During pregnancy, several conditions may necessitate operative procedures on the vulva, vagina, or cervix. Of surgeries, cervical cerclage is one of the more common. Other procedures are used during delivery and include Dührssens incisions, division of a vaginal septum, and release of female genital mutilation scarring. A brief review of procedures relevant to cervical dysplasia and cervical polyps concludes the chapter.
The primary function of the cervix during pregnancy is to keep the uterus and its contents sequestered until controlled cervical dilatation and delivery ensues at term. Failure of this function may result in preterm birth. Thus, to reinforce an insufficient cervix, cerclage procedures are often performed.
When the cervix fails because of an intrinsic weakness during the midtrimester, it has been historically referred to as cervical incompetence. Today, the term cervical insufficiency is preferred to avoid negative connotations. The intrinsic cervical defect classically results in painless dilatation of the cervix with pregnancy loss during the midtrimester. Easterday and Reid (1959) described this process: "The cervix in these patients usually dilates without discomfort, over a period of days or possibly weeks, to the point where the membranes are plainly visible on speculum examination. Unless this is recognized early, the membranes will rupture, and the pregnancy will terminate prematurely." However, overreliance on this classic history may impede the diagnosis of cervical insufficiency. In fact, early symptoms frequently develop and include urinary frequency and urgency, lower abdominal pressure, or watery discharge (Toaff, 1974). After rupture of membranes, this process may become overtly painful due to contractions, further distention of the cervix, and passage of the uterine contents. Such devastating early losses often recur in subsequent pregnancies, and this supports the concept of intrinsic cervical deficiency.
Intrinsic Genetic and Biochemical Deficiencies
The etiology of this cervical deficiency has been debated and may stem from either congenital or acquired defects. Given that 25 percent of women with a history of cervical insufficiency have a first-degree relative with the condition, a genetic factor seems very plausible (Warren, 2009). As putative elements, extracellular matrix components and several genes have been studied in affected women. Notably, women with prior cervical insufficiency do not have intrinsically low collagen levels within the extracellular matrix, nor do they appear to have an inferior quality of collagen or an excessive number of smooth muscle cells (Oxlund, 2010). Although polymorphisms in certain genes associated with inflammation and collagen metabolism have been identified in women with cervical insufficiency, their role in intrinsic cervical deficiency remains unclear (Warren, 2009).
During pregnancy, the biochemistry and structure of the cervix undergo important changes. These alterations include significantly decreased stromal stiffness, greater water content, increased sulfated glycosaminoglycan content, increased collagen solubility, and decreased collagen organization (Myers, 2008, 2009). These changes occur early, typically within the first 4 to 6 weeks ...