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