Risk Of Anal Sphincter Injury Research Articles

Research progress on the application of Chinese herbal medicine in anal fistula surgery.

Anal fistula is a rapidly developing anorectal disease that can lead to anal dysfunction if left untreated. Minimally invasive surgery is an important treatment option for anal fistula, as it can reduce the risk of anal sphincter injury and protect anal function. However, postoperative complications such as infection, pain, bleeding, edema, and fat liquefaction can occur, resulting in slow wound healing thus negatively impacting the patient's quality of life. Recent studies have shown that Chinese herbal therapy has distinct pharmacological effects and is more effective in treating postoperative complications in anal fistula patients compared to conventional drug therapy. It not only promotes wound healing but also reduces the occurrence of complications. Chinese herbs can also modulate relevant signaling pathways such as PI3K/Akt, HIF-1, and TGF-β/Smad to enhance the wound healing process. Various methods of Chinese herbal medicine (CHM) have been used to treat post-anal fistula operation wounds, including traditional Chinese medicine (TCM) sitz baths, external application of TCM, internal administration of TCM, anal absorption, and acupuncture, all of which have shown promising therapeutic effects in clinical practice. This article aims to review the theory and clinical application of CHM in anal fistula surgery in recent years and provide valuable references for its treatment.

Risk of obstetric anal sphincter injury associated with female genital mutilation/cutting and timing of deinfibulation.

A greater risk of obstetric anal sphincter injury has been reported among African migrants in several host countries compared with the general population. To what degree female genital mutilation/cutting affects this risk is not clear. In infibulated women, deinfibulation prevents anal sphincter injury. Whether the timing of deinfibulation affects the risk, is unknown. This study aimed to investigate the risks of anal sphincter injury associated with female genital mutilation/cutting and timing of deinfibulation in Norway, and to compare the rates of anal sphincter injury in Somali-born women and the general population. In a historical cohort study, nulliparous Somali-born women who had a vaginal birth in the period 1990-2014 were identified by the Medical Birth Registry of Norway and data collected from medical records. Exposures were female genital mutilation/cutting status and deinfibulation before labor, during labor or no deinfibulation. The main outcome was obstetric anal sphincter injuries. Rates of obstetric anal sphincter injury did not differ significantly by female genital mutilation/cutting status (type 1-2: 10.2%, type 3: 11.3%, none: 15.2% P=0.17). The total rate of anal sphincter injury was 10.3% compared to 5.0% among nulliparous women in the general Norwegian population. Women who underwent deinfibulation during labor had a lower risk than women who underwent deinfibulation before labor (odds ratio 0.48, 95% confidence interval 0.27-0.86, P=0.01). The high rate of anal sphincter injury in Somali nulliparous women was not related to type of female genital mutilation/cutting. Deinfibulation during labor protected against anal sphincter injury, whereas deinfibulation before labor was associated with a doubled risk. Deinfibulation before labor should not be routinely recommended during pregnancy.

Non-diabetic fetal macrosomia: outcomes of elective delivery versus expectant management.

BackgroundMacrosomia in the absence of diabetes can be associated with increased neonatal and maternal morbidity. Management is usually undertaken on a case-by-case basis.AimsIn order to inform local practice, this study aimed to evaluate the outcomes of the management of non-diabetic macrosomia in an Irish tertiary center.MethodsA retrospective observational study was performed on all women with estimated fetal weight over 4000 g after 37 weeks’ gestation. Maternal demographics and obstetric and neonatal outcomes were recorded using the hospital information system. Women with diabetes, previous caesarean section, non-cephalic presentation, or any other complicating condition were excluded. Women were divided into two groups:Active management: Elective delivery for macrosomia—between 38 + 0 and 40 + 6 weeks’ gestationExpectant management: with induction of labour offered after 41 weeks' gestationResultsThere were 397 women included, 188 with active and 209 with expectant management. There was no difference in adverse neonatal outcomes, major maternal morbidity, or mode of delivery, after exclusion of pre-labor caesarean section. Women with expectant management were more likely to go into spontaneous labor (46.9 vs 1.6%, p < 0.001) and to have a favorable cervix at the onset of induction of labor if nulliparous (86.1 vs 70.0%, p = 0.021), but have higher rates of episiotomy (28.6 vs 18.2%, p = 0.021). With active management, nulliparas with an unfavorable cervix had increased risk of anal sphincter injury (6.5 vs 0.0%, p = 0.007) and postpartum hemorrhage (59.0 vs 35.5%, p = 0.003).ConclusionsOverall, there was no difference in major maternal or neonatal outcomes between management options for fetal macrosomia. However, inducing nulliparas with an unfavorable cervix for non-diabetic macrosomia was associated with obstetric anal sphincter injury and postpartum hemorrhage.

Are women attending a midwifery-led birthing center at increased risk of anal sphincter injury?

In recent years there has been renewed interest in midwifery-led care for women, with studies reporting similar neonatal outcomes despite lower rates of intervention in midwifery-led birthing centers. Research into obstetric anal sphincter injuries (OASI) in these birthing centers is scarce. The objective of this study was to compare the rate of OASI after spontaneous vaginal delivery in nulliparous women in consultant or midwifery-led units over a ten-year period. All spontaneous vaginal deliveries in nulliparous women from 2008 to 2017 were analyzed in a single-center retrospective study. Women who had neuraxial analgesia were excluded. The primary endpoint was OASI. Labor characteristics in both groups were compared, and a multiple regression model was created. During the study period, there were 3260 spontaneous vaginal deliveries in nulliparous women; 75.7% (2467/3260) delivered in the consultant-led unit and 24.3% (793/3260) in the midwifery-led unit (MLU). Women delivering in the MLU had a greater risk of anal sphincter injury than those delivering in the CLU (4.9% [39/793] vs 2.5% [62/2467], OR 2.01, 95% CI 1.32 - 3.01). Significant risk factors that increased the risk of OASI on regression analysis were birthweight and delivery in the midwifery-led unit. Women delivering in the midwifery-led unit appear to be at double the risk of OASI when compared to those delivering in the consultant-led unit. These results are in contrast to previous studies in midwifery-led centers. This difference may be site-specific and further research is required before these results form part of patient counseling.

A Clinical Risk Model to Predict Obstetric Anal Sphincter Injuries in Laboring Patients.

Our objective was to develop a risk stratification tool for predicting obstetric anal sphincter injury risk in women during labor. In this retrospective cohort study of singleton deliveries within Kaiser Permanente Northern California, a predictive model for anal sphincter injury was developed within the 2013 birth cohort and validated in the 2014 birth cohort of 22,741 births. Predictors of obstetric anal sphincter injury were identified using multiple regression analysis and used to create a risk calculator tool based on effect size and clinical judgment. Duration of second stage of labor, vacuum delivery, history of anal sphincter injury, maternal and gestational ages, and maternal race and ethnicity were associated with elevated risk of anal sphincter injury. Using these risk factors, we developed a validated parity-stratified scoring system. Among nulliparous women, 116 (1.3%) had a score of zero, corresponding to a 0.9% risk, and 1024 (11.7%) had a score higher than 6, corresponding to a 27.5% risk of anal sphincter injury. Among the multiparous women, 1181 (8.4%) had a score of zero, corresponding to a 0.1% risk, and the 260 (1.9%) with a score higher than 10 had a 7.7% risk. The predictive ability of the score derived based on the 2013 data was applied to the 2014 data, and results showed that the predictive abilities were statistically similar, except for one subgroup: multiparous women with a total score of ≥10. Our anal sphincter injury risk stratification tool effectively predicts individual risk and can inform clinician and patient decision making to minimize maternal birth trauma.

Anal sphincter injury associated with shoulder dystocia

Objective: Shoulder dystocia is an obstetric emergency, occurring in 0.2–3% of vaginal deliveries. Research has mainly focused on the neonatal morbidity arising from shoulder dystocia, such as brachial plexus injury and hypoxic-ischemic encephalopathy. Maternal morbidity is thought to be increased with shoulder dystocia though is much less commonly reported. Obstetric anal sphincter injury remains the leading cause of fecal incontinence in women and shares several antenatal and intrapartum risk factors with shoulder dystocia. The aim of this study was to identify risk factors for sphincter injury associated with shoulder dystocia.Methods: This retrospective analysis included all cases of shoulder dystocia from 2008 to 2017 in a single unit in North-East Ireland. Maternal characteristics and delivery outcomes were analyzed. Two groups were compared, those with and without anal sphincter injury in our shoulder dystocia cohort and those with and without shoulder dystocia, regardless of sphincter injury. Univariate and multivariate logistic regression models were used to examine risk factors for sphincter injury.Results: There were 24,159 singleton cephalic vaginal deliveries over the study period, with 495 cases of shoulder dystocia, giving an incidence of 2.1% (495/24 159). The rate of anal sphincter injury in those with shoulder dystocia was 4.4% (22/495), with 7.6% (12/158) in nulliparas, and 3.0% (10/337) among multiparas. Women with sphincter damage were more likely to be nulliparous than those with an intact sphincter (54.5% [12/22] vs. 30.9% [146/473]; p = .036) and have an operative vaginal delivery (72.7% [16/22] vs. 39.1% [185/473]; p = .004). Episiotomy was more common in those with a sphincter injury (68.2% [15/22] vs. 37.0% [175/473]; p = .007). On univariate regression analysis, nulliparity (OR 2.69) and operative vaginal delivery (OR 4.15) were associated with sphincter injury. No risk factors were identified on multivariate regression analysis.Discussion: In our population, the risk of anal sphincter injury with shoulder dystocia is 4.4%. Risk factors include nulliparity and operative vaginal delivery. After controlling for other factors, these associations became nonsignificant. Further research into sphincter injury at shoulder dystocia is warranted.

Single prior caesarean section and risk of anal sphincter injury.

Injury to the anal sphincter at vaginal delivery remains the leading cause of faecal incontinence in women. Previous studies reported an increased incidence of obstetric anal sphincter injury (OASI) in women attempting vaginal birth after caesarean section (VBAC). The aim of the paper was to establish whether women in their second pregnancy, with one previous uterine scar, are at a higher risk of OASI compared with nulliparous women. All primiparous and secundiparous women with a previous caesarean section who delivered from 2008 to 2017 were analysed in a single-centre retrospective study. The primary endpoint was OASI. Labour characteristics in both groups were compared, and a multiple regression model was created. There were 8573 vaginal deliveries of nulliparous women and 3453 deliveries of women in their second pregnancy with a previous caesarean section, of whom 550 had a successful VBAC. There was no significant difference in the rate of OASI between primiparous women and those who had a successful VBAC: 3.5% (297/8573) versus 3.1% (17/550), P = 0.730). Foetal macrosomia (>4kg) and forceps delivery were risk factors for sphincter injury, while episiotomy and epidural anaesthesia were protective. VBAC does not confer an increased risk of OASI after a first delivery by caesarean section when compared with nulliparous women. The rate of successful VBAC may be contributory and suggests that the risk conferred by VBAC may be unit-specific. Unit and national-level audit is necessary to investigate this risk further.

578: Right instrument, right patient, right time: vacuum and forceps vs. forceps alone

Forceps delivery has decreased in frequency due to concerns regarding morbidity and this has lead to clinicians citing a lack of experience and confidence with the instrument. Similarly caution has been urged in the use of sequential instruments (most often vacuum followed by forceps) at the time of operative vaginal delivery due to excessive traction on the fetal head and related poor outcomes. We sought to examine outcomes of deliveries using vacuum followed by forceps with those where forceps was the only instrument applied. This is a secondary analysis of the Genesis Study, a prospective multi-center study, consisting of 2,336 nulliparous patients with a vertex presentation. Morbidity outcomes at operative vaginal delivery were examined and cases of forceps alone were compared with cases where there was sequential use of vacuum followed by a forceps to complete the delivery. Markers of birth injury such as Erbs palsy, cephalohematoma, fetal laceration, facial nerve palsy, fracture of the clavicle, skull or humerus were also examined. There were 864 operative vaginal deliveries carried out in the study cohort. Almost 60% (511/864) were vacuum assisted, while 29% (248/864) were forceps alone, 12% (105/864) of deliveries involved sequential vacuum and forceps. There was an increased risk of anal sphincter injury in those delivered with sequential instruments compared with those needing forceps alone (14% [15/105] vs. 7.7% [19/248]; p=0.05). The rates of shoulder dystocia and PPH were similar in both groups. Infants requiring sequential instruments were more likely to have a cephalohematoma (8.6% [9/105] vs. 0% [0/248]; p<0.001), and laceration to the fetal head (6.7% [7/105] vs. 2.0% [5/248]; p=0.02). There was no difference in the risk of facial nerve palsy, fracture of the clavicle, skull or humerus regardless of whether a forceps or both vacuum and forceps were used. Rates of Apgar <7 at 1 and 5 minutes, arterial cord pH <7.20 and NICU admission were similar among both groups. Deliveries carried out using a vacuum followed by a forceps carry significant morbidity in excess of those requiring forceps alone. In embarking on an operative vaginal birth, the operator should prioritize the appropriate use of a single intervention, including consideration for primary forceps selection or recourse to cesarean delivery.

Anal sphincter injury in vaginal deliveries complicated by shoulder dystocia.

Shoulder dystocia is an obstetric emergency that occurs in 0.2-3% of all cephalic vaginal deliveries. We hypothesized that because of the difficult nature of deliveries complicated by shoulder dystocia, the condition may be associated with anal sphincter injury. We sought to identify risk factors for obstetric anal sphincter injury in women with shoulder dystocia. This retrospective analysis included all cases of shoulder dystocia from 2007 to 2011 at two large tertiary referral centers, in the USA and Ireland. Details of maternal demographics, intrapartum characteristics, and delivery outcomes in cases of shoulder dystocia were analyzed. Univariate and multivariate analyses were used to describe the association between shoulder dystocia and anal sphincter injury. There were 685 cases of shoulder dystocia, and the rate of shoulder dystocia was similar at both institutions. The incidence of anal sphincter injury was 8.8% (60 out of 685). The rate was 14% (45 out of 324) in nulliparas and 4.2% (15 out of 361) in multiparas. Women with sphincter injury were more likely to be nulliparous (75% [45 out of 60] vs 45% [279 out of 625]; p<0.0001), have had an operative vaginal delivery (50% [30 out of 60] vs 36% [226 out of 625]; p=0.03) and require internal maneuvers (50% [30 out of 60] vs 32% [198 out of 625], p=0.004) than those with an intact sphincter. On multivariate regression analysis, these predictors of sphincter injury remained significant when adjusted for other risk factors. Episiotomy was negatively associated with sphincter injury on multivariate regression analysis. In a retrospective cohort of 685 women with shoulder dystocia, the risk of anal sphincter injury is 9%. Risk factors include nulliparity, operative vaginal delivery, and use of internal maneuvers, whereas episiotomy was found to have a protective effect against anal sphincter injury during cases of shoulder dystocia.

Differences in characteristics of mediolateral episiotomy in proffesionals at the same hospital

Objectives: The objective of our study was to compare the theoretical concept of the accoucheur in our institution with regard to the characteristics of the mediolateral episiotomy (MLE), with a crowning head and after a delivery. Methods: We devised two simple pictorial questionnaires (one with a crowning head and the other in rest after a delivery) in order to explore possible differences in clinical practice between the accoucheurs of our institution with respect to the MLE characteristics. Results: With a crowning head, we found more acute angles when the age of accoucheurs was greater than 35 years old and more than 15 years of experience, but no with the perineum at rest. No difference was found between doctors and midwives, nor between males and females. 28.1% of accoucheurs indicated an acuter episiotomy angle with a crowning head. Conclusion: This study confirmed that the individual interpretation of MLE differed widely among professionals at the same hospital. These differences which have been shown could predispose women to a greater risk of anal sphincter injuries. For this reason, there is a need to standardize this practice, to make the technique more homogeneous, particularly in the context of future research into the risks and benefits of episiotomy with respect to major perineal trauma.

Kielland's forceps: does it increase the risk of anal sphincter injuries? An observational study.

Rotational instrumental deliveries are thought to carry additional risks compared with non-rotational instrumental deliveries, including trauma to maternal tissues, and require specific expertise and training. We conducted a retrospective study to investigate the association between the type of forceps delivery and maternal perineal trauma, and in particular to investigate if Kielland's rotational forceps delivery increases obstetric anal sphincter injuries (OASIS). This is a retrospective observational study of 1,515 women who attended a tertiary maternity unit over a period of 5 years and had operative vaginal deliveries primarily or completed by forceps. Data were obtained through the hospital's maternity reporting system. The severity of maternal perineal trauma, particularly third and fourth-degree tears in relation to the type of forceps delivery was explored. Multinomial logistic regression models were used to estimate the crude and the adjusted relative risks (RR) of sustaining third-degree tears compared with other types of vaginal tears. Univariate analyses explored the crude associations between relative risks and age, ethnicity, birth weight, type of instrumental delivery and operator's experience. A multivariate multinomial logistic regression model estimated the adjusted relative risks and included all the previous variables as independent covariates. Of the 1,492 women included in the study, 150 women (77 %) had sustained category 1 tears, 63 women (4 %) had sustained category 2 tears and 279 women (19 %) had sustained third-degree tears. There was no statistically significant association between the severity of maternal perineal trauma and the type of forceps delivery (failed ventouse vs Kielland's forceps RR 1.52, p = 0.159 CI 0.84-2.72, Wrigleys vs Kielland's RR 0.59, p = 0.249, CI 0.24-1.43; Andersons vs Kielland's RR 1.16, p = 0.603, CI 0.65-2.05) after adjusting for age, birth weight, BMI, ethnicity and operator experience (full list of covariates not included). The incidence of third- and fourth-degree tears following rotational Kielland's forceps delivery and other non-rotational forceps deliveries is comparable.

Mode of vaginal delivery: a modifiable intrapartum risk factor for obstetric anal sphincter injury.

The aim of this study was to analyze the comparative risks of this anal sphincter injury in relation to the type of intervention in vaginal delivery. We performed an observational, retrospective study of all vaginal deliveries attended at a tertiary university hospital between January 2006 and December 2009. We analyzed the incidence of obstetric anal sphincter injury for each mode of vaginal delivery: spontaneous delivery, vacuum, Thierry spatulas, and forceps. We determined the proportional incidence between methods taking spontaneous delivery as the reference. Ninety-seven of 4526 (2.14%) women included in the study presented obstetric anal sphincter injury. Instrumental deliveries showed a significantly higher risk of anal sphincter injury (2.7 to 4.9%) than spontaneous deliveries (1.1%). The highest incidence was for Thierry spatulas (OR 4.804), followed by forceps (OR 4.089) and vacuum extraction (OR 2.509). The type of intervention in a vaginal delivery is a modifiable intrapartum risk factor for obstetric anal sphincter injury. Tearing can occur in any type of delivery but proportions vary significantly. All healthcare professionals attending childbirth should be aware of the risk for each type of intervention and consider these together with the obstetric factors in each case.

Are women having a vaginal birth after a previous caesarean delivery at increased risk of anal sphincter injury?

To examine the incidence of obstetric anal sphincter injury in women who had a successful vaginal birth after a previous caesarean delivery (VBAC). Retrospective analysis of prospectively gathered data. A tertiary referral university institution. All secundiparous women with a previous caesarean delivery who had a VBAC from 2001 to 2011. Details of maternal demographics, intrapartum characteristics and outcomes were examined in cases of VBAC with accompanying anal sphincter injury. Rates of obstetric anal sphincter injury and associated risk factors. During the study period there were 3071 trials of labour in secundiparous women with a previous caesarean delivery; 65% (1981/3071) of these had a successful VBAC. Women having a VBAC were at greater risk of anal sphincter injury than nulliparous women having a vaginal delivery over the same period (5% [98/1981] versus 3.5% [1216/34,496], P = 0.001, odds ratio 1.4, 95% CI 1.15-1.75). The rate of instrumental delivery in woman having a VBAC was 39% (771/1981). On multiple logistic regression analysis an increased rate of instrumental delivery was a strong predictor of sphincter injury (P = 0.03, odds ratio 1.15, 95% CI 1.01-1.3). When the first labours of women with sphincter injury in the VBAC group were examined, 70% (60/86) had been in labour before undergoing their caesarean delivery. The incidence of anal sphincter injury in women undergoing VBAC is 5% and birthweight is the strongest predictor of this. The rate of instrumental delivery in this group was also increased.

Complications maternelles des extractions instrumentales

Operative vaginal delivery significantly increases the risk of anal sphincter injury compared with spontaneous vaginal delivery, particularly when an instrumental application at high station, persistent occipital posterior presentation and/or macrosomia are associated. Risks of vaginal tears, postpartum haemorrhage and urinary retention appear to be increased compared with spontaneous vaginal delivery. There is no evidence that one type of forceps is less safe than another. Different vacuum extractors (soft, rigid and single-use instruments) have similar maternal outcomes. A risk of anal incontinence in the first year postpartum is associated with operative vaginal delivery, particularly forceps. Operative vaginal delivery also appears to increase the risk of occult anal sphincter injury regardless of the instrument used, but does not appear to be associated with the risk of postpartum urinary incontinence and genital prolapse compared with spontaneous vaginal delivery. It does, however, increase the risks of perineal pain, postpartum dyspareunia and sexual disorders compared with spontaneous vaginal delivery, particularly in cases of perineal tears.

Modified Ritgen’s Maneuver for Anal Sphincter Injury at Delivery

To investigate whether Ritgen's maneuver decreases the risk of third- to fourth-degree perineal tears compared with simple perineal support. A total of 1,623 nulliparous women in term labor, singleton pregnancy, and cephalic presentation were randomly assigned to Ritgen's maneuver or standard care. Ritgen's maneuver denotes extracting the fetal head, using one hand to pull the fetal chin from between the maternal anus and the coccyx, and the other on the fetal occiput to control speed of delivery. Ritgen's maneuver was performed during a uterine contraction, rather than, as originally recommended, between contractions. Our standard care entailed perineal support with one hand and control of the speed of crowning with the other, and use of Ritgen's maneuver only on specific indications. Women delivered by cesarean delivery (n=10) or instrumentally (n=142) were excluded, as well as 39 erroneously included women (parous or in preterm labor), six inaccurately assigned participants, one with missing data, and two participants who withdrew consent. For the remaining 1,423 women, the result was analyzed according to intention to treat. Ritgen's maneuver was performed in 554 (79.6%) of 696 women randomly assigned to this procedure and in 31 (4.3%) of 727 women randomly assigned to simple perineal support. The rate of third- to fourth-degree tears was 5.5% (n=38) in women assigned to Ritgen's maneuver and 4.4% (n=32) in those assigned to simple perineal support (relative risk 1.24; 95% confidence interval 0.78-1.96). Ritgen's maneuver does not decrease the risk of anal sphincter injury at delivery, at least not when performed during a contraction.

Mediolateral episiotomy reduces risk for anal sphincter injury during operative vaginal delivery

Objective To determine the risk factors for anal sphincter injuries during operative vaginal delivery. Setting and design A population-based observational study. Population All 21 254 women delivered with vacuum extraction and 7478 women delivered with forceps, derived from the previously validated Dutch National Obstetric Database from the years 1994 to 1995. Methods Anal sphincter injury was defined as any injury, partial or complete, of the anal sphincters. Risk factors were determined with multivariate logistic regression analysis. Main outcome measures Individual obstetric factors, e.g. fetal birthweights, duration of second stage, etc. Results Anal sphincter injury occurred in 3.0% of vacuum extractions and in 4.7% of forceps deliveries. Primiparity, occipitoposterior position and fetal birthweight were associated with an increased risk for anal sphincter injury in both types of operative vaginal delivery, whereas duration of second stage was associated with an increased risk only in vacuum extractions. Mediolateral episiotomy protected significantly for anal sphincter damage in both vacuum extraction (OR 0.11, 95% CI 0.09–0.13) and forceps delivery (OR 0.08, 95% CI 0.07–0.11). The number of mediolateral episiotomies needed to prevent one sphincter injury in vacuum extractions was 12, whereas 5 mediolateral episiotomies could prevent one sphincter injury in forceps deliveries. Conclusions Primiparity and occipitoposterior presentation are strong risk factors for the occurrence of anal sphincter injury during operative vaginal delivery. The highly significant protective effect of mediolateral episiotomies in both types of operative vaginal delivery warrants the conclusions that this type of episiotomy should be used routinely during these interventions to protect the anal sphincters.

Extraction instrumentale par spatules de Thierry : évaluation du risque périnéal en fonction du dégagement

Risk factors for severe perineal lacerations are nowadays well-known and they include operative vaginal deliveries and extractions in occiput posterior (OP) positions. The aim of this study was to assess whether OP position increases the risk for anal sphincter injury when compared with occiput anterior (OA) positions in operative deliveries using Thierry's spatulas.Retrospective study of 163 extractions with Thierry's spatulas over a five-year period (January 2000 to December 2005) performed in a general hospital. Singleton cephalic pregnancies at term were studied and the incidence of severe perineal lacerations was noted in deliveries in OP and OA positions.In these 163 cases, the varieties of presentation obtained by vaginal examination were 129 in anterior and 34 in posterior positions. Eleven posterior positions rotated anteriorly on delivery and 23 remained in a posterior position. The OA group (n=140) and the OP group (n=23) were constituted. Anal sphincter injury occurred significantly more often in the OP group compared with the OA group (17.4% versus 2.9%, p=0.014) with an odds ratio of 7.1 (95% CI 1.6-31). Only one fourth-degree laceration was noted. Within the OP group, the incidence of vaginal lacerations was increased compared to the OA group, but without any significant difference (43.5% versus 27.9%, p=0.20). In a logistic regression model, the OP position was 6.4 times (95% CI 1.3-31.5) more likely to be associated with anal sphincter injury than OA position. The incidence of OP position was 14.1% within the whole population studied and Thierry's spatulas permit anterior rotations of occipito posterior presentation in only 32.4% of cases.The efficiency of Thierry's spatulas is proven. As with forceps and vacuum extractors, extraction with Thierry's spatulas is a risk factor for perineal laceration compared to a spontaneous delivery. In deliveries with spatulas, OP head positions further increase this perineal risk against OA positions. OP positions before fetal extractions do not seem to be an ideal situation for using spatulas, even if an anterior rotation is achieved in one-third of cases.

Mediolateral Episiotomy Reduces the Risk for Anal Sphincter Injury During Operative Vaginal Delivery

Injury to the anal sphincter during childbirth is accepted as a major risk factor for fecal incontinence in women. As many as 50% of women with such injury report fecal incontinence, due mainly to a persistently defective sphincter. Risk factors for anal sphincter injury during operative vaginal delivery were examined in a population-based observational study of 7478 Dutch women who had forceps delivery and 21,254 who delivered by vacuum extraction. Cases were taken from a validated Dutch national obstetrical database for the years 1994–1995. Partial sphincter injuries were included. Anal sphincter injury occurred in 646 women delivered with vacuum extraction (3.0%) and in 348 of those who had forceps delivery (4.7%). Risk factors for anal sphincter injury during delivery aided by vacuum extraction included primiparity, higher fetal birth weight, an occipitoposterior position, and the duration of the second stage of labor. Induction of labor did not appear to alter the risk. Mediolateral episiotomy during vacuum extraction had a highly protective effect, lowering the risk of a third-degree perineal tear by nearly 90% (odds ratio [OR], 0.11; 95% confidence interval [CI], 0.09–0.13). The number of mediolateral episiotomies needed to prevent 1 anal sphincter injury after vacuum-assisted delivery was 12.4. Significant risk factors for anal sphincter damage in forceps deliveries included primiparity, occipitoposterior position, and higher fetal birth weight. The duration of second-stage labor was not a significant risk factor. As with vacuum extraction, induced labor carried no added risk. Mediolateral episiotomy correlated with a considerable reduction in the risk of anal sphincter damage (OR, 0.09; 95% CI, 0.07–0.11). The number of episiotomies needed to prevent a single sphincter injury during forceps delivery was 5.0 (95% CI, 4.4–5.7). The investigators conclude that mediolateral episiotomy should be routinely performed during operative vaginal deliveries in order to avoid injuring the anal sphincter.

Mediolateral episiotomy reduces the risk for anal sphincter injury during operative vaginal delivery

To determine the risk factors for anal sphincter injuries during operative vaginal delivery. A population-based observational study. All 21 254 women delivered with vacuum extraction and 7478 women delivered with forceps, derived from the previously validated Dutch National Obstetric Database from the years 1994 to 1995. Anal sphincter injury was defined as any injury, partial or complete, of the anal sphincters. Risk factors were determined with multivariate logistic regression analysis. Individual obstetric factors, e.g. fetal birthweights, duration of second stage, etc. Anal sphincter injury occurred in 3.0% of vacuum extractions and in 4.7% of forceps deliveries. Primiparity, occipitoposterior position and fetal birthweight were associated with an increased risk for anal sphincter injury in both types of operative vaginal delivery, whereas duration of second stage was associated with an increased risk only in vacuum extractions. Mediolateral episiotomy protected significantly for anal sphincter damage in both vacuum extraction (OR 0.11, 95% CI 0.09-0.13) and forceps delivery (OR 0.08, 95% CI 0.07-0.11). The number of mediolateral episiotomies needed to prevent one sphincter injury in vacuum extractions was 12, whereas 5 mediolateral episiotomies could prevent one sphincter injury in forceps deliveries. Primiparity and occipitoposterior presentation are strong risk factors for the occurrence of anal sphincter injury during operative vaginal delivery. The highly significant protective effect of mediolateral episiotomies in both types of operative vaginal delivery warrants the conclusions that this type of episiotomy should be used routinely during these interventions to protect the anal sphincters.

The Impact of Occiput Posterior Fetal Head Position on the Risk of Anal Sphincter Injury in Forceps-Assisted Vaginal Deliveries

The Impact of Occiput Posterior Fetal Head Position on the Risk of Anal Sphincter Injury in Forceps-Assisted Vaginal Deliveries