Multiple studies confirm the impact of anal sphincter laceration during the first delivery on the risk of a sphincter laceration in a second delivery (129–132). These studies have calculated odds ratios ranging between 2.5 and 5.3 for a second sphincter disruption. Two recent population-based studies revealed adjusted odds ratios of 4.2 (95% confidence interval [CI], 3.9–4.6) and 4.3 (95% CI, 3.8–4.8) (130,131). These odds ratios probably represent underestimates because they do not take into account higher cesarean delivery rates in subsequent births for women with a history of sphincter laceration. Both of these studies observed significantly increased risk of recurrent sphincter laceration associated with increased birth weight. The studies estimated that approximately 25 cesarean deliveries have to be performed to prevent one recurrent sphincter laceration. In fact, only 10% of women with anal sphincter lacerations at second delivery had a history of prior sphincter laceration. Although a history of prior sphincter laceration increases the risk of recurrent sphincter laceration, the risk remains relatively small. It is important to accurately counsel expectant mothers about their risk of sphincter laceration. Using this information, they can decide whether the risk of recurrent laceration outweighs the risk of elective cesarean birth. The risk of subsequent vaginal delivery on symptoms of fecal incontinence is unknown for women with a repaired anal sphincter. The presence or absence of preexisting fecal incontinence, as well as the estimated fetal weight, should be considered in counseling for a subsequent pregnancy.
Graciloplasty Surgical reconstruction with a muscle ﬂap should be considered in cases in which there is insufficient muscle to repair the EAS and all conservative measures have failed. Insufficient muscle can be caused by trauma or severe atrophy that results from denervation injury and congenital disease. Most patients considering this procedure have already undergone an overlapping sphincteroplasty that failed. Graciloplasty, first described by Pickrell et al. in 1952, is a skeletal muscle transposition procedure that uses the gracilis to create a new anal sphincter (133). There are three suitable muscles for this type of procedure: the gracilis, sartorius, and gluteus maximus. The muscle should be easily mobilized and transposed but not essential for locomotion or posture. The sartorius and gluteus maximus are suboptimal because the sartorius receives segmental vascularization, which restricts rotation, and the gluteus maximus is important in daily activities such as running, climbing stairs, and rising from a sitting position. The gracilis is a better choice because it can easily be mobilized without damage. As the most superficial adductor, it receives neurovascular supply proximally and has no important independent function.