Instrumental Delivery
The guidelines recommend management of common obstetric conditions at primary and referral level, based on local experience and evidence-based practice. They are not intended as strict protocols nor as standard operating procedures, but rather as a guide to safe effective management of common obstetric problems. The guidelines should be most useful to interns, medical officers and registrars.
VACUUM EXTRACTION
Vacuum extraction may be performed by advanced midwives & doctors
Indications for vacuum extraction
- Maternal cardiac or respiratory disease, or BP≥160/110 mmHg
- Fetal distress in the second stage of labour
- Prolonged second stage with inadequate pushing or maternal exhaustion
Conditions for safe vacuum extraction
- Vertex presentation, does not have to be occipito-anterior
- Estimated fetal weight ≥2 kg
- Head not more than 1/5 palpable above the pelvic brim
- Cervix fully dilated
- Membranes ruptured
- Bladder empty – insert a urinary catheter, leave the bulb deflated
- Strong uterine contractions (>40 seconds) – use oxytocin if necessary
Equipment & techniques vary. Disposable Kiwi hard & soft cups, soft Silc cups & Bird metal cups (anterior 50 & 60 mm, & posterior 50 mm) are available. Hard cups give better traction force, & for these at least 3-4 minutes should be given for the cup to become securely attached to the head vacuum. A negative suction pressure of 0.7 to 0.8 Bar is needed for effective traction.
Important practical points & precautions
- Check & test the equipment thoroughly before using it
- Check the fetal heart rate just before starting the procedure
- Apply traction only during contractions, with maternal pushing
- Traction must be in a direction perpendicular to the vacuum cup
- During traction with the dominant hand, keep fingers of the other hand on the vacuum cup & head, to feel for decent & detect incipient cup detachment
- Failed vacuum extraction is an indication for caesarean section:
- There should be noticeable descent with each pull
- The vacuum cup must not be applied for more than 30 minutes
- No more than 2 cup detachments are allowed
- No more than 3 pulls (one pull = one contraction) are allowed
- Write up the procedure fully: operator, indication, clinical findings included level of head in fifths, time taken, cup type & size, number of pulls, number of detachments, & baby’s condition at birth
FORCEPS DELIVERY
Forceps delivery is associated with greater maternal trauma & pain than vacuum extraction, but is useful for face presentation, unconscious women & women with cardiac disease. Wrigley or Anderson forceps are used. In addition to those that apply to vacuum extraction, the following precautions must be observed:
- Forceps delivery must be done or supervised by an experienced person
- Fetal head position must be direct occipito-anterior
- The head must be 0/5 palpable above the brim (outlet forceps)
- Use pudendal block for analgesia
PUDENDAL BLOCK
Transvaginal pudendal block can be employed for any vaginal delivery where analgesia is needed, but is especially useful for forceps delivery.
- Use a guarded needle with an introducer if available
- Use lidocaine 1% solution
- For the right pudendal nerve, identify the right ischial spine with the right index & middle fingers
- Pass the needle next to the fingers & inject about 2 mL of lidocaine into the sacrospinous ligament
- Inject a further 2 mL just beyond the sacrospinous ligament
- Withdraw the needle out of the ligament & inject about 5 mL just lateral and above the ischial spine
- Repeat the procedure on the left side
- Inject any remaining lidocaine along the track of a proposed episiotomy
- Remember to withdraw the syringe plunger before every injection to prevent accidental intravascular injection