An Isolated Rectal Buttonhole Tear During Vaginal Delivery: A Rare Case Report

Miao Yang, Biyan Zhang, Shuo Yang, Chunhong Yan Department of General Gynecology, the Affiliated People’s Hospital of Ningbo University, Ningbo, Zhejiang, People’s Republic of ChinaCorrespondence: Miao Yang, Department of General Gynecology, the Affiliated People’s Hospital of Ningbo University, No. 251 Baizhang East Road, Ningbo, Zhejiang, 315100, People’s Republic of China, Email [email protected]: Obstetric perineal tears are a common complication of vaginal delivery. When a tear involves the rectal mucosa without injury to the anal sphincter complex, it is referred to as a rectal buttonhole tear rather than a fourth-degree perineal tear. This condition is rare, with an estimated incidence ranging from 0.014% to 0.06%. Reported risk factors include instrumental delivery, prolonged second stage of labor, fetal macrosomia, and malposition. Rectal buttonhole tears may be easily missed because the perineum can remain intact or show only minor injury. Therefore, accurate diagnosis relies on a thorough and systematic examination, including both vaginal and digital rectal assessment following delivery. Failure to identify and promptly repair the defect may result in complications such as rectovaginal fistula. We report the case of a 28-year-old gravida 2, para 0 woman who sustained a rectal buttonhole tear during spontaneous vaginal delivery at 38 weeks of gestation. The injury was recognized intraoperatively and repaired successfully, and the patient had an uncomplicated recovery. This case highlights the importance of maintaining a high index of suspicion for rectal buttonhole tears. Routine combined vaginal and rectal examination prior to suturing is essential to ensure accurate diagnosis and to prevent missed injuries and subsequent morbidity.Keywords: rectal buttonhole tear, rectal examination, anal sphincter, fourth-degree tear, dinoprostone