Types of Forceps Deliveries: Outlet, Low, Mid, and High
The clinical practice of medicine is becoming increasingly standardized. Publication of clinical standards and guidelines allows providers to precisely define indications for procedures and the specific steps in performing techniques. Guidelines for forceps deliveries encourage providers to carefully assess the mother's bony pelvis as well as the position and station of the baby's head prior to any operative procedure.
The position and station of the baby's head are critically important in the decision of whether to perform a forceps delivery and what type of forceps to use. Over the past 50 years, the definitions of fetal position and station have resulted in several different systems for classifying forceps deliveries. The American College of Obstetricians and Gynecologists developed a classification system in 1988 that has become the accepted clinical standard in the . This classification system outlines criteria for forceps deliveries according to station and rotation as follows:
- Outlet forceps delivery is forceps-assisted delivery performed when the baby's scalp is visible at the vaginal opening. This type of assisted delivery is performed only when the baby's head is in a straight forward or backward position (facing either toward the mother's pubic bone or toward the mother's tailbone) or in slight rotation (less than 45 degrees to the right or left) from one of these positions.
- Low forceps delivery is forceps-assisted delivery performed when the baby's head is at +2 station or lower. There is no restriction on rotation for this type of delivery.
- Midforceps delivery is forceps -assisted delivery performed when the baby's head is above +2 station. The head must be engaged.
- High forceps delivery would be a forceps -assisted vaginal delivery performed when the baby's head is not yet engaged. These types of deliveries are not performed in modern obstetrics practice.
It is now clear that outlet forceps deliveries pose no greater risks to the mother or baby than do spontaneous vaginal deliveries. The potential risks for mother and baby increase with the performance of low forceps and midforceps deliveries. There should always be a clearly outlined reason for any forceps delivery and this is particularly true of midforceps deliveries. When a more complicated procedure is performed, the benefits and causes should always outweigh the risks. Midforceps deliveries should only be practiced by a physician with great experience with forceps deliveries as they are incrementally more difficult than low or outlet forceps deliveries. High forceps deliveries pose such great risks to mother and baby that cesarean birth is always preferable.