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What is an Instrumental Delivery? 

Instrumental delivery refers to the use of the Vacuum or Forceps instrument to assist the delivery of your baby. Instrumental delivery is actually an aid to facilitate natural birth​. Your cervix needs to be fully dilated (10 cm) before either instrument can be used. Your doctor will decide which instrument is more suitable for you and the baby. 

How Is a Forceps Delivery Conducted? 

Your doctor will gently apply two sterile instruments (forceps blades) into your vagina around the baby’s head. The instruments look like curved spoon-shaped​ ​tongs, and are specially designed to fit comfortably around the baby’s head. As you push during each uterine contraction, your doctor will deliver the baby’s head using the forceps blades. 

How Is a Vacuum Delivery Conducted? 

Your doctor places an instrument called a vacuum extractor on the baby’s scalp. The vacuum extractor looks like a cup. A vacuum is then gently created using a pump. As you push with each uterine contraction, your doctor will gently pull so that your baby’s head is delivered using the vacuum extractor. There are many forms of vacuum extractors available but the most commonly used one is the ‘Kiwi cup’. 

When Will I need an Instrumental (Forceps/Vacuum) Delivery? 

There are also a number of reasons why it may be necessary for you to have an assisted delivery (forceps/vacuum delivery) during your second stage of labour (i.e. when the cervix is fully opened). 

  • You are too tired to push effectively to deliver your baby. 
  • You have been pushing for too long (usually >1 hour). This avoids the obstetrical complications from prolonged pushing such as excessive bleeding from a ‘tired womb’ after delivery or a deterioration of your baby’s condition. 
  • The baby’s condition has deteriorated and an instrumental delivery would be the most suitable for an immediate delivery. This is usually ​shown on the cardiotocograph (CTG) that monitors your baby’s heartbeat. 

An episiotomy​ may be required when the vacuum or forceps is used. 

When Should an Instrumental Delivery be Avoided? 

There are actually very few instances where an instrumental delivery should be avoided. The following is a list of clinical scenarios where a Cesarean section​ may be a better option: 

  • ​​The baby suffers from any rare conditions, such as bone mineralization defects or bleeding disorders, predisposing it to injuries or bleeding when delivered instrumentally. 
  • The baby is premature (<34 weeks gestation) and avoiding a vacuum extraction will reduce more trauma to the scalp and brain. Forceps delivery may be preferred under these circumstances. 

What are Some of the Factors to be Considered Just Before an Instrumental Delivery is Carried Out? 

There are certain prerequisites that must be present before an instrumental delivery can be carried out. 

  • ​​In addition to your cervix being fully dilated, your doctor will need to perform an internal examination to ensure that the membranes are ruptured and that the exact position of the baby’s head is known. 
  • The baby’s head should have descended low enough into your pelvis to increase the chance of a safe delivery (engaged). 
  • The uterine contractions must be optimal and if necessary, an oxytocin infusion can be started to ensure this. Your doctor may also apply gentle pressure (fundal pressure) onto your womb to aid in your pushing efforts. 
  • Just before the application of the instrument, a catheter will be inserted into your bladder to drain out the urine and a local anesthetic drug may be infiltrated into your perineal area to reduce your discomfort. 
  • The more effectively the mother pushes during the contractions, the less the doctor will have to pull with the forceps or vacuum. This good cooperation and coordination between the mother and doctor increases the chance of a safe delivery. ​

​What are the Complications with An Instrumental Delivery? 

It has to be stressed that most of the assisted deliveries are uneventful and will be performed with you and your baby’s interests in mind. This will only be carried out if it is felt that you will be able to deliver safely through the vagina

However, some of the possible problems include: 

  • ​​Failure of the assisted delivery with one instrument — There may be several factors involved. Your doctor will make a re-assessment and decide if you need a cesarean section or if an alternate instrument may be used instead. 
  • Complications to the mother — Pain at and after delivery. Tears or trauma to the vaginal and back passage that may necessitate a repair in the operating theater under anesthesia. 
  • Complications to the baby — Skull fractures or intra-cranial bleeding, potentially life threatening conditions, may rarely occur. Injuries to the facial nerve or eye may happen. During an instrumental delivery, a condition known as shoulder dystocia (whereby the baby’s shoulders may be stuck at the birth canal) can happen and is more commonly seen in bigger babies. 

Aftercare Following Instrumental Delivery 

If an episiotomy was done, you will need some stitches (read the article on Pushing and delivery: Is an episiotomy needed?​). 

Occasionally, your doctor may insert an indwelling catheter to help “rest your bladder” for a day or two till your discomfort reduces. 

Frequently Asked Questions

1. Which is better? Forceps or vacuum delivery? 

Although these instruments may be used under similar conditions, your obstetrician will choose the instrument most appropriate to the clinical circumstance and personal preference. 

2. Should I opt for a cesarean section instead? 

It has to be stressed that most of the assisted deliveries are uneventful and will be performed with you and your baby’s interests in mind. This will only be carried out if it is felt that can deliver vaginally safely. A cesarean section performed under these circumstances may be more risky at a late stage of labour. 

​3. What will I need to do during an instrumental delivery? 

It is important to follow the doctor’s instructions closely during instrumental delivery. You should relax and not bear down when the instrument is inserted into your vagina and applied to the baby’s head. Similarly, you should push well when asked to do so. This is when you are experiencing a contraction. During a contraction, when you are pushing, your doctor will assist you with the forceps or vacuum to deliver the baby’s head. 

Sometimes, if your doctor attempts an assisted delivery and the baby cannot be delivered safely, you will need an emergency cesarean section. 

You would also be required to sign on the appropriate consent forms once the decision for an instrumental delivery is made. 

Acknowledgement

Source: Dr TAN Thiam Chye, Dr TAN Kim Teng, Dr TAN Heng Hao, Dr TEE Chee Seng John, The New Art and Science of Pregnancy and Childbirth, World Scientific 2008.