Description #
Shoulder dystocia is defined as failure to deliver the fetus by usual maneuvers after birth of the head. Shoulder dytocia presents the birth attendant with an acute emergency that calls for an immediate response from a calm and skilled provider to accomplish the birth of the baby while minimizing harm to mother and infant. This unit summarizes and evidence based approach to the prevention, diagnosis and treatment of this event.
Learning Objectives #
Upon completion of this unit the learner will be able to:
1. Define shoulder dystocia.
2. Describe the three most frequently occurring risk factors for shoulder dystocia.
3. Identify three effective risk reduction strategies recommended to reduce the risk of shoulder dystocia
4. Describe the 4 most frequently occurring newborn morbidities associated with shoulder dystocia.
5. Describe a management style for the second stage of labour that may reduce the risk of shoulder dystocia.
6. Review second stage signs of probably shoulder dystocia.
7. Describe external and internal maneuvers that have been demonstrated to facilitate the birth of obstructed shoulders.
8. Identify essential criteria for comprehensive and complete documentation following a shoulder dystocia.
Shoulder Dystocia Slide Show???? #
Definition #
Shoulder dystocia is diagnosed when the fetal shoulders fail to delivery by usual maneuvers after the birth of the head. It is caused by the impaction of the anterior shoulder against the maternal symphysis pubis or the posterior shoulder on the sacral promontory. The reported incidence ranges from 0.0078 to 7% (Locatelli et al, 2011; Gurewitsch et al 2011). Although most cases of shoulder dystocia resolve without injury, the condition and the maneuvers that are used to resolve it can lead to significant harm to the infant and the woman.
Shoulder dystocia can occur without warning in women without risk factors, so the attendant must anticipate and recognize the problem, and then initiate a systematic series of maneuvers to enable the birth ideally within 5 minutes of birth of the head (Leung et al 2011; Locatelli et al, 2011; Gurewitsch, 2011).
Normally, the fetal bisacromial diameter (the measurement between the most distal portions of the fetal shoulders) enters the pelvis obliquely, leading with the posterior shoulder. The pelvic brim is narrower front to back than in the oblique dimension, and the fetus gravitates towards the roomier dimension. The fetus rotates to the anterior-posterior position at the pelvic outlet when the head externally rotates, allowing the anterior shoulder to slide beneath the symphysis pubis and deliver. If the shoulders enter the pelvis in an anteroposterior orientation rather than obliquely, or comes through the pelvic inlet simultaneously rather than sequentially, the anterior shoulder can lodge behind the symphysis pubis. The posterior shoulder can also become wedged on the sacral promontory.
Risks to the Newborn
If the baby’s head continues to descend, the brachial plexus nerves, which supply motor function to the arm, may stretch or tear, potentially sustaining irreversible lifelong disability. The birth attendant can also cause brachial plexus injury by pulling or twisting the head, by lateral traction, or by applying pressure to the baby’s anterior axilla. In addition to the risk of brachial plexus injury (8.4%) Infants are also at risk for hypoxic ischemic encephalopathy (0.5%), fractures of the clavicle or humerus (7.8%), and death (0.0001%) (Leung et al 2011). It can be difficult to determine whether shoulder dystocia-related injuries originate as a prenatal insult, trauma from the impaction of the shoulder through the natural process of labor, acidemia from cord compression or other intrauterine events, or from the provider’s attempts at extrication.
Risk Factors #
Only 50% of labours that experience shoulder dystocia present with any antecedent risk factors. Of all the risk factors known, three of the most cited include fetal macrosomia (> 4500 grams), diabetes and history of shoulder dystocia with previous birth (Gurewitsch et al, 2011; Pondaag et al, 2011). Shoulder dystocia occurs with less than 1% of deliveries involving fetuses weighing less than 4,000 g, and 5–7% of deliveries with fetuses weighing more than 4,000 g (Rodis, 2007a; Leung et al 2011). Infants born to mothers with diabetes are two to six times more likely to suffer shoulder dystocia, not only because diabetes is associated with macrosomia, but also because these fetuses have proportionately wider shoulders. Identification of a truly macrosomic fetus can be difficult. Sonography is only 22–69% accurate in identifying fetuses over 4,500 g, about as accurate as Leopold’s maneuvers. Macrosomia tends to recur in subsequent pregnancies, as does shoulder dystocia, which carries a recurrence risk of about 14% (Rodis, 2007a).
Risk increases with greater maternal weight gain, labor abnormalities such as precipitous delivery or prolonged second stage, fetal congenital anomalies and tumors, fetus heavier than previous fetuses, postdate pregnancies, maternal pelvic deformities, and short maternal stature.
Speed of the birth may influence shoulder dystocia. Pardoxically, both precipitous birth and instrumentation with vacuum or forceps increases the incidence of shoulder dystocia. The rapid descent of the shoulders through the pelvic inlet my cause the impacted shoulders. This may explain the wide variance in reporting of shoulder dystocia if some accouchers attempt to delivery the shoulder prior to restitution while others await the next contraction.
There is a relationship between oxytocin augmentation and shoulder dystocia. Women with epidural anesthesia may experience impaired rotation due to relaxed muscle tone and inability to push effectively. A combination of risk factors may be more meaningful—one small study showed that in women with macrosomic infants and a history of shoulder dystocia, the recurrence rate was above 50% (Rodis, 2007a). It is difficult to determine which is most important predicter: the long labour or the long labour that requires the augment, the epidural and subsequent instrumental birth.
Shoulder dystocia can be prevented by cesarean delivery. For this reason elective cesarean delivery should be offered to women with a history of prior shoulder dystocia where the newborn suffered significant disability. However, 3,695 prophylactic cesareans would be needed to prevent one brachial plexus injury among nondiabetic women with suspected fetal macrosomia (Rodis, 2007a). Induction for suspected macrosomia does not reduce shoulder dystocia (Irion & Boulvain, 2010)
Based upon current data, the most responsible recommendation to be made for the prevention of shoulder dystocia is ensuring a health pre-pregnant BMI, good glycemic control in pregnancy and regular exercise.
During the birth there may be physical clues that shoulder dystocia is developing. Babies heads often quickly emerge after being born to the eyebrows. The baby with shoulder dystocia may have a slow birth from the brows to neck. The birth attendant may have to press back the perineum to aid the birth of the face. The head then may be seen to retract tightly against the perineum in the turtle sign. Whereas most babies spontaneously restitute to the right or left, the baby with shoulder dystocia may remain with the face oriented posteriorly, looking toward the mother’s anus, thus failing to restitute. The head begins to darken as it congests with blood secondary to impaired venous return, a condition that can result in brain hemorrhage. The actual diagnosis is made when the usual maneuvers fail to delivery the fetal shoulders.
Head to Body Delivery Interval (HBDI) #
An argument to define shoulder dystocia by head to body delivery interval of 60 seconds has been made. However, this definition is problematic. Standard midwifery competencies for supporting physiological birth advocates awaiting restitution after the birth of the head and spontaneous birth of the shoulders with maternal effort and the next contraction. Based upon this definition, most babies would not be born by a one minute HBDI.
The time that elapses between the birth of the head and the rest of the body is also important to consider as fatalities and permanent disability in shoulder dystocia do increase with prolonged HBDI. After the head is born, the cord is compressed between the fetal body and the maternal tissues. In addition maternal tissues compress the fetal neck and carotid vessels, influencing blood flow to and from the brain and finally, placental separation can occur before the body is born. However, the rush to deliver the baby quickly may also contribute to brachial plexus injury, fractures and maternal trauma. Investigators have attempted to discover what the optimal HBDI may be to reduce mortality and morbidity.
Wood (1973) examined head to body birth interval and newborn cord pH. He randomly assigned 22 women to either rapid or normal management after the birth of the head. He described rapid management as early episiotomy, forced pushing in supine lithotomy, and the liberal use of forceps. He described using wrigleys forceps in 3 of his 11 births in the rapid arm of his trial. He did not describe the normal approach. He measured scalp pH at onset of second stage, at crowning, and cord gases immediately at the birth. He reported a drop of 0.14 Units/min with an average head to body interval of 43 seconds in the rapid group. There were no differences in Apgars. He advocated an ideal head to body interval of 40 seconds to improve fetal acid base status.
Leung and colleagues (2010) measured the HBDI in 212 births complicated by shoulder dystocia to be 2.5 minutes (+/- 1.5 minutes). His population represented a shoulder dystocia rate of 0.34% with 96.7% of infants delivered by 5 minutes. The umbilical artery pH dropped 0.011 units/ minute and there was a 0.5% risk of HIE when birth occurred under 5 minutes. Although they report an incidence of 23.5% HIE in births that occurred after 5 minutes it is important to review each of these 5 cases. All were instrumental births, initiated for abnormal fetal heart rate tracings, 4 of the 5 cases resolved without sequelae. The only infant with sustained brain injury of the five had an HBDI of 14 minutes and this baby developed CP and died at 3 years of age. In a subsequent publication Leung et al (2011) report a 0.5% HIE rate in births that occurred with an HBDI of > 5 min following shoulder dystocia.
Locatelli at colleagues (2011) investigated outcomes associated with a two step approach to managing the final steps of second stage with the head to body delivery interval and cord pH. The two step approach included expectant management during the transition phase, maternal position of choice, avoidance of any unnecessary manual intervention, supporting maternal pushing efforts to coincide with their urge to push, restricted episiotomy, waiting for restitution of the fetal head following its delivery with a hands off approach, and waiting for uterine contractions to accomplish spontaneous delivery of the shoulders and the rest of the body.
The authors reported on 1231 vaginal births in which they were able to measure HBDI in 789 of them. Their study protocol instructed attendants to place the woman in McRoberts if they observed the “turtle sign” (which occurred in 1.9% of the cases) but no other ancillary maneuvers would be initiated. A hands on approach after birth of the head was initiated in the presence of clinical indicators such as abnormal fetal heart rate and this occurred in 5% of the births. In the remaining 95% the two step approach was followed. In the trial period there were 3 shoulder dystocias (0.24% of 1231) and they all occurred in the group with HBDI measured. The average HBDI was 88 seconds (+/- 60 seconds) and the cord pH dropped 0.0078 units/ minute. Only 16.8% of women delivered the body in the same contraction that delivered the head. There were no cases of brachial plexus injury or hypoxic ischemic encephalopathy. There was no statistically significant linear relationship between the head-to-body delivery interval and fetal pH when the birth occurred within 5 min. Only an abnormal fetal heart rate tracing during second stage of labor and operative vaginal delivery were associated with academia (pH <7.1 and / or B.D. <12) whereas head-to-body interval was not.
Management of Shoulder Dystocia #
Do NOT PULL, PIVOT, PUSH or PANIC #
Shoulder dystocia cannot be resolved by traction on the baby. Attempts to pull or pry the baby out, twisting the head, or pressing on the fundus can stretch and injure the brachial plexus, rupture the uterus, or worsen the obstruction (Gurewitsch, 2011). Lateral traction is associated with a 30% increase in traction forces necessary to achieve delivery (Gornik et al, 2003). Leung and colleagues (2011) reported a 75% brachial plexus injury rate and a 25 % incidence of clavicular fracture when lateral forces were documented as used to resolve shoulder dystocia. Fundal pressure is always contraindicated because it may rupture the uterus or worsen the impaction. Extrication maneuvers attempt to dislodge the anterior shoulder from behind the symphysis pubis by changing the orientation of the fetus or maternal pelvis. These interventions should be attempted with a sense of calm urgency. After about 5 minutes of entrapment, the infant risks brain damage increases (Leung et al 2010). All interventions should be initiated in rapid and logical sequence and immediate assistance sought including transport initiated in case of need for newborn resuscitation, maternal trauma and PPH.
Stay calm.
Most shoulder dystocias are resolved in less than 4 minutes using 3 or less maneuvres including maternal position changes, maternal effort and rotational forces employed by a skilled attendant (Leung et al 2011).
Get assistance.
Let everyone know you need help with the shoulders. Tell the woman you need her help. Enlist as many helpers as possible. At home: include your second birth attendant, the woman’s partner, the student, the doula. Call 911 and Call the hospital – alert your team of nursing, OB and Pediatrician. Anticipate the need for neonatal resuscitation and the likelihood of postpartum hemorrhage. In hospital, organize a team response that includes extra nursing, OB and Pediatrics. Helpers can always be graciously cancelled if they are not needed.
Progress through maneuvers
Move systematically from simple to complex, less invasive to more invasive. From this moment on you Do NOT wait for contractions – quickly engage the woman in following your commands to only push when you need her to. You will learn maneuvers in a linear fashion, but in the context of an actual emergency situation, you should vary application as the circumstances demand. There is some evidence that some maneuvers are more effective than others and we will review them here (Gurewitsch et al 2011) The goal of management is to free the baby without significant asphyxia or permanent Erb’s palsy.
Prepare to resuscitate the neonate and recommend active management of third stage.
McRobert’s Maneuver #
McRobert’s maneuver involves flexing the maternal thighs onto the abdomen and lowering the maternal head. This position does not increase pelvic diameters but rather acts to flatten the sacral promontory, straightens the lumbosacral lordosis, and increases the available space in the posterior pelvis for the posterior shoulder to fall down and allow the anterior shoulder to slip under the symphysis with maternal effort. McRobert’s maneuver combined with suprapubic pressure is associated with a 25 – 53% resolution of shoulder dystocia (Leung et al 2011; Gherman,2005)
Caution is advised as overzealous application of McRobert’s may cause injury to the mother, including symphyseal separation, sacroiliac joint dislocation, and transient dysfunction of the femoral nerve. When compared to forces of birth required to deliver in lithotomy, McRoberts was found to require a 53% reduction in axial force to achieve birth in a simulator (Gonik, 2003).
Suprapubic Pressure #
An assistant to the midwife (preferably the strongest person available) stands on the side of the fetal back and applies moderately deep lateral suprapubic pressure with two hands and with locked elbows in a CPR like motion. This maneuver adducts the fetal shoulder toward the fetal chest or shifts it into an oblique orientation, to help it to move beneath the symphysis. Pressure should be applied into the soft tissue above the pubic bone, not over the bone itself. In Grimm’s (2010) simulator suprapubic pressure of 40-140 Newtons reduced the required force to achieve birth from the baseline lithotomy by 14.8 – 23 %.
Reattempt Delivery #
With the woman in McRobert’s position, and the assistant applying suprapubic pressure, the midwife should grasp the fetal head between two hands and ask the mother for her strongest pushing effort. With axial, not lateral, traction, gently guide the head downwards, toward the mother’s anus, with the goal of helping the posterior shoulder to slip into the hollow of the sacrum, making room for the anterior shoulder to move beneath the pubis. Only careful, gentle, symmetric pressure should be used—the mother’s expulsive efforts are the force that delivers the baby. Meanwhile, maintain McRobert’s position with suprapubic pressure. Be cautious as lateral or outward traction or excessive pressure can cause permanent damage to the infant.
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Gaskin’s Maneuver #
Ina May Gaskin, CPM, introduced the hands and knees position to mainstream medicine (Bruner & Gaskin, 1998). To perform the Gaskin maneuver, turn the mother to hands and knees—NOT knee-chest. The act of changing position to hands and knees and the effects of gravity are often enough to bring the anterior shoulder forward and make room for the posterior shoulder (now uppermost) to move through the hollow of the sacrum and deliver first. As soon as she has assumed this position, instruct here to give a strong push. The midwife should apply gentle downward traction to deliver the uppermost, posterior shoulder first, then upward traction on the anterior shoulder (which rests against the symphysis pubis). Although medical texts often list this maneuver near the bottom of possible interventions for shoulder dystocia, for the mobile, unanesthetized woman, Gaskin’s maneuver may be the most appropriate choice for initial management. Bruner (1998) reported an 83% resolution of shoulder dystocia with this maneuver. The midwife may choose to employ this technique in preference to McRobert’s maneuver as the first intervention or as a preventative position at a birth where risk factors are present.
Rotational Maneuvers #
By initiating a protocol to check shoulder position and alignment resulted in improved outcomes with shoulder dystocia maneuvres, ask the woman to stop pushing while you Insert your hand into the vagina and reach back to the anterior shoulder. Feel the shoulders and note how they fit into the pelvis. Is the anterior shoulder difficult to reach because it is lodged above the pelvic brim? Are the shoulders transverse and jammed sideways? If so, suprapubic pressure will not be useful. Is there a fetal hand blocking progress, or an abducted arm? Is a tight nuchal cord impeding birth? Resolve the obstruction and ask the woman to push.
Modified Rubin’s Maneuver #
The modified Rubin’s maneuver, employed with the woman in McRobert’s position or in hands and knees, involves adducting the fetal shoulder and orienting it obliquely in the pelvis. This action creates more space for delivery and allows the posterior arm to enter the pelvis with maternal effort. Rubin’s maneuver requires significantly less traction force than McRobert’s and involves significantly lower brachial plexus extension (Gurewitsch, et al., 2005). Place your hand in the vagina behind the posterior fetal shoulder and then rotate it toward the fetal chest. As you feel the shoulder rotate into the oblique instruct the woman to push. If the fetal spine lies to the left, use your right hand; if it lies to the right, use your left. This maneuver may be difficult and painful for the unanesthetized client, and it may be difficult to get your hand into the vagina without cutting an episiotomy. Birthing simulator research has provided evidence that the modified Rubin’s maneuver results in a 22.2% reduction in force when compared to lithotomy to facilitate birth (Grimm, 2011). A variation of this technique is the Rubin II maneuver, which involves displacing the anterior fetal shoulder toward the fetal chest and beyond the midline of the maternal symphysis, from the 12 o’clock position to either 11 o’clock or 1 o’clock. When you have move the shoulder into the oblique or are pressing the shoulder in that direction – ask the woman to push.
Reattempt Delivery #
Woods Screw #
Woods compared shoulder dystocia to the “crossed thread” of a bolt in a nut. A bolt cannot be forced into a nut, but advances when turned repeatedly. The Woods screw maneuver turns the baby through the pelvis like a bolt through a nut until the anterior shoulder advances from behind the pubic symphysis. This is an extension of the Rubin. With the woman NOT pushing, the midwife rotates the fetus by exerting pressure on the posterior aspect of the anterior shoulder and on the anterior surface of the posterior shoulder. Do not twist the fetal head and neck. With the rotation, as soon as the shoulder is moved into the oblique – ask the woman to push and continue to do so as the fetus is rotated 180 degrees. If this does not result in progress, ask the woman to stop pushing. The Midwife will replace her hands using the opposite sides of the fetal shoulders and attempt to place the fetus back – in the “reverse woods” while asking the woman to push. Failing to reverse the baby may result in increased tension on the cord.
Posterior Arm #
The delivery of the posterior arm is an extremely effective method for extricating the baby and has a reported efficacy of over 80%. Insert an entire hand into the vagina. If the woman is in the hands and knees position this manoeuvre may be easier to perform as there may be more room to enter and remove the posterior arm. In hands and knees the posterior arm is nearest the woman’s spine – and thus is the top arm.
Ask the woman to stop pushing. If the fetal abdomen faces the maternal right, use your left hand (your right hand if the fetus faces the maternal left). Find the posterior arm and follow it to the elbow. Flex the elbow across the fetal chest by applying pressure in the antecubital fossa with your thumb, then grasp the forearm or hand, and guide the arm gently across the fetal chest and out of the vagina. Delivery of the posterior arm brings the posterior shoulder into the pelvis. Ask the woman to push. If the anterior shoulder is still wedged, rotate the baby and deliver the other arm. A major risk of this maneuver is inadvertent fracture of the baby’s humerus. If the arm is trapped behind the fetus, you must maneuver the arm gently to the front of the fetus, then sweep it across the chest and out of the vagina.
Episiotomy #
Although shoulder dystocia is a bony obstruction, an episiotomy has historically been advocated in the routine management of shoulder dystocia. Recently its usefulness has been challenged (Gurewitsch et al 2004; Paris, 2011) In some cases episiotomy is needed so the birth attendant can insert her hands deeply enough to maneuver the fetus Unless the attendant is unable to enter the vagina to accomplish the internal maneuvers it has little value and may waste valuable time. Episiotomy also risks extension into a 3rd- or 4th-degree laceration
Other Measures #
Humeralb or Clavicular Fracture #
If the baby is still impacted and time is running out, the midwife can intentionally fracture the baby’s clavicle to narrow the shoulder width or fracture the humerus to get the posterior arm delivered. Clavicular fracture can be very difficult to accomplish, and it carries the risk of injury to the fetal lungs and vasculature. However, bone fractures heal well and do not usually lead to any long term disability.
Symphysiotomy #
Symphysiotomy, or bisecting the symphysis pubis, effectively frees the baby, but can create lifelong pain and ambulation difficulties for the mother. This technique requires minimal equipment and is frequently used in developing countries. It poses little risk to the fetus and is effective when performed early (Menticoglou, 1990). Under local anesthesia, the provider displaces the urethra after placing a urinary catheter. The pubic skin and tissue above the pubic phone is infiltrated with lidocaine and a straight scalpel is used to cut through the cartilage that unites the two bony halves of the symphysis. This technique is not recommended, and it is employed only if all other maneuvers fail and cesarean delivery is not possible (Rodis, 2007b).
Rapid Transport #
If initial attempts to dislodge the baby fail, rapid transport is essential. You may transport the mother either on hands and knees or in McRobert’s position, and you should continue to repeat the above maneuvers en route. In most areas, transport by an advanced life support EMS squad is preferable to use of a private car if response times are rapid. The mother should receive high-flow oxygen by mask and should have at least one large-bore IV line of crystalloid solution. You should be prepared to do active management of third stage. The mother may hemorrhage after delivery, and hemorrhage can lead to shock and even death.
If delivery is accomplished, the baby who has suffered a significant shoulder dystocia will often require resuscitation. Clavicular and humeral fractures are fairly common following a shoulder dystocia, but usually heal well with no long-term damage. Transient brachial plexus palsy occurs with aproximately 8% of all shoulder dystocia cases and the incidence depends on maneuvers and forces used. Less than 2% of brachial plexus palsies are permanent (Rodis, 2007b). Many cases of infant injury following shoulder dystocia cannot be attributed to the birth attendant; a significant number of infants with or without shoulder dystocia sustain these fractures or nerve injuries secondary to the forces of labour, position, and maternal pushing efforts, and even cesarean section cannot prevent them. Half of all babies with brachial plexus injuries are delivered spontaneously without shoulder dystocia. In fact, brachial-plexus injury has been documented in babies delivered by Cesarean section (Gherman, Ouzounian, & Goodwin, 1999).
Because every delivery carries the potential for shoulder dystocia, mothers should be instructed prenatally that strong pushing efforts may be necessary to accomplish delivery. This is especially true for women who have learned Hypnobirthing and other childbirth courses that encourage the natural descent of the infant and discourage Valsalva pushing. Although open-glottis pushing is beneficial in many cases, shoulder dystocia requires strong pushing efforts.
REMEMBER
Active Management of Third Stage of Labour is recommended to reduce the incidence of a postpartum hemorrhage.
- Women who experience shoulder dystocia are at increased risk of a PPH
- Their newborns are more likely to require resuscitation – and the provider team may be busy managing the newborn’s needs impacting their ability to manage a concurrent PPH.
Newborn Resuscitation is more likely required after a shoulder dystocia
- Plan ahead, ensure your resuscitation equipment is set up at every birth
- Call for help early – 911/ pediatric/ team support should be mobilized on recognition of the shoulder dystocia – you can always thank them and send them away if not required.
- Consider resuscitation with the cord intact – especially in an out of hospital environment – as these infants may also be hypovolemic due to the cord compression during the delay in the birth of the torso. They may respond quicker if they receive the placental transfusion along with the stored oxygen reserves.
Documentation for Shoulder Dystocia #
Documentation following a shoulder dystocia should include #
× Demonstration of thought processes through delivery of the fetal head
× Time of birth of the head and trunk
× Need (or lack of need) for episiotomy
× Force, direction, and duration of traction
× Sequence, description, and duration of maneuvers used
× Personnel involved and their roles
× Cord gases
× Complete maternal and newborn exam
Delivery of the shoulders can be aggravated by maternal position, fetal position, full bladder, or excessive adipose tissue that interferes with the birth.
“Bed dystocia” occurs when delivery is attempted on a soft mattress with the woman supine, limiting the capacity of the pelvis to expand and the ability of the birth attendant to guide the head downward.
Other impediments to birth can mimic shoulder dystocia. The body may not deliver spontaneously in the event of a short cord, a tight cord wrapped around the neck or body, an amniotic band, a fetal hand or foot wedged awkwardly and preventing birth, Bandell’s ring, uterine rupture, certain fetal deformities, maternal pelvic tumors, or entanglement with a twin still in utero.
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