Clinical Review

2014 Update on minimally invasive gynecology

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The cesarean scar defect: A common etiology of abnormal uterine bleeding

CESAREAN SCAR DEFECT DIAGNOSED WITH HYSTEROSCOPY

VIDEO 1. Digital flexible hysteroscopy

VIDEO 2. Fiberoptic flexible hysteroscopy

Videos courtesy of Amy Garcia, MD


 

References

CASE: POSTMENSTRUAL BLEEDING, HISTORY OF CESAREAN DELIVERIES
A 36-year-old woman (G3P3) reports prolonged and postmenstrual bleeding. Her cycles are regular, every 28 to 30 days, and are associated with ovulatory symptoms. She bleeds for 8 to 10 days with each cycle, having heavy bleeding on cycle day 2 requiring use of super tampons every 3 hours. Beginning on day 5 of the cycle, the blood becomes much darker and scant requiring a small pad, which she changes twice daily. Often, she experiences dark bleeding with physical activity—specifically, running—usually several days after her cycle has ended. She is otherwise healthy and uses no medications. She uses condoms for contraception. She has had a prior vaginal delivery followed by two cesarean sections. Physical examination is normal.

What is causing this patient’s abnormal bleeding pattern?
From 1996 to 2009, the total US cesarean delivery rate increased steadily from 20.7% to 32.9% and has remained stable at 32.8% through 2012.1 With 3,952,841 registered births in 2012, the number of operative procedures performed annually approximates 1.3 million.2 This means, potentially, that one-third of pregnant American women will undergo cesarean delivery annually, translating into an increasing prevalence of long-term sequelae of this surgery.

An increasingly recognized etiology of AUB
One long-term complication of cesarean delivery, not often discussed, is the presence of a defect within the uterine scar that is directly associated with a type of abnormal uterine bleeding (AUB) referred to as postmenstrual bleeding. Stewart first reported this post–cesarean delivery phenomenon in 1975.3 It is postulated that the cesarean scar defect (CSD)4 forms a pocket, which holds the menstrual effluent, allowing bleeding to occur after regular menstrual cycle bleeding has concluded. Often, remnant menstrual blood is extruded slowly over several days, and is generally dark brown, indicating old blood. Physical activity sometimes can initiate expulsion of the old blood even after the regular cycle has ceased (FIGURE 1).

As early as 1995, Morris reported the histopathologic changes within the cesarean scar in a series of 51 hysterectomy specimens with scar present for 2 to 15 years. His findings included distortion and widening of the lower uterine segment (75%), congested endometrium above the scar recess (61%), marked lymphocytic infiltration (65%), capillary dilation (65%), residual suture material with foreign body giant cell reaction (92%), fragmentation and breakdown of the endometrium of the scar (37%), and iatrogenic adenomyosis confined to the scar (28%). Morris concluded that in addition to AUB, these scar abnormalities could give rise to clinical symptoms such as pelvic pain, dyspareunia, and dysmenorrhea.5 It also has been suggested that otherwise unexplained infertility is associated with anatomic and physiologic changes seen with CSD.6 A recent review article published by Tower summarized additional clinical outcomes of CSD, such as ectopic pregnancy and increased surgical risks for such gynecologic procedures as uterine evacuation in the nonpregnant or postpartum state, hysterectomy, endometrial ablation, and intrauterine device placement.4

The CSD generally is described as a triangular or circular sonographically anechoic area in the myometrium of the anterior lower uterine segment or cervix at the site of a previous cesarean section. In nonpregnant patients, the defect is best evaluated with contrast infusion sonography (CIS), such as saline infusion or gel infusion, versus transvaginal ultrasound (TVUS) alone (FIGURE 2).4,7,8 However, the precise dimensions and definition of the scar defect vary among investigators.4,6,7,8,10

The reported prevalence of CSD has varied in the literature and appears to depend on the modality of diagnosis and the population studied. For instance, van der Voet and colleagues reported that in random populations of women who had undergone cesarean delivery, the defect was evident in 24% to 69% of women evaluated with transvaginal noncontrast ultrasound; the defect was evident in 56% to 78% of women evaluated with transvaginal contrast sonography.8

The scar defect also has been identified with magnetic resonance imaging (MRI) and found to be equal in sensitivity to TVUS.9,10 When identified hysteroscopically, a definitive out-pouching is visualized in the lower uterine segment, where the defect has been termed an “isthmocele.”6 Hysteroscopically, the defect also is visualized commonly within the cervical canal, indicating that cesarean incisions often are made through cervical tissue at the time of delivery (FIGURE 3, VIDEO 1, VIDEO 2 [see below]). Not all women with CSD report bleeding abnormalities, but it appears that the deeper and wider the defect, the more likely a woman is to present with postmenstrual AUB.7 According to the International Federation of Gynecology and Obstetrics (FIGO) Classification of AUB, CSD-associated postmenstrual bleeding falls into the “iatrogenic” category in the PALM-COIEN pneumonic.11

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