Reply: Niche risk factor for uterine rupture?

Cesarean scar niche, fertility and uterine rupture during labor - A retrospective study

OBJECTIVES

To determine how does a uterine niche diagnosed prior to conception, affects future fertility and obstetrical outcomes, in a group of patients with secondary infertility undergoing fertility treatments.

STUDY DESIGN

A retrospective case-control study was performed, recruiting patients after cesarean delivery, before fertility treatment. Using stored ultrasound photos and video loops, we determined niche's sonographic parameters during the preconception period and retrieved the fertility and obstetrical outcomes thereafter.

RESULTS

104 patients met the inclusion criteria, and 86 were available for analysis. 56 (65%) had uterine niches larger than 2 mm in depth, and 30 (34%) had a uterine scar of 2 mm or less. Demographic characteristics were not different between groups. No statistically significant differences were observed regarding rates of implantation and clinical pregnancy between the groups. There were four cases of cesarean scar rupture during failed trial of labor (TOLAC), all of which were in the group with larger than 2 mm niche (33% of all TOLAC cases in the respected group).

CONCLUSIONS

While it appears that pre-conception presence of uterine niches larger than 2 mm in depth does not adversely affect future fertility, these niches might serve as a risk factor for future uterine rupture during TOLAC.

Post-Caesarean section niche-related impaired fertility: hypothetical mechanisms

Caesarean section can result in an indentation of the myometrium at the site of the Caesarean scar, called a niche. Niches can cause symptoms of abnormal uterine blood loss, dysmenorrhoea, chronic pelvic pain and dyspareunia and are possibly related to subfertility. Various other explanations for the cause of subfertility after Caesarean section have been proposed in the literature, such as uterine pathology, intra-abdominal adhesions and women’s reproductive choices. Not all niches cause symptoms and the relation with subfertility and a niche in the uterine scar still needs further study since direct evidence is lacking so far. Based on the limited available evidence, and in combination with observations made during sonographic hysteroscopic evaluations and laparoscopic niche repair, we propose and discuss three hypothetical mechanisms: (i) the environment for sperm penetration and implantation may be detrimental; (ii) there could be a physical barrier to embryo transfer and implantation; and (iii) psychogenic factors may reduce the likelihood of pregnancy. Several innovative surgical treatments have been developed and are being implemented for niche-related problems. Promising results are reported, but more evidence is needed before further implementation in daily practice. The additional value of niche resections should be compared to expectant management or fertility therapies, such as ART, in randomized controlled trials. Therefore, our suggested hypotheses should, for the time being, not be used for justification of any specific procedures outside clinical trials.

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

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.