Operative Vaginal Deliveries in Contemporary Obstetric Practice

The expectation of every pregnant woman is to undergo a spontaneous vaginal delivery with minimal or no resort to operative procedures at the end of pregnancy. For the majority of women this expectation becomes a reality. For some however, assistance is required either in the form of caesarean sections or operative vaginal procedures in order to avert adverse maternal and fetal outcomes. Assisting laboring women to deliver vaginally using specialized instruments is a practice that dates back several centuries. Forceps and ventouse are the most popular of the operative vaginal procedures with comprehensive documentation of their development and use in the lay and medical media. Procedures like symphysiotomy and destructive operations to remove a dead fetus are probably now materials for the waste bins of medical history. However some still argue for a place for them in modern obstetric practices especially in low income countries where the indications for their use may still be found (Maharaj and Moodley, 2002).


Introduction
The expectation of every pregnant woman is to undergo a spontaneous vaginal delivery with minimal or no resort to operative procedures at the end of pregnancy. For the majority of women this expectation becomes a reality. For some however, assistance is required either in the form of caesarean sections or operative vaginal procedures in order to avert adverse maternal and fetal outcomes. Assisting laboring women to deliver vaginally using specialized instruments is a practice that dates back several centuries. Forceps and ventouse are the most popular of the operative vaginal procedures with comprehensive documentation of their development and use in the lay and medical media. Procedures like symphysiotomy and destructive operations to remove a dead fetus are probably now materials for the waste bins of medical history. However some still argue for a place for them in modern obstetric practices especially in low income countries where the indications for their use may still be found (Maharaj and Moodley, 2002).
Instrumental vaginal delivery is a key element of essential obstetric care, scaling up its use in resource poor countries through training and supply of appropriate equipment is likely to contribute significantly to reduced maternal and newborn morbidity/mortality (Ameh and Weeks, 2009).

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 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

The vacuum extractor
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). Obstetric forceps can be classified based on the depth of the pelvic cavity in which they can be applied to effect delivery (low/outlet, midcavity or high foceps). Worldwide low cavity and outlet forceps delivery are the mostly frequently performed in current practice. High and mid-cavity forceps delivery which could involve rotation of the fetal head are rarely perfomed. At the Ahmadu Bello University Teaching Hospital, only outlet forceps are performed with low-cavity forceps used occasionally (Adaji et al., 2009).

Vacuum extractor
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 extractor with rigid or soft cups.
(i) (ii) A more recent design for the vacuum extractor is the rigid plastic cup Kiwi® vacuum assisted fetal delivery device (Clinical Innovat i o n s , M u r r a y , U T ) . I t i s d e s i g n e d a s a n integrated unit for complete control without an assistant. The suction for this device is provided by a PalmPump TM . The Kiwi has two versions; the ProCup® for low outlet delivery occipito-posterior positions and the OmniCup® for low occipito-posterio asynclitic and lateral fetal malpositions. The OmniCup® has a disposable and a recently developed reusable version suitable for resource poor settings. The cost, portability and ease of maintenance of the reusable OmniCup® makes it attractive for use in resource poor settings.
The disposable version on the other hand reduces the potential risk of viral infections between patients (Ismail et al., 2008a).
Metal cups appear to be more suitable for 'occipito-posterior', transverse and difficult 'occipito-anterior' position deliveries because they allow a greater traction force to be applied without cup slip offs. The soft cups seem to be appropriate for straightforward deliveries (Johanson and Menon, 2007).
Several studies have evaluated the effectiveness of the OmniCup compared to the standard vacuum extraction equipment (Malstrom metal rigid cup or Silc cups). Two randomized controlled trials found a higher failure rate: 43% vs. 21% (OR = 1.9; 95%CI = 1.01 -1.36) (Attilakos et al., 2006) and 30%-19.2%, (RR 1.58; 95% CI = 1.10-2.224) with the OmniCup and one RCT found it to be a suitable alternative to the standard cups (100% delivery rate in both groups) (Ismail et al., 2008b). There was no difference in maternal morbidity between both groups in all 3 RCTs. Only one of the RCTs reported a significant increase in neonatal admission for sub-aponeurotic hemorrhage (p = 0.015, OR = 0.11; 95CI = 0.001 -0.87). Several observational studies also reported higher rates of successful vaginal delivery which was not statistically different from that for the standard equipment (Ismail et al., 2008a, Hayman et al., 2002, Baskett et al., 2008. Successful vaginal delivery was attributed to familiarity with the equipment. There was also no difference in maternal morbidity in all of these studies. However, Hayman, Gilby and Arulkumaran (2002) reported a significant increase in superficial scalp abrasions in the OmniCup group compared to the standard cup group (Hayman et al., 2002).
The experience from many centers is that nulliparous women with untested pelvis are more likely to need assistance with an operative vaginal delivery procedure. In the Zaria study, more than three-quarters of the parturients who were assisted were nulliparas (Adaji et al., 2009

Epidemiology
Operative vaginal delivery prevalence rates vary from country from country and facility to facility. The rates have however remained fairly stable over the past 3 decades. A recent survey by the World Health Organization (WHO) of method of delivery and pregnancy outcomes in 9 Asian countries analyzed 107, 950 births. Of these births, 3.2 percent were by operative vaginal delivery procedures (Lumbiganon et al., 2010).
Demissie et al comprehensively reviewed operative vaginal delivery rates in US hospitals between 1995 and 1998. Obstetrical forceps were utilized to conduct deliveries in 4.4% of births in 1995, 4% in 1996, 3.6% in 1997 and 3.2% in 1998. The use of ventouse was 7.4%, 7.8%, 7.8% and 7.6% over the same period (Demissie et al., 2004). In the UK, a operative vaginal delivery rates (forceps and ventouse) of between 10 to 15% percent has been estimated (Johanson and Jones, 1999 (Gei and Pacheco, 2011) Assisted vaginal delivery is one of the underutilized and least available emergency obstetric care signal functions in resource poor countries (Kongnyuy et al., 2008, Tsu andCoffe, 2009). Unmet training needs, lack of suitable equipment and human resource shortages are some reasons for this (Bailey, 2005, Fauveau, 2006, Hillier and Johanson, 1994. In many resource poor settings vacuum extraction is performed only by medical doctors who may only be regularly available in large urban hospitals (Fauveau, 2006).

Types and classification of operative vaginal delivery procedures
Forceps and vacuum delivery are the most common procedures employed for assisted vaginal delivery. Others like symphysiotomy and fetal destructive operations are rarely if ever performed in developed countries. The ACOG developed a classification system that takes into account the station and position of the fetal head in the maternal pelvis (ACOG, 1992). (Figure 3 and Table 2

Mid cavity
Fetal head is 1/5 palpable per abdomen Leading point of the skull is above station plus 2 cm but not above the ischial spines Two subdivisions (a) rotation of 45 degrees or less (b) rotation more than 45 degrees

Guidelines and indications
The invention of obstetrical forceps may have been driven by the search for a way to address one of the tragic outcomes of pregnancy of those days; prolonged obstructed labor with a dead fetus. With no luxury of ability to perform a caesarean section, the dilemma faced by the birth accoucheur was undoubtedly formidable. As the tools of the trade grew in number and design, the indications also multiplied. Some institutions like the Royal College of Obstetricians and Gynaecologists (RCOG) UK, The American Congress of Obstetricians and Gynaecologists and the Society of Obstetricians and Gynaecologists of Canada have helped to clearly define the indications for operative vaginal delivery (Table  3). There are several indications for assisted vaginal delivery; these could be due to fetal compromise, maternal indications to avoid Valsalva or inadequate progress in labour. No indication is absolute and each case should be considered individually.

Type Indication Fetal
Presumed fetal compromise Maternal Medical indications to avoid Valsalva (e.g. cardiac disease Class III or IV*, hypertensive crises, cerebral vascular disease, particularly uncorrected vascular malformations, myasthenia gravis, spinal cord injury) Inadequate progress Nulliparous women: Lack of continuing progress for three hours (total of active and passive second stage labour) with regional anaesthesia, or two hours without regional anaesthesia Multiparous women: Lack of continuing progress for two hours (total of active and passive second stage labour) with regional anaesthesia, or one hour without regional anaesthesia *New York Heart Association classification Table 3. Indications for operative vaginal delivery (no indication is absolute and each case should be considered individually) The safe use of both the vacuum extractor and obstetric forceps require prerequisites one of which is that "the operator must have the knowledge, experience and skills necessary to use the instrument" (ACOG, 1994). A list of the essential pre-requisites for operative vaginal delivery is presented in Table 4.

Preparation Essential Full abdominal and vaginal examination
Head is ≤ 1/5 palpable per abdomen Vertex presentation Cervix is fully dilated and the membranes ruptured Exact position of the head can be determined so proper placement of the instrument can be achieved Pelvis is deemed adequate Mother Informed consent must be obtained and clear explanation given Appropriate analgesia is in place, for mid-cavity rotational deliveries this will usually be a regional block A pudendal block may be appropriate, particularly in the context of urgent delivery Maternal bladder has been emptied recently Indwelling catheter should be removed or balloon deflated Aseptic techniques Staff Operator must have the knowledge, experience and skills necessary to use the instruments Adequate facilities and back-up personnel are available Back-up plan in place in case of failure to deliver Anticipation of complications that may arise (e.g. shoulder dystocia, postpartum haemorrhage) Personnel present who are trained in neonatal resuscitation After coming head of a breech presentation. Piper forceps is used to maintain the fetal head in flexion and also enables traction on the fetal head. It has unique features of having only a pelvic curve but no cephalic curve. -During caesarean section a Kiwi vacuum extractor or Wrigley's obstetric forceps can be used to deliver a 'floating' fetal head. -Some obstetricians have also used a single forcep blade as an elevator during difficult delivery of an impacted fetal head.

Contraindications
The following are contraindications to the performance of operative vaginal deliveries. Blood-borne viral infections of the mother e.g HIV are not a contraindication to operative vaginal delivery. However, it is sensible to avoid difficult operative delivery where there is an increased chance of fetal abrasion or scalp trauma and to avoid fetal scalp clips or blood sampling during labour.

Complications
While the role of operative vaginal deliveries using instruments like forceps and vacuum extractor has received wide acclaim, complications, sometimes of profound severity have been documented for both mother and child. These undesired outcomes have made operative vaginal delivery an object of great scrutiny by the medical and lay press. While a diverse number of complications have been ascribed to these procedures causality has been difficult to establish.

Maternal
In the Zaria study, maternal/ fetal complication was found in 22.3% of cases of instrumental delivery. Table 6 above provides details of these complications. The most severe of the complications were the fetal deaths recorded for vacuum deliveries. However the deaths may have been due to the severity of the fetal distress that indicated the procedure rather than the procedure itself.
Newborn intracranial injuries and shoulder dystocia were other complications associated with operative vaginal deliveries from large reviews. Intracranial injuries documented include epidural, subdural and subarachnoid haemorrhages. The fetus could also develop sub-galeal (subaponeurotic) haemorrhage (Doumouchtsis).

Symphysiotomy
Cutting a parturient's symphysis pubis allows the two halves of her pelvis to separate up to 2.5 c m p e r m i t t i n g a n o t h e r w i s e d i f f i c u l t l a b o u r t o p r o g r e s s a n d a l l o w i n g a n a s s i s t e d o r spontaneous birth. The procedure is performed by cutting through the fibro-cartilage of the symphysis pubis and the supportive ligaments with a scalpel while ensuring asepsis. At its introduction, symphysiotomy was reputed to play a key role in providing an alternative mode of delivery for mild to moderate cephalo-pelvic disproportion thereby reducing caesarean delivery rates. Cynics however doubt this and worry about the risks to the pelvic bones and the nearby lower urinary tract structures. As a result, this procedure has fallen out of favour and rarely employed in obstetric practice even in least resource parts of the world.
In the Zaria study, no single symphysiotomy was performed in 5 years despite the existence of indications for the procedure (Adaji et al., 2009). Moreover the skill to perform the procedure has dwindled among obstetricians over time. However, some still argue for a role for this procedure because it meets women's socio-cultural expectation of a vaginal delivery in areas with dislike and apathy for caesarean sections (Maharaj and Moodley, 2002)

Fetal destructive operations
These refer to procedures to deliver a dead fetus in the presence of obstructed labour. The value of a caesarean section in this circumstance is low and the maternal situation may even make any resort to an abdominal operation rather dangerous. Craniotomy could be performed to reduce the diameter of the fetal head to allow vaginal delivery, and transverse lie could be relived by decapitation. Cleidotomy could be performed sometimes to reduce bisacromial diameter when the shoulders of a dead fetus are impacted while evisceration or embryotomy could be performed if the dead fetus is large and or the abdomen is swollen due to an intra-abdominal tumor. Destructive operations are no longer performed in developed countries where the indications for it no longer exists. Even in developing countries most obstetricians shy away from performing the procedure. In Zaria, only 0.1% of deliveries were by destructive procedures (Adaji et al., 2009).

Conclusion
Operative vaginal procedures, mainly vacuum extraction and obstetric forceps delivery have a long history but both still have a place in contemporary obstetric practice. In competent hands and with strict adherence to guidelines, the outcomes for the mother and child are excellent. There is great gain in ensuring that these arts are not lost to the modern day obstetrician. On the other hand, procedures like symphysiotomy and destructive operations may still have value in obstetric practice in low income settings. However the evidence for their value need to be laid out clearly and the guidelines for their use comprehensively updated.