Complications of Delivery
Larry C. Gilstrap
Edward R. Yeomans
Introduction
Although there are many potential complications associated with delivery of the newborn, postpartum hemorrhage is probably the most common cause of maternal mortality from both vaginal and operative abdominal delivery. Amniotic fluid embolism, on the other hand, is a rare complication of delivery but is associated with significant morbidity and a very high mortality rate when it does occur.
Postpartum Hemorrhage
Hemorrhage is one of the four leading causes of maternal death in women delivering after 20 weeks gestation. Thromboembolism, hypertensive disorders, and infection are the three other major causes of mortality. These latter complications are addressed elsewhere in this text.
The exact incidence of postpartum hemorrhage is unknown because there is no uniformly accepted definition for postpartum hemorrhage. However, it is of paramount importance that clinicians caring for pregnant women be both knowledgeable and skilled in the management of this potentially life-threatening complication.
Definitions
The classic definition of postpartum hemorrhage is a blood loss of 500 mL or more during the first 24 hours after delivery. Considering that the average blood loss following an uncomplicated vaginal delivery is approximately 500 mL, it is obvious that this classical definition is not helpful from a clinical standpoint. First and foremost, it has been well established that the blood volume in a normal, uncomplicated pregnant woman is increased by approximately 1,500 to 1,000 ml of plasma and 500 mL of red blood cells. Second, in a classic study almost half a century ago, it was shown that red blood cells equivalent to 445 mL of blood loss occurred with uncomplicated vaginal delivery, and red cell loss equivalent to over 1,000 mL blood loss occurred with cesarean delivery (over 1,500 mL loss for cesarean hysterectomy) (Table 25.1). Thus, the vast majority of pregnant women losing a liter of blood would not suffer any ill effects and should not be classified (or coded) as postpartum hemorrhage. An exception to the latter is a woman with severe preeclampsia whose blood volume may expand little, if at all. A blood loss of 1,000 mL in this patient may be sufficient to require blood transfusion.
Other definitions of postpartum hemorrhage have included a significant drop in hemoglobin or hematocrit or a specific percentage of blood volume lost. A major problem with utilizing a change in hematocrit in this way is that the level of hematocrit most often depends on the degree of vasoconstriction (as seen in severe preeclampsia) and the volume of fluid administered during labor and delivery, including “preloading” prior to regional anesthesia. Moreover, the major problem with utilizing a percentage of blood volume lost in defining hemorrhage is not knowing with any degree of accuracy what the initial blood volume is in a given woman. At best, it can only be estimated in a given woman from her height and weight. Accurate estimation of blood loss at the time of delivery also is difficult. Finally, ≥10% blood loss, while potentially significant or serious in a nonpregnant woman, is probably of little significance in a normal pregnant woman who has expanded her blood volume by some 40% to 50%.
TABLE 25.1 Blood Loss following Vaginal Delivery, Cesarean Delivery, and Cesarean Delivery Plus Total Hysterectomya | |||||||||||||||
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The authors of this chapter have suggested in previous writings that the “diagnosis of postpartum hemorrhage is based primarily on clinical judgment.” It would seem reasonable to define postpartum hemorrhage or at least significant hemorrhage as that amount of blood loss that produces signs and symptoms of hemodynamic instability or bleeding to a degree that will result in hemodynamic changes if left untreated.
Postpartum hemorrhage also is classified as early or late hemorrhage. The former is hemorrhage that occurs within the first 24 hours following delivery (i.e., “early” hemorrhage), while the latter is defined as hemorrhage occurring after 24 hours and up to 6 weeks postpartum (i.e., “late” hemorrhage). This classification of early versus late is useful when considering the various etiologies of hemorrhage.
Incidence
It should be obvious from the above that in the absence of a universally accepted definition, the incidence of postpartum hemorrhage is difficult to ascertain. In the classic study previously mentioned regarding average blood loss at delivery, it was reported that approximately 5% of women will lose >1,000 mL from vaginal delivery. Importantly, 5% is similar to the incidence of postpartum hemorrhage reported by others.
Etiology
Postpartum hemorrhage is caused by uterine atony, genital tract lacerations, retained products of conception, or defective coagulation. In any given case, more than one cause may be found. Uterine atony is by far the most common cause of bleeding postpartum. Once the placenta is delivered, cessation of bleeding is dependent on adequate myometrial contractility to constrict blood vessels supplying the implantation site. A flaccid, atonic uterus cannot achieve the necessary vasoconstriction. With uterine blood flow of approximately 600 mL per minute, life-threatening hemorrhage can occur rapidly. In many but not all cases, uterine atony is predictable based on certain risk factors, which are summarized in Table 25.2. Occasionally, especially when the placenta is implanted in the lower uterine segment, there may be brisk bleeding despite a well-contracted fundus. This will be discussed in the section on Medical Management.
TABLE 25.2 Common Causes of Uterine Atony | |
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The second most common cause of postpartum hemorrhage is genital tract laceration, which can occur anywhere from the fundus to the introitus and should be strongly suspected when bright red bleeding occurs despite a firm, well-contracted uterus. Manual exploration of the uterine cavity along with careful examination of the cervix, vagina, and introitus should allow the clinician to identify the source of bleeding and take corrective action. An appreciable amount of bleeding can occur from the site of an episiotomy, particularly if it was performed early in the delivery process.
Retained products of conception, placental fragments, accessory lobes, or membranes may cause ongoing bleeding. Inspection of the delivered placenta and membranes may increase suspicion that tissue remains in the uterus. Routine manual exploration of the uterus is not indicated, however, and this procedure should be performed only if the bleeding is excessive.
Finally, coagulopathy can occur de novo or may aggravate one of the previously mentioned causes. Placental abruption with a dead fetus is the most common cause of coagulapathy in obstetrics. Other causes are listed in Table 25.3. Dilutional coagulopathy may result when excessive
blood loss is replaced by a combination of crystalloid and packed red blood cells, without clotting factors or platelets.
blood loss is replaced by a combination of crystalloid and packed red blood cells, without clotting factors or platelets.
TABLE 25.3 Conditions Associated with Coagulopathy during Pregnancy | ||
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TABLE 25.4 General Principles in the Management of Postpartum Hemorrhage | |
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Medical Management
Medical management pertains primarily to the treatment of uterine atony and/or associated coagulopathy (Table 25.4). Many clinicians utilize a prophylactic infusion of oxytocin consisting of 10 to 20 U of oxytocin in 1,000 mL of Ringer’s lactate or saline administered at 10 to 20 mL per minute to prevent uterine atony. Others prefer a 5 to 10 U intravenous bolus of oxytocin either in lieu of or in combination with a dilute oxytocin infusion. In an earlier study, it was reported that an intravenous bolus of 10 U was associated with a marked, transient fall in blood pressure; a decrease in systemic vascular resistance; and an increase in heart rate. In a more recent randomized controlled study, bolus oxytocin was reported to be efficacious and was not associated with adverse hemodynamic effects. However, the present authors prefer to utilize dilute oxytocin as opposed to a bolus regimen because of the unknown effects in the rare patient with undiagnosed heart disease or in the patient who presents with significant blood loss or in hemorrhagic shock. Moreover, the dilute regimen has been shown to be efficacious for prevention of uterine atony.
Another drug that may prove useful for the treatment of postpartum hemorrhage secondary to uterine atony is the ergot derivative methylergonovine. The usual dose is 0.2 mg given intramuscularly. This agent should not be utilized in women who are hypertensive or who have preeclampsia, as it might cause dangerous levels of hypertension. Moreover, this drug should not be administered intravenously for the same reasons.
Prostaglandin derivatives are probably the most commonly used agents following an ineffective response to oxytocin. A popular prostaglandin derivative for postpartum hemorrhage is carboprost tromethamine (Hemabate), which is 15-methyl prostaglandin F2α. This drug has been approved by the Food and Drug Administration (FDA) for the treatment of uterine atony, and the recommended dose is 0.25 mg (250 mcg) given intramuscularly. This can be repeated at 15- to 90-minute intervals for a maximum of eight doses. This medication should be avoided in asthmatic women, and commonly reported side effects include nausea and vomiting, diarrhea, fever, tachycardia, and hypertension. A serious side effect of acute arterial oxygen desaturation has been reported with this medication. This side effect obviously could have detrimental effects on pregnant women with significant cardiovascular or pulmonary disease.
Other prostaglandins have also been utilized for postpartum hemorrhage from uterine atony. For example, prostaglandin E2 or dinoprostone (Prostin E2) and the prostaglandin E1 analog misoprostol (Cytotec) have been reported to be effective. Dinoprostone has been utilized as either a vaginal or rectal suppository in 20 mg doses every 2 hours. Misoprostol has been used rectally in a dose of 800 to 1,000 μg.
Recently, recombinant factor VIIa has been reported to be effective in controlling refractory, life-threatening hemorrhage. Although there are no large series, factor VIIa appeared to be both efficacious and safe in individual case reports. In one review of 17 cases, 12 of the women had hysterectomies. Therapy with this factor is expensive, and the optimal dosing regimen is unclear. Moreover, one potential life-threatening adverse event that has been reported with this therapy is thromboembolism. Given the current level of available information, it would seem prudent to reserve therapy with recombinant factor VIIa to women with severe hemorrhage in whom other more commonly used protocols have failed.
Attention to blood volume replacement should begin with crystalloid followed by packed red blood cells as needed to maintain a urine output of 25 to 30 mL or more per hour and the hematocrit at or near 30%. This strategy has been referred to as the “30–30 rule” and is of proven effectiveness to prevent or treat hemodynamic instability. Transfusion of other clotting factors such as fibrinogen (fresh frozen plasma) or platelets should be considered in the woman with active bleeding and a coagulopathy. However, in the absence of a coagulopathy, there is little evidence to support the prophylactic use of fresh frozen plasma in women requiring multiple transfusions or packed erythrocytes.
Uterine Packing
Uterine packing has been advocated by some clinicians prior to resorting to hysterectomy for severe, refractory bleeding. The major concerns regarding uterine packing have centered around the potential for concealed hemorrhage and for infection. Most of the recent reports regarding the successful treatment of postpartum hemorrhage are 30 to 50 years or more old. However, in a report of nine women in 1993, the successful control of hemorrhage was accomplished by utilizing a special packing instrument called a Torpin packer. This instrument used a plunger
device to tightly place 4-inch-wide gauze into the uterine cavity. It is the authors’ opinion that packing should be used primarily as a temporizing method to allow time for adequate blood volume replacement prior to laparotomy. If packing is utilized as a “last resort” prior to surgical intervention, the patient must be closely monitored to detect continued bleeding or significant concealed hemorrhage. Consideration also should be given to the use of prophylactic antibiotics while the uterine pack is in place.
device to tightly place 4-inch-wide gauze into the uterine cavity. It is the authors’ opinion that packing should be used primarily as a temporizing method to allow time for adequate blood volume replacement prior to laparotomy. If packing is utilized as a “last resort” prior to surgical intervention, the patient must be closely monitored to detect continued bleeding or significant concealed hemorrhage. Consideration also should be given to the use of prophylactic antibiotics while the uterine pack is in place.
Closely related to uterine packing but perhaps more effective is the use of one of a variety of intrauterine balloon devices. The assumption is that a balloon would exert more uniform pressure than gauze on the walls of the uterine cavity and serve to diminish hemorrhage in that manner. The Sengstaken-Blakemore tube, used for esophageal varices, has been reported to be effective, but more promising is the Bakri balloon, which has a capacity of 500 mL and a separate port to facilitate evaluation of ongoing bleeding. A Rusch urological balloon, with up to a 500 mL capacity, also has been used. The accumulated experience with these different devices is minimal, and the same caveats offered previously for gauze packing apply.
Surgical Management
There are several surgical techniques that can be utilized for the treatment of postpartum hemorrhage (Table 25.5). Some of these techniques require both anatomical knowledge and surgical skill. If a clinician lacks this knowledge and experience, he or she should seek the help of a surgeon with these skills such as a gynecologic oncologist or vascular specialist. Many clinicians and their patients would be better served if a hysterectomy was performed in lieu of attempting hypogastric artery ligation without experienced help.
Most clinicians, however, can easily perform one of several techniques of uterine compression sutures. Uterine artery ligation, although not so successful for severe hemorrhage, also can generally be performed safely by trained obstetrician–gynecologists.
Uterine Compression Sutures
Several different types of uterine compression sutures have been described in the literature. Although the authors are unaware of any randomized controlled trial comparing one technique with another, each of these techniques is relatively easy to perform and is associated with few serious side effects. As well, all would appear to offer a relatively safe alternative to either hysterectomy or hypogastric artery ligation. In addition, future fertility may be preserved with the use of compression sutures.
TABLE 25.5 Surgical Techniques for the Management of Postpartum Hemorrhage | |
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