Does a missed obstetric anal sphincter injury at time of delivery affect short-term functional outcome?

Prevalence and Predictors of Anal Sphincter Injuries in Primipara with Vacuum-Assisted Deliveries

INTRODUCTION AND HYPOTHESIS

Women undergoing a vacuum-assisted (VA) delivery are at an increased risk of experiencing an obstetric anal sphincter injury (OASI). Studies using three-dimensional-endoanal ultrasound (3D-EAUS) have shown that not all OASIs are recognized immediately postpartum. In primipara with VA deliveries, the presence of and the potential clinical implications of undetected OASIs are undetermined and consequently, we examined prospectively a 1-year cohort of this population. We hypothesized that the total rate of OASIs would be higher than the clinically reported rates and wanted to identify potential associated predictors.

METHODS

The participants were examined 10-14 days postpartum with 3D-EAUS. Two experienced examiners, blinded to the clinical data, rated the results. The primary outcome was the combined rate of clinically recognized OASIs and clinically unrecognized ultrasound anal sphincter injuries. Logistic regression analysis was used to calculate the odds ratios for selected variables.

RESULTS

Of 334 eligible women, 271 (81%) were included. The total rate of OASIs was 19% (95% CI 14-24; 14% clinically recognized and 5% clinically unrecognized). Prolonged second-stage/maternal exhaustion, occiput posterior presentation, and birthweight ≥ 4000g were significant and independent risk factors, increasing the odds two- to three-fold. The indication fetal distress alone or in combination with others significantly reduced the odds.

CONCLUSIONS

About 1 in 5 primipara undergoing a VA delivery experienced an OASI and about one quarter of them were not recognized clinically. The VA procedure is a modifiable intervention, and the identified risk and protective factors may help clinicians to decide whether it should be performed.

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.

Determination of anal sphincter injury location using impedance spectroscopy in obstetric patients

Early detection of obstetric anal sphincter injuries (OASI) presents a significant challenge due to lack of both effective and practically available diagnostic tools. Thus, ONIRY, a medical device employing electrical impedance spectroscopy combined with machine learning (ML), was introduced to detect OASI quickly after vaginal delivery. For this post-hoc analysis of the ML approach for determining the OASI location, data was utilized from a clinical study that enrolled 152 women post-vaginal delivery with varying degrees of perineal injuries or no such injuries. Both endoanal ultrasound (EUS), as the reference method, and impedance spectroscopy were performed. ML classification was also performed. The ML model developed within this analysis not only detects OASI but also suggests the location the injury detected. This location analysis had an average accuracy of 85.6% compared with the location indicated by investigators based on EUS.

A Triboelectric Nanocomposite for Sterile Sensing, Energy Harvesting, and Haptic Diagnostics in Interventional Procedures from Surgical Gloves

Advanced interfacial engineering has the potential to enable the successful realization of three features that are particularly important for a variety of healthcare applications: wettability control, antimicrobial activity to reduce infection risks, and sensing of physiological parameters. Here, a sprayable multifunctional triboelectric coating is exploited as a nontoxic, ultrathin tactile sensor that can be integrated directly on the fingertips of surgical gloves. The coating is based on a polymer blend mixed with zinc oxide (ZnO) nanoparticles, which enables antifouling and antibacterial properties. Additionally, the nanocomposite is superhydrophobic (self-cleaning) and is not cytotoxic. The coating is also triboelectric and can be applied directly onto surgical gloves with printed electrodes. The sensorized gloves so obtained enable mechanical energy harvesting, force sensing, and detection of materials stiffness changes directly from fingertip, which may complement proprioceptive feedback for clinicians. Just as importantly, the sensors also work with a second glove on top offering better reassurance regarding sterility in interventional procedures. As a case study of clinical use for stiffness detection, the sensors demonstrate successful detection of pig anal sphincter injury ex vivo. This may lead to improving the accuracy of diagnosing obstetric anal sphincter injury, resulting in prompt repair, fewer complications, and improved quality of life.

Anal endosonographic assessment of the accuracy of clinical diagnosis of obstetric anal sphincter injury

INTRODUCTION AND HYPOTHESIS

Obstetric anal sphincter injuries (OASIS) are a common cause of maternal morbidity with an overall incidence in the UK of 2.9% (range 0-8%). They can cause a range of physical symptoms and psychological distress. This study aims to assess the accuracy of clinical diagnosis of OASIS using endoanal ultrasound (EAUS) and the correlation between confirmed injury and change to anorectal physiology squeeze pressure and the incidence of bowel symptoms.

METHODS AND MATERIALS

Retrospective study of prospectively collected data from 1135 women who attended the Third- and Fourth-Degree Tears Clinic at our institution, 12 weeks post-delivery, between June 2008 and October 2019.

RESULTS

OASIS was confirmed in 876 (78.8%) women and 236 (21.3%) had no injury. Of the women who underwent anorectal physiology, 45.6% had a mean maximal resting pressure below the normal range and 68.8% had a mean incremental squeeze pressure below normal. Women with confirmed OASIS had significantly lower pressures (p < 0.001) than those without a confirmed sphincter injury. Three hundred ninety-three (34.8%) women reported bowel symptoms, with those with endosonographic evidence of injury more likely to develop flatus incontinence.

CONCLUSION

Of the women in this study with a suspected OASIS, 21.2% could be reassured that they did not have an injury. This information is useful for women considering future mode of delivery. Those with confirmed injury are more likely to complain of flatus incontinence and have reduced anal sphincter pressures.

Can transperineal ultrasound improve the diagnosis of obstetric anal sphincter injuries?

INTRODUCTION AND HYPOTHESIS

Women with missed obstetric anal sphincter injuries (OASIs) are at an increased risk of anal incontinence. Our aim was to assess the accuracy of three-dimensional (3D) transperineal ultrasound (TPUS) compared with clinical examination for detecting OASIs.

METHODS

A cross-sectional study of women undergoing their first vaginal delivery. Perineal trauma was initially assessed by the doctor or midwife performing the delivery (accoucheur) and women were then re-examined by the trained research fellow (KW). A 3D TPUS was performed immediately after delivery before suturing to identify OASIs. The research fellow's clinical diagnosis was used as the reference standard. A power calculation determined that 216 women would be required for the study.

RESULTS

Two hundred and sixty-four women participated and 226 (86%) delivered vaginally. Twenty-one (9%) sustained OASIs. Six (29%) of these tears were missed by the accoucheur but were identified by the research fellow. TPUS identified 19 of the 21 (90.5%) OASIs. One percent (n = 2) had sonographic appearances of an anal sphincter defect that was not seen clinically. The positive and negative predictive value of TPUS to detect OASIs was 91% and 99% respectively. TPUS identified 91% of OASIs compared with 71% detected by the accoucheur, which was not statistically significant.

CONCLUSIONS

The detection rate of OASIs with TPUS and with the clinical findings of the accoucheur was similar. Given the training and financial implications needed for TPUS, attention needs to be focused on the training of midwives and doctors to identify anal sphincter injuries by clinical examination.

Under-classified obstetric anal sphincter injuries

INTRODUCTION AND HYPOSTHESIS

Obstetric anal sphincter injuries (OASIs) that are missed at delivery can have long-term consequences. OASIs that are under-classified at delivery are likely to be inadequately repaired, resulting in a persistent anal sphincter defect. We aimed to identify women who have persistent defects on endoanal ultrasound, inconsistent with the original diagnosis, and compare the effect on St Mark's incontinence scores (SMIS). We also aimed to look for changes in numbers of under-classification over time.

METHODS

Records of women attending a perineal clinic who had endoanal ultrasound from 2012 to 2020 were reviewed. Women who had a modified Starck score implying a defect greater than the classification [indicated by the depth of external anal sphincter or internal anal sphincter (IAS) defect] at delivery were identified.

RESULTS

A total of 1056 women with a diagnosis of 3a or 3b tears were included. Of these, 120 (11.36%) were found to have a defect greater than the original diagnosis and therefore were incorrectly classified at delivery. Women who had a 3b tear diagnosed at delivery, but had an IAS defect, had a significantly higher SMIS (p < 0.01). When comparing two 4-year periods, there was a significant improvement in the diagnosis of IAS tears.

CONCLUSION

Some women with OASIs that have under-classified OASIs are associated with worse anorectal symptoms. This is likely because of an incomplete repair. Some improvement in diagnosis of IAS tears has been noted. We propose improved training in OASIs can help reduce the number of incorrectly classified tears and improve repair.

Management of subsequent pregnancies following fourth-degree obstetric anal sphincter injuries (OASIS)

OBJECTIVES

The management of subsequent pregnancy in women who sustained OASIS remains an enigma. Nearly all studies include all grades of OASIS including fourth-degree tears. In addition, most protocols require endoanal ultrasound and anal manometric assessment to provide advice regarding mode of delivery. In reality, most women who sustain an OASI do not undergo these investigations. The aims of our study were firstly to evaluate outcomes of fourth-degree OASIS in terms of sphincter defects, anal manometry and anal incontinence symptoms. Secondly, we wished to review recommendations made regarding subsequent mode of delivery after fourth-degree OASIS according to different published protocols.

STUDY DESIGN

An observational study of all women who had undergone a primary repair of a fourth-degree tear and seen in the perineal clinic of a tertiary urogynaecology unit between January 2006 and December 2017. Three-dimensional endoanal ultrasound and anal manometry were performed on all women, and symptoms assessed using the validated modified St Mark's Score for anal incontinence. Diagnostic test accuracy analysis was performed for use of symptoms in predicting abnormal investigations.

RESULTS

74 fourth-degree tears were identified (mean follow-up 5.9 months; SD 11.5). Endoanal scan showed an internal anal sphincter defect in 77 % and an external anal sphincter defect in 49 %. Only 18 % had no defect. The mean incremental pressure rise was 12.6 mmHg (SD 15.5). 61 % were asymptomatic with a mean St Mark's Score of 3.8 (SD 5.4). The presence of symptoms alone had poor accuracy in predicting abnormal investigations. Based on Royal College of Obstetricians and Gynaecologists guidance, only 7% would not be offered a caesarean section as they are asymptomatic women with normal scan and manometry findings and would be counselled for a vaginal delivery.

CONCLUSIONS

Given that only a few units offer these specialist investigations to their OASI population, it would be reasonable to offer caesarean section to all women who have sustained a fourth-degree tear. However, in centres where endoanal ultrasound and anal manometry are available, individualised counselling can be offered.

The consequences of undiagnosed obstetric anal sphincter injuries (OASIS) following vaginal delivery

INTRODUCTION AND HYPOTHESIS

We aimed to compare anal and urinary incontinence symptoms and anal manometry between women with undiagnosed obstetric anal sphincter injuries (OASIS) and women who had OASIS diagnosed and repaired.

METHODS

This was a matched retrospective cohort study. Each missed OASI was matched with a diagnosed OASI for severity [minor (3a/b) or major (3c)], parity and length of follow-up. Women completed the modified St Mark's Incontinence Score and International Consultation on Incontinence Questionnaire. Women with OASIS or those without OASIS but with anal incontinence symptoms were seen in perineal clinic for perineal examinations, anorectal manometry and three-dimensional endoanal ultrasound 8-12 weeks postnatally or in a subsequent pregnancy.

RESULTS

Forty missed OASIS were matched with 40 recognised OASIS (16 3a/b; 24 3c). The median modified St Mark's scores were higher for missed tears [11 (4, 15) vs. 1 (0, 4), p < 0.001] as well as the urinary incontinence scores [4 (0, 6) vs. 0 (0, 2), p = 0.01] than for the control group. Missed OASIS patients had a shorter perineal body [1.6 ± 1.3 vs. 2.4 ± 0.8, p = 0.009]. All missed OASIS had larger defects on endoanal ultrasound. One in four missed OASIS required further surgery [aOR 4.1 (95% CI 1.0-16.3), p = 0.04] and almost all needed colorectal input [aOR 24.1 (95% CI 7.3-80.0), p < 0.0001]. There were no differences in anal manometry.

CONCLUSIONS

Women with symptomatic missed OASIS are compromised in terms of anal and urinary incontinence symptoms, sphincter defect size and perineal body size requiring additional colorectal input. This highlights the importance of preventing OASIS and perseverance with training to diagnose OASIS.

Prevention and Management of Severe Obstetric Anal Sphincter Injuries (OASIs): a National Survey of Nurse- Midwives

INTRODUCTION AND HYPOTHESIS

There are no data on midwives' knowledge and management of obstetric anal sphincter injuries (OASIs) in the USA. We performed a cross-sectional national survey characterizing OASI practice by certified nurse midwives (CNMs), hypothesizing that few midwives personally repair OASIs and that there are gaps in CNM OASI training/education.

METHODS

We emailed a REDCap internet-based survey to 6909 American College of Nurse Midwives members (ACNM). We analyzed responses from active clinicians performing at least one delivery per month, asking about OASI risks, prevention, repair, and management. We summarized descriptive data then evaluated OASI knowledge by patient and provider characteristics.

RESULTS

We received 1070 (15.5%) completed surveys, and 832 (77.8%) met the inclusion/exclusion criteria. Participants were similar to ACNM membership. Respondents most frequently identified prior OASI (87%) and nutrition (71%) as antepartum OASI risk factors and, less frequently, nulliparity (36%) and race (22%). Identified intrapartum risks included forceps delivery (94%) and midline episiotomy (88%). When obstetric laceration is suspected, 13.6% of respondents perform a rectal examination routinely. Only 15% of participants personally perform OASI repair. Overall, participants matched 64% of evidence-based answers. OASI education/training courses were attended by 30% of respondents, and 44% knew of OASI protocols within their group/institution. Of all factors evaluated, the percent of evidence-based responses was only different for respondent education/CME and protocols.

CONCLUSIONS

Quality initiatives regarding OASI prevention and management may improve care. Our data suggest OASI training for midwives may improve delivery care in the US. Further studies of other obstetric providers are needed.