Does the early consideration of the Zavanelli manoeuver in a difficult case of shoulder dystocia result in a better obstetric outcome?

A critical evaluation of the external and internal maneuvers for resolution of shoulder dystocia

In the management of shoulder dystocia, it is often recommended to start with external maneuvers, such as the McRoberts maneuver and suprapubic pressure, followed by internal maneuvers including rotation and posterior arm delivery. However, this sequence is not based on scientific evidence of its success rates, the technical simplicity, or the related complication rates. Hence, this review critically evaluates the success rate, technique, and safety of different maneuvers. Retrospective reviews showed that posterior arm delivery has consistently higher success rates (86.1%) than rotational methods (62.4%) and external maneuvers (56.0%). McRoberts maneuver was thought to be a simple method, however, its mechanism is not clear. Furthermore, McRoberts position still requires subsequent traction on the fetal neck, which presents a risk for brachial plexus injury. The 2 internal maneuvers have anatomic rationales with the aim of rotating the shoulders to the wider oblique pelvic dimension or reducing the shoulder width. The techniques are not more sophisticated and requires the accoucher to insert the correct hand (according to fetal face direction) through the more spacious sacro-posterior region and deep enough to reach the fetal chest or posterior forearm. The performance of rotation and posterior arm delivery can also be integrated and performed using the same hand. Retrospective studies may give a biased view that the internal maneuvers are riskier. First, a less severely impacted shoulder dystocia is more likely to have been managed by external maneuvers, subjecting more difficult cases to internal maneuvers. Second, neonatal injuries were not necessarily caused by the internal maneuvers that led to delivery but could have been caused by the preceding unsuccessful external maneuvers. The procedural safety is not primarily related to the nature of the maneuvers, but to how properly these maneuvers are performed. When all these maneuvers have failed, it is important to consider the reasons for failure otherwise repetition of the maneuver cycle is just a random trial and error. If the posterior axilla is just above the pelvic outlet and reachable, posterior axilla traction using either the accoucher fingers or a sling is a feasible alternative. Its mechanism is not just outward traction but also rotation of the shoulders to the wider oblique pelvic dimension. If the posterior axilla is at a higher sacral level, a sling may be formed with the assistance of a long right-angle forceps, otherwise, more invasive methods such as Zavanelli maneuver, abdominal rescue, or symphysiotomy are the last resorts.

The Zavanelli manoeuvre revisited: A review of the literature and a guide to performing cephalic replacement for severe shoulder dystocia

The Zavanelli manoeuvre is often the final resort of the clinician facing undeliverable shoulder dystocia and we present retrospective pooled data comprising 110 shoulder dystocia cases, 11 impacted breech and 11 locked twin deliveries assessed from ten case series and 38 individual case reports. Although recommended when other external and internal manipulations have failed, we suspect that many clinicians have not had formal training on how to conduct the manoeuvre and may be unfamiliar with the steps involved, leading to a reluctance and delay in initiating this. We describe original descriptions of the manoeuvre, examine its use in intractable shoulder dystocia and illustrate stepwise the cephalic replacement technique. For this review, we have concentrated mainly on the outcomes of the Zavanelli manoeuvre in shoulder dystocia but have also touched on its role in impacted breech and locked twin deliveries. Lastly, we discuss the cognitive load an obstetrician faces when having to make time critical decisions in severe shoulder dystocia and share how other disciplines train and prepare their personnel to manage similar rare and unexpected scenarios.