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Wound Complications After Obstetric Anal Sphincter Injuries

Lewicky-Gaupp, Christina, MD; Leader-Cramer, Alix, MD; Johnson, Lisa L., MD; Kenton, Kimberly, MD; Gossett, Dana R., MSCI

doi: 10.1097/AOG.0000000000000833
Contents: Urogynecology: Original Research
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OBJECTIVE: To estimate the incidence of and risk factors for wound complications in women who sustain obstetric anal sphincter injuries.

METHODS: This was a prospective cohort study of women who sustained obstetric anal sphincter injuries during delivery of a full-term neonate between September 2011 and August 2013. Women were seen in the urogynecology clinic within 1 week of delivery and at 2, 6, and 12 weeks postpartum for perineal wound assessment. A visual analog scale for pain was administered at each visit.

RESULTS: Five hundred two women met inclusion criteria for the study, and, ultimately, 268 women (54%) were enrolled. Eighty-seven percent of the cohort was nulliparous and 81% had a third-degree laceration. The majority (n=194) underwent an operative vaginal delivery (66.0% forceps and 6.0% vacuum). The overall risk was 19.8% (95% confidence interval [CI] 15.2–25.1%) for wound infection (n=53) and 24.6% (95% CI 19.6–30.2%) for wound breakdown (n=66). Operative vaginal delivery was associated with wound complications (infection, breakdown, or both) (adjusted odds ratio [OR] 2.54, 95% CI 1.32–4.87, P=.008). Intrapartum antibiotic therapy for obstetric indications was associated with a decreased risk of wound complications (adjusted OR 0.50, 95% CI 0.27–0.94, P=.03). Women with a wound complication reported significantly more pain within 1 week of delivery than women with a normally healing perineum (visual analog scale: 40.1±25.6 compared with 31.0±23, P=.002); this persisted at 12 weeks postpartum (6.6±7.5 compared with 3.4±7.1, P=.005).

CONCLUSION: Women who sustain obstetric anal sphincter injuries are at high risk for the development of wound complications in the early postpartum period, warranting immediate and consistent follow-up.

LEVEL OF EVIDENCE: II

Women who sustain obstetric anal sphincter injuries are at high risk for the development of a wound complication in the early postpartum period.

Department of Obstetrics and Gynecology, Division of Female Pelvic Medicine and Reconstructive Surgery, Northwestern University, Chicago, Illinois.

Corresponding author: Christina Lewicky-Gaupp, MD, Assistant Professor, Prentice Women's Hospital, 250 E. Superior Street, Suite 05-2370, Chicago, IL 60611; e-mail: cgaupp@nmff.org.

Supported by the Evergreen Invitational Women's Health Initiative.

Presented at the 40th Annual Society of Gynecologic Surgeon's Meeting, March 23–26, 2014, Scottsdale, Arizona.

Financial Disclosure The authors did not report any potential conflicts of interest.

The reported rate of obstetric anal sphincter injuries at the time of vaginal delivery varies from 0.0–23.9% with the highest and lowest rates represented by studies with smaller sample sizes.1 On the other hand, perineal wound breakdown is much less commonly reported with incidences of 0.1–4.6%.2–5 Perineal wound complications can cause significant morbidity including chronic pain, infection, embarrassment, depression, loss of sexual function, and, ultimately, fecal incontinence.2,6–8 Although the risk factors for obstetric anal sphincter injuries have been identified in previous studies, little research has focused on the factors associated with obstetric anal sphincter injury wound complications. The few studies addressing these associations are limited in their retrospective design.2,3,9

The purpose of this study was to prospectively estimate the incidence of and risk factors for wound complications in women who sustain obstetric anal sphincter injuries at a high-volume, tertiary care obstetric center.

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MATERIALS AND METHODS

The For Optimal Recovery, Care After Severe Tears study was a prospective cohort study of women who sustained obstetric anal sphincter injuries at Northwestern Medicine's Prentice Women's Hospital, an academic, tertiary care center in Chicago, between September 2011 and August 2014. The study was approved by the Northwestern University institutional review board (STU00031398). Inclusion criteria were all women who delivered a full-term singleton neonate, sustained obstetric anal sphincter injuries, and whose primary obstetrician agreed the patient could be approached for study participation. Women with multifetal pregnancies and premature deliveries (less than 37 weeks of gestation) were excluded. Patients with obstetric anal sphincter injuries were identified daily using the Northwestern University Enterprise Data Warehouse, an electronic repository of all data from the electronic medical records of Northwestern Memorial Hospital. If a woman met inclusion criteria, a study coordinator then approached patients of consenting physicians for enrollment either while they were still in the hospital or by telephone if the patient had been discharged. Written informed consent was obtained in the hospital or at the first study visit.

Demographic, medical, and obstetric data (including age, race, smoking status, body mass index, birth weight, method of vaginal delivery, performance of episiotomy and type, and degree of perineal laceration) were collected through the Enterprise Data Warehouse. Data not hard-coded in the Enterprise Data Warehouse (length of passive and active second stages of labor) were collected by chart review by the authors. We defined third-degree lacerations as tears involving any amount of the anal sphincter muscles and fourth-degree lacerations as those with any rectal mucosal involvement.

All consenting women were seen initially in the urogynecology clinic by one of three board-certified Female Pelvic Medicine and Reconstructive surgeons within 1 week of delivery and again at 2, 6, and 12 weeks postpartum as well as annually for perineal evaluation and completion of a validated symptom inventory. Women with clinical examinations warranting closer follow-up were seen more frequently at the health care provider's discretion. At each visit, a perineal evaluation was performed. Wound infection was defined by having three or more of the following on examination: heat, erythema, edema, or purulent discharge. Wound breakdown of at least 1 cm was also documented. A wound complication was defined as wound infection, breakdown, or both for the purpose of this analysis.

Women also completed a visual analog scale for pain10 at each study visit. Visual analog scale scores could range from 0 (no pain) to 100 (maximum pain).

SPSS 20.0 was used for all data analysis. Categorical variables were evaluated using a χ2 analysis or Fisher's exact test for variables with low frequencies. The 95% confidence interval (CI) for each estimate was calculated using the binomial proportions method. Continuous variables were assessed for normalcy using histograms and well as normal probability plots. Normally distributed variables were analyzed using the Student's t test. Nonparametric variables were analyzed using the Mann-Whitney U test. We estimated odds ratios (ORs) between various demographic and clinical characteristics and wound complications. Alpha was set to 0.05 for all analyses. Binary logistic regression was performed to evaluate the contributions of multiple risk factors for perineal complications and generate adjusted ORs for infection and breakdown.

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RESULTS

During the study period, 615 women sustained an obstetric anal sphincter injury, and 502 women met inclusion criteria. Two hundred sixty-eight women (54%) were ultimately enrolled in the study (Fig. 1). Most women did not offer a reason for declining enrollment, and a significant number did not respond to a recruitment phone call or were unable to be reached once discharged from the hospital. Most study participants were young, nulliparous, and Caucasian (Table 1). Just more than 20% reported a history of tobacco use, although none were current smokers. More than half of the cohort received intrapartum antibiotics for various obstetric indications (including chorioamnionitis, group B streptococcus prophylaxis, endometritis, or a combination). Nearly three fourths of patients underwent an operative vaginal delivery with forceps-assisted deliveries being far more common than vacuum-assisted deliveries (Table 1). The most common indication for operative delivery was maternal exhaustion in 40% (n=77) of women. Sixty-nine women (36%) underwent operative delivery for fetal indications and 23% (n=44) had arrest of descent. In two women, the indication for operative delivery was not documented.

Fig. 1

Fig. 1

Table 1

Table 1

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.

Table 2

Table 2

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).

Table 3

Table 3

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).

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DISCUSSION

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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