What are the different types of forcep (forceps) delivery?

Types of Forceps Delivery

Forceps deliveries are classified into three main types based on fetal head station and position: outlet forceps, low forceps (non-rotational), and mid-pelvic forceps (rotational), with rotational forceps (such as Kielland's) requiring the most skill but offering safe management of persistent fetal malposition when performed by experienced operators. 1, 2

Classification by Station and Rotation

Outlet Forceps Delivery

• Applied when the fetal scalp is visible at the introitus without separating the labia, the skull has reached the pelvic floor, and the sagittal suture is in the anteroposterior diameter or right/left occiput anterior or posterior position (rotation does not exceed 45 degrees) 3
• This represents the lowest-risk forceps application with minimal maternal and neonatal complications 4
• Does not significantly shorten the second stage of labor compared to spontaneous delivery, but is associated with increased maternal perineal trauma, particularly episiotomy (93% vs 78%) and deep perineal lacerations (24% vs 10%) in nulliparous women 4

Low Forceps (Non-Rotational) Delivery

• Applied when the fetal head is at station +2 cm or more and not on the pelvic floor 1, 3
• Rotation does not exceed 45 degrees from the occiput anterior position 3
• Associated with lower failure rates compared to vacuum extraction, making it the preferred operative vaginal method when the fetal head is palpable in the vagina 1, 5
• Carries higher rates of postpartum hemorrhage (4.3%) compared to cesarean section (0.6%), but lower rates of maternal infection (2.2% vs 4.7%) 6
• When performed for fetal indications, achieves faster delivery (12.3 ± 3.5 minutes vs 19.1 ± 5.0 minutes for cesarean) and lower rates of perinatal mortality/hypoxic ischemic encephalopathy (0.5% vs 1.9%) 6

Mid-Pelvic Rotational Forceps (Kielland's) Delivery

• Applied when the fetal head is engaged but the leading bony point is above station +2 cm, requiring rotation of more than 45 degrees to achieve occiput anterior position 3, 2
• Kielland's forceps are specifically designed for rotation with minimal pelvic curve, allowing safe rotation of malpositioned fetal heads 7, 2
• Requires experienced operators and appropriate patient selection, with supervision essential during resident training 7
• Associated with longer labor (671 ± 285.8 minutes vs 614 ± 226.5 minutes) and longer second stage (184 ± 74.71 minutes vs 161 ± 65.79 minutes) compared to non-rotational forceps 7
• Carries higher rates of one-minute Apgar scores <6 (18.2% vs 4.7%) and meconium at delivery (14.5% vs 5.6%) compared to non-rotational forceps 7

Comparative Safety Profile

Kielland's vs Other Delivery Methods

• No significant difference in postpartum hemorrhage rates compared to rotational ventouse delivery 2
• Lower postpartum hemorrhage rates compared to non-rotational forceps (RR 0.79,95% CI 0.65-0.95) and second-stage cesarean section (RR 0.45,95% CI 0.36-0.58) 2
• Higher shoulder dystocia rates compared to ventouse delivery (RR 1.79,95% CI 1.08-2.98), but lower neonatal birth trauma rates (RR 0.49,95% CI 0.26-0.91) 2
• No differences in anal sphincter injuries or NICU admission rates across delivery methods 2
• Lower 5-minute Apgar scores <7 compared to second-stage cesarean section (RR 0.47,95% CI 0.23-0.97) 2

Clinical Decision-Making Algorithm

When to Choose Forceps Over Cesarean

• Proceed with operative vaginal delivery when the fetal head is palpable in the vagina during second stage labor with Category 2 CTG, as this minimizes maternal and neonatal morbidity compared to cesarean section at full dilation 1
• Cesarean section at full dilation with deeply engaged fetal head carries substantially higher maternal morbidity, including impacted fetal head complications in up to 10% of cases, with risks of uterine incision extensions, hemorrhage, and bladder/ureteric injuries 1

Forceps vs Ventouse Selection

• Both are acceptable when the head is palpable in the vagina 1
• Forceps provide more controlled traction and have lower failure rates 1, 3
• Ventouse is gentler on maternal tissues but requires more application time and has higher failure rates 1
• Vacuum extraction should be avoided at low station due to increased risk of intracranial and subgaleal hemorrhage 5

Critical Prevention Measures

Avoiding Facial Nerve Injury

• Never use a single forceps blade as a lever during delivery, as this is the primary mechanism of facial nerve paralysis 8
• The facial nerve exits the skull base through the stylomastoid foramen before branching, making it vulnerable to compression from improper forceps technique 8
• Proper training in forceps application techniques is essential, with high-fidelity simulation training recommended for difficult deliveries 8

Special Populations

• In patients with skeletal dysplasia, operative delivery should be avoided when possible due to C1-C2 instability concerns present in approximately 25% of cases 9
• For osteogenesis imperfecta, cesarean delivery does not decrease fracture rates and should only be performed for standard maternal or fetal indications 9

Management of Failed Forceps Delivery

• If forceps delivery fails, proceed immediately to cesarean section rather than attempting vacuum extraction 5
• Prepare for manual vaginal disimpaction or reverse breech extraction to manage impacted fetal head 1
• Administer uterine tocolysis to relax the uterus and facilitate disimpaction 1
• Avoid attempting delivery during contractions, as this exacerbates difficulty 1