Gynecological and postpartum ultrasonography of cesarean uterine scar defects: a pictorial essay

Abstract

There is an increasing incidence of cesarean scar defect. This article will discuss and show different and variable sonographic presentations of scar niches and uterine postpartum ultrasonography with vaginal birth after cesarean section that can be confusing and many should be unaware of. This brief review aims to help practitioners to avoid confusion and be aware and acquainted with the different sonographic findings encountered in practice related to cesarean scar. It can lead to uterine rupture I labour, dehiscence in pregnancy and placenta accreta in the future pregnancy, but this is not evidence-based and not even a contraindication for pregnancy. It is neither an indication of repair for the presenting patient nor an indication to screen these patients for such complications. It is treated if associated with infertility or bleeding and not in asymptomatic ones.

Keywords: Cesarean; Niche; Scar; Ultrasound.

Fig. 1

Ultrasound showing inward retraction (discontinuation of myometrium) niche in retroverted flexed (RVF) uterus (external V-shaped defect affecting nearly all the deapth of the myometrium with symptoms)

Fig. 2

Ultrasound showing droplet-shaped niche (fluid retention) (wedge hypoechoic defect)

Fig. 3

Ultrasound showing triangular-shaped niche (wedge hypoechoic defect)

Fig. 4

Ultrasound showing inclusion hypoechoic cyst niche

Fig. 5

Ultrasound showing inward retraction niche in anteverted flexed (AVF) uterus with uterovesical peritoneum, in contact with endometrium with blood in niche and nearly loss of myometrium (discontinuation and hypoechogenicity)

Fig. 6

LUS by TVUS after VBAC, a thin rim of fluid in uterovesical pouch and a hypoechoic scar site of cribriform shape of infiltrating blood by stretch of scar in labor and retraction of the LUS that appears as a dehiscent scar, for follow-up as long as no vaginal bleeding or deterioration in general condition. No role of vaginal scar examination or ultrasound in the absence of suspicious vaginal bleeding or clinical findings. A dehiscence after delivery with no clinical findings on ultrasound or examination of 1cm or a finger width can be managed conservatively

Fig. 7

Low echogenicity at CS scar site, which is different from, surrounding the myometrium. It is related to fluid retention. (Hematoma niche with myometrial discontinuation affecting full thickness of myometrium with fibrosed retracted ends in the second photo and the first photo (hypoechoic) should be differentiated from Adenomyosis by Doppler signal)

Fig. 8

Cribriform heterogeneous scar with fluid retention (hematoma niche with inward protrusion)

Fig. 9

3-D photos showing central anterior defect (right photo) and central anterior defect extending to lateral uterine wall (left photo) (total dehiscent scar) (full thickness niche)

Fig. 10

Complete dehiscent uterine scar with fluid intrauterine accumulated and extended below the utero vesical pouch reaching uterine fundus, with the total loss of uterine tissue at the related site (dumbbell-shaped uterine niche) (outward protrusion) (discontinuation and hypoechogenicity)

Fig. 11

Echogenic appearance of the uterine scar at the usual site of the section with nearly same thickness related to the upper and lower segment. We can claim that this scar characters can sustain labour pains with minimal dehiscence in opposite to others seen before which are thinner and nearly absent in some cases where dehiscence can occur even in pregnancy. A dehiscence especially of more than 50% of the thickness of the uterine wall can lead to silent dehiscence in pregnancy