Let’s talk a little bit about Trauma and Surgery in Pregnancy.

Accidental injury is more likely during pregnancy than at other times for a number of reasons, but two are quite significant.

Under the influence of the hormone relaxin, all of the connective tissue, joints and ligaments become soft and stretchy. This is good if you are a pelvis trying to accommodate the passage of a fetal head, but not so good if you are a joint trying to remain stable when externally stressed. Bad knees, shoulders or elbows tend to get worse during the course of pregnancy. Athletes need to be particularly careful not to overly stress their joints during their pregnancies, because the joints are significantly more vulnerable to injury than in the non-pregnant state.

Second, maternal balance is disturbed, making slips and falls more likely during pregnancy. For someone as far pregnant as this woman, it is not difficult to understand the role of shifting center of gravity as being partially responsible. But the change in maternal balance actually starts in the first trimester, long before there is any measurable shift in the maternal center of gravity. This likely is a hormonal effect on the maternal inner ear. The clinical consequences of this change are that it becomes unwise for the pregnant woman to engage in physical activities during pregnancy in which her personal well-being is dependent on her sense of balance. Downhill skiing, for example, becomes dangerous, even for the experienced skier. In contrast, swimming requires little from the balance centers, and is not particularly dangerous while the woman is pregnant.

The effect of blunt trauma on the developing pregnancy depends to a large extent on when during the pregnancy the trauma occurs. During the first trimester, the uterus is protected within the pelvic bones, and blunt trauma at this time will either be so severe as to cause a miscarriage, or it will have no effect at all.

Catastrophic trauma would include such events as maternal death, hemorrhagic shock, with multiple compound fractures and liver or spleen ruptures. This is the type of trauma that may result in the woman being in the Intensive Care Unit for days or weeks before finally starting her recovery. This type of catastrophic trauma is associated with first trimester pregnancy loss, and there is little if anything you can do to modify the course of this. Consequently, it is important to do whatever you need to do to save the mother’s live and preserve her normal function.

Non-catastrophic trauma, in contrast, includes all the minor bumps, bruises, fractures of small bones, and minor burns, which are not associated with pregnancy loss. In these cases, there is no increased risk of pregnancy loss during the first trimester.

During the first trimester, if necessary to evaluate or treat trauma, x-rays are OK, as well as surgery, narcotics, anesthesia, and many if not most antibiotics.

It is better to avoid x-rays if they are not needed, but that is always true and not limited to just pregnancy. While high doses of radiation (nuclear bomb type radiation) are unquestionably dangerous for the fetus, the consensus, based on many studies, is that diagnostic levels of x-rays have no measurable adverse effect on the developing fetus. If needed, they should not be withheld, although appropriate shielding of the maternal pelvis can provide some additional reassurance and is a good idea.

If surgery is needed during the first trimester to treat trauma, it can be safely undertaken. Similarly, local, regional, and general anesthesia is considered safe, although the use of epinephrine in local anesthetics is discouraged because of its mostly unpredictable effects on uterine blood flow.

Long-term narcotic usage poses some threat to fetal addiction, but that is the only fetal concern with these medications, and you would need a pretty long exposure to narcotics to achieve that addiction. For the typical short-term use of narcotics to provide pain relief from acute injuries, I’m not worried about fetal addiction and narcotics should not be withheld.

Most antibiotics can be safely used during pregnancy, including the penicillins, cephalosporins, macrolides, and during the first and second trimesters, sulfonamides. Although previously thought to be dangerous from a bone-formation point of view, several of the flouroquinolones are now considered safe to use during pregnancy, including the two most useful, Cipro and Levaquin, based on human registry studies.

Some antibiotics are considered contraindicated during pregnancy. For example, tetracyclines are known to stain the decidual teeth, and are not recommended for use during pregnancy. But in the event a fetus were inadvertently exposed to tetracycline during the first few weeks of pregnancy, before the woman realized she was pregnant, we would expect no consequences, because at that stage of pregnancy, there are no fetal teeth to stain.

So the management of blunt trauma during the first trimester involves caring for the injury, ultrasound scanning to demonstrate the ongoing viability of the fetus, a check for vaginal bleeding to rule out the presence of a pre-existing inevitable abortion which may coincidentally become clinically evident around the time of the trauma, and reassurance to the mother that non-catastrophic trauma during the first trimester is not associated with any adverse pregnancy outcome.

During the second and third trimester of pregnancy, the significance of blunt trauma is exactly the opposite. Even minor trauma at this time can have significant adverse effects, primarily placental abruption.

Preterm labor is occasionally seen following blunt trauma, but in the absence of placental abruption, the risk of preterm labor resulting in delivery is no greater than the background incidence of preterm labor. So our concern in looking for preterm labor is its’ association with placental abruption.

Premature rupture of membranes, uterine rupture and direct fetal injury are all possibilities following blunt trauma, but they are rare, and their occurrence is immediately with the trauma.

The reason for the placental abruptions can be explained through this example of a rear-end collision. The belted pregnant driver is waiting at a stop sign when her vehicle is struck from the rear. Her seat is propelled forward. The egg-shaped uterus at rest is suddenly accelerated forward by the seat. But because the uterus and its contents are mostly water, there is a distortion of its’ shape, rapidly flattening and then rebounding back into its’ egg shape once it is up to speed.

Eventually, something will stop the woman’s forward motion…her seat belt, and air bag, or the steering wheel. When this happens, the changes in uterine shape occur again, for the same reason. Rapid deceleration of the uterus causes a distortion in the egg shape, flattening it before it rebounds again back to its’ normal shape.
These two rapid distortions in shape apply shearing force to the fragile placental connections to the uterus, making a placental separation relatively easy. Even with small abruptions, the subsequent release of cytokines and local inflammatory response may aggravate and enlarge the placental abruption. With trauma, the abruption or placental separation occurs immediately, but the symptoms of the abruption may become evident only after the abruption has had a chance to grow.

When we evaluate these patients in the emergency room, uterine contractions are common, and are seen in more than half the patients in some studies. Preterm labor, however, is seen in only 5 to 15% of patients, and other than the background incidence, is only seen among women with at least some placental abruption. Actual preterm delivery occurs in 1 to 2.5%, again only in association with placental abruption. If preterm labor is to occur, clinical evidence of it would be expected within 4 hours of the traumatic event.
Among the valuable of the diagnostic tools following abdominal trauma in the second or third trimester is electronic fetal monitoring. While the presence of uterine contractions is more or less expected, an abnormal fetal heart rate tracing is not.
In this example, uterine contractions are occurring every two to three minutes and they are accompanied by late decelerations of the fetal heart. If this persists, despite position change, hydration and oxygenation, it would be strong evidence of uteroplacental insufficiency, such as is seen with some placental abruptions, strong enough to lead to prompt delivery.

Although the abruptions occur immediately with the trauma, we expect to see clinical evidence of them within 3 days of the event, and usually the evidence is seen within the first few hours of the event.

If preterm labor is to result from the incident, I would expect labor to begin within 4 hours of the incident. The other rare adverse events, including premature rupture of the membranes, uterine rupture and direct fetal injury occur immediately with the trauma.
So our management of these patients includes an ultrasound scan and electronic fetal monitoring. These look for evidence of fetal well-being, normal amniotic fluid volume, and absence of sonographic evidence of abruption. Of course, with small abruptions, there usually is no sonographic evidence of them, although with large abruptions there may be.

With traumatized patients, it is important to examine the abdomen and pelvis, looking both for maternal injuries, as well as clinical evidence of abruption or uterine laceration. Laboratory studies may be helpful, with fibrinogen going down and fibrin split products going up in the presence of a significant abruption. Serial hemoglobin measurements can be helpful if there is lingering concern about a subacute abruption. If the patient is Rh negative, Rh immune globulin can prevent Rh sensitization among those who have sustained an abruption.

Most patients will require a period of observation to determine whether they will or will not have any pregnancy-related problems following the trauma. The duration of observation is best individualized, but observation periods ranging from 4 hours to 24 hours are common, depending on the circumstances.

Now a few words about normal hematologic changes during pregnancy.

Maternal blood volume normally increases about 40% during pregnancy, and is accompanied by a 40% increase in maternal cardiac output. However, the red cell mass increases only 33%, so there is a measurable drop in both hemoglobin and hematocrit over the course of pregnancy. This is sometimes called a physiologic anemia or dilutional anemia of pregnancy. That’s an important consideration, though, because if you are looking at a traumatized pregnant patient with a hemoglobin of 11, that could easily be normal for her during this pregnancy.

Another important physiologic issue is that there is basically no autoregulation of uterine blood flow. Any drop in maternal cardiac output will result in a drop in uterine blood flow. Whether that’s a problem or not depends on how much of a drop, how long it lasts, and what the fetal reserve status is. For the average patient, a drop of 5% of her cardiac output won’t be enough to have any measurable effect on the fetus. But a drop of 80% probably will result in the fetal metabolic needs not being met.

Two large vessels course through the maternal abdomen, wedged between the spine posteriorly and the uterus anteriorly. These are the aorta and inferior vena cava. The aorta is a high pressure system that is difficult to effectively compress. The vena cava is a low pressure system that is relatively easy to compress.

Whenever a pregnant woman lies flat on her back after the 20th week of pregnancy, the heavy uterus presses down on both the aorta and vena cava. But the aorta resists compression, while the vena cave gets compressed. As a result, blood continues to be pumped through the aorta to the maternal legs, but it can’t easily return to the heart because of vena caval compression. Over time, more and more blood becomes sequestered in the legs and the mother becomes functionally hypovolemic. She will become restless, hypotensive, tachycardic, and if not restricted, will move to find a more comfortable position, usually moving to her side. This movement relieves the caval compression and her functional circulation is restored.

Traumatized patients may not be able to freely move, and the normal position for transporting them, flat on their back, predisposes toward caval compression. So in general, it is better to transport them turned 90 degrees onto their side, with a pillow between their knees. In this position, they can be on either side, since the vena cava will not be compressed either way over on their right or their left side.

Some traumatized patients can’t be safely transported on their sides. For them, even though they remain orthogonal to the litter, it will still be helpful if the entire litter is tilted at least 20 degrees toward the maternal left. This will shift the weight of the uterus off the vulnerable vena cave and onto the high pressure aorta, which can tolerate the uterine weight without reduction in flow. In other cases, manually lifting the uterus off the vena cava and displacing to the maternal left will be sufficient to maintain good flow.
There are some differences in how pregnant women deal with hypovolemic shock.

Normal women generally show progressive changes in pulse, blood pressure, respiratory rate, urinary output and mental status with progressive blood loss. Pregnant women, in contrast, tend to remain relatively stable, with only minimal changes in their vital signs until they lose about 30% of their blood volume, at which point, their vital signs deteriorate rapidly. For the average woman, 30% blood loss would be equivalent to three 500 ml or pint bottles.

Other factors that may contribute to this dampening of the normal vital sign response are what I call shock mediators, including IV fluids and early release of RBCs. For pregnant women who are already in the hospital and receiving IV fluids, the acute loss of blood is dampened by the effects of the crystalloid, which tends to support the vascular volume, up to a point. Also, in the presence of acute blood loss, the maternal hematopoetic system can release immature but still functional red blood cells to help support the oxygen carrying capacity…up to a point. While these two factors are occurring, once vascular collapse occurs, the immature red cells have already been released, and the woman has already received IV fluids, so it may be more difficult to bring the vascular tree back to normal.

So hemorrhagic shock is more difficult to predict during pregnancy, and more difficult to reverse during pregnancy. Accurate visual assessment of blood loss is difficult, but aggressive use of weighing of sponges and blood transfusion can be very helpful.
During pregnancy, the diaphragm rises in the chest, and widens, to accommodate the intra-abdominal bulk, which is displaced upward by the enlarging uterus. This change has some clinical consequences.
In the event of a penetrating wound of the chest of a pregnant woman, the wound tract is more likely to involve and intra-abdominal injury because of the high and wide diaphragm.
In the event of a penetrating wound of the abdomen, the wound tract is less likely to involve maternal intra-abdominal contents, other than the uterus, because the uterus displaces these structures laterally and superiorly.

The incidence of various surgical conditions is influenced by the presence or absence of pregnancy. Conditions that are somewhat more likely during pregnancy include cholecystitis, ovarian torsion, fibroid infarctioin, ruptured corpus luteum cyst, pancreatitis, and bowel obstruction. Conditions that are somewhat less likely to occur during pregnancy are diverticulitis, peptic ulcer disease and salpingitis. That said, I don’t personally find those observations to be clinically useful, because, for example, diverticulitis while less likely, can still occur during pregnancy.

30% of pregnant women will experience some minor trauma during their pregnancy, and about 3% will need surgery for some gynecologic issue. About 1% will undergo surgery for some non-gynecologic issue such as appendicitis or major trauma.
In terms of risk to the pregnancy, it is better to avoid purely elective surgery during pregnancy. If surgery is needed during pregnancy, but you have some influence over when the surgery is to occur, the second trimester is the safest for the fetus. It is past the development stage and the risk of preterm labor is small.
During surgery, it’s a good idea to monitor the fetus and avoid drops in maternal cardiac output, particularly long drops in cardiac output. It is also desirable to avoid any unnecessary manipulation of the uterus.

During the course of pregnancy, the location of the appendix changes. By the 22nd week of pregnancy, the appendix is usually about even with the umbilicus and to the right. By 30 weeks of pregnancy, the appendix in the right upper quadrant, close to the costal margin. By 36 weeks, the appendix has move laterally. The consequence of this movement is to make the diagnosis of appendicitis more difficult to suspect and to confirm.
Right lower quadrant tenderness is seen in only 14% of pregnant appendicitis patients in the third trimester. Because there is a normal mild leukocytosis seen in normal pregnancy, mild elevations in white blood cell count are not helpful in identifying potential appendicitis patients. Because of the thermogenic properties of progesterone, pregnant women often normally have a mild elevation in temperature, so this finding is not helpful. Back pain and flank pain are much more common with appendicitis, which can be misleading to those accustomed to seeing appendicitis pain at or near MacBurney’s point. As a result, 70% of the appendicitis cases identified in the third trimester will show evidence of perforation by the time the appendix is removed.

In the case of suspected appendicitis, some physicians opt for immediate CT scan of the abdomen, since it will quickly establish who has and who doesn’t have appendicitis. It will also detect other important clinical abnormalities that may be provoking clinical symptoms suggestive of appendicitis. Others will first try an abdominal ultrasound scan. While the ultrasound is not as sensitive or specific as the CT scan for appendicitis, it may be sensitive enough to make the diagnosis in an individual patient, sparing her the exposure to the diagnostic radiation of the CT scan, for which there can be no shielding of the fetus. However, if the ultrasound scan is negative or equivocal, then CT scanning remains the preferred method for diagnosing this clinical problem.