Shoulder dystocia Dr. S.K.S TMU

Definition:- it means difficulty in the delivery of the shoulder following birth of the head.

Shoulder dystocia occurs when either the anterior or, less commonly, the posterior fetal shoulder impacts on the maternal symphysis or sacral promontory. There can be a high perinatal mortality and morbidity associated with the condition, even when it is managed appropriately. Maternal morbidity is also increased, particularly postpartum haemorrhage (11%) and fourth-degree perineal tears (3.8%).

Incidence North America and the UK found a 0.6% incidence.

Aetiology 1.Large baby/ fetal macrosomia 2.Anencephaly 3.Contracted pelvis 4.Failure of the shoulder to rotate into the anterior-posterior diameter of the outlet following delivery of the head. 5.Foetal Ascitis

Diagnosis a.Antenatal diagnosis :-  History of diabetes is important.  Diagnosis of big baby by clinical estimation and USG.  Diagnosis of anencephaly by USG and alpha feto protein.  Diagnosis of contracted pelvis clinically.

b. During labour:-  Failure of head for crowning, a head which is large in size and difficulty in delivering the face and chin are warning signs of shoulder dystocia.

Management An experienced obstetrician, should be available on the labour ward for the second stage of labour when shoulder dystocia is anticipated. However, it is recognized that not all cases can be anticipated and therefore all birth attendants should be ready with the techniques required to facilitate delivery complicated by shoulder dystocia. Timely management of shoulder dystocia requires prompt recognition.

The attendant health-care taker should routinely observe for: 1.Difficulty with delivery of the face and chin 2.The head remaining tightly applied to the vulva or even retracting 3.Failure of restitution of the fetal head 4.Failure of the shoulders to descend.

Immediately after recognition of shoulder dystocia, extra help should be called. In a hospital setting, this should include further assistance, an obstetrician, a pediatric resuscitation team and an anesthetist. Maternal pushing should be discouraged, as this may lead to further impaction of the shoulders, thereby exacerbating the situation. The woman should be maneuvered to bring the buttocks to the edge of the bed. How should shoulder dystocia be managed?

Fundal pressure should not be used for the treatment of shoulder dystocia. It is associated with an unacceptably high neonatal complication rate and may result in uterine rupture.

Episiotomy Episiotomy is not necessary for all cases. Some obstetrician have advocated that episiotomy is an essential part of the management in all cases but it does not affect the outcome of shoulder dystocia. The episiotomy does not decrease the risk of brachial plexus injury with shoulder dystocia. An episiotomy should therefore be considered but it is not mandatory.

McRoberts ’ manoeuvre The McRoberts’ manoeuvre is the single most effective intervention, with reported success rates as high as 90%. It has a low rate of complication and therefore should be employed first.

The McRoberts' manoeuvre

The McRoberts’ manoeuvre is flexion and abduction of the maternal hips, positioning the maternal thighs on her abdomen. It straightens the lumbo-sacral angle, rotates the maternal pelvis cephalad and is associated with an increase in uterine pressure and amplitude of contractions. McRoberts ’ manoeuvre

No increase in pelvic dimensions. Decrease in the angle of pelvic inclination P=0.001 Straightening of the sacrum P= 0.04% Tends to free the impacted anterior shoulder McRoberts manoeuvre: X ray pelvimetry study

. Mc Roberts ’ manoeuvre + Supra-pubic pressure

Supra-pubic pressure can be employed together with Mc Roberts’ manoeuvre to improve success rates. External supra-pubic pressure is applied in a downward and lateral direction to push the posterior aspect of the anterior shoulder towards the fetal chest. It is advised that this is applied for 30 seconds. Supra-pubic pressure reduces the bi-sacromial diameter and rotates the anterior shoulder into the oblique pelvic diameter. The shoulder is then free to slip underneath the symphysis pubis with the aid of routine traction.

Advanced manoeuvres should be used if the McRoberts ’ manoeuvre and suprapubic pressure fail. If these simple measures fail, then there is a choice to be made between the all-fours-position and internal manipulation. For a slim mobile woman without epidural anaesthesia and with a single attendant, the all fours- position is probably the most appropriate. For a less mobile woman with epidural anaesthesia in place and a senior obstetrician in attendance, Internal rotation manoeuvres (Woods manoeuvre ) are more appropriate.

All- Fours Manoeuver It consists of placing the patient onto her hands and knees

Delivery of the fetal shoulders may be facilitated by rotation into an oblique diameter or by a full 180- degree rotation of the fetal trunk. Delivery may also be facilitated by delivery of the posterior arm. The fetal trunk will either follow directly or the arm can be used to rotate the fetal trunk to facilitate delivery. Internal rotation manoeuvres (Woods manoeuvre )

. Woods manoeuvre: The hand is placed behind the posterior shoulder of the fetus. The shoulder is rotated progressively 180 d in a corkscrew manner so that the impacted anterior shoulder is released.

By inserting a hand into the posterior vagina and ventrally rotating the arm at the shoulder delivery over the perineum Delivery of the posterior arm.

Persistent failure of first- and second-line manoeuvres

What measures should be taken if first- and second-line manoeuvres fail? Third-line manoeuvres require careful consideration to avoid unnecessary maternal morbidity and mortality. It is difficult to recommend a time limit for the management of shoulder dystocia, as there are no conclusive data available.

Several third-line methods have been described for those cases resistant to all simple measures. These include : 1.Cleidotomy (bending the clavicle with a finger or surgical division), 2.Symphysiotomy (dividing the symphyseal ligament) and the 3.Zavanelli manoeuvre. It is rare that these are required.

Zavanelli manoeuvre Cephalic replacement of the head, and delivery by caesarean section has been described but success rates vary. Zavanelli manoeuvre may be most appropriate for rare bilateral shoulder dystocia, where both the shoulders impact on the pelvic inlet, anteriorly above the pubic symphysis and posteriorly on the sacral promontory.

The maternal safety of this procedure is unknown, however, and this should be borne in mind, knowing that a high proportion of fetuses have irreversible hypoxia-acidosis by this stage. Zavanelli manoeuvre

Symphysiotomy Has been suggested as a potentially useful procedure, both in the Developing and developed world. There is a high incidence of serious maternal morbidity and poor neonatal outcome. After delivery, the birth attendants should be alert to the possibility of postpartum haemorrhage and third- and fourth-degree perineal tears.

Complications A. Fetal :- 1.Birth asphyxia II. Traumatic injury 1.Fractures of Humerus or clavicle 2.Erb’s palsy Brachial plexus injuries a) Short term complication 1. Metabolic acidosis 2.Shock 3.Renal failure 4. CNS depression 5. Seizures b) Long term complication 1.Mental Retardation 2.Cerebral palsy 3.Seizures disorder 4.Speech defect

Brachial plexus injuriesBrachial plexus injuries

B. Maternal:- 1. Prolonged labour 2. Obstructed labour 3. Lacerations of the cervix, Vagina & perineum 4. Rupture of Uterus 5. PPH 6. Shock, death

MATERNAL CONSEQUENCES Postpartum hemorrhage, usually from uterine atony, but also from vaginal and cervical lacerations, is the major maternal risk

FETAL CONSEQUENCES Shoulder dystocia may be associated with significant fetal morbidity and even mortality. Gherman and co-workers (1998) reviewed 285 cases of shoulder dystocia and found 25 percent were associated with fetal injuries. Transient Erb or Duchenne brachial plexus palsies were the most common injury, accounting for two thirds;38 percent had clavicular fractures; and 17 percent sustained humeral fractures. There was one neonatal death, and four newborns had persistent brachial plexus injuries.

In this series, almost half of the cases of shoulder dystocia required a direct fetal manipulation such as the Woods maneuver, in addition to the McRoberts procedure, to effect release of the impacted shoulders. Direct fetal manipulation, however, when compared with use of the McRoberts procedure alone, was not associated with an increased rate of fetal injury.