**2. The obstetrical forceps**

'Use only on the most urgent occasions

'Head on the perineum for 6 hours

'If the head advances, no matter how slowly, no interference unless the child be dead

'Use the forceps sparingly –

'Where they save one they murder many'

~A summary of the guidelines for the use forceps in Smellie's time

The obstetrical forceps is probably the earliest instrument designed to assist vaginal delivery. Behind its design, invention and evolvement lies florid and interesting history

Operative Vaginal Deliveries in Contemporary Obstetric Practice 257

The principle of the vacuum was first applied for the treatment of depressed skull fractures in infants in 1632! That force generated in a closed space (vacuum) can be increased to aid the delivery of a fetus was first reported by James Young, surgeon to the Naval Hospital in Plymouth, England in 1655 (Malmstrom, 1957). About 100 years later Seaman of Jena described his dream of the use of a vacuum device to assist delivery without injury to the mother or baby. "….*an air pump which wherewith one can seize the head of the infant without injury to mother and child. The pump was made of brass and had a covering of rubber with ventilators*….". The European medical and lay literature is replete with such fancies, designs and attempts but none drew international attention and widespread acceptance (Vacca, 2003). Malmstrom's device eventually received international acceptance in the middle of the 20 century. He first introduced his device in 1953 and refined it further by 1957; it was originally used in the first stage of labour to improve uterine action by 'pulling the head down to the cervix'. Malmstrom is therefore credited as the father of the modern vacuum extractor. The unique feature of the Malmstrom's Vacuum Extractor is that the metal cup has an in-curved rounded margin which is of a narrower diameter than the base (see figure 2 below). This design produces a chignon on the fetal scalp thereby minimizing the risk of detachment during traction. Other components include a vacuum pump, a guage, vacuum container and rubber tubing. Malmstrom's device has been modified by other inventors as extensively discussed in the

Bird significantly modified the cup such that the suction port and the traction port are separated; the suction port located close to the rim of the convex surface of the cup and the traction port located at its center. This helps to reduce the leverage on the cup during traction and reduces the risk of detachment. A further advantage of this modification is the improved accessibility to the flexion point in deflexed occipito-transverese and occipito-posterior positions. The Bird modification is also referred to as the 'OP' cup. Over the next 20 years several modifications of the vacuum extractor became popular in Scandanavia, Europe and Africa. This may have been due to a commonly held perception that it required less training for safe use compared to the alternative-obstetric forceps. This view was first suggested about 150

Fig. 2. A Malmstrom's vacuum extractor with its essential components. Inset: Bird's

**3. The vacuum extractor** 

history of vacuum extraction by Baskett (Vacca, 2003).

years earlier by Neil Arnott (Vacca, 2003).

modification of metal cup

with ancient Egyptian, Greek, Roman, and Persian texts containing references to the use of forceps to deliver women in cases of intrauterine fetal deaths. The refugee family of William Chamberlain, who facing religious persecution in their home country of France, migrated to London in the 16th Century is widely credited with the development of the obstetrical forceps as is known today. This family takes credit for the design, invention and use of obstetrical forceps to deliver women with obstructed labour for about three generations (Dunn, 1999). The instruments and their use were a well-kept family secret, only revealed nearly 200 years after their invention! Obstetrical forceps have undergone several modifications over time. It is estimated that there may well be over 700 different types of obstetrical forceps in existence, not counting those that did not make it beyond the design stage. The types vary by designer, intended objective of using it, material, place and sometimes the ingenuity of the inventor. Forceps are designed to aid the delivery of the fetal head by the application of traction. To effect a delivery, a pair with each one a mirror image of the other are applied around the fetal head. Each of a pair consists basically of a blade, shank, and a handle (see figure 1 below).

Fig. 1. Parts of the two main types of obstetrical forceps

Based on ability to rotate the fetal head in the birth canal, forceps could be classified into those that can effect traction only and those that can be used to effect rotation and traction. The main difference in the design is in the blades and the lock. An archetype of traction only forceps is the Simpson's forceps with an 'English' lock and pelvic and cephalic curves on the blade while Kielland's forceps is the archetype of traction and rotation forceps with only the cephalic curve and sliding lock (Chiswick and James, 1979).

#### **3. The vacuum extractor**

256 From Preconception to Postpartum

with ancient Egyptian, Greek, Roman, and Persian texts containing references to the use of forceps to deliver women in cases of intrauterine fetal deaths. The refugee family of William Chamberlain, who facing religious persecution in their home country of France, migrated to London in the 16th Century is widely credited with the development of the obstetrical forceps as is known today. This family takes credit for the design, invention and use of obstetrical forceps to deliver women with obstructed labour for about three generations (Dunn, 1999). The instruments and their use were a well-kept family secret, only revealed nearly 200 years after their invention! Obstetrical forceps have undergone several modifications over time. It is estimated that there may well be over 700 different types of obstetrical forceps in existence, not counting those that did not make it beyond the design stage. The types vary by designer, intended objective of using it, material, place and sometimes the ingenuity of the inventor. Forceps are designed to aid the delivery of the fetal head by the application of traction. To effect a delivery, a pair with each one a mirror image of the other are applied around the fetal head. Each of a pair consists basically of a blade,

it,

shank, and a handle (see figure 1 below).

Fig. 1. Parts of the two main types of obstetrical forceps

cephalic curve and sliding lock (Chiswick and James, 1979).

Based on ability to rotate the fetal head in the birth canal, forceps could be classified into those that can effect traction only and those that can be used to effect rotation and traction. The main difference in the design is in the blades and the lock. An archetype of traction only forceps is the Simpson's forceps with an 'English' lock and pelvic and cephalic curves on the blade while Kielland's forceps is the archetype of traction and rotation forceps with only the The principle of the vacuum was first applied for the treatment of depressed skull fractures in infants in 1632! That force generated in a closed space (vacuum) can be increased to aid the delivery of a fetus was first reported by James Young, surgeon to the Naval Hospital in Plymouth, England in 1655 (Malmstrom, 1957). About 100 years later Seaman of Jena described his dream of the use of a vacuum device to assist delivery without injury to the mother or baby. "….*an air pump which wherewith one can seize the head of the infant without injury to mother and child. The pump was made of brass and had a covering of rubber with ventilators*….". The European medical and lay literature is replete with such fancies, designs and attempts but none drew international attention and widespread acceptance (Vacca, 2003). Malmstrom's device eventually received international acceptance in the middle of the 20 century. He first introduced his device in 1953 and refined it further by 1957; it was originally used in the first stage of labour to improve uterine action by 'pulling the head down to the cervix'. Malmstrom is therefore credited as the father of the modern vacuum extractor. The unique feature of the Malmstrom's Vacuum Extractor is that the metal cup has an in-curved rounded margin which is of a narrower diameter than the base (see figure 2 below). This design produces a chignon on the fetal scalp thereby minimizing the risk of detachment during traction. Other components include a vacuum pump, a guage, vacuum container and rubber tubing. Malmstrom's device has been modified by other inventors as extensively discussed in the history of vacuum extraction by Baskett (Vacca, 2003).

Bird significantly modified the cup such that the suction port and the traction port are separated; the suction port located close to the rim of the convex surface of the cup and the traction port located at its center. This helps to reduce the leverage on the cup during traction and reduces the risk of detachment. A further advantage of this modification is the improved accessibility to the flexion point in deflexed occipito-transverese and occipito-posterior positions. The Bird modification is also referred to as the 'OP' cup. Over the next 20 years several modifications of the vacuum extractor became popular in Scandanavia, Europe and Africa. This may have been due to a commonly held perception that it required less training for safe use compared to the alternative-obstetric forceps. This view was first suggested about 150 years earlier by Neil Arnott (Vacca, 2003).

Fig. 2. A Malmstrom's vacuum extractor with its essential components. Inset: Bird's modification of metal cup

Operative Vaginal Deliveries in Contemporary Obstetric Practice 259

(a) (b) (c)

d) (e) (f)

There are different types of vacuum extractors, depending on the type of suction mechanism (manual or electrical) and type of cup-rigid or soft (Silc, Malmstrom, Bird, or the OmniCup). The manual suction mechanism which is suitable for resource poor settings due to frequent power outages may be operated via a foot pump, a hand held "bicycle like" pump both operated by an assistant or a hand held pump operated by the birth attendant (Figure 2). The most common and widely available in resource poor settings is the Malmstrom vacuum

settings

(i) (ii)

Fig. 5. Vacuum extractor soft cups (i) and the Kiwi Omnicup (ii) which has a rigid plastic cup

Fig. 4. (a-f) – Application and traction on the fetal head using forceps

**4.2 Vacuum extractor** 

extractor with rigid or soft cups.
