Retrospective Evaluation of Pelvic Capacity and Infant Biometry The contour of the pelvis undergoes modification and expan-

Retrospective Evaluation of Pelvic Capacity and Infant Biometry The contour of the pelvis undergoes modification and expan-

sion during pregnancy and delivery by a progressive laxity that develops in the cartilage between the pubic rami and within the sacroiliac joints. Thus, the prospective de novo assessment of the likelihood of shoulder dystocia by tradi- tional clinical or even medical image-derived pelvimetry per- formed in either a nullipara or someone who previously has had uneventful deliveries is bound to have a low yield. It is also probable that the simple assessment of pelvic diameters as done in traditional pelvimetry may be too crude an assess- ment of pelvic capacity where propensity toward shoulder dystocia is concerned. It is unknown whether volumetric (three-dimensional) or surface-rendered (topographical) analysis of bony contours rather than geometric (two-dimen- sional) assessment could better differentiate women with otherwise “normal” or “adequate” pelves who nonetheless may have a predilection for shoulder dystocia from similar- sized pelves of women who are unlikely to have shoulder dystocia.

Similarly, not all fetuses of the same weight, even when large-for-gestational age, are equally predisposed to shoulder dystocia. The notion of macrosomia refers not simply to an arbitrary weight cut-off, but rather a disproportionately large fetal trunk relative to the head. Thus, anthropomorphic mea- surements of an infant whose delivery was complicated by shoulder dystocia may also yield some insight into pathogen- esis.

Table 3 depicts the results of traditional and novel pelvim- etry and corresponding infant biometry performed within 24 hours of delivery on three mother–infant pairs who experi-

enced shoulder dystocia. 26 Based on clinical history alone without benefit of postpartum pelvimetry, it would be rea- sonable to surmise that patient 1 must have a “borderline” pelvis where large-for-gestational-age fetuses are concerned. She was unable to deliver a 10-lb baby at all, and a baby weighing just less than 9 lbs experienced shoulder dystocia during delivery. Patient 2, on the other hand, by clinical judgment and without benefit of retrospective pelvic and fetal biometry, could have been judged to be at reduced risk for developing shoulder dystocia based on her documented compliance with blood sugar management and ultrasound-

estimated fetal weight that was in a reasonable range. 27 Yet, of the three shoulder dystocia cases, hers was the most severe. Patient 3 was only modestly compliant with management of her blood sugar, as demonstrated by sonographic evidence of accelerated fetal growth by the time she reached term. How- ever, given the extensive history of her “tested pelvis” for presumably similarly “macrosomic” (trunk-to-head dispro- portionate) infants in the past and the relatively mild nature of the shoulder dystocia she experienced in the context of her precipitous delivery, it might be reasonable to suspect that positional misalignment resulting from precipitous delivery

188

E.D. Gurewitsch, T.L. Johnson, and R.H. Allen

After shoulder dystocia 189

Table 3 Clinical and Computerized Tomographic Pelvimetric Data from Mother–Infant Dyads Examined Within 24 Hours of Delivery Complicated by Shoulder Dystocia

Clinical presentation

VBAC, prior c-sec for CPD

Primigravida, insulin-requiring

Grand grand multipara

Prior infant 4318 g

GDM, euglycemic during

(10th delivery),

BMI 46.9, non-diabetic,

pregnancy, BMI 34.5, 33-lb

recurrent insulin

28-lb wt gain, EFW

wt gain, EFW 3900 g,

requiring GDM, largest

3800 g, 39-wk NSVD

induction at 39 wk, NSVD

prior infant 3973 g, no

after 27-min second

after 70-min second stage

prior history shoulder

stage

dystocia, 3476-g sono EFW @ 37 wk, precipitous delivery on arrival to hospital at 38 wks

Shoulder dystocia severity

Head-to-body interval 70

Head-to-body interval 2

Head-to-body interval 45

Required McRoberts’,

Required McRoberts’,

Required McRoberts’ and

posterior Rubins’ and

suprapubic pressure, and

suprapubic pressure

Modified Woods’ Screw

Woods’ Screw

Immediate neonatal outcome

Apgars 9/9, cord pH 7.3,

Apgars 7/9, no neonatal

Apgars 8/9, temporary

facial bruising, no

complications

Erb’s palsy

fractures or neurapraxia

Birth weight (g)

4,880 Bisacromial width (cm)

14.33 14.83 14.67 Largest transverse diameter

15.76 12.09 11.72 (normal > 12 cm) Sacral promontory to top of

11.63 10.41 11.21 pubic symphysis (normal >11cm)

Interspinous distance (normal 12.47 10.57 11.18 >10 cm)

Intertuberous distance (cm) 14.71 13.36 13.53 Symphyseal separation (cm)

1.82 0.62 0.64 Right/left sacroiliac joint

0.58/0.62 space (cm) Volume (cm 3 )*

1463 Surface area (cm 2 )*

2690 *Novel pelvimetry was derived using 3D Doctor™ and reconstructing CT images in Matlab™ via intensity-based segmentation, stacking, and

surface-fitting of a mesh to the images. Results were validated by comparing 3D Doctor™ measurements against those derived by the radiologist interpreting the CT scans.

was a greater factor in her shoulder dystocia pathogenesis nally without shoulder dystocia a 3945-g infant, similar to the than true fetopelvic disproportion.

previous child who developed shoulder dystocia. Interest- It is noteworthy that all three infants had similar bisacro-

ingly, the pelvimetric assessment following her initial shoul- mial widths. Babies 1 and 3 had proportionate upper and

der dystocia delivery was consistent with a low recurrence lower body anthropomorphic dimensions, whereas Baby 2

risk since it suggested that a true fetopelvic disproportion was had markedly asymmetric shoulder girth despite normal

not evident. In light of the retrospective evaluation of pelvic overall body weight and ponderal index, the latter of which is

capacity and infant biometry following this patient’s shoulder

dystocia delivery, it is more probable that dynamic positional spectively, the traditionally derived sonographic estimation

consistent with well-controlled gestational diabetes. 28 Retro-

misalignment was more contributory to the pathogenesis of of fetal weight of Baby 2 obtained before delivery overesti-

shoulder dystocia and her 27-minute second stage was more mated the actual birth weight, yet did not fully detect this

significant in producing this than was any presumed discrep- shoulder width asymmetry that perhaps might have been

ancy in fetal shoulder and maternal pelvic dimensions based detectable by additional nonstandardized means. 29-32

on her prior cesarean delivery indication. Anecdotally, patient 1 had a subsequent pregnancy that

By contrast, the shoulder dystocia deliveries of patients 2 was scheduled for a repeat cesarean section at 39 weeks to

and 3 were more likely to have resulted from size discrepancy avoid recurrent shoulder dystocia. However, she presented

than from positional misalignment of otherwise compatible only a few hours before her scheduled operation already in

bony dimensions between mother and fetus. In the case of rapidly progressive labor. She successfully delivered vagi-

patient 2, postpartum CT pelvimetry obtained after her index

E.D. Gurewitsch, T.L. Johnson, and R.H. Allen

dystocia. The sharp angulation of the sacrococcygeal joint ( Fig. 1 b) likely impeded normal occupancy of the hollow of the sacrum by the posterior shoulder in the index delivery. This, in turn, would have caused the anterior shoulder to be displaced forward and cephalad and become lodged behind the pubic symphysis in an anteroposterior orientation. Such

a sacrococcygeal deformity could potentially reduce the effi- cacy of first-line shoulder dystocia maneuvers that still main- tain the shoulders in the anteroposterior orientation. 33 Addi- tionally, given the borderline small transverse diameter of her pelvic inlet, the anteroposterior orientation is perhaps more naturally predisposed to being the “path of least resistance” for fetal descent in this patient. Thus, the combination of her acquired deformity and her anthropoid-type pelvic architec- ture makes her likely to experience recurrent shoulder dys- tocia in future deliveries. A planned cesarean delivery for future pregnancy should be considered. If a vaginal delivery is planned, then antenatal management should focus on bet- ter antenatal control of fetal growth and, with awareness of the potential interference by the pelvic deformity, the deliv- ering clinician can opt to prioritize rotational type maneuvers

Figure 1 Postpartum CT pelvimetry following shoulder dystocia. CT as initial management for any recurrent shoulder dystocia, which could reduce the risk of injury. images were obtained from a grand grand multiparous (para 9) 34 woman immediately following delivery, which was complicated by shoulder dystocia. (A) Largest transverse diameter. (B) Anteropos- terior diameter (sacral promontory to top of pubic symphysis); im-

Patient Counseling

age shows marked angulation of sacrococcygeal joint consistent It is often counterintuitive or seemingly premature to attempt with healed fracture. (C) Interspinous diameter. (D) Intertuberous

to counsel a patient regarding the possible pathogeneses of a diameter. Acquired pelvic deformity, likely sustained during earlier

just-experienced shoulder dystocia or to prognosticate either delivery, probably contributed to “high-riding” anterior shoulder

about its possible recurrence or about the long-term outcome resulting in shoulder dystocia.

of any associated injuries. Nevertheless, it is important to explain, in a candid and honest manner, what transpired, what are the possible causes, and what might be anticipated

shoulder dystocia event revealed a reduced pelvic capacity, in the future and to begin to involve the patient actively in her suggesting that she and her infant were size incompatible.

own and her child’s future care. Perhaps precisely because Given these findings, it would seem reasonable to propose

there are so many unknowns about exact pathogeneses, risk that recurrence of shoulder dystocia would be likely in this

factors, prognostic indicators, and future management plans, patient, and she would be a good candidate for a scheduled

it is critically important to educate the woman whose delivery elective cesarean delivery in her next pregnancy.

was complicated by shoulder dystocia about the often unpre- Patient 3’s postpartum CT evaluation ( Fig. 1 ) shows a

dictable and unpreventable nature of the complication, en- rather capacious pelvic cavity by standard measurements.

sure her understanding that it is a significant issue as far as Given the clinical history alone, it would appear as though

future childbearing is concerned, and elicit the patient’s pref- the shoulder dystocia was more likely “sporadic” and attrib-

erences and priorities when planning future deliveries. utable to positional misalignment in this patient. Even

Until more information is amassed through epidemiolog- though her infant was large-for-gestational age, it was not

ical and clinical studies, it is reasonable to encourage the “macrosomic” as defined by trunk-to-head disproportion (or

patient’s cooperation in investigating possible causes and even by criteria for diabetic gravida given in the 2002 ACOG

commitment to compliance with proposed management Practice Bulletin on Shoulder Dystocia). Indeed, her antena-

schema that would aim to ameliorate potentially modifiable tal estimated fetal weight was at the 72nd percentile. Based

contributors to risk. However, the inability to guarantee a on this, it might have been reasonable to surmise that recur-

particular outcome or to entirely avoid risk in any chosen rence of shoulder dystocia based on fetopelvic size discrep-

mode of delivery should always be explained clearly. De- ancy would be relatively low in this patient, and potentially

pending on a particular patient’s degree of risk aversion, she could be modified further with improved diabetic manage-

should be encouraged to consider how willing she would be ment to avoid excess neonatal adiposity.

to maintain a flexible, dynamic, and evolving plan for deliv- However, a surprise finding of an acquired pelvic defor-

ery throughout the next pregnancy and perhaps even during mity from a healed coccygeal fracture (likely sustained at the

her next trial of labor. Knowledge of the occurrence of shoul- delivery that immediately preceded the index shoulder dys-

der dystocia, even if otherwise uneventful in terms of diffi- tocia delivery) suggests a different pathogenesis for shoulder

culty of management or associated morbidity, is important

After shoulder dystocia 191

Table 4 Comparison of Risk Factors Between Mild and Severe Shoulder Dystocia 56

Mild Shoulder

Severe Shoulder

Value** P value

162.7 ⴞ 6.8 0.82 Maternal weight (kg)

Maternal height (cm)

93.7 ⴞ 22.0 0.002 Weight gain (>15.9 kg)

81 (58.7) 0.0004 Second stage abnormality

61 (39.6) 0.30 Prolonged second stage

23 (14.9) Precipitous second stage

38 (24.6) Operative vaginal delivery

11 (6.5) *Severe shoulder dystocia defined as have met at least one of the following three criteria: 1) head-to-body interval >90 seconds; 2) use of either

deliberate proctoepisiotomy or direct manipulation of the fetus (eg, rotational maneuvers, delivery of the posterior arm); and/or 3) evidence of neonatal depression at birth (5-minute Apgar <7 and/or arterial cord pH <7.1).

**Mean ⴞ SD or N (%).

for the empowerment of both the patient and the obstetrician with shoulder dystocia management techniques that could who will deliver her next child.

reduce necessary traction at any delivery. 34,42,43

The Interval Period:

Preconceptual

Before the Next Pregnancy

Management of Maternal Risk Factors Among women with a history of shoulder dystocia in a pre-

Follow-Up of Infant Status

vious pregnancy, predictors of recurrence seem to vary. Sig- If the infant had sustained an injury at the index shoulder

nificant differences, as well as lack thereof between women dystocia delivery, whether skeletal or neurologic, the im-

with and without recurrent shoulder dystocia, have been portance of follow up of the infant’s condition must be

found for such variables as parity at index delivery (eg, prior

successful delivery without shoulder dystocia), maternal as well as to the delivering clinician. Not only is ongoing

stressed to the patient (to optimize long-term outcome 18 ),

weight or diabetic status, operative delivery, and length of sensitive and caring communication with the family sig-

second stage. 8-10 However, a consistent correlation has been nificant from a risk management perspective, 35,36 the in-

found between subsequent shoulder dystocia and high birth formation is also invaluable to management of the subse-

weight in the subsequent pregnancy, as well as comparative quent pregnancy and delivery. Parental input is extremely

birth weight with the index pregnancy, especially in diabetic important in this process.

pregnancies. 44

For the delivering clinician, knowledge of whether an The most recognized antepartum risk factors for shoulder infant that was discharged from the newborn nursery with

dystocia are also the same risk factors for fetal macrosomia. an as-yet unresolved brachial plexus palsy eventually re-

Aside from a history of shoulder dystocia in a prior preg- covers completely or requires surgical intervention and

nancy, other risk factors include maternal obesity, weight remains with a permanent deficit is critical to retrospective

gain during pregnancy of more than 35 pounds, gestational assessment of the management of the index shoulder dys-

diabetes and pregestational diabetes without vascular com- tocia. Whereas many brachial plexus injuries of a tempo-

plications, and postdatism. 21 As shown in Table 4 , severe rary or even mild permanent nature (eg, restricted to the

compared with mild shoulder dystocia is more likely to be upper plexus with only mild functional deficit in the

associated with obese gravidas weighing more than 200 shoulder’s active range of motion) may have myriad etiol-

pounds or who gain excessive weight during pregnancy. If a

clinician is fortunate enough to have a motivated patient with tocia-associated brachial plexus injuries involving all

ogies (including malpositioning in utero), 37 shoulder dys-

a history of shoulder dystocia who wishes to reduce the risk nerve roots from C5 to C8/T1 and/or avulsion of any nerve

of fetal macrosomia before her next pregnancy, recommen- root from the spinal cord must have involved some degree

dation of weight reduction may be the single intervention of externally applied lateral traction of sufficient magni-

with the greatest impact.

tude and rate to produce an injury of such an extent. 38-41 Screening for occult diabetes is also reasonable. Some Setting aside whether the degree of traction applied was

women with a history of a false-positive glucose challenge within the standard of care, the contribution of externally

test may well be predisposed to macrosomia, suggesting applied traction to the eventual outcome cannot, and

some degree of impaired glucose tolerance not yet manifested should not, be denied. Rather, it behooves the clinician to

as overt diabetes. 45 In most instances, these women likely learn from the experience, and familiarize him/herself

have some degree of a metabolic syndrome or excess adipose

E.D. Gurewitsch, T.L. Johnson, and R.H. Allen

tissue that contributes to hyperinsulinemia, a precursor to cose intolerance, aggressive management of diet and blood overt diabetes. Proper nutrition and exercise are well estab-

glucose is warranted.

lished as effective modifiers of this effect. A commitment to For those women with a history of shoulder dystocia who sustained lifestyle changes may improve future pregnancy

are diagnosed with gestational diabetes in a subsequent preg- outcome, as well as the woman’s long-term health status

nancy, it is especially important to monitor blood glucose overall.

levels at several time points each day. A low threshold for initiating oral hypoglycemic or insulin therapy may be ap- propriate in these gravidas as well, especially if there is evi-

Antenatal Management

dence of accelerated fetal growth while on diet despite report

of the Subsequent Pregnancy

of normal blood glucose levels. 47

Eliciting the History and Assessment of Fetal Growth Assessing Patient-Specific Recurrence Risk

It is well established that the margin for error for ultrasound Just as it is important for the delivering clinician who man-

estimation of fetal weight is too large to be relied on heavily aged a given patient’s shoulder dystocia to carefully docu-

for predicting delivery complications. 48 However, when ment and communicate to the patient the details of the event, so

there has been a previous shoulder dystocia (similar to cases too should any practitioner meeting an obstetric patient for

with gestational diabetes), serial ultrasound measurements of the first time specifically attempt to elicit a history of shoulder

the trajectory of fetal growth are often more informative than dystocia in a prior pregnancy. The major antepartum (listed

a single growth estimation for assessing the need for inter- above) and intrapartum risk factors for shoulder dystocia

vention. Particular attention should be given to evidence of should be assessed. Intrapartum risk factors include opera-

asymmetrical growth using ponderal indices. tive vaginal delivery and abnormal second-stage length, ei-

The most common way to assess for accelerated truncal ther prolonged or precipitous. Even if there is no history of

growth is the head circumference-to-abdominal circumfer- gestational diabetes, the patient should be asked to recall

ence ratio. 49 If below 0.9 near term, the risk for shoulder

dystocia may be increased, even when the overall estimated perhaps had not been screened. If the infant whose delivery

whether she had a false-positive glucose challenge test 45 or

fetal weight has not surpassed the 90th percentile. was complicated by shoulder dystocia had weighed more

For the gestational diabetic apparently well managed on than 4 kg at birth, this is reason enough to perform an early

diet alone, there is some evidence to suggest that empiric glucose screen at registration. A specific discussion of nutri-

initiation of insulin therapy once the abdominal circumfer- tion and monitored weight gain is warranted, especially if the

ence exceeds the 75th percentile may curtail further acceler- ated fetal growth. previous infant was large-for-gestational age. Vigilance for 46 Although not studied prospectively, this

impaired glucose tolerance leading to accelerated fetal may be reasonable in a gestational diabetic with a history of a growth, with dietary modification and flexible medical ther-

previous shoulder dystocia who desires to have a subsequent apy as needed, 46,47 should be a mainstay of antenatal man-

vaginal delivery.

agement throughout the next pregnancy of any such patient, especially one with a history of prior shoulder dystocia.

Planning the Delivery: Mode and Timing

For those women whose early glucose screen is negative, it The practice of inducing labor for “impending macrosomia” is important to rescreen at the appropriate gestational age

has no proven benefit. Such practices increase the rate of (26-28 weeks). For those with a false-positive 1-hour 50-g

cesarean delivery performed for failed induction without im- glucose screen (normal 3-hour glucose tolerance test) early in

pacting the incidence of shoulder dystocia. 50-52 This lack of gestation, repeat “screening” in the early third trimester

evidentiary support for early “elective” inductions and the should be by the diagnostic 3-hour test rather than the

persistent inability to shrink the margin of error in ultra- 1-hour screening test. This is based on the principle that a

sound estimation of fetal weight 14 led the American College false-positive screening test may not be sensitive enough,

of Obstetricians and Gynecologists in 2002 to revise their when repeated in a given patient, to consistently detect the

Practice Bulletin entitled “Shoulder Dystocia,” raising the cut- condition being screened for.

offs for estimated fetal weight above which primary cesarean Patients who have a normal glucose screening test at 26 to

section without trial of labor may be offered, to 4500 g for the

28 weeks who later develop either clinical or sonographic diabetic gravida and to 5000 g for the nondiabetic gravida. evidence of accelerated fetal growth should be considered for

However, these recommendations may not apply for some retesting again at 30 to 34 weeks since there may be delayed

women. There is still some evidence that lower estimated detection of up to 15% of gestational diabetics. For those

fetal weight thresholds for cesarean birth may be appropriate, women with a history of shoulder dystocia who, in the sub-

particularly in women with “preexisting” predilection for sequent pregnancy, manifest one abnormal value on the

shoulder dystocia. 53,54 Although this evidence is not specific 3-hour glucose tolerance test obtained after an abnormal glu-

to the woman with a history of shoulder dystocia, these cose screen at 26 to 28 weeks, retesting should probably

women may benefit the most from lower thresholds. Contin- occur at 30 to 34 weeks, regardless of growth parameters by

ued research is needed to more appropriately individualize that stage. If there is any maternal or fetal suggestion of glu-

intrapartum management for such women.

After shoulder dystocia 193

Regardless of the specific estimated fetal weight cut-off Simulation-based experimentation has also proven the hy- used to offer a primary cesarean section, only a small percent-

pothesis that rotational maneuvers to resolve shoulder dys- age of parturients will ever meet these criteria. What then can

tocia require less applied force than McRoberts’ positioning.

be said about the strategy of elective induction of labor in an Indeed, brachial plexus stretch is also reduced by a factor of attempt to ensure a lower birth weight than would result

three with use of Rubin’s maneuver as an initial approach to from expectant management and, thereby, potentially avoid

shoulder dystocia management. 34 The comparative advan- shoulder dystocia? Whereas ineffective as a strategy when

tage of fetal maneuvers for reducing brachial plexus strain applied to the general population, this may have merit in the

was also predicted computationally. 64 Clinicians are enjoined gravida with a history of prior shoulder dystocia. First, since

not to fear fetal manipulation, but to familiarize themselves she is already parous, her risk of failed induction is signifi-

with the techniques by availing themselves of simulation- cantly lower compared with her nulliparous counterpart.

based training and even to practice routine assessment of fetal Second, postdatism is among the potentially modifiable an-

shoulder position by direct palpation at every delivery. 65 tepartum risk factors for shoulder dystocia that would be

The likelihood of favorable outcome of shoulder dystocia eliminated by elective induction at term. Third, the risk of

is maximized by preparation and coordination of a well-re- recurrence of shoulder dystocia correlates with similar or

hearsed response by all members of the health care team. greater birth weight at subsequent delivery compared with

Such resource utilization and management is best ensured by

systematic rehearsal. 66 Communication and continuous feed- portantly, it is the severe shoulder dystocia, which is more

the index shoulder dystocia delivery. 10 Finally, and most im-

back to team members regarding effectiveness of interven- likely to occur in obese gravida with macrosomic infants, 55 tions or lack thereof is essential to this effort. Otherwise,

cross-purposeful actions of two or more team members can, would most wish to prevent or mitigate. However, these se-

that is most predictive of subsequent injury, 56 and that we

albeit unintentionally, increase the risk for injury. Important vere shoulder dystocias occur in the same type of patient in

components of shoulder dystocia management include a whom complications of cesarean delivery are also more likely

continuous assessment of the success or failure of each ma- to occur. Therefore, a strategy of early induction of labor at

neuver, employing an alternative maneuver within approxi- term, before development of substantial trunk-to-head size

mately 30 seconds of a previous failed maneuver, 67 and main- discrepancy, may present a balanced alternative to elective

taining a calm and unhurried approach by the primary primary cesarean delivery in these women.

clinician. Each of these elements, as well as how and when to communicate with the family during and after a shoulder dystocia, can be rehearsed during drills until they progress

Anticipating

smoothly.

Shoulder Dystocia Recurrence

Simulation-Based Training and Rehearsal

Conclusion

Since the exact threshold for permanent injury in in vivo Considered one of the greatest fears of obstetric providers, shoulder dystocia is not known, the goal in shoulder dystocia

associated with considerable risk for injury to both mother management should be to reduce uterine force and clinician

and fetus and fraught with potential liability for the clinician, traction as much as possible. Maternal pushing and uterine

severe shoulder dystocia is an emergency that no one would forces can only be controlled in a limited way; these also have

care to relive. Thus, after a woman has experienced the com-

plication, managing the risk of its recurrence in a subsequent going research must focus on how clinician-applied traction

limited contribution to injury. 57 Therefore, training and on-

delivery is desirable and prudent. Indeed, unlike other spo- might be reduced. 43 This is especially important for shoulder

radically occurring and unpredictable complications of preg- dystocia management because the very natural, unconscious

nancy, recurrence of shoulder dystocia is not infrequent. Yet response when attempting to deliver the fetus once first at-

shoulder dystocia’s definitive prevention, namely cesarean tempts have failed is to increase traction on subsequent at-

delivery, while expedient and facile is also costly and poten- tempts. 33,43,58 This training can be accomplished through

tially risky, 54,68 especially in the obese and diabetic gravida. simulation-based training and with drills.

Because many women choose to attempt a vaginal birth after Already addressed in other fields of medicine, obstacles to

a shoulder dystocia, it is important to use what information comparative research and provider training within the clinical

there is in the literature to form a rational and reasonable setting are best overcome by use of medical simulation. 59,60 For

management plan for risk modification and for management surgically oriented skills, including vaginal delivery techniques,

of a shoulder dystocia event should it recur. At least some of there is no substitute for mechanical simulation to allow haptic

the risk of shoulder dystocia recurrence indeed may be quan- feedback and biofidelic learning for the student obstetric pro-

tifiable and potentially modifiable during subsequent preg- vider. 61,62 Real-time measurement of actual clinician-applied

nancies of individual women with a history of shoulder forces during simulated shoulder dystocia deliveries—where as-

dystocia. Importantly, avoidance of shoulder dystocia recur- sociated mechanical fetal response can be measured prospec-

rence per se should neither be expected nor used as a mea- tively in a fetal model—may enable clinicians to self-assess more

sure of success in management. As with other medical and accurately the magnitude, direction, and rate of traction they

obstetric conditions at higher risk for morbidity and mortal- apply during delivery. 63 ity, it is the untoward outcomes of shoulder dystocia and not

E.D. Gurewitsch, T.L. Johnson, and R.H. Allen

necessarily shoulder dystocia itself that we wish to prevent.

22. Gross TL, Sokol RJ, Williams T, et al: Shoulder dystocia: a fetal-physi-

Thus, circumstances and conditions that increase the risk of

cian risk. Am J Obstet Gynecol 15:1408-1414, 1987

injury from shoulder dystocia should be targeted, and if there 23. Verspyck E, Goffinet F, Hellot MF, et al: Newborn shoulder width: a

prospective study of 2222 consecutive measurements. Br J Obstet Gy-

69 the shoulder dystocia. necol 106:589-593, 1999 24. Gurewitsch ED, Donithan M, Stallings S, et al: Episiotomy versus fetal

is recurrence, the goal becomes the atraumatic resolution of

manipulation in managing severe shoulder dystocia: a comparison of

Acknowledgments

outcomes. Am J Obstet Gynecol 191:911-916, 2004 25. Bofill JA, Rust OA, Devidas M, et al: Shoulder dystocia and operative

The authors wish to thank Dr. Elliot Fishman of The Johns

vaginal delivery. J Matern Fetal Med 6:220-224, 1997

Hopkins University School of Medicine’s Department of Ra-

26. Johnson T, Allen R, Fishman E, et al: Use of traditional and novel CT

diology for his assistance with interpretation of the CT pel-

pelvimetry distinguish between different types of shoulder dystocia. J