Obstetrical forceps are a pair of hinged, spoon-shaped instruments used to assist in vaginal childbirth. These tools gently cradle the baby’s head to guide it through the birth canal when the mother’s pushing efforts are insufficient. While the technique has a long history, its use has dramatically declined due to advances in alternative delivery methods. Despite this decrease, obstetrical forceps remain a part of modern obstetric practice as a tool for assisted delivery.
Current Status and Rationale for Use
The use of obstetrical forceps has become much less common in the United States, accounting for less than 1% of total vaginal deliveries in recent years. This decline is attributed to the increasing safety of cesarean sections and the preference for vacuum extraction as an alternative operative vaginal delivery method. However, forceps retain a specific role when a rapid, assisted delivery is necessary to ensure the well-being of the mother or the baby.
Forceps are utilized when the second stage of labor (the pushing phase) is prolonged or when there is suspicion of fetal compromise, such as a non-reassuring fetal heart rate pattern. The instrument may also be indicated for maternal benefit, such as when a mother is medically restricted from prolonged pushing due to a preexisting condition like cardiac or pulmonary disease. In these scenarios, forceps shorten the duration of labor, reducing physical strain on the mother.
A primary advantage of forceps is their ability to assist in rotating the fetal head when it is positioned unfavorably for birth, a maneuver vacuum extraction cannot perform as effectively. Forceps may also be recommended over vacuum extraction when delivering a premature baby (typically before 36 weeks gestation). The rigid nature of the blades offers greater protection to the softer, more vulnerable fetal skull. The procedure offers a safe alternative to a cesarean delivery when used by an experienced practitioner.
The Procedure and Classification
The obstetrical forceps instrument consists of two mirror-image metal blades gently placed around the fetal head inside the birth canal. The blades lock together at an articulation point, creating a handle the practitioner uses to apply gentle traction and rotation. The design includes a cephalic curve, which conforms to the baby’s head, and a pelvic curve, which follows the natural shape of the birth canal.
Several prerequisites must be met before a forceps delivery can be attempted to ensure safety. The cervix must be fully dilated, the membranes must be ruptured, and the fetal head’s position in the birth canal must be precisely known. The procedure is classified based on the level of the baby’s head, known as the station, relative to the mother’s pelvis.
The classifications range from outlet forceps (where the baby’s scalp is visible at the vaginal opening) to low forceps (where the head is at a station of +2 cm or lower). The most complex category is mid-forceps, applied when the head is engaged but positioned above the +2 station. Modern obstetrics favors the use of outlet and low forceps deliveries, as these procedures are associated with lower risks. High forceps applications are not performed today.
Comparing Forceps to Vacuum Extraction
Forceps and vacuum extraction are the two primary methods of operative vaginal delivery, each offering distinct advantages and disadvantages. The vacuum extractor (ventouse) uses a soft or rigid cup applied to the baby’s scalp, connected to a suction device to provide traction. Vacuum extraction is considered easier for the practitioner to apply and is associated with less maternal trauma, including a lower risk of severe perineal lacerations.
Forceps have a higher success rate in achieving a vaginal birth than a vacuum extractor and are less likely to detach from the fetal head during the procedure. Forceps are particularly advantageous when the fetal head requires rotation to facilitate delivery, as the blades offer better control for this maneuver. The choice between the two instruments depends on the specific clinical situation and the expertise of the delivering physician.
The two methods carry different potential risks for the neonate. Vacuum extraction is associated with the formation of a cephalohematoma (a collection of blood under the baby’s scalp) and caput succedaneum (a temporary swelling of the scalp). Forceps delivery carries a higher risk for temporary facial nerve injury due to the pressure of the blades, as well as minor abrasions or bruising to the face. Both instruments share similar overall rates of severe neonatal injury, and the decision is guided by which tool is better suited to the immediate challenge.
Potential Maternal and Neonatal Outcomes
The potential outcomes associated with forceps use are a major factor in the decision-making process for assisted delivery and must be weighed against the risks of prolonged labor or a cesarean section. For the mother, the primary concern is the increased risk of trauma to the birth canal. Forceps delivery is linked to a higher incidence of severe perineal lacerations, specifically third- and fourth-degree tears that extend into or through the anal sphincter muscle.
These severe tears can lead to short-term issues like postpartum hemorrhage and may contribute to long-term pelvic floor dysfunction, including a greater risk of anal incontinence. Postpartum hemorrhage (heavy bleeding after delivery) is also more frequent with forceps use compared to unassisted vaginal delivery. The extent of these maternal risks depends on the classification of the procedure, with higher-station forceps applications carrying greater risk.
For the baby, the risks are generally minor and transient, including temporary facial nerve palsy, which typically resolves on its own. Other minor neonatal outcomes include abrasions, bruising, and subconjunctival hemorrhage (a small bruise in the eye). While rare, there is a possibility of more serious injuries, such as skull fractures or intracranial injury, particularly with difficult mid-forceps procedures. The overall risk profile is influenced by the skill and experience of the practitioner performing the assisted delivery.