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OBSTETRICS REPORT

Update on Obstetric Emergencies

Fadi G. Mirza, MD; Patricia C. Devine, MD; Sreedhar Gaddipati, MD

Obstetric emergencies involving hemorrhage are life-threatening. Uterine atony, rupture, and inversion are developments that require immediate intervention.

Although the 20th century witnessed a remarkable decline in maternal mortality in the United States, little progress has been made during the past 2 decades.1 Obstetric hemorrhage, which accounts for approximately 17% of all maternal deaths, represents the second most common cause of pregnancy-related mortality.2 Although obstetric hemorrhage most often occurs in association with abnormal placentation, several other clinical scenarios can result in excessive blood loss. The purpose of this article is to review a number of obstetric emergencies that can lead to life-threatening hemorrhage.

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Uterine Atony

The most common cause of postpartum hemorrhage is uterine atony, which denotes poor tone of the uterine musculature, resulting in continued blood flow from the vasculature supplying the placental bed.3 A number of risk factors have been identified, including multiple gestations, macrosomia, polyhydramnios, fibroids, use of uterine relaxants and oxytocin, prolonged labor, and chorioamnionitis.4,5 With proper use of medical therapy for postpartum atony, surgical therapy can often be avoided. Medications currently available for the treatment of atony include oxytocin, methylergonovine maleate, carboprost tromethamine, and misoprostol.

Several reports have described intrauterine compression with balloon devices to control postpartum hemorrhage. Bakri and colleagues designed an intrauterine balloon that conforms to the contour of the uterine cavity and resembles a Foley catheter.6,7 This device has an opening at its distal end that allows intrauterine contents to drain, a feature that may decrease the likelihood of a concealed hemorrhage within the cavity in case of tamponade failure. The balloon is inflated with 500 cc saline, and the catheter is either secured to the leg or attached to a weight, providing traction and compression of the balloon against the lower uterine segment. Success at arresting hemorrhage has been demonstrated with this approach, although no randomized studies have been performed that compare various balloon devices.

A well-established surgical technique for management of hemorrhage in the setting of uterine atony is the B-Lynch suture.8 The abdomen must be opened and the uterus exteriorized, and a low transverse hysterotomy is created if not already present. The B-lynch suture was initially described using no. 2 chromic catgut, although different sutures have been utilized in later reports. The suture is made by entering the anterior uterine wall 3 cm below the hysterotomy and exiting 3 cm above the incision. The suture is then looped over the fundus and brought in and out of the posterior uterine wall at the level of the uterosacral ligaments. The suture is again brought over the fundus on the opposite side of the uterus, giving the appearance of suspenders. Finally, the suture is passed 3 cm above the hysterotomy and exits 3 cm below. With continued manual compression, the suture is tied.

Interventional radiology procedures to localize and occlude bleeding vessels have been performed since the 1960s. Use of interventional radiology in obstetrics was first published in 1979.9 Gelatin pledgets are commonly used, although some authors have cited better results in high-flow settings with the addition of embolization coils to the pledgets.10 In a review of 67 cases of embolization, one group noted a 97% success rate in controlling hemorrhage, with a 6% to 7% complication rate.11 Another group noted a success rate of 90.7% in the review of nearly 200 cases.12 Complications from embolization can be transient, such as low-grade fever or hematoma formation at the catheter insertion site. However, more rare yet concerning complications include uterine and bladder necrosis, fistula formation, neurologic injury, perforation or occlusion of the external iliac artery, and small bowel injury.12,13 It is noteworthy that embolization may not be possible in patients with profuse, continued hemorrhage.

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Uterine Rupture

Uterine rupture represents one of the most life-threatening emergencies in obstetrics. The clinical presentation can vary, ranging from findings that evolve over time (eg, uterine tenderness, nonreassuring fetal heart rate patterns) to a rapid onset of hypovolemic shock. However, a nonreassuring fetal heart rate pattern is the most common presenting sign in patients who experience uterine rupture during labor. The incidence of uterine rupture varies in the literature, although the figure generally quoted is 0.1%.

Uterine rupture has traditionally been linked to history of prior cesarean deliveries. In a recent population-based cohort study that included 371,000 pregnant women, the absolute risk for uterine rupture in women with a uterine scar was 1 in 1,709, although 13% of cases of uterine rupture occurred in unscarred uteri.14 The risk for uterine rupture in labor is directly related to the number and type of uterine scars. In one study, it had been shown that the risk for uterine rupture during labor was nearly 5 times greater in women with 2 prior cesarean deliveries compared with women who had a history of only 1 prior cesarean delivery.15 The prevalence of uterine rupture is also dependent on the uterine incision type; its prevalence in women with prior classical and T-shaped incisions reaches 4% to 9%, while that reported for low vertical and low transverse incisions is 1% to 7% and 0.2% to 1.5%, respectively.16

ACOG recognizes that a vaginal trial of labor is a safe and reasonable management option for certain patients, although it directs that certain criteria must be in place in order to minimize the risks associated with this clinical option. A vaginal trial of labor following a cesarean delivery is generally limited to patients with 1 previous low-transverse cesarean delivery, a clinically adequate pelvis, and no other uterine scars or history of prior rupture.16 Labor must be managed in a hospital that can provide continuous fetal monitoring throughout active labor. Furthermore, a physician and all other resources necessary for monitoring labor and performing an emergent cesarean delivery must be available.

Additional risk factors have been linked to uterine rupture, including other types of uterine surgery, congenital uterine malformations, agents utilized for induction of labor and termination of pregnancy, and trauma.17 Induction of labor, regardless of method, is associated with an increased risk for rupture when compared with spontaneous labor, with an odds ratio of 2.9 (95% confidence interval [CI], 1.8-4.7).18 The risk for uterine rupture associated with induction of labor reported by Zwart and colleagues was 3.6 (95% CI, 2.7-4.8).14 Of note, in this series, 72% of ruptures occurred during spontaneous labor. The risk for rupture is increased with the use of prostaglandins, such that ACOG discourages their use in the third trimester for induction of labor in a woman with a prior cesarean delivery. Augmentation of labor with oxytocin is also associated with an increased risk for rupture, with an odds ratio of 2.4 (95% CI, 1.5-3.9).18

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Uterine Inversion

The incidence of uterine inversion is variable, with recent reports suggesting a value close to 1 in 2,500.19 Causes remain poorly defined, although overly aggressive management of the third stage of labor, including excessive fundal pressure and cord traction, is commonly described. Additional risk factors include nulliparity, fundal placentation, macrosomic infants, magnesium sulfate, precipitous labor, congenital uterine malformations, and adherent placenta accreta.19-22 The most common presentation of a uterine inversion is postpartum hemorrhage. Physical examination at that time generally reveals a mass in the vagina which represents the fundus.

Management of uterine inversion requires prompt recognition and concurrent actions.23 Uterotonics, if utilized, should be discontinued. The obstetrician should attempt to restore the uterus to its correct position, which can often be accomplished by applying pressure to the fundus with a vaginal hand directed towards the umbilicus (Johnson maneuver). Some authors have advocated using ring forceps on the cervix for countertraction.20,21 Uterine relaxation, achieved by the use of tocolytic therapy or nitroglycerin, can assist in restoration of the uterine fundus.22

If initial attempts at restoring the uterus to its normal position fail, general anesthesia can be used both to maximize uterine relaxation, in an attempt to replace the fundus from a vaginal approach, and to be ready for a potential laparotomy to correct the inversion if the vaginal approach fails. The most commonly described abdominal procedure is the Huntington technique, which involves grasping the round ligaments and sequentially drawing them upward from the depression within the inverted fundus. A variant of this has been described utilizing suction applied to the fundus via a vacuum instrument.19,24 If this is unsuccessful, the Haultain technique may be pursued, which involves incising the cervical ring posteriorly from an abdominal approach, followed by the Huntington technique. Once the inversion has been resolved, exploration of the uterine cavity is warranted to assess for uterine perforation or adherent placenta, while the vaginal cavity should be assessed for lacerations. Furthermore, uterotonic therapy should be optimized once the inversion is corrected. Finally, a recent report explored the novel use of the SOS Bakri balloon in a case of recurrent uterine inversion.25

The authors report no actual or potential conflicts of interest in relation to this article.

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Fadi G. Mirza, MD, is Clinical Fellow; Patricia C. Devine, MD, is Assistant Clinical Professor; and Sreedhar Gaddipati, MD, is Assistant Clinical Professor; all in the Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY.

References

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4. Rouse DJ, Leindecker S, Landon M, et al; National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. The MFMU Cesarean Registry: uterine atony after primary cesarean delivery. Am J Obstet Gynecol. 2005;193(3 Pt 2):1056-1060.
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19. Watson P, Besch N, Bowes WA Jr. Management of acute and subacute puerperal inversion of the uterus. Obstet Gynecol. 1980;55(1):12-16.
20. Kitchin JD 3rd, Thiagarajah S, May HV Jr, Thornton WN Jr. Puerperal inversion of the uterus. Am J Obstet Gynecol. 1975;123(1):51-58.
21. Lipitz S, Frenkel Y. Puerperal inversion of the uterus. Eur J Obstet Gynecol Reprod Biol. 1988;27(3):271-274.
22. Brar HS, Greenspoon JS, Platt LD, Paul RH. Acute puerperal uterine inversion: new approaches to management. J Reprod Med. 1989;34(2):173-177.
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