**5. Epidemiology**

260 From Preconception to Postpartum

A more recent design for the vacuum extractor is the rigid plastic cup Kiwi® vacuum assisted fetal delivery device (Clinical Innovations, Murray, UT). It is designed as an integrated unit for complete control without an assistant. The suction for this device is provided by a PalmPumpTM. 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

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

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

(a) (b) (c)

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

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).

for sub-aponeurotic hemorrhage (p = 0.015, OR = 0.11; 95CI = 0.001 - 0.87).

Fig. 6. (a-c) – Position of cup and direction of traction with vacuum extractor

between patients (Ismail et al., 2008a).

deliveries (Johanson and Menon, 2007).

group (Hayman et al., 2002).

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).

Due to weak health systems, national figures for instrumental vaginal deliveries are either unavailable or incomplete from developing countries. Reports from comprehensive emergency obstetric health care facilities may provide the most reliable source of information in such settings. For example, a 5 year review of births at the Ahmadu Bello University Teaching Hospital, Zaria revealed that of 6662 vaginal births between 1997 and 2001, 3.9% were by operative vaginal delivery procedures. Forceps delivery rate was 2.2% while vacuum delivery rate was 1.5%. In addition, fetal destructive operation to deliver confirmed intrauterine fetal deaths was employed in 0.1% of cases (Adaji et al., 2009). This procedure is rarely reported in literature from developed countries suggesting that they are no longer performed. However, in developing countries where moribund mothers, neglected obstructed labour and intrauterine fetal deaths are still seen, fetal destructive operation remains an option [Moody & Maharaj 2002]. Table 1 below shows the situation of operative vaginal procedures based on hospital-based studies in selected countries.


Table 1. Operative vaginal deliveries in 5 countries(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 and Coffe, 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).

Operative Vaginal Deliveries in Contemporary Obstetric Practice 263

Maternal Medical indications to avoid Valsalva (e.g. cardiac disease Class III

Inadequate progress Nulliparous women: Lack of continuing progress for three hours

Table 3. Indications for operative vaginal delivery (no indication is absolute and each case

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

Head is ≤ 1/5 palpable per abdomen

Cervix is fully dilated and the membranes ruptured Exact position of the head can be determined so proper

Appropriate analgesia is in place, for mid-cavity rotational

A pudendal block may be appropriate, particularly in the

Indwelling catheter should be removed or balloon deflated

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

Personnel present who are trained in neonatal resuscitation

placement of the instrument can be achieved

deliveries this will usually be a regional block

Maternal bladder has been emptied recently

dystocia, postpartum haemorrhage)

Vertex presentation

given

Pelvis is deemed adequate **Mother** Informed consent must be obtained and clear explanation

context of urgent delivery

Aseptic techniques **Staff** Operator must have the knowledge, experience and skills necessary to use the instruments

or IV\*, hypertensive crises, cerebral vascular disease, particularly uncorrected vascular malformations, myasthenia gravis, spinal

(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

**Type Indication** 

\*New York Heart Association classification

should be considered individually)

delivery is presented in Table 4.

**Full abdominal and vaginal examination**

**Preparation Essential** 

Table 4. Prerequisites for operative vaginal delivery

Fetal Presumed fetal compromise

cord injury)
