Stats: September 13, 2006 OB Case: Shapiro – Arcuate Uterus/C-section Questioner: B. Trivax 1. Define “arcuate uterus”. Mullerian duct anomalies are categorized into 7 classes according to the American Fertility Society (AFS) Classification Scheme (1988). Class VI relates to the arcuate uterus. It is defined as having a single uterine cavity with a convex or flat uterine fundus and an endometrial cavity demonstrating a small fundal cleft or impression between 1-1.5cm. The outer contour of the uterus is convex or flat. The arcuate uterus is usually considered a normal variant since it is not significantly associated with the increased risks of pregnancy loss and other complications found in other subtypes. 2. What are the important differences between an arcuate uterus and a septate uterus? A septate uterus (Class V) results from failure of resorption of the septum between the two uterine horns. In other words, it arises from a defect in canalization or resorption of the midline septum between the two mullerian ducts. The degree of septation varies from a small midline septum to total failure in resorption resulting in a septate uterus with a longitudinal vaginal septum. Partial and complete uterine septa are defined by the proximity of the septum to the internal os. It is important to note that the presence or absence of a vaginal septum is not relevant to the classification. The uterine fundus is typically convex but can be flat or slightly concave with a <1 cm fundal cleft. Women with septate uterus have the highest incidence of reproductive complications. Differentiation between a septate and a bicornuate uterus is important because septate uteri are treated using transvaginal hysteroscopic resection of the septum, while if surgery is indicated for the bicornuate uterus (Class IV), an abdominal approach is required to perform metroplasty. 3. There are three types of breech presentation. Define each one and include its percentage of presentation at term. Do you believe the arcuate uterus led to the breech presentation of this baby? a. Frank breech (50-70%) refers to a fetus with both hips flexed and both knees extended so its feet are near its head b. Complete breech (5-10%) refers to a fetus with both hips and both knees flexed. The feet are opposite the fetal trunk rather than the head, but do not present in advance of the buttocks. c. Footling or incomplete breech (10-40%) refers to a fetus with one or both hips or one or both knees not flexed. As a result, one or both feet present before the buttocks. Fetal malpresentation is often associated with abnormalities of the uterus, this includes altered intrauterine contour or volume as seen in bicornuate or septate uterus---not an arcuate uterus. 4. Was external cephalic version offered to this patient prior to her presentation to Labor and Delivery? If not, Why? What are the exclusion criteria for external cephalic version? Review the procedure protocol for a version. It is known that the incidence of PROM and preterm labor is increased in breech presentations. Due to this, it is important for obstetricians to diagnose the breech presentation as close to 37 weeks of gestation as possible, and ideally by the 36th week. This early diagnosis allows time for scheduling the external version and ultrasound examination. Otherwise, the window of opportunity to perform external version may be lost. Thus, careful Leopold’s maneuvers, followed by ultrasonography must be performed during third-trimester prenatal visits in order for early diagnosis. Exclusion criteria for external cephalic version include: a. Multiple pregnancy b. Evidence of uteroplacental insufficiency c. Significant third-trimester bleeding d. Suspected intrauterine growth restriction e. Amniotic fluid abnormalities f. Uterine malformation g. Placenta previa h. Maternal cardiac disease i. Pregnancy-induced hypertension j. Nonreassuring fetal monitoring pattern k. Major fetal anomaly Procedure protocol for external cephalic version: a. Ultrasound exam should be performed to confirm breech position, determine amniotic fluid index, note placental location, and to rule out congenital anomalies. b. NST is performed to confirm absence of fetal heart rate abnormalities c. Blood is drawn for CBC and blood type and screen in the event that an urgent cesarean section is necessary d. Intravenous access should be established e. Tocolytic agent such as terbutaline can be administered. This is optional as its effectiveness in improving the success rate is equivocal. Under no circumstances should oral, parenteral, or general anesthesia be used because of the increased risk of complications. f. After the procedure (regardless of success or failure), a nonstress test and ultrasound examination should be performed to exclude fetal bradycardia and to confirm successful version g. Rhogam should be administered after the procedure to all Rh- patients because of a 4.1 percent risk of fetomaternal hemorrhage in these patients. References 1. American Fertility Society (1988) The American Fertility Society classifications of adnexal adhesions, distal tubal occlusions secondary to tubal ligation, tubal pregnancies, Mullerian anomalies and intrauterine adhesions. Fertil Steril., 49: 944-955. 2. Golan A, Langer R, Bukovsky I, Caspi E. (1989) Congenital anomalies of the Mullerian system. Fertil Steril., 51: 747-755. 3. Jacobsen IJ, DeCherney A. (1997) Shall We operate on Mullerian defects? Results of conventional and hysteroscopic surgery. Human Reprod., 12: 1376- 1380. 4. Iverson R, DeCherney A, Laufer M. (2006) Clinical manifestations and diagnosis of congenital anomalies of the uterus. UpToDate 2006. 5. Cruikshank DP. (1986) Breech presentation. Clin Obstet Gynecol., 29: 255-63. 6. Zhang J, Bowes WA Jr, Fortney JA. (1993) Efficacy of external cephalic version: a review. Obstet Gynecol., 82: 306-12. 7. Sanling E, Muller-Holve W. (1975) External cephalic version under tocolysis. J Perinat Med., 3(2): 115-22. 8. American College of Obstetricians and Gynecologists: ACOG practice patterns. External cephalic version. Int J Gynaecol Obstet., 2000 Feb; No. 413. 9. Flamm BL, Fried MW, Lonky NM, Giles WS. (1991) External cephalic version after previous cesarean section. Am J Obstet Gynecol., 165(2): 370-2.