OBGMANAGEMENT ■ BY MARTIN GIMOVSKY, MD, AND GREGORY MICHAEL, MD Delivery dilemmas: shoulder dystocia It’s obstetric challenges such as these that test our skills in the delivery room—and expose us to greatest medicolegal risk. Here, the authors detail predelivery warning signs and specific intrapartum maneuvers that can help obstetricians rise to the challenge of this difficult delivery. houlder dystocia is an obstetric KEY POINTS emergency requiring skillful inter- ■ The most frequently described occurrence Svention from all delivery person- prior to a shoulder dystocia emergency is the nel. The good news is there are several “turtle” sign during contractions, in which the techniques clinicians can utilize when vertex is seen at the introitus, but subsequently recedes after maternal expulsive efforts. this condition arises—and even ways to spot it prior to delivery. A thorough ■ Upon encountering a shoulder dystocia, knowledge of these approaches, coupled immediately announce the condition, summon with expert support from a staff of skill- help, and alert the anesthesia department. The ful, proficient assistants, can help reduce mother’s pelvic capacity and the estimated the frequency and severity of this chal- fetal weight help determine just how difficult resolving shoulder dystocia may be. lenging disorder. CONTINUED ■ Dr. Gimovsky is professor and director, division of maternal-fetal ■ Physicians should concentrate gentle, medicine, department of OBG, and Dr. Michael is a third-year downward applied force at the shoulder gir- resident, department of OBG, Newark Beth Israel Medical Center, dle—either to rotate it or dislodge it directly. Newark, NJ. ■ Do not apply fundal pressure, as it tends to December 2002 • OBG MANAGEMENT 35 further aggravate shoulder impaction. Delivery dilemmas: shoulder dystocia TABLE 1 Antepartum signs of possible shoulder dystocia • Fetal macrosomia (EFW > 4,500 g, nondiabetic gravida; or EFW > 4,000 g, diabetic gravida) • Fetal habitus (chest diameter-biparietal diameter > 1.4 cm) • Maternal habitus (maternal prepregnancy weight > 200 lb., stature < 5’3, maternal birthweight > 4,000 g) • Prior macrosomia (previous infant weighing more than 5,000 g) • Prior traumatic delivery (previous infant with brachial plexus injury) EFW=estimated fetal weight Though not a common obstetric occur- defined as any nonspontaneous birth requir- rence, shoulder dystocia has the potential to ing extensive traction and specific maneuvers lead to significant fetal morbidity—including to disimpact the infant’s shoulder girdle. nerve plexus injury, clavicle or humerus frac- Under these conditions, the reported preva- ture or dislocation, soft tissue injury to the face, lence of shoulder dystocia is 0.15% to 1.7% of and asphyxia of varying severity1—and even all live births.3 mortality. Additionally, injuries sustained by the mother in the course of delivery may have Diagnosis of shoulder dystocia is lifelong consequences. In an effort to reduce these adverse outcomes, here we describe the made after the fetal head is delivered risk factors predisposing a patient to shoulder and is seen to tightly approximate the dystocia, review the condition’s mechanism, outline management protocols, and offer our maternal perineum. techniques for carrying out a safe delivery. How it happens In general, if the shoulder girdle fails to n a normal delivery, once the fetal head is achieve rotation into the oblique diameters Iexpelled, external rotation—or “restitu- available at the inlet, or if that diameter is tion”—realigns the head to its proper location inadequate due to fetal size or maternal pelvic in relation to the cervical spine. With the head shape, completing the delivery process perpendicular to the shoulder girdle, the becomes difficult.4 shoulders enter the pelvis in an oblique diam- eter at the inlet. Maternal expulsive efforts Identifying those at risk cause the anterior shoulder to transit under- here are a number of clues obstetricians neath the pubis. Tmay encounter in the antepartum and When both rotation and expulsive intrapartum stages of pregnancy that can indi- processes during the pelvic phase of labor fail, cate a potential shoulder dystocia case (TABLE however, shoulder dystocia results. While 1). Still, while these associations are helpful, there are differing opinions as to what consti- it’s important to evaluate each labor and deliv- tutes true shoulder dystocia,2 it is usually ery individually.5-10 CONTINUED 36 OBG MANAGEMENT • December 2002 TABLE 2 Things to keep in mind during delivery SIGNS OF SHOULDER DYSTOCIA • Prolonged second stage • Minor degrees of malpresentation • Presence of cranial moulding • Presence of “turtle” sign during contractions SHOULDER DYSTOCIA IS NOT CAUSED BY • Operative delivery, oxytocin, or epidural anesthesia • The use of delivery instruments • Nonperformance of episiotomy Recognizing dystocia be. An experienced examiner should therefore s delivery progresses, clinicians must con- assess the maternal pelvis for signs of contrac- Atinually assess the labor curve. Progress of tion or inadequacy. An ultrasound may be used the station during the second stage should be to estimate fetal weight (these assessments may greater than 1 cm/hr. Prolongation of this vary by 6% to 22% in the fetus at term), though stage—defined as more than 2 hours in the manual techniques can be just as reliable. nulliparous patient and 1 hour in the parous During this time, we recommend talking with patient, with arrest of descent at station 3 cm the patient about her previous obstetric history. or higher—signals possible shoulder dystocia, Since many of the pregnancies in question as does minor degrees of malpresentation, involve parous women, it’s helpful to inquire such as occiput transverse, occiput posterior, whether this baby is bigger than her last. and the presence of asynclitism (TABLE 2). In addition, the presence of cranial moulding, a sign of potential cephalopelvic disproportion, There are several maneuvers the Ob/Gyn indicates a potential traumatic birth. The most frequently described occur- can utilize in delivering a child with shoulder rence prior to a shoulder dystocia emergency dystocia, including the McRobert’s. is the presence of the “turtle” sign during contractions—that is, the vertex is seen at the introitus, but subsequently recedes after Upon encountering a shoulder dystocia, maternal expulsive efforts. Diagnosis of immediately announce the condition, sum- shoulder dystocia is made after the fetal head mon help, and alert the anesthesia depart- is delivered and is seen to tightly approximate ment. Reassessment of risk factors is then the maternal perineum. called for. Since shoulder dystocia is a bone- to-bone apposition of the maternal symphysis Resolving the problem pubis and the fetal shoulder, with opposing he mother’s pelvic capacity and the esti- force vectors at right angles, increased traction Tmated fetal weight (EFW) help determine on the fetal head will only increase the fetal just how difficult resolving this condition may shoulder’s impaction while stretching the CONTINUED December 2002 • OBG MANAGEMENT 37 Delivery dilemmas: shoulder dystocia One sequela of shoulder dystocia: brachial plexus injury he brachial plexus is formed by the anterior the position of the scapula, and the attitude of the Trami of spinal segments C5, C6, C7, C8, and wrist. (Though Phrenic nerve involvement—C4 T1. Three cords—lateral, medial, and posterior—are spinal segment—with resultant paralysis of the formed as a result of the intermingling of these seg- diaphragm has been described in conjunction with mental spinal fibers and make up the peripheral Erb’s palsy, it is very rare.) nerves of the upper extremity. Klumpke’s palsy, meanwhile, primarily affects In 1872, Duchenne was the first to associate the forearm and wrist. It is the direct result of injury injury to the brachial plexus due to traumatic deliv- to the lower trunk, which is comprised of nerve ery of the shoulder girdle. Two years later, Erb fur- input from spinal segments C8 and T1. Flexion at ther clarified brachial plexus injury as it relates to the elbow accompanied by supination at the fore- shoulder girdle impaction, describing localized trau- arm results in the classic claw-like deformity of the ma to the fifth and sixth cervical nerve roots.1 Erb’s hand. If the sympathetic fibers of T1 are affected, palsy—the most common brachial plexus injury— Horner’s syndrome may result. compromises the uppermost trunk, formed from spinal segments C5, C6, and C7. The resulting dys- REFERENCE 1. Swaiman KF, Wright FS. The Practice of Pediatric Neurology. 2nd ed. St. Louis, function manifests in the posture of the upper arm, Mo: CV Mosby; 1982. fragile brachial plexus. There are several clinical maneuvers the Instead, physicians should concentrate Ob/Gyn can utilize in delivering a child with applied force at the shoulder girdle—either to shoulder dystocia. We’ve found the following rotate it or dislodge it directly. Primarily, this sequence to be efficacious in our practice. As force should be directed straight downward, previously noted, this procedure should be though transverse pressure may facilitate the well rehearsed and familiar to all labor and shoulder’s movement into an oblique diame- delivery personnel. ter of the pelvis.11-12 McRobert’s maneuver. Once extra assistants Note that if the fetal shoulders are inade- have arrived, perform the McRobert’s maneu- ver by flexing the fetal legs upward toward the mother’s abdomen.