies have shown a correlation between the above ultrasound indices and birth outcomes. These ultrasound indices are therefore used in clinical practice to assess the progression of the presented fetal part in the birth canal and the presence of fetal malpresentation/malposition. Despite this, to date, few studies have evaluated the correlation between dynamic changes in these ultrasound parameters between rest and maximal maternal pushing during the second stage of labor and birth outcomes.

Knowing before delivery which parameters are suggestive of possible dystocia would allow the clinician to adopt therapeutic strategies aimed at resolving them and thus increase the rate of spontaneous vaginal deliveries.

The investigators want to evaluate the role of an ultrasound parameter obtained by transabdominal ultrasound in the second stage of labor, the occiput-column angle, in predicting spontaneous delivery vaginally in fetuses with transverse occiput

Participants will be recruited at the time of admission or in the delivery room. Routine clinical practice involves transabdominal ultrasound, performed in the lithotomy position, placing the probe transversely and longitudinally at the abdominal level for evaluation of the fetal situation and presentation.

In addition to normal ultrasound, the position of the fetal occiput will also be assessed in women who agree to participate in the study, and in fetuses with a transverse occiput, the occipitecolumn angle will be measured. All study participants will then undergo transperineal ultrasound, performed by placing the probe, covered by a sterile glove, at the level of the labia majora, first longitudinally and then transversely. In this way, a series of ultrasound landmarks will be visualized: pubic symphysis, bladder, urethra, vagina, rectum, pubo-rectal muscle, and fetal head.

Inclusion Criteria:

• Women aged >= 18 years
• Single pregnancy at term (37-42 gestational weeks)
• Fetus in cephalic presentation and in expulsive period (complete cervical dilatation and premature sensation)
• Acquisition of informed consent form

Exclusion Criteria:

• Placenta previa
• Uterine malformations
• Previous uterine surgery
• Cardiotocographic tracing (CTG) abnormalities
• Any contraindication to vaginal delivery

It is planned to enroll patients afferent to the Department of Obstetrics and Prenatal Age Medicine, Sant'Orsola-Malpighi Polyclinic.