Diagnosis and Treatment of Obstetric Anal Sphincter Injuries: New Evidence and Perspectives

Skeletal Muscle Complex Between the Vagina and Anal Canal: Implications for Perineal Laceration

INTRODUCTION AND HYPOTHESIS

The anatomy of the skeletal muscles located between the vagina and anus is important during complex obstetric laceration reconstructions. We aimed to clarify the composition of skeletal muscles located between the vagina and anal canal and their three-dimensional configuration relevant to perineum repair.

METHODS

This observational study involved ten female cadavers. An anatomical dissection was performed to observe the muscles around the vagina and anal canal. Immunohistological analysis of the midsagittal section was performed to clarify the composition of the muscles, and dissection was performed to correspond to the cross-section. Wide-range serial sectioning and three-dimensional reconstruction were used to support these findings histologically and visualize the three-dimensional arrangement.

RESULTS

The region between the vagina and anal canal included the anterior part of the external anal sphincter, superficial transverse perineal muscle approaching from the lateral side, and levator ani, located cranially. They converge three-dimensionally in the median from each direction, forming a muscle complex between the vagina and anal canal.

CONCLUSIONS

The medial region between the vagina and anal canal in those giving birth includes a skeletal muscle complex formed by the confluence of the external anal sphincter, anterior bundle of the levator ani, and superficial transverse perineal muscle. In cases of severe perineal lacerations, these muscles could be injured. The anatomical knowledge that a part of the levator ani forms a muscle sling anterior to the anal canal is particularly important for obstetricians and gynecologists repairing obstetric lacerations and treating pelvic floor disorders.

A sensorised surgical glove to improve training and detection of obstetric anal sphincter injury: A preclinical study on a pig model

OBJECTIVE

To create a sensorised surgical glove that can accurately identify obstetric anal sphincter injury to facilitate timely repair, reduce complications and aid training.

DESIGN

Proof-of-concept.

SETTING

Laboratory.

SAMPLE

Pig models.

METHODS

Flexible triboelectric pressure/force sensors were mounted onto the fingertips of a routine surgical glove. The sensors produce a current when rubbed on materials of different characteristics which can be analysed. A per rectum examination was performed on the intact sphincter of pig cadavers, analogous to routine examination for obstetric anal sphincter injuries postpartum. An anal sphincter defect was created by cutting through the vaginal mucosa and into the external anal sphincter using a scalpel. The sphincter was then re-examined. Data and signals were interpreted.

MAIN OUTCOME MEASURES

Sensitivity and specificity of the glove in detecting anal sphincter injury.

RESULTS

In all, 200 examinations were performed. The sensors detected anal sphincter injuries in a pig model with sensitivities between 98% and 100% and a specificity of 100%. The current produced when examining an intact sphincter and sphincter with a defect was significantly different (p < 0.001).

CONCLUSION

In this preliminary study, the sensorised glove accurately detected anal sphincter injury in a pig model. Future plans include its clinical translation, starting with an in-human study on postpartum women, to determine whether it can accurately detect different types of obstetric anal sphincter injury in vivo.

Is epidural analgesia an independent risk factor for OASIS? A population-based cohort study

INTRODUCTION

To evaluate whether epidural analgesia is an independent risk factor for OASIS.

METHODS

A population-based cohort study including all women who delivered by spontaneous vaginal delivery or by instrumental delivery beyond 24 weeks gestation was conducted. Deliveries occurred between 1988 and 2016 at a large university tertiary medical center. Women with multiple gestations and those lacking prenatal care were excluded from the analysis.

RESULTS

During the study period, 252,542 women delivered at the Soroka University Medical Center and met the inclusion criteria. Of these, 583 (0.23%) were diagnosed with OASIS. Women with OASIS were more likely to be younger, nulliparous, with suspected fetal macrosomia, had higher rates of labor induction and vacuum extraction delivery, higher rates of conceiving after infertility treatments, more advanced gestational age at delivery, higher mean birth weight, higher rates of post-partum hemorrhage and need for blood transfusions. Use of epidural analgesia during pregnancy was significantly high among the OASIS group. Rates of episiotomy were not significantly different between the groups. Using a multimodal logistic regression model, after controlling for vacuum delivery, large for gestational age, nulliparity, gestational age, ethnicity, maternal age, induction of labor, fertility treatments, non-reassuring fetal heart rate and non-progressive second stage of labor, epidural analgesia was found to be significantly associated with OASIS.

CONCLUSION

Epidural analgesia was found to be an independent risk factor for OASIS in our population.

Quality assessment of transperineal ultrasound in Chinese tertiary medical centers: a multicenter study

Background

Transperineal ultrasound (TPUS) is a vital examination method for diagnosing pelvic floor diseases. However, the quality of TPUS largely relies on the operator's experience, and there is a lack of studies on the evaluation of TPUS quality. Therefore, the objective of this study was to assess the quality of TPUS examinations in Chinese tertiary medical centers.

Methods

This multicenter study conducted in 44 Chinese tertiary medical centers recruited postpartum women between September 2020 and September 2021. All participants underwent a standardized inquiry and TPUS examination. The participating centers were required to submit 5 parts of ultrasound data to the National Ultrasound Quality Control Center: 2-dimensional images at rest, 2-dimensional images at strain; 4-dimensional images of the levator ani hiatus; 4-dimensional images of the levator ani muscle; and 4-dimensional images of the anal sphincter. Quality assessment was performed by 2 experts with more than 5 years of experience in TPUS, and the reasons for nonqualification were stated.

Results

In this study, 31 hospitals that were distributed across 20 provinces in China were included, submitting 2,251 cases in total. The overall qualified rate ranged from 12.00% to 86.92%. In each part, the qualified rate of 2-dimensional images at rest, 2-dimensional images at straining, levator ani hiatus, levator ani muscle, and anal sphincter was 94.27% (2,122/2,251), 78.54% (1,768/2,251), 85.52% (1,925/2,251), 93.03% (2,094/2,251), and 88.09% (1,983/2,251), respectively. Most of the nonqualified images belonged to 2-dimensional images at strain, and the errors in image acquisition (221/483, 45.76%) and measurement (262/483, 54.24%) were the main reasons for nonqualification. For levator ani hiatus images, error in image acquisition (275/326, 84.36%) was the main reason for nonqualification. Reconstruction error was the most common reason for nonqualification for levator ani muscle (133/157, 84.71%) and anal sphincter images (133/268, 49.63%).

Conclusions

This multicenter study assessed the quality of TPUS in tertiary medical centers in China and identified the common reasons for nonqualification in each part. These findings can aid in forming the basis for quality control management and training for TPUS.

Are we using best practice to guide laxative use in post-partum patients with obstetric anal sphincter injuries - A retrospective review

OBJECTIVE

Obstetric anal sphincter injury (OASI) is the leading cause of anal incontinence (AI) in young women. Laxatives are recommended to enhance recovery, however there are no consistent guidelines to guide best practice on the type, frequency, and dose of laxative should be used. This study aimed to evaluate the current use of laxatives following repair of OASIs, and to determine any association with AI. Study design A retrospective cohort study of 356 women who sustained OASIs between January 2016 and June 2020, at a single tertiary centre in Adelaide. Data regarding the type, dose and frequency of laxatives prescribed was extracted from each patient. The degree of OASIs was determined by clinical examination and endoanal ultrasound, and AI was measured by the St Marks incontinence score.

RESULTS

Multiple combinations and classes of laxatives were prescribed including bulking agent (Metamucil and Fybogel), emollients (Coloxyl), and osmotic laxatives (lactulose and Movicol). Bulking agents were prescribed for 245 women (68.8%), which is contrary to the current recommendations based on two previous randomised controlled trials. AI reported by 51 (14.3%) women. There were no statistical differences between AI and laxative type, dose, or frequency.

CONCLUSION

Considerable variation existed in laxatives prescription. Bulking agents was not associated with higher rates of AI. Further research is required to improve post-partum care in women following repair of OASIs.

Neonatal head circumference as a risk factor for obstetric anal sphincter injuries: a systematic review and meta-analysis

OBJECTIVE

Between 53% and 79% of women will sustain some degree of perineal laceration during vaginal delivery. Third- and fourth-degree perineal lacerations are known as obstetric anal sphincter injuries. Timely diagnosis and prompt treatment of obstetric anal sphincter injuries can help to prevent the development of severe consequences like fecal incontinence, urinary incontinence, and rectovaginal fistula. Neonatal head circumference is routinely measured postpartum but is often not mentioned as a risk factor for obstetric anal sphincter injuries in clinical guidelines. Thus far, no review article on the risk factors for obstetric anal sphincter injuries has discussed the role of neonatal head circumference. This study aimed to review and analyze the relationship between head circumference and the occurrence of obstetric anal sphincter injuries among previous studies to conclude whether head circumference should be recognized as an important risk factor.

DATA SOURCES

Through study screening on Google Scholar, PubMed, Scopus, and Science Direct for articles published between 2013 to 2023, followed by assessment of eligibility, this study ended up reviewing 25 studies, 17 of which were included in the meta-analysis.

STUDY ELIGIBILITY CRITERIA

Only studies that reported both the neonatal head circumference and the occurrence of obstetric anal sphincter injuries were included in this review.

METHODS

The included studies were appraised using the Dartmouth Library risk of bias assessment checklist. Qualitative synthesis was based on the study population, findings, adjusted confounding factors, and suggested causative links in each study. Quantitative synthesis was conducted using calculation and pooling of odds ratios and inverse variance using Review Manager 5.4.1.

RESULTS

A statistically significant association between head circumference and obstetric anal sphincter injuries was reported in 21 of 25 studies; 4 studies reported that head circumference was a true independent risk factor. A meta-analysis of the studies that reported neonatal head circumference as a dichotomous categorical variable with a cutoff point of 35±1 cm yielded statistically significant pooled results (odds ratio, 1.92; 95% confidence interval, 1.80-2.04).

CONCLUSION

The risk for obstetric anal sphincter injuries increased as the neonatal head circumference increased-this should be considered in decision-making during labor and postpartum management to attain the best outcome.

Maternal and perinatal outcomes of prolonged second stage of labour: a historical cohort study of over 51,000 women

BACKGROUND

Prolonged second stage of labour has been associated with adverse maternal and perinatal outcomes. The maximum length of the second stage from full dilatation to birth of the baby remains controversial. Our aim was to determine whether extending second stage of labour was associated with adverse maternal and perinatal outcomes.

METHODS

A retrospective cohort study was conducted using routinely collected hospital data from 51592 births in Aberdeen Maternity Hospital between 2000 and 2016. The hospital followed the local guidance of allowing second stage of labour to extend by an hour compared to national guidelines since 2008 (nulliparous and parous). The increasing duration of second stage of labour was the exposure. Baseline characteristics, maternal and perinatal outcomes were compared between women who had a second stage labour of (a) ≤ 3 h and (b) > 3 h duration for nulliparous women; and (a) ≤ 2 h or (b) > 2 h for parous women. An additional model was run that treated the duration of second stage of labour as a continuous variable (measured in hours). All the adjusted models accounted for: age, BMI, smoking status, deprivation category, induced birth, epidural, oxytocin, gestational age, baby birthweight, mode of birth and parity (only for the final model).

RESULTS

Each hourly increase in the second stage of labour was associated with an increased risk of obstetric anal sphincter injury (aOR 1.21 95% CI 1.16,1.25), having an episiotomy (aOR 1.48 95% CI 1.45, 1.52) and postpartum haemorrhage (aOR 1.27 95% CI 1.25, 1.30). The rates of caesarean and forceps delivery also increased when second stage duration increased (aOR 2.60 95% CI 2.50, 2.70, and aOR 2.44 95% CI 2.38, 2.51, respectively.) Overall adverse perinatal outcomes were not found to change significantly with duration of second stage on multivariate analysis.

CONCLUSIONS

As the duration of second stage of labour increased each hour, the risk of obstetric anal sphincter injuries, episiotomies and PPH increases significantly. Women were over 2 times more likely to have a forceps or caesarean birth. The association between adverse perinatal outcomes and the duration of second stage of labour was less convincing in this study.

Incidencia, complicaciones inmediatas y tempranas de desgarros perineales graves durante el parto en una institución de referencia de atención obstétrica en Medellín, Colombia

Introducción: los desgarros perineales severos (DPS) son complicaciones obstétricas que se presentan durante la atención del parto. Pueden desencadenar fístulas rectales e incontinencia fecal y urinaria, morbilidad a mediano y largo plazo que requiere un diagnóstico, manejo y seguimiento adecuado. Objetivo: determinar la incidencia de los DPS y las complicaciones relacionadas inmediatas −primeras 48 horas− y tempranas −primeros tres meses− posteriores a la atención del parto.Metodología: se hizo un estudio de cohorte descriptiva de pacientes con DPS durante la atención del parto en un centro de referencia de atención obstétrica en Medellín, Colombia, entre enero del 2015 y diciembre del 2017. Se revisaron las historias clínicas y se registraron los datos clínicos y las complicaciones inmediatas y tempranas en las que asistieron a cita de control de piso pélvico. Se presentan medidas descriptivas de resumen.Resultados: se atendieron 14.247 partos vaginales. La incidencia de DPS fue del 1,6 % (233/14.247), 1,3 % (184/14.267) de grado III y 0,3 % (49/14.247) de grado IV. El 66,5 % (155/233) tuvo parto vértice instrumentado, 81,9 % (191/233) episiotomía; la mediana del periodo expulsivo fue de 19 minutos (RIQ 12-35), y el 3 % (7/233) presentó distocia de hombros. Las complicaciones inmediatas en las pacientes con DPS fueron: 0,85 % (2/233) dehiscencia de sutura e infección de la herida, 0,85 % (2/233) solo dehiscencia y 0,42 % (1/233) solo infección de la herida. El 18,4 % (43/233) asistieron al control uroginecológico al tercer mes. Entre ellas, el 38,2 % (13/43) tuvo al menos una complicación, principalmente incontinencia fecal y de flatos, 16,3 % (7/43) y 13,9 % (6/43) respectivamente. Conclusiones: la incidencia de DPS y de complicaciones del posparto inmediato en la institución fueron poco frecuentes. Se deben mejorar las estrategias de seguimiento posparto mediante protocolos institucionales, con el fin de identificar y brindar un manejo oportuno de las complicaciones a mediano plazo.  

Comparison of the outcomes of overlapping and direct apposition sphincteroplasty techniques in anal sphincter repair

OBJECTIVES

Sphincteroplasty is of great importance in the repair of anal sphincter damage. In the present study, we compared the results of overlapping sphincteroplasty and direct apposition techniques used in anal sphincter repair.

MATERIAL AND METHODS

Between 2011 and 2021, 36 patients underwent sphincteroplasty for anal sphincter injury and were analysed retrospectively. Sex, age, etiologic factors, repair technique, degree of laceration, postoperative complications, length of hospital stay, time between injury and repair, follow-up time and postoperative Cleveland Clinic Incontinence Score (CCIS) were recorded for analysis, and the two techniques were compared statistically using SPSS statistics, Version 17.0.

RESULTS

Of the sample, 31 were females and five were males, with a mean age of 31.50 ± 6.7 years. The etiologic factors were obstetric trauma in 25 patients, perianal interventions in seven patients and other traumas in four patients. The overlapping technique was applied to 14 patients and the direct apposition technique was applied to 22 patients. Mean postoperative CCIS of all cases was 5.53 ± 2.59, and was significantly lower in those who underwent overlapping sphincteroplasty technique than those who underwent apposition repair (p= 0.006). It was observed that postoperative CCIS decreased as the time between sphincter injury and repair decreased (p <0.001; r= 0.625).

CONCLUSION

It is vital to repair anal sphincter damage as early as possible. The overlapping sphincteroplasty and direct apposition methods can both be considered safe for anal sphincter repair although in terms of faecal incontinence, the outcomes of overlapping sphincteroplasty are better than those of the direct apposition technique.