MRI findings of complications related to previous uterine scars

Abstract

Although the World Health Organization suggests 10-15% as the adequate cesarean delivery rate to assure optimal prognosis for mother and children, cesarean rates have continuously increased worldwide over the last three decades, even in primiparous women. Moreover, uterine scars after myomectomies, complications of obstetrical interventions and more recently, after fetal surgery, are often observed. This review article describes the most commonly seen complications related to prior uterine scars and discusses their imaging findings, with emphasis on the increasing role of Magnetic Resonance Imaging for diagnosis.

Keywords: Cesarean delivery; Ectopic pregnancy; MRI; MRI, Magnetic resonance imaging; Placental anomalies; TVUS, Transvaginal ultrasound; US; US, Ultrasound; WHO, World Health Organization.

Fig. 1

Progression of cesarean delivery rates for all deliveries (a) and in primiparous women (b) in some reference countries from 1990 to 2010.

Fig. 2

Uterine scar dehiscences (Cases 1 and 2): TVUS image (a) shows a light dehiscence of the uterine wall at the level of the uterine scar in a 30 y.o. patient with a prior cesarean delivery (a, Case 1, white arrow). (b) Severe scar dehiscence (white arrow) with complete disruption of the myometrial uterine layer and preservation of the serosa in a 32 y.o. patient with 2 prior cesarean deliveries (Case 2).

Fig. 3

Uterine scar dehiscence: 30 y.o. patient with 2 prior cesarean deliveries and non-specific abdominal pain. Sagittal (a) and axial (b) T2- W MR images show incomplete rupture of the ventral uterine wall at the level of the old cesarean scar (white arrow), involving the myometrium but with intact overlying serosa layer. V = Fluid-filled vagina.

Fig. 4

Chronic uterine scar rupture with formation of a “niche”.- 38 y.o. patient with 3 previous cesarean sections presenting abdominal pain and persistent vaginal spotting. Sagittal (a) T2-W MR images and axial (b) FS T1-W MR image show a semicircular defect of the ventral uterus wall at the level of the isthmus (white arrow). The cavity is filled with hematic fluid (B), also present at the cavum uteri. Menstruation normalized after surgical correction. V = Vagina.

Fig. 5

Stable uterine rupture. 27 y.o. patient with antecedents of iatrogenic uterine rupture at laparotomy. Sagittal and coronal (a, b) T2-W MR images at the 29th week of pregnancy revealed a focal uterine rupture in the right uterine fundus wall, at the level of the old uterine scar, with prolapsed amniotic sac (As). The patient was treated conservatively with bed rest, i.v tocolysis and fetal lung maturation. US control at 32th pregnancy week (c) shows increased rupture of the uterine wall (double white arrow), with a leg of the fetus now extending through it. Diagnosis was confirmed at cesarean delivery. After birth, the left leg presented edema and deep furrows at the upper thigh (d).

Fig. 6

Pelvic adhesions after cesarean delivery.- 39 y.o. patient with 2 prior cesarean deliveries and 2 curettages presenting with pain during miction. The sagittal (a, b) T2-W MR images show the uterine dehiscence at the level of the prior cesarean scar. Note fine adhesions (white arrow) between the uterine dehiscence and the bladder dome. Symptoms released after surgical adhesiolyisis.

Fig. 7

Intrauterine synechias: 28 y.o. patient with 2 previous cesarean deliveries and status post uterine rupture, presenting with vaginal bleeding at the 32th week of pregnancy. TVUS image (a) shows the transverse positioned fetus and reveals anomalous distribution of amniotic fluid with central located, unclear intrauterine tissue (S: synechia). Coronal and sagittal (b, c) T2-W MR images show a normal inserted placenta (P). A wide bridge of tissue arising from the right lateral uterine wall (S:synechia), divides the uterus in 2 compartments. The cranial one contains the transverse located fetus whereas the caudal one contains the prolapsed umbilical cord (black arrows b, c), surrounded by most of the amniotic fluid. Diagnosis was confirmed at surgery (d).

Fig. 8

Cesarean scar ectopic pregnancy.- 33-y.o. patient with a prior cesarean section presenting with vaginal bleeding at the 13th week of pregnancy. TVUS image (a) and color Doppler image (b) at the 13th week of pregnancy show the gestational sac located at the level of the old cesarean scar (block arrow). The viable embryo is well identifiable (fine arrows, a). Angiographic image before embolization (c) shows the catheter inserted in the uterine artery.

Fig. 9

Placenta previa.- 39 y.o. patient with a prior cesarean delivery presenting with light vaginal bleeding at the 24th week of pregnancy. PP was detected at US. Complementary sagittal T2- W MR images (a, b) clearly show the placenta (P), entirely covering the internal uterine os (white arrows).

Fig. 10

Anomalous placental infiltration. In placenta accreta the chorionic villi are attached to the myometrium but do not invade it. In placenta increta, the villi partially invade the myometrium whereas in placenta percreta, invasion involves the entire myometrial thickness, reaching the uterine serosa or even extending beyond it. Printed with permission from Ref. [53].

Fig. 11

PP and percreta.- 28 y.o. patient with 2 prior cesarean deliveries. The sagittal (a, b) and axial (c) T2-W MR images at the 36th w. of a twin pregnancy show the placenta previa of the second fetus (P2), entirely covering the internal uterine os (fine black arrow, b). Compared to the normal placenta of the first fetus (P1), P2 is markedly heterogeneous (b, c). Note the tethering of the bladder dome (white arrow, b) and the infiltration of the bladder dome (thick black arrow, a), confirming a placenta percreta. Despite prophylactic insertion of bilateral iliacal angioplasty catheters before delivery, severe intrapartum hemorrhage required urgent hysterectomy. The patient developed a lung embolism 4 days after delivery, showed in this axial contrast enhanced computed tomography scan image (white arrow, d).

Fig. 12

PP and percreta.- 26 y.o. patient with 1 prior cesarean delivery and status post dilation and curettage. Sagittal T2-W (a, b), sagittal T1-W (c) and axial (d) T2-W MR images at the 24th week of pregnancy show a placenta previa (P), markedly heterogeneous, with multiple intraplacental dark bands (curved arrows, b) and hematic rests, hyperintense on T1-W imaging (c). Note prominent anomalous uterine contour with uterine “bulging” and absence of clear identification of the myometrium between the white arrows in a and d. The patient developed acute severe vaginal bleeding and abdominal pain 24 h after MR exam. Emergency surgery discovered uterine rupture at the old cesarean scar level with partial protrusion of the placenta. The fetus died and hysterectomy was required.

Fig. 13

Proposed algorithm for the appropriate use of imaging methods in pregnant patients with previous cesarean delivery and/or hysterotomy.