Clinical Insights into Second-Stage Labor Abnormalities

The second stage of labor, extending from complete cervical dilatation to delivery, is traditionally assessed by its duration. Still, progress can be more meaningfully evaluated by monitoring fetal station over time. In this stage, the fetus moves down and rotates through the birth canal. Descent usually begins during the deceleration phase of dilation, when the cervix is pulled upward around the fetal presenting part. Accurate assessment of fetal descent is critical for determining normal progression and the need for intervention.

Three abnormal patterns of fetal descent have been identified: protracted descent, arrest of descent, and failure of descent. These are strongly linked to cephalopelvic disproportion but may also be due to maternal obesity, uterine infection, excessive sedation, or fetal malposition. Clinical interpretation must consider fetal size, position, degree of cranial molding, pelvic capacity, and uterine contractility while determining the progress of fetal descent.

Oxytocin may treat protracted or arrested descent caused by inhibitory factors, such as dense neuraxial block, but should only be used after excluding cephalopelvic disproportion. The routine use of Valsalva pushing, fundal pressure, and episiotomy is now debated, and experts recommend using them only when truly needed based on the situation.

Reference:

Cohen WR, Friedman EA. The second stage of labor. American journal of obstetrics and gynecology. 2024 Mar 1;230(3):S865-75.

https://www.ajog.org/article/S0002-9378(22)00460-4/fulltext