The majority of women sustained a third-degree laceration, and only one third of women received prophylactic antibiotics for their obstetric anal sphincter injuries (Table 1). Antibiotics prescribed for obstetric anal sphincter injuries were variable based on numerous delivering providers' preferences (Table 1).
At the initial evaluation, the overall risk for wound infection and wound breakdown was 19.8% (95% CI 15.2–25.1%) and 24.6% (95% CI 19.6–30.2%), respectively. Women who presented at their initial visit with a wound infection (n=53) were treated with a standardized course of oral antibiotics (875 mg amoxicillin–clavulanate and 500 mg metronidazole twice daily) for a 7-day course. Women with wound breakdown (n=66) were offered immediate operative repair (if clinically appropriate) or conservative management with perineal wound packing changes and perineal care (which included twice-daily baths in warm water for 10–15 minutes and good drying techniques including patting dry with a towel and using a hairdryer on a cool setting) afterward. Almost all women with wound breakdowns opted for conservative management; only nine (3.4%) were taken to the operating room for various indications (Table 2). Of those taken to the operating room, only one (who required wound débridement in the operating room over 2 days secondary to severe infection and necrosis) was readmitted on initial presentation; this was at 4 days postpartum. All others were discharged on the day of operation.
Women who sustained a wound complication were demographically similar and had similar intrapartum characteristics as those who did not have a wound complication (Table 3). In univariable analyses, women who underwent an operative vaginal delivery were more likely to develop a wound complication compared with those who had a spontaneous delivery (OR 2.48, 95% CI 1.31–4.68, P=.005). Compared with third-degree lacerations, fourth-degree lacerations were no more likely to result in wound infection (19.6% compared with 19.8%, P=.98) or wound breakdown (17.6% compared with 26.3%, P=.2). However, women who were given antibiotics for any obstetric indication during their admission were less likely to have a wound complication (OR 0.59, 95% CI 0.36–0.99, P=.04). Rates of wound complication were similar between women who did and did not receive prophylactic antibiotics with obstetric anal sphincter injury repair being the sole indication (Table 3). Binary logistic regression was then performed to assess the influence of multiple covariates on perineal outcomes. We incorporated maternal age, operative vaginal delivery, degree of laceration, and use of antibiotics. In this model, operative delivery was associated with wound infection (adjusted OR 2.69, 95% CI 1.12–6.08, P=.018), with wound breakdown (adjusted OR 2.29, 95% CI 1.11–4.75, P=.026), and with the composite outcome of wound complication (adjusted OR 2.54, 95% CI 1.32–4.87, P=.008). Antibiotic use was not associated with either infection or breakdown separately, but was protective against the composite infection and breakdown endpoint (adjusted OR 0.50, 95% CI 0.27–0.94, P=.03).
All postpartum women in the study were given a standard institutional pain regiment on discharge consisting of 600 mg ibuprofen every 6 hours and one to two tablets of acetaminophen–hydrocodone (10/235) every 4–6 hours. Despite this, significantly higher pain scores were reported by women with a perineal wound complication compared with those with a normally healing perineum at the initial visit (visual analog scale: 40.1±25.6 compared with 31.0±23.6, P=.002) and the 12-week postpartum visit (6.6±7.5 compared with 3.4±7.1, P=.005).
Using rigorous clinical criteria, one in four women who sustained an obstetric anal sphincter injury in this large prospective cohort of well-characterized women developed a postpartum wound breakdown, and one in five women developed a wound infection. Operative vaginal delivery was associated with a greater than twofold increase in the rates of wound infection, wound breakdown, and overall wound complications.
Our definitions of wound infection and wound breakdown in this study were stringent and despite this, our findings directly contradict the notion that complications after obstetric anal sphincter injuries are rare events. Only a few groups have published on wound complications after vaginal delivery with severe tears and have reported an incidence of approximately 5–13%.11,12 In fact, in our own retrospective study of 909 women at this same institution, 66 sustained a complication secondary to obstetric anal sphincter injuries for an overall rate of 7.3%.9 One of the most common sequelae of perineal wound complications in these studies is infection, leading to hospital readmission. For example, Liu et al reported that women delivered by forceps (OR 1.43, 95% CI 1.34–1.53) and vacuum (OR 1.21, 95% CI 1.15–1.28) were at an increased risk of postpartum readmission. The most common cited reasons for readmission in this study included pelvic injury and wounds, obstetric surgical complications, and major puerperal infection.13 The same was true in a study by Lydon-Rochelle, in which assisted vaginal delivery was associated with an increased risk of readmission within 60 days of delivery secondary to infection.14 In our retrospective study, despite the lower rate of complications overall, 29 (44%) required hospital readmission and 21 of those (72%) were readmitted within the first 2 weeks postpartum.9 These studies focus attention on the need for controlling postpartum infection overall. Although we report a higher rate of wound complications in this cohort, only one patient was readmitted; this readmission occurred within the first postpartum week. The most significant practice change among our retrospective study, other published literature, and the currently reported study is the follow-up and standardized treatment of participants in a specialty perineal clinic. It is possible that this is why we observed a lower rate of readmissions related to wound complications.
One known risk factor for wound complications in women who sustain obstetric anal sphincter injuries is infection.2 In our previous retrospective study, we also found that smoking (OR 4.04, 95% CI 1.4–12.2; P=.01), increasing body mass index (OR 1.06, 95% CI 1.01–1.12; P=.04), fourth-degree laceration (OR 1.89, 95% CI 0.99–3.61; P=.05), and operative vaginal delivery (OR 1.76, 95% CI 1.15–2.68; P=.009) were associated with wound complications after obstetric anal sphincter injuries.9 In the current study, operative vaginal delivery persisted as a significant risk factor for wound infection, breakdown, and overall complications. Other demographic factors were not associated with wound complications in this cohort, likely secondary to a smaller sample size or perhaps a recruitment bias for more complicated tears. Although Chames et al identified operative vaginal delivery to be an overall risk factor for wound breakdown (OR 3.6, 95% CI 1.8–7.3),3 to our knowledge, ours is the only study that has specifically identified operative vaginal delivery as a risk factor for wound complications in women who sustain obstetric anal sphincter injuries. Not surprisingly, pain levels were reported to be higher in the group of women who had a wound complication. These findings point not only to the need for early follow-up in women who sustain obstetric anal sphincter injuries, but, even more importantly, those who sustain obstetric anal sphincter injuries during an operative vaginal delivery.
As was seen in our same retrospective study,9 any intrapartum antibiotic use for obstetric indications was associated with a lower rate of wound complications. This is not surprising, because the antibiotics used to treat group B streptococcus colonization and chorioamnionitis are relatively broad-spectrum and specific to genitourinary flora; therefore, they may prevent postpartum wound infections. The role for prophylactic antibiotics in the setting of obstetric anal sphincter injuries still remains unclear, however. In a small randomized trial, Duggal et al15 found that administering antibiotics at the time of obstetric anal sphincter injury repair was associated with a lower incidence of perineal wound complications. In the current study, there was a lower rate of wound complications in women who received antibiotics in the setting of obstetric anal sphincter injury repair; however, it was not statistically significant. This may be explained by our relatively small cohort as well as by the variable and nonstandardized antibiotic regiments at the time of repair in some patients. A larger, randomized controlled trial with a specific antibiotic protocol is needed to address whether prophylactic antibiotics at the time of obstetric anal sphincter injury repair should be the standard of care.16
Our biggest study limitation was that of 54% recruitment rate. Similar to the Childbirth and Pelvic Symptoms study,17 we attempted primary recruitment in the hospital after delivery. This, coupled with needing the patient's primary obstetrician's permission to recruit, hindered our ability to collect a larger sample. Despite this limitation, however, we were able to accurately collect many variables in a large cohort of women. This collection of outcome data was integral to the study and not part not of routine care, and the eligible women who declined participation did not consent to collection of such data. Therefore, another limitation of the study is that we do not have demographic or outcomes data on these women. Also, although we were able to collect antibiotic data on all patients, the variable antibiotic regimens used by different health care providers make it difficult to draw robust conclusions regarding the use of antibiotics for obstetric anal sphincter injury repair. Most of the patients were Caucasian, and therefore this study may not be generalizable to a more ethnically diverse patient population.
To date, there are no standard guidelines for the follow-up of patients who sustain a severe perineal laceration,18 and women frequently are not seen until their sixth postpartum week. Our high rates of wound complications in the immediate postpartum period in this prospective study point to the benefit of and need for early and consistent follow-up in women who sustain obstetric anal sphincter injuries; this follow-up may decrease rates of readmission in the postpartum period.
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© 2015 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.
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