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Clinical Reviews


Shoulder dystocia: What is the legal standard of care?

It’s your job to educate the jury that, even in the best of hands, permanent brachial plexus injuries can occur

August 2006 · Vol. 18, No. 8

IN THIS ARTICLE

No matter how excellent the care you provide, you have good reason to worry about shoulder dystocia. It is one of the most difficult and frightening complications, and is essentially unpredictable and unpreventable. It can happen even in apparently routine deliveries, and can cause permanent injury to the child despite the best possible care by experienced obstetricians.

If permanent injury occurs after shoulder dystocia, it can also trigger a lawsuit that can last for years and end in a large jury verdict—even if you handled the case with textbook perfection. Lawsuits involving brachial plexus injuries following shoulder dystocia are now the second most common type of lawsuit in obstetrics, exceeded only by those due to neurologic damage from birth asphyxia.1 Brachial plexus injury is often difficult to defend in court and results in scores of millions of dollars in damages each year. The plaintiff is usually a lovely child with an obvious and permanent injury, and the defense is typically an undocumented claim that the obstetrician applied no undue force at delivery.(Sidebar)

Given the difficulties of knowing when shoulder dystocia will occur, how best to resolve it, and whether a claim is likely, how can we prepare for this event? What is the accepted standard of care? This article answers these questions by surveying the evidence on these aspects of management:

  • risk factors for shoulder dystocia
  • how to choose mode of delivery
  • specific labor-management practices
  • the 4 most widely used maneuvers to resolve shoulder dystocia
  • what information the documentation should include.

No single “standard of care”

In many states, the term “standard of care” has a specific legal meaning, but in most of the United States—and to most physicians— the term means care that would be rendered by the majority of well-trained individuals. Complicating this definition is the fact that medicine often offers no single “right way.” Thus, it may be more appropriate to speak of “standards of care”: the range of therapeutic choices a reasonable practitioner might decide to use.

The traction reaction: Why plaintiffs focus on “force”

Traction is the most used and abused of terms in shoulder dystocia lawsuits. Many plaintiff expert witnesses claim that traction should never be applied to a baby’s head during delivery. Other “experts” claim only “gentle” traction is warranted. These statements are designed to support the most frequent contention against obstetricians when permanent brachial plexus injury occurs: As there is an injury, it must have been caused by a doctor or midwife who used “excessive traction” to deliver the baby. This statement is usually made without defining “excessive” and without evidence that more force than necessary was used.

“Excessive” vs “minimum necessary” traction

Routine or “moderate” traction is used in most deliveries. The birth attendant almost always depresses the fetal head and applies a moderate amount of traction to it to help the baby’s anterior shoulder slide beneath the mother’s pubic bone.38 The only time traction is unnecessary is when the expulsive forces of the mother are so strong or uncontrolled that she pushes the baby out entirely on her own.

There is ambiguity—often contrived—about what exactly constitutes mild, moderate, routine, and “excessive” traction. No study has ever been published that accurately and unambiguously quantifies the amount of force used in actual deliveries.

Once shoulder dystocia is diagnosed, further attempts at routine traction without the use of other maneuvers should be avoided. At best these attempts are unavailing. At worst they serve only to keep the anterior shoulder lodged behind the maternal symphysis.

Much misinformation surrounds the role of traction during the McRoberts maneuver and other efforts to resolve dystocia. The reality is simple: An obstetrician cannot determine whether a maneuver has released the anterior shoulder unless moderate traction is applied after the maneuver to see if the baby can be delivered. Although extreme force at this or any point is not appropriate, moderate traction is entirely appropriate.

“Excessive traction” is an oxymoron, although plaintiff lawyers often use the term. An obstetrician uses a given amount of force in attempting to free a stuck shoulder. Once the shoulder is freed, no more force is applied. Thus, by definition, “excessive force”—more force than is necessary to deliver the baby—is never used. The proper term to describe the amount of force applied by a physician to resolve shoulder dystocia is “minimum necessary traction.”

Injury can follow a traction-free delivery

For many years, obstetricians familiar with shoulder dystocia have claimed that brachial plexus injuries can occur even in the absence of significant traction—either in utero or as a result of the natural forces of labor. Yet plaintiff attorneys and expert witnesses have contended that all brachial plexus injuries are the result of someone pulling “too hard.”

A recent case reported by Allen and Gurewitsch39 settled this question once and for all. They describe a delivery in which a patient requested no intervention of any kind. Despite no hand having touched the baby during delivery—thus, no “excessive traction” having been applied —the baby suffered a brachial plexus injury. This case proved that brachial plexus injuries can occur spontaneously and are not necessarily caused by traction.

Why dystocia cannot be predicted

…despite known risk factors

The risk of shoulder dystocia is higher in women with diabetes,2-5 a macrosomic fetus,2,6-8 obesity,5,8 or a previous shoulder dystocia.9-11 The problem: The predictive value of these factors is so low and their false-positive rate so high they cannot be used reliably in clinical decision-making.11-13

Prevention is impossible

Even if prediction were possible, the only preventive option is elective cesarean section. After all, this is the only intervention that might potentially avoid the infrequent but dreaded outcomes of asphyxia and permanent brachial plexus injury. But as the literature shows, even this is not an absolute guarantee.14,15 Moreover, the strategy of inducing labor several weeks prior to the due date to prevent a baby from becoming “too big” has been shown in many studies to be ineffective in lowering the shoulder dystocia rate.16-18

Risk factors are not clinically useful

The American College of Obstetricians and Gynecologists (ACOG) and Williams Obstetrics concur that risk factors for shoulder dystocia cannot be applied in a clinically useful way to prevent brachial plexus injury. As the ACOG practice bulletin on shoulder dystocia19 observes:

  • “Shoulder dystocia cannot be predicted or prevented because accurate methods for identifying which fetuses will experience this complication do not exist.”
  • “Elective induction of labor or elective cesarean delivery for all women suspected of carrying a fetus with macrosomia is not appropriate.”

Identify highest risk

Nevertheless, there are generally accepted guidelines for attempting to ascertain which patients are at the absolute highest risk for shoulder dystocia:

  • Any woman with gestational diabetes. For any given week of gestation in the third trimester, the ratio of thorax and shoulder size to head volume is larger in babies of diabetic mothers.20 Thus, in these women, it is important to estimate fetal weight near term to determine whether a trial of vaginal delivery makes sense.
  • If, for any reason, the fetus appears to be larger than average. Indications of size may come from palpation of the maternal abdomen, fundal height measurements significantly greater than dates, ultrasound estimation of large fetal weight, or maternal perception. In these cases, ultrasound imaging is advisable near term to estimate fetal weight. This estimate can be factored into the selection of delivery mode.

How big is “too big”?

There are 2 problems with using estimates of fetal weight in determining mothers and babies at highest risk:

  • How is “too big” defined?
  • What action should one take if a baby is thought to be “too big”?

The rate of shoulder dystocia increases with the size of the fetus (TABLE). ACOG defines macrosomia in the context of shoulder dystocia as a fetal weight exceeding 5,000 g in a nondiabetic woman and 4,500 g in a diabetic woman.19

As for what to do if a fetus is estimated to be in this size range, ACOG states: “Planned cesarean delivery to prevent shoulder dystocia may be considered [emphasis added] for suspected fetal macrosomia within the above weight parameters.”19 The decision as to whether to recommend or perform a cesarean section in these circumstances is intentionally left up to the physician and the patient.

The problem, of course, is that all our data are from measurements of babies after delivery—information obstetricians do not have at the time they must decide on the mode of delivery.

TABLE

How fetal weight affects the rate of dystocia

ESTIMATED FETAL WEIGHT

RATE OF SHOULDER DYSTOCIA (%)

 

NONDIABETIC MOTHERS

DIABETIC MOTHERS

<4,000 g

1.1

3.7

4,000–4,499 g

10

23.1

>5,000 g

22.6

50

Source: Acker D et al2

Choosing a mode of delivery: Not so simple

The obstetrician must determine whether the risk of shoulder dystocia is high enough to outweigh the risks to a mother of elective cesarean section. This is far from simple. Although it is true that women at the highest risk for dystocia—those with gestational diabetes and suspected macrosomia— have a risk for shoulder dystocia somewhere between 25% and 50%, this is not the main concern.

The main concern is this: What percentage of even these high-risk patients will have a shoulder dystocia that results in a permanent brachial plexus injury? The answer: Permanent injury is rare, even in highest-risk cases.

Only 10% to 20% of infants born after shoulder dystocia suffer brachial plexus injuries.16,21-23 Of these, only 10% to 15% are permanently injured.5,24,25 Thus, even in women at highest risk, the odds of having an infant with permanent brachial plexus injury are roughly 1 in 450.14 In women at lower risk for shoulder dystocia, the odds of permanent brachial plexus injury are much lower: somewhere between 1 in 2,500 and 1 in 10,000.

When is cesarean section warranted?

In deciding the answer to this question, the obstetrician must consider that cesarean section is not without its own risks: excessive bleeding, infection, injury to bowel or bladder, deep venous thrombosis, and the need for hysterectomy.

These adverse events occur much more frequently than does permanent brachial plexus injury.26 And the risks are higher yet for the very same patients at greatest risk for shoulder dystocia—diabetic and obese women.

Prevent “I didn’t know” accusations

This is the point at which the patient’s input becomes vital. It is important to convey to her in readily understandable terms the risks—to both her and her child—of cesarean section versus attempted vaginal delivery. Plaintiff attorneys often claim that, had their client known there was a 1 in 450 chance of her baby having a permanent injury, she would have opted for cesarean section. The truth of this claim is, of course, open to question. However, from a medicolegal perspective, it is extremely important that the woman be informed of the degree of risk to herself and her baby so that her decision is truly informed—even if it is not the choice the obstetrician would have made.

The consensus in surgery is that the patient should be informed when the threshold of risk for an adverse event reaches 1% or higher. Although it is an informal teaching, this threshold is documented in the medical literature.27

Continued...
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